1.	Which of the following are connected by hydrogen bonds?
A.	Hydrogen to oxygen within a molecule of water
B.	Phosphate to sugar in a DNA molecule
C.	Base to sugar in a DNA molecule
D.	Hydrogen to oxygen between two different molecules of water
(Total 1 mark)

2.	The graph below shows the effect of substrate concentration on enzyme activity. What conclusion can be drawn about section X of the graph?
		
A.	The enzyme has started to denature and the reaction slows down.
B.	The reaction has finished and the substrate has been used up.
C.	The enzyme is saturated and is working at its maximum reaction rate.
D.	Some of the enzyme has been consumed and the reaction has reached a plateau.
(Total 1 mark)

3.	Which type of molecule is shown in the diagram below?
		
A.	Peptide
B.	Carbohydrate
C.	Lipid
D.	Nucleic acid
(Total 1 mark)

4.	The percentage of thymine in the DNA of an organism is approximately 30%. What is the percentage of guanine?
A.	70%
B.	30%
C.	40%
D.	20%
(Total 1 mark)

5.	What is denaturation?
A.	A structural change of a protein that results in the loss of its biological properties
B.	A change in the genetic code of an organism
C.	A change in the amino acid sequence of a protein causing a disruption of its 3D shape
D.	The process by which amino acids are broken down and ammonia is released
(Total 1 mark)

6.	How do cells capture the energy released by cell respiration?
A.	They store it in molecules of carbon dioxide.
B.	They produce glucose.
C.	The energy is released as pyruvate.
D.	They produce ATP.
(Total 1 mark)

7.	What is the source of the oxygen released into the air as a product of photosynthesis?
A.	Chlorophyll
B.	Carbon dioxide only
C.	Water only
D.	Both water and carbon dioxide
(Total 1 mark)

8.	What property of water makes it a good evaporative coolant?
A.	High latent heat of evaporation
B.	Relatively low boiling point
C.	Volatility
D.	Transparency
(Total 1 mark)

9.	A number of different proteins are involved in nerve function. Which of the following does not require a membrane protein?
A.	Active transport of sodium
B.	Diffusion of K+ into the cell
C.	Diffusion of the neurotransmitter across the synapse
D.	Binding of the neurotransmitter to the post-synaptic membrane
(Total 1 mark)

10.	What is the difference between galactose and lactose?
A.	Lactose is a disaccharide and galactose is a monosaccharide.
B.	Lactose is the product of anaerobic respiration in humans and galactose is the product of anaerobic respiration in yeast.
C.	Lactose is an enzyme and galactose is a hormone.
D.	Galactose is a sugar found in milk but lactose is not found in milk.
(Total 1 mark)

11.	Which process produces the most ATP per molecule of glucose?
A.	Anaerobic respiration in a yeast cell
B.	Aerobic respiration in a bacterial cell
C.	Glycolysis in a human liver cell
D.	The formation of lactic acid in a human muscle cell
(Total 1 mark)

12.	Which type of light is least useful for photosynthesis in terrestrial plants?
A.	Blue
B.	Green
C.	White
D.	Red
(Total 1 mark)

13.	How many molecules of water are required to completely hydrolyse a polypeptide made up of 23 amino acids?
A.	11
B.	22
C.	23
D.	44
(Total 1 mark)

14.	Which of the following is part of the process of cellular respiration?
A.	Changes in the volume of the thoracic cavity
B.	Exchange of gases across the surface of the alveoli
C.	Exchange of gases across the surface of capillaries
D.	Glycolysis
(Total 1 mark)

15.	Which variable has the least effect on enzyme activity?
A.	Temperature
B.	Light intensity
C.	pH
D.	Substrate concentration
(Total 1 mark)

16.	PanI is a gene in cod fish that codes for an integral membrane protein called pantophysin.
Two alleles of the gene, PanIA and PanIB, code for versions of pantophysin, that differ by four amino acids in one region of the protein. Samples of cod fish were collected from 23 locations in the north Atlantic and were tested to find the proportions of PanIA and PanIB alleles in each population. The results are shown in pie charts, numbered 1–23, on the map below. The proportions of alleles in a population are called the allele frequencies. The frequency of an allele can vary from 0.0 to 1.0. The light grey sectors of the pie charts show the allele frequency of PanIA and the black sectors show the allele frequency of PanIB.
		
	[RAJ Case et al. 2005.  “Macro- and micro-geographic variation in pantophysin (PanI) allele frequencies in NE Atlantic cod Gadus morhua.” MEPS. Vol 301. Pp 267–278. Figs 1 and 3.]
 
(a)	(i)	State the two populations with the highest PanIB allele frequencies.
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(1)
 
(ii)	State the population in which the allele frequencies were closest to 0.5.
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(1)
 
(b)	Deduce the allele frequencies of a population in which half of the cod fish had the genotype PanIA PanIA, and half had the genotype PanIA PanIB.
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(1)
 
	The graphs below show the latitude and the mean surface sea temperature in June of the sampling locations and the frequency of the PanIA allele.

	[RAJ Case et al. 2005.  “Macro- and micro-geographic variation in pantophysin (PanI) allele frequencies in NE Atlantic cod Gadus morhua.” MEPS. Vol 301. Pp 267–278. Figs 1 and 3.]

(c)	State the relationship between
(i)	latitude and the frequency of the PanIA allele.
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(1)
(ii)	mean surface sea temperature in June and the frequency of the PanIA allele.
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(1)
 
(d)	Suggest how natural selection could have caused the relationships shown in the graphs.
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(2)

(e)	The sites close to Iceland, at a latitude of 60–65°, had very varied allele frequencies, with both PanIA and PanIB occurring. The water at these sample sites was highly stratified, with much warmer water at the surface and much colder water below. Suggest reasons for both PanIA and PanIB alleles occurring at these sites.
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(2)
 
(f)	Using the data in this question, predict the effects of global warming on cod fish populations.
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(2)
(Total 11 marks)

17.	(a)	State the missing source, optimum pH requirement, substrate and product of the human enzymes in the table below.

Enzyme	Source	Optimum pH	Substrate	Products	
Amylase	Salivary gland	7			
Lipase			Lipids	Fatty acids and glycerol	
(2)
 
(b)	Explain the need for enzymes in digestion.
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(2)
 
(c)	Draw a labelled diagram to show the interconnections between the gall bladder, pancreas and small intestine.

(3)
(Total 7 marks)

18.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Living organisms at every trophic level are part of the carbon cycle. Draw a labelled diagram of the carbon cycle to show the processes involved.
(9)
 
(b)	Explain, using an example of a food chain, how trophic levels can be deduced.
(4)
 
(c)	Explain methods that can be used to measure the rate of photosynthesis.
(5)
(Total 20 marks)

19.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9)
 
(b)	Compare the use of carbohydrates and lipids in energy storage.
(4)
 
(c)	Compare how pyruvate is used in human cells when oxygen is available and when oxygen is not available.
(5)
(Total 20 marks)

20.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Outline condensation and hydrolysis reactions using a different example for each.
(5)
(b)	Outline the effect of temperature and substrate concentration on the activity of enzymes.
(4)
(c)	Explain methods by which the rate of photosynthesis can be measured, including conditions that affect the rate.
(9)
(Total 20 marks)

21.	The rate of photosynthesis in the marine seagrass, Zostera marina, was investigated under a range of pH conditions. After a period of darkness, the plants were illuminated at a constant light intensity at 15°C and the rate of photosynthesis was measured. Zostera marina can use both dissolved carbon dioxide (CO2) and hydrogen carbonate ions for photosynthesis. The rate of photosynthesis is plotted on the y-axis on the left. In addition, the concentration of carbon dioxide was measured for each pH investigated and is plotted on the y-axis on the right.
		
	[Source: Plant physiology by AMERICAN SOCIETY OF PLANT PHYSIOLOGISTS. Copyright 2008 Reproduced with permission of AMERICAN SOCIETY OF PLANT BIOLOGISTS in the format CD ROM via Copyright Clearance Center.]
 
(a)	State the carbon dioxide concentration at pH 7.2.
......................................................................................................................................
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(1)

(b)	Calculate the percentage decrease in the rate of photosynthesis from pH 7 to pH 7.5.
......................................................................................................................................
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(1)
 
(c)	Outline the relationship between pH and the rate of photosynthesis.
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(2)
 
(d)	Suggest how Zostera marina can perform photosynthesis even at very low carbon dioxide concentrations.
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(1)

(e)	Based on the information and data provided, discuss the role of one limiting factor, other than carbon dioxide, and suggest how this would affect the rate of photosynthesis.
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(2)
(Total 7 marks)

22.	(a)	State one example of a fibrous protein and one example of a globular protein.
Fibrous protein: ...........................................................................................................
Globular protein: .........................................................................................................
(1)
 
(b)	Compare the structure of fibrous and globular proteins.
......................................................................................................................................
......................................................................................................................................
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(2)

(c)	Amino acid polarity is an important factor in determining the functions of proteins.
Explain the importance of polar and non-polar amino acids in membrane proteins.
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(3)
(Total 6 marks)

23.	(a)	Draw a labelled diagram of a mitochondrion.

(3)

(b)	Explain how the structure of a mitochondrion is adapted for its function.
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(2)
(Total 5 marks)

24.	The effect of temperature on photosynthesis was studied in sweet orange (Citrus sinensis) using leaf discs. The production of oxygen was used to measure the rate of photosynthesis.
Gross photosynthesis refers to the sum of net photosynthesis and respiration. Net photosynthesis was calculated by subtracting the rate of respiration in the dark from gross photosynthesis.

	[Source: Adapted from R Ribeiro et al. 2006. Ciência e Agrotecnologia. Vol 30. Pp 670–678.]
 
(a)	Identify the optimum temperature for photosynthesis in this plant.
......................................................................................................................................
(1)
 
(b)	Determine the difference between gross photosynthesis and net photosynthesis at 40°C and 50°C.
40°C: ..........................................................................................................................
50°C: ..........................................................................................................................
(2)
 
(c)	Deduce what happens to the rate of respiration as the temperature increases between 40°C and 50°C.
......................................................................................................................................
(1)

(d)	(i)	Describe the general pattern of change in photosynthesis in sweet orange as the temperature increases.
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(1)
 
(ii)	Compare the effect of temperature on photosynthesis with the effect of temperature on respiration in sweet orange.
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(2)
(Total 7 marks)

25.	(a)	Distinguish between fibrous proteins and globular proteins giving one example of each.
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(3)
 
(b)	Outline the differences between competitive and non-competitive inhibitors.
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(4)
(Total 7 marks)

26.	Explain the link reaction that occurs between glycolysis and the Krebs cycle.
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(Total 4 marks)

27.	Which statement about water is correct?
A.	The atoms within a molecule of water are held together by hydrogen bonds.
B.	Water has a low heat capacity allowing enzymatic reactions to happen at a wide range of temperatures.
C.	Water molecules are polar, therefore fatty acids do not dissolve.
D.	Ice has a higher density than liquid water, therefore some organisms can live under the ice.
(Total 1 mark)

28.	What does a nucleosome consist of ?
A.	DNA and histones
B.	DNA and chromatin
C.	Chromatin and nucleotides
D.	Mature RNA and histones
(Total 1 mark)

29.	What are Okazaki fragments?
A.	Short lengths of RNA primase attached to the DNA during replication
B.	Short sections of DNA formed during DNA replication
C.	Nucleotides added by DNA polymerase I in the same direction as the replication fork
D.	Sections of RNA removed by DNA polymerase III and replaced with DNA
(Total 1 mark)

30.	The sequence of nucleotides in a section of RNA is:
		GCCAUACGAUCG
	What is the base sequence of the DNA sense strand?
A.	CGGUAUGCUAGC
B.	GCCATACGATCG
C.	CGGTATGCTAGC
D.	GCCAUACGAUCG
(Total 1 mark)

31.	The electron micrograph below shows an organelle in a eukaryotic cell. What is the area labelled X and what is the type of reaction occurring there?
		
[Source: http://scienceblogs.com/clock/2006/11/cell_structure.php]

	X	Reaction	
A.	matrix	photolysis	
B.	stroma	Krebs cycle	
C.	stroma	photolysis	
D.	matrix	Krebs cycle	
(Total 1 mark)

32.	Where is chlorophyll found in a plant cell?
A.	Thylakoid membranes
B.	Stroma
C.	Matrix
D.	Cristae
(Total 1 mark)

33.	What is produced by the light-dependent reactions of photosynthesis and used in the Calvin cycle?
A.	Hydrogen and oxygen
B.	ATP and NADPH
C.	NADPH and oxygen
D.	ATP and CO2
(Total 1 mark)

34.	Which base is connected to its complementary base in a base pair by three hydrogen bonds?
A.	Uracil
B.	Thymine
C.	Guanine
D.	Adenine
(Total 1 mark)

35.	This question refers to the following micrograph of a liver cell.
		
	In which organelle does the production of ATP, due to chemiosmosis, occur?
A.	A
B.	B
C.	C
D.	D
(Total 1 mark)

36.	Which molecule is found in both DNA and RNA?
A.	Ribose
B.	Uracil
C.	Phosphate
D.	Amino acid
(Total 1 mark)

37.	The photosynthetic activity of desert plants is often reduced in the middle of the day. What is the most reasonable explanation for this fact?
A.	Enzymes are denatured by the high temperatures.
B.	There is not sufficient water for photosystem I.
C.	Most of the light is reflected by the thick cuticle.
D.	The stomata close to preserve water and gas exchange decreases.
(Total 1 mark)

38.	Which of the following is true of the link reaction of aerobic respiration?
A.	The reduction of FAD+ occurs.
B.	The decarboxylation of pyruvate occurs.
C.	It occurs in the cytoplasm.
D.	The regeneration of NAD+ occurs.
(Total 1 mark)

39.	Where does the RNA polymerase bind during the process of transcription?
A.	The polysome
B.	The operator
C.	The promoter
D.	The initiator
(Total 1 mark)

40.	What is a difference between cohesion and adhesion?
A.	Only adhesion is involved in transpiration pull.
B.	Only cohesion is involved in the movement of water in soil.
C.	Only cohesion involves the interaction of water with soil mineral particles.
D.	Only adhesion involves the interaction of water with xylem.
(Total 1 mark)

41.	The diagram below shows one DNA nucleotide and part of a second nucleotide.

(a)	State the names of structures I and II.
I. ..................................................................................................................................
II. .................................................................................................................................
(1)
 
(b)	On the diagram above, draw the structures that are missing from the second nucleotide.
(1)
 
(c)	The two nucleotides would be permanently separated during DNA replication. State one process during which they would be temporarily separated.
......................................................................................................................................
(1)
 
(d)	Outline the method that can be used to amplify small quantities of DNA to obtain large enough quantities for DNA profiling.
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(2)
(Total 5 marks)

42.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Membrane proteins vary in their positions within the membrane and in their functions.
Outline the positions and functions of proteins in membranes.
(8)
 
(b)	Explain how polar and non-polar amino acids help channel proteins and enzymes carry out their functions.
(5)

(c)	Compare competitive and non-competitive inhibition of enzymes.
(5)
(Total 20 marks)

43.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	All organisms in an ecosystem are involved in the carbon cycle. Outline the roles of living organisms in the carbon cycle.
(8)
 
(b)	Explain how triose phosphate is produced and used in the chloroplasts of a plant.
(5)
 
(c)	Explain the conditions that are needed to allow a seed to germinate.
(5)
(Total 20 marks)

44.	Investigators carried out experiments to find the relationship between the energy used by mice (the metabolic rate) and their activity. They found that the amount of time mice are active depends on the time of day, whether they are single or in groups and on the temperature of their surroundings. The bar chart below shows the percentage of time mice were active during three-hour periods at three different temperatures.
		
	[Source: L E Mount and J V Willmott. 1967. Journal of Physiology. Vol  190. Pp 371–380. Published by Wiley-Blackwell. Used with permission]

(a)	Calculate how many minutes the group mice are active between 21:00 and 00:00 at 8 °C.
......................................................................................................................................
(1)
 
(b)	Outline the relationship between activity and temperature from 21:00 to 03:00 in all of the mice.
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(1)
 
(c)	Animals which are active at night are nocturnal. Suggest one advantage for mice being nocturnal.
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(1)

	The investigators also found that the metabolic rate of the mice changed at different times of the day. Mice were kept at one of the three constant temperatures for 24 hours and their oxygen consumption was measured. The graph below shows the results for single mice and the mean values for group mice.

	[Source: L E Mount and J V Willmott. 1967. Journal of Physiology. Vol  190. Pp 371–380. Published by Wiley-Blackwell. Used with permission]
 
(d)	State the relationship between temperature and metabolic rate.
......................................................................................................................................
(1)

(e)	Compare the results for the single mice at 15 °C with those for the group mice at 15 °C.
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(2)
 
(f)	Suggest one reason why the results differ for single mice and group mice.
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(1)
 
(g)	Explain why oxygen consumption is used as a measure of metabolic rate.
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(2)

(h)	Using the data from both graphs, evaluate the hypothesis that increased activity causes an increase in metabolic rate in mice.
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(2)
(Total 11 marks)

45.	The diagram below shows two nucleotides linked together to form a dinucleotide.

(a)	(i)	Identify the chemical group labelled I.
...........................................................................................................................
(1)

(ii)	State the type of bond labelled II.
...........................................................................................................................
(1)
 
(b)	Distinguish between the sense and antisense strands of DNA during transcription.
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(1)
 
(c)	Compare the DNA found in prokaryotic cells and eukaryotic cells.
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(2)
(Total 5 marks)

46.	Which substance in prokaryotes contains sulfur?
A.	DNA
B.	Phospholipids
C.	Proteins
D.	Antibiotics
(Total 1 mark)

47.	Which describes these molecules correctly?

	I	II	
A.	ribose	amino acid	
B.	glucose	amino acid	
C.	ribose	fatty acid	
D.	glucose	fatty acid	
(Total 1 mark)

48.	What sequence of processes is carried out by the structure labelled X during translation?
		
A.	Combining with an amino acid and then binding to an anticodon
B.	Binding to an anticodon and then combining with an amino acid
C.	Binding to a codon and then combining with an amino acid
D.	Combining with an amino acid and then binding to a codon
(Total 1 mark)

49.	The diagram below shows a biochemical pathway in a yeast cell. Which of the following correctly identifies a compound in the diagram?
		
A.	I is fat.
B.	II is pyruvate.
C.	III is lactate.
D.	IV is carbon dioxide.
(Total 1 mark)

50.	The following diagram shows a short stretch of DNA. What bases are indicated by labels Y and Z?

	Y	Z	
A.	thymine	adenine	
B.	thymine	guanine	
C.	uracil	guanine	
D.	uracil	adenine	
(Total 1 mark)

51.	A plant is exposed to increasing light intensity from very dim to bright light, while the carbon dioxide concentration and temperature are kept at an optimum level. What will happen to the rate of oxygen production?
A.	It will increase exponentially.
B.	It will remain constant.
C.	It will decrease to a minimum level.
D.	It will increase to a maximum level.
(Total 1 mark)

52.	In some people, hemoglobin always contains the amino acid valine in place of a glutamic acid at one position in the protein. What is the cause of this?
A.	An error in transcription of the hemoglobin gene
B.	An error in translation of the mRNA
C.	Lack of glutamic acid in the diet
D.	A base substitution in the hemoglobin gene
(Total 1 mark)

53.	What is a role of sulfur in living organisms?
A.	Formation of proteins
B.	Formation of carbohydrates
C.	Formation of teeth
D.	Transmission of nerve impulses
(Total 1 mark)

54.	Which molecules form the nucleotide marked in the diagram?
		
A.	phosphate, deoxyribose and nitrogenous base
B.	phosphorus, ribose and nitrogenous base
C.	phosphorus, deoxyribose and guanosine
D.	phosphate, ribose and guanine
(Total 1 mark)

55.	Which enzyme catalyzes the elongation of the leading strand?
		
	[Source: image from W K Purves, et al., (2003) Life: The Science of Biology, 4, Sinauer Associates (www.sinauer.com) and W H Freeman (www.whfreeman.com)]
A.	RNA polymerase
B.	Helicase
C.	DNA polymerase
D.	Ligase
(Total 1 mark)

56.	Which of the following is a function of cellulose in plants?
A.	Storage of fat
B.	Formation of mitochondria
C.	Storage of energy
D.	Formation of cell walls
(Total 1 mark)

57.	Which of the following is the best definition of cell respiration?
A.	A process needed to use energy, in the form of ATP, to produce organic compounds
B.	A process used to provide oxygen to the atmosphere
C.	A controlled release of energy, in the form of ATP, from organic compounds in cells
D.	A controlled release of energy in the production of food from organic compounds
(Total 1 mark)

58.	The graph below shows the effect of temperature on the separation of the strands in DNA to form single strands. The temperature at which 50% of the DNA is single-stranded is called the melting temperature (TM).
		
	What do the results show?
A.	When the temperature reaches 85°C there are no more double-stranded DNA molecules.
B.	When the temperature reaches 85°C the DNA strands start separating rapidly.
C.	A TM of 85°C means that DNA is not stable at room temperature (25°C).
D.	The separation of the DNA strands is directly proportional to the increase in temperature.
(Total 1 mark)

59.	(a)	Glucose and galactose are examples of monosaccharides. State one other example of a monosaccharide.
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(1)
 
(b)	The equation below shows the production of glucose and galactose from lactose.

(i)	There are several different types of carbohydrate. State which type of carbohydrate lactose is.
...........................................................................................................................
(1)
 
(ii)	State the type of chemical reaction that occurs when lactose is digested into glucose and galactose.
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(1)

(c)	Lactase is widely used in food processing. Explain three reasons for converting lactose to glucose and galactose during food processing.
1. ..................................................................................................................................
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2. ..................................................................................................................................
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3. ..................................................................................................................................
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(3)
 
(d)	Simple laboratory experiments show that when the enzyme lactase is mixed with lactose, the initial rate of reaction is highest at 48°C. In food processing, lactase is used at a much lower temperature, often at 5°C. Suggest reasons for using lactase at relatively low temperatures.
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(2)
(Total 8 marks)

60.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Explain why DNA must be replicated before mitosis and the role of helicase in DNA replication.
(4)
(b)	Explain how the base sequence of DNA is conserved during replication.
(5)
(c)	Describe the events that occur during mitosis.
(9)
(Total 20 marks)

61.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Plants are a diverse group of eukaryotic organisms. Describe the different characteristics of the bryophyta, filicinophyta, coniferophyta and angiospermophyta.
(9)
(b)	Plants store carbohydrate in the form of starch. Explain the reasons for starch being digested by the human digestive system.
(4)
(c)	Compare the structure of prokaryotic and eukaryotic cells.
(5)
(Total 20 marks)

62.	Male Lepidoptera (butterflies and moths) commonly drink from pools of water or from moist soil. This behaviour, called puddling, was investigated in an undisturbed area where male tiger swallowtails, Papilio glaucus, had been seen puddling.
	Four successive sets of experiments were performed under similar conditions of temperature and humidity. In each set, equal samples of sand were spread out evenly on trays and then treated differently. Except for one dry sample (in the first set), all others were saturated with a different liquid. Results of the observations are given in the table below.

	[Source: adapted from K Arms et al., “Sodium: Stimulus for Puddling Behaviour by Tiger Swallowtail Butterflies, Papilio glaucus” (1974) Science, 185: 5 (5 July–27 Sept) #4148, pp. 372–374. Reprinted with permission from AAAS]
 
(a)	Identify the dissolved element always present in the three samples with most puddling time.
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(1)

(b)	Discuss the relationship between sampling visits (V) and puddling time (T) in experiments 1, 2 and 3.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Analyse the results for experiment 4.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

	Study of the male moth Gluphisia septentrionis revealed that their puddling behaviour can last for hours. Though drinking results in the uptake of hundreds of gut-loads of fluid, this fluid becomes rapidly expelled from the digestive system through frequent anal ejections. In this experiment, the ion concentration change was calculated by subtracting ions ejected from ions taken in. The following data was collected from males drinking laboratory solutions and from natural puddles.

	[Source: adapted from SR Smedley and T Eisner “Sodium Uptake by Puddling in a Moth” (1995) Science, 270 (15 Dec) #5243, pp. 1816–1818. Reprinted with permission from AAAS]
 
(d)	(i)	Identify which ion the moths are retaining in their body from the laboratory solutions.
...........................................................................................................................
(1)

(ii)	Compare the gain and loss of ions in the male moths which have drunk from laboratory solutions with the changes in those that have drunk from natural puddles.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
 
	The diagram below shows the digestive system anatomy of the male and female moth.
		
	[Source: adapted from SR Smedley and T Eisner “Sodium Uptake by Puddling in a Moth” (1995) Science, 270 (15 Dec) #5243, pp. 1816–1818. Reprinted with permission from AAAS]

(e)	Using the diagram above, evaluate the hypothesis that male moths are better adapted than female moths to benefit from puddling behaviour.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(f)	Suggest one reason for puddling behaviour in male Lepidoptera.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 12 marks)

63.	(a)	Outline the bonding between DNA nucleotides.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(b)	Explain how chemical bonding between water molecules makes water a valuable coolant in living organisms.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Describe the movement of water across membranes.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(d)	State the role of water in photosynthesis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 8 marks)

64.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Outline the role of hydrolysis in the relationships between monosaccharides, disaccharides and polysaccharides.
(4)
(b)	Describe the use of biotechnology in the production of lactose-free milk.
(6)
(c)	Explain the importance of enzymes to human digestion.
(8)
(Total 20 marks)

65.	Global atmospheric carbon dioxide levels are rising. A study was carried out to test if the temperature dependence of photosynthesis was altered by elevated atmospheric CO2.
Maize plants were grown in natural sunlight in controlled environmental chambers at different temperatures using current atmospheric and doubled CO2 levels.
	The graph below shows daily patterns of CO2 exchange at three different temperatures.
Open shapes (○, Δ, □) represent current atmospheric CO2 levels and closed shapes (●, ▲, ■) represent elevated CO2 levels.
		
	[Reprinted from: Kim, S H et al. 2007. “Temperature dependence of growth, development, and photosynthesis in maize under elevated CO2”. Environmental and Experimental Botany. Vol 61. Pp 224–236.]

(a)	(i)	State the time at which carbon dioxide exchange rate is maximal.
...........................................................................................................................
(1)
 
(ii)	Explain the reasons for maximum carbon dioxide exchange rate at this time.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(b)	State the temperature that resulted in the highest rate of photosynthesis under current atmospheric conditions.
......................................................................................................................................
(1)

(c)	Using the data in the graph, discuss whether rising carbon dioxide levels in the atmosphere will increase growth rates in maize.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)

66.	(a)	State two functions of proteins, giving a named example of each.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(b)	Explain the significance of polar and non-polar amino acids.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 5 marks)

67.	The diagram below shows part of the respiratory pathway. The number of carbon atoms in each molecule is indicated.

(a)	(i)	Label pyruvate and acetyl coenzyme A on the diagram above.
(1)

(ii)	Indicate two places where decarboxylation occurs on the diagram.
(1)
 
(iii)	List one product other than carbon dioxide formed in this stage of respiration.
...........................................................................................................................
(1)
 
(b)	State precisely where in a cell this stage of respiration is occurring.
......................................................................................................................................
(1)
(Total 4 marks)

68.	Explain the control of metabolic pathways.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 3 marks)

69.	Primary production is directly related to the amount of photosynthesis that occurs in a cubic metre of water. In the waters around Bermuda (32° N) in the Atlantic Ocean, microscopic phytoplankton are the producers. They use trace nutrients from seawater in their metabolism. These nutrients are a limiting factor in total population size. A dense phytoplankton population makes the water cloudy. The data shows primary production per day for each month for the year 2000 at different water depths.

	[Source: DataStreme Ocean, American Meteorological Society (2004). Reprinted with permission.]
 
(a)	State the month when total photosynthesis was greatest.
......................................................................................................................................
(1)
 
(b)	Identify, with a reason, the water depth that receives no light.
......................................................................................................................................
......................................................................................................................................
(1)

(c)	In the upper 40 m there is a drop in photosynthesis from March to June. This is probably due to lack of nutrients, reducing the population density.
	Suggest, with a reason other than nutrient levels, what might have increased photosynthesis at 100 m from April to August.
......................................................................................................................................
......................................................................................................................................
(1)
 
(d)	Compare production in March with production in September.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 6 marks)

70.	(a)	Draw a labelled diagram showing the structure of a mitochondrion as seen in electron micrographs.

(4)
 
(b)	Explain the relationship between the structure of the mitochondrion and its function.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)

71.	(a)	List three functions of proteins, giving a named example of each.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
 
(b)	Explain the significance of polar amino acids and non-polar amino acids in membranes.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 5 marks)

72.	Which substance in prokaryotes contains sulfur?
A.	DNA
B.	Phospholipids
C.	Proteins
D.	Antibiotics
(Total 1 mark)

73.	What is the reason for Okazaki fragments being formed during DNA replication?
A.	To enable replication of the 3′ → 5′ (lagging) strand
B.	To form the template for the RNA primers
C.	To initiate replication on the 5′ → 3′ (leading) strand
D.	To help the DNA helicase unwinding the DNA helix
(Total 1 mark)

74.	Which is correct for the non-competitive inhibition of enzymes?

	Inhibitor resembles
substrate	Inhibitor binds to
active site	
A.	yes	yes	
B.	yes	no	
C.	no	yes	
D.	no	no	
(Total 1 mark)

75.	What is removed during the formation of mature RNA in eukaryotes?
A.	Exons
B.	Introns
C.	Codons
D.	Nucleosomes
(Total 1 mark)

76.	During glycolysis a hexose sugar is broken down to two pyruvate molecules. What is the correct sequence of stages?
A.	Phosphorylation → oxidation → lysis
B.	Oxidation → phosphorylation → lysis
C.	Phosphorylation → lysis → oxidation
D.	Lysis → oxidation → phosphorylation
(Total 1 mark)

77.	Where are the light-dependent and light-independent reactions taking place in the diagram below?

	Light-dependent	Light-independent	
A.	I	IV	
B.	II	III	
C.	III	II	
D.	IV	I	
(Total 1 mark)

78.	The table below shows the codons that determine different amino acids in protein translation.

First base	Second base in codon	Third base	
in codon	U	C	A	G	in codon	
U	Phe	Ser	Tyr	Cys	U	
	Phe	Ser	Tyr	Cys	C	
	Leu	Ser	—	—	A	
	Leu	Ser	—	Trp	G	
C	Leu	Pro	His	Arg	U	
	Leu	Pro	His	Arg	C	
	Leu	Pro	Gln	Arg	A	
	Leu	Pro	Gln	Arg	G	
A	Ile	Thr	Asn	Ser	U	
	Ile	Thr	Asn	Ser	C	
	Ile	Thr	Lys	Arg	A	
	Met	Thr	Lys	Arg	G	
G	Val	Ala	Asp	Gly	U	
	Val	Ala	Asp	Gly	C	
	Val	Ala	Glu	Gly	A	
	Val	Ala	Glu	Gly	G	
	What is the sequence of the amino acids that is being translated from the following mRNA sequence?
		5´ AUGGGUGCUUAUUGGUAA 3´
A.	Met-Pro-Arg-Ile-Thr
B.	Met-Cys-Ser-Tyr-Trp
C.	Met-Gly-Ala-Tyr-Trp
D.	Met-Gly-Tyr-Ala-Thr
(Total 1 mark)

79.	What does the universal nature of the genetic code allow?
A.	Change of genetic code in the same species
B.	Transfer of genes between species
C.	Formation of clones
D.	Infection by bacteria
(Total 1 mark)

80.	Which of the following forms the nucleosome?
A.	DNA and histone molecules
B.	DNA only
C.	RNA and histone molecules
D.	Histone molecules only
(Total 1 mark)

81.	What happens during the formation of Okazaki fragments?
A.	DNA polymerase III adds nucleotides in the 3´ → 5´ direction.
B.	DNA polymerase III adds nucleotides in the 5´ → 3´ direction.
C.	DNA polymerase I adds nucleotides in the 5´ → 3´ direction.
D.	RNA polymerase adds nucleotides in the 3´ → 5´ direction.
(Total 1 mark)

82.	Why is oxaloacetate a competitive inhibitor?

	[Source: image from W K Purves, et al., (2003), Life: The Science of Biology, 4, Sinauer Associates (www.sinauer.com) and W H Freeman (www.whfreeman.com)]
A.	It causes a conformational change to the active site.
B.	It binds to the enzyme away from the active site.
C.	It is structurally similar to succinate.
D.	It is structurally similar to succinate dehydrogenase.
(Total 1 mark)

83.	What is the link reaction in aerobic respiration?
A.	Pyruvate is carboxylated, acetyl reacts with coenzyme A, reducing NADH + H+
B.	Pyruvate is decarboxylated, acetyl reacts with coenzyme A, forming NADH + H+
C.	Pyruvate reacts with coenzyme A, forming NADH + H+
D.	Pyruvate is decarboxylated, reacting with coenzyme A, reducing NADH + H+
(Total 1 mark)

84.	What is chemiosmosis?
A.	Coupling of ATP synthesis to the electron transport and proton movement
B.	Phosphorylation of glucose in the mitochondrial matrix
C.	H+ ions moving down a concentration gradient into the mitochondrial matrix
D.	Activation of ATPase in order to synthesize ATP
(Total 1 mark)

85.	The diagram below shows the structure of a chloroplast.
		
	What is the structure labelled X?
A.	Ribosome
B.	Stroma
C.	Inner membrane
D.	Thylakoid
(Total 1 mark)

86.	During aerobic cell respiration, oxygen is consumed and carbon dioxide is produced inside cells. This generates concentration gradients between respiring cells and the environment, which cause diffusion of oxygen and carbon dioxide. Both oxygen and carbon dioxide are soluble in water. As the temperature rises, water becomes saturated at a lower concentration of the gas.
	Laternula elliptica is a mollusc that lives on the sea bed in Antarctica. Its body temperature is always similar to that of the environment around it. To investigate the effect of temperature on Laternula elliptica, specimens were kept in temperature-controlled aquaria. The oxygen concentrations of water near the gills and in the body fluids were measured, at a range of temperatures from 0°C to 9°C. The graph below shows the mean results.
		
	[With kind permission from Springer Science+Business Media and the author.]
 
(a)	(i)	Outline the relationship between temperature and oxygen concentration in the body fluids in Laternula elliptica.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(ii)	Suggest two reasons for the relationship.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(b)	In its natural environment, Laternula elliptica buries itself in the mud on the sea bed.
In this investigation, it was found that above 6°C it is unable to bury itself. Suggest a reason for this.
......................................................................................................................................
......................................................................................................................................
(1)

	The world’s oceans can absorb large amounts of carbon dioxide. This process has been studied in the Pacific Ocean near Hawaii, by measuring carbon dioxide concentrations in the atmosphere and in surface water every month, from October 1988 onwards. The graph below shows the carbon dioxide concentration expressed as partial pressures (Pco2).

	[Source: Nature by Nature Publishing Group. Reproduced with permission of Nature Publishing Group in the format Journal via Copyright Clearance Centre.]

(c)	(i)	Describe the trends in atmospheric carbon dioxide concentration, shown in the graph.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(ii)	Suggest two reasons for the trends that you have described.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(d)	(i)	Diffusion of carbon dioxide only occurs when there is a concentration gradient.
Deduce the pattern of carbon dioxide diffusion, between water and atmosphere, from 1988 to 2002.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(ii)	The graph provides evidence for the hypothesis that there will be no net diffusion of carbon dioxide between water and atmosphere by 2020. Explain this evidence.
...........................................................................................................................
...........................................................................................................................
(1)
 
	The concentration of carbon dioxide in the atmosphere is currently 385 ppm (parts per million).
Variations in the concentration of carbon dioxide in the atmosphere can be studied using ice-cores. An ice-core record covering the last 400 000 years has been obtained from Vostok in the Antarctic. The graph below shows the carbon dioxide concentrations that were measured at different depths in the ice. Atmospheric temperatures are also shown on the graph. These were deduced from ratios of oxygen isotopes. The upper line on the graph shows CO2 concentrations and the lower line shows temperature.

	[Source: Nature by Nature Publishing Group. Reproduced with permission of Nature Publishing Group in the format Journal via Copyright Clearance Centre.]
 
(e)	(i)	State the highest carbon dioxide concentration shown on the graph.
...........................................................................................................................
(1)

(ii)	State the highest temperature shown on the graph.
...........................................................................................................................
(1)
 
(f)	Using the data in the graph, deduce the relationship between atmospheric carbon dioxide concentration and temperature.
......................................................................................................................................
......................................................................................................................................
(1)
 
(g)	Using the data in this question, explain reasons for concern about the long-term survival of Antarctic species, such as Laternula elliptica.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 18 marks)

87.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Eukaryotic cells have intracellular and extracellular components. State the functions of one named extracellular component.
(4)
 
(b)	Outline, with an example, the process of exocytosis.
(5)
 
(c)	Translation occurs in living cells. Explain how translation is carried out, from the initiation stage onwards.
(9)
(Total 20 marks)

88.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Most of the DNA of a human cell is contained in the nucleus. Distinguish between unique and highly repetitive sequences in nuclear DNA.
(5)
 
(b)	Draw a labelled diagram to show four DNA nucleotides, each with a different base, linked together in two strands.
(5)
 
(c)	Explain the methods and aims of DNA profiling.
(8)
(Total 20 marks)

89.	Migrating birds must refuel along the way in order to continue flying. A field study was conducted among four different species of migrating birds known to stop at high quality and low quality food sites. Two techniques were used to assess food quality in the stopover sites. Birds were captured and weighed at the two sites. Blood samples were taken from the birds to determine nutrient levels in their blood. The two techniques were compared for their effectiveness.
	The table below shows data collected from the two sites during one season.

	Site 1	Site 2	
Species	N
(number captured)	Mean bird
mass / g	N
(number captured)	Mean bird
mass / g	
Hermit thrush	46	29.8	28	28.3	
White-throated sparrow	47	27.9	48	27.2	
American robin	8	78.3	10	77.6	
Magnolia warbler	30	8.4	10	8.2	
[Source: adapted from C Guglielmo, et al., (2005), Physiological and Biochemical Zoology, 78(1), pages 116–125]
 
(a)	Considering all the birds sampled, identify which species was sampled the most and which was sampled the least.
Most: ...........................................................................................................................
Least: ...........................................................................................................................
(1)
 
(b)	Using the data from the table, calculate the percentage difference in mean bird mass for the hermit thrushes refueling at Site 1 compared to those refueling at Site 2.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(1)

	A method was used to determine the average mass change in grams per hour (g h–1) during the study. Graph A represents a summary of data collected during one season whereas Graph B represents a summary of data collected over 17 years.

[Source: adapted from C Guglielmo, et al., (2005), Physiological and Biochemical Zoology, 78(1), pages 116–125]
 
(c)	Compare the 17-year summary data for the hermit thrush and the magnolia warbler.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(d)	Evaluate the one season data for the hermit thrush and the American robin with regard to average mass change per hour at Site 1.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
	Among birds, high triglyceride concentration in blood plasma indicates fat deposition whereas high butyrate concentration in blood plasma indicates fat utilization and fasting.
The following data summarizes triglyceride levels and butyrate levels measured for the same groups of birds.

[Source: adapted from C Guglielmo, et al., (2005), Physiological and Biochemical Zoology, 78(1), pages 116–125]

(e)	Describe, using the triglyceride levels graph, the results at Site 1 and Site 2 for all of the birds.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(f)	Explain the differences in the triglyceride level and butyrate level for the hermit thrush at Site 1 and Site 2.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(g)	Scientists have hypothesized that the food quality is better at Site 1 than at Site 2.
Evaluate this hypothesis using the data provided.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(h)	Suggest one advantage and one disadvantage for blood sampling rather than weighing birds to assess food quality at stopover sites.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 13 marks)

90.	(a)	Outline the bonding between DNA nucleotides.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(b)	Explain how chemical bonding between water molecules makes water a valuable coolant in living organisms.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	State a word equation for anaerobic cell respiration in humans.
......................................................................................................................................
(1)
(Total 5 marks)

91.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Outline the structure of a ribosome.
(4)
 
(b)	Distinguish between fibrous and globular proteins with reference to one example of each protein type.
(6)
 
(c)	Explain the role of auxin in phototropism.
(8)
(Total 20 marks)

92.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Outline the process of glycolysis.
(5)
 
(b)	Describe how pancreatic cells directly affect blood glucose levels.
(5)
 
(c)	Explain why diabetes could be detected through the analysis of urine.
(8)
(Total 20 marks)

93.	A group of non-smoking men and women were studied for the effects of environmental contamination with cadmium, a toxic metal. A study was conducted to see the effect of cadmium exposure on the metabolism of the liver, as measured by the activity of a cytochrome enzyme that metabolizes drugs, and on renal tubular damage in the kidney as indicated by the excretion of a substance, NAG.

	[Source: Satarug, S et al. 2004. Environmental Health Perspectives. Vol 111, issue 15. Pp 1512–1518. Reproduced with permission from Environmental Health Perspectives.]
 
(a)	(i)	Identify the highest hepatic cytochrome activity value in women.
...........................................................................................................................
(1)
 
(ii)	Identify the lowest renal tubular damage value in men.
...........................................................................................................................
(1)

(b)	Compare the correlation between hepatic and renal functions for men and for women.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	The scientists who conducted the study hypothesized that exposure to cadmium causes toxicity in both hepatic and renal functions. Using the data, evaluate the hypothesis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)

94.	Which diagram best illustrates the interactions between water molecules?

(Total 1 mark)

95.	What chemical reaction is taking place when a dipeptide becomes two amino acids?
A.	Condensation
B.	Hydrolysis
C.	Denaturation
D.	Polymerization
(Total 1 mark)

96.	The base ratios in the DNA and RNA for an onion (Allium cepa) are given below.

Bases	A / %	G / %	C / %	T / %	
DNA	31.8	18.4	18.2	31.3	

Bases	A / %	G / %	C / %	U / %	
RNA	24.9	29.8	24.7	20.6	
	What is the reason for the difference between these figures?
A.	DNA is only found in the nucleus but RNA is found throughout the cell.
B.	DNA is made entirely of double helix but RNA is not.
C.	In DNA, bases A and T are complementary but in RNA, bases A and C are complementary.
D.	RNA comes in three forms but DNA only comes in one form.
(Total 1 mark)

97.	Which of the following will cause an enzyme to permanently lose its properties?
I.	Hydrolysis
II.	Freezing to –20°C
III.	Dissolving it in water
A.	I only
B.	II only
C.	I and II only
D.	I and III only
(Total 1 mark)

98.	What is lactase used for?
A.	It is used to make sugar-free milk.
B.	It hydrolyses lactose to glucose and fructose.
C.	It improves the digestion of milk by some people.
D.	It decreases the acidity of the milk.
(Total 1 mark)

99.	How can the rate of photosynthesis of a plant be directly measured?
A.	By measuring the rate of oxygen produced
B.	By measuring the rate of carbon dioxide produced
C.	By measuring the rate of plant growth
D.	By measuring the rate of light absorbed
(Total 1 mark)

100.	What is true of the source, products and optimum pH of the lipase found in the human digestive system?

	Source	Products	Optimum pH	
A.	salivary glands	fatty acids	8	
B.	stomach	starch	2	
C.	pancreas	fatty acids	8	
D.	liver	amino acids	2	
(Total 1 mark)

101.	Rice (Oryza sativa) is usually intolerant to sustained submergence under water, although it grows rapidly in height for a few days before dying. This is true for one variety, Oryza sativa japonica. The variety Oryza sativa indica is much more tolerant to submergence.
	Three genetically modified forms of O. sativa japonica, GMFA, GMFB and GMFC, were made using different fragments of DNA taken from O. sativa indica.
	The plants were then submerged for a period of 11 days. The heights of all the plants were measured at the beginning and at the end of the submergence period.

	[Adapted by permission from Macmillan Publishers Ltd, Xu et al. 2006. “Sub1A is an ethylene-response-factor-like gene that confers submergence tolerance to rice.” Nature. Vol 442. Pp 705–708. Copyright 2006. http://www.nature.com/]
 
(a)	(i)	State which group of rice plants were the shortest at the beginning of the experiment.
...........................................................................................................................
(1)

(ii)	Calculate the percentage change in height for the O. sativa japonica unmodified variety during the submergence period. Show your working.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(b)	Explain how the error bars can be used to compare the results for O. sativa indica.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Deduce the general relationship between the growth of all the japonica varieties and their stated tolerance level.
......................................................................................................................................
......................................................................................................................................
(1)

(d)	Outline the use of the binomial system of nomenclature in Oryza sativa.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
	In the same experiment, the researchers hypothesized that the capacity to survive when submerged is related to the presence of three genes very close to each other on rice chromosome number 9; these genes were named Sub1A, Sub1B and Sub1C. The photograph below of part of a gel shows relative amounts of messenger RNA produced from these three genes by the submergence-intolerant variety, O.  sativa japonica, and by the submergence-tolerant variety, O. sativa indica, at different times of a submergence period, followed by a recovery period out of water.

	[Adapted by permission from Macmillan Publishers Ltd, Xu et al. 2006. “Sub1A is an ethylene-response-factor-like gene that confers submergence tolerance to rice.” Nature. Vol 442. Pp 705–708. Copyright 2006. http://www.nature.com/]
 
(e)	(i)	Determine which gene produced the most mRNA on the first day of the submergence period for variety O. sativa japonica.
...........................................................................................................................
(1)

(ii)	Outline the difference in mRNA production for the three genes during the submergence period for variety O. sativa indica.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(iii)	Compare the mRNA production for the three genes during the submergence period between the two varieties.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(f)	Deduce, using all the data, which gene was used to modify GMFC.	
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(g)	Evaluate, using all the data, how modified varieties of rice could be used to overcome food shortages in some countries.
......................................................................................................................................
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......................................................................................................................................
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(2)
(Total 17 marks)

102.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	State four elements that are needed by living organisms, other than carbon, hydrogen and oxygen, giving one role of each.
(4)
(b)	Outline how light energy is used and how organic molecules are made in photosynthesis.
(6)
(c)	Explain the significance of complementary base pairing for replication, transcription and translation.
(8)
(Total 20 marks)

103.	What will be produced during aerobic respiration?
I.	Water
II.	ATP
III.	Ethanol
A.	I only
B.	I and II only
C.	II and III only
D.	I, II and III
(Total 1 mark)

104.	Which graph best represents the effect of temperature on the rate of photosynthesis of a plant?

(Total 1 mark)

105.	Which of the following correctly shows a peptide bond between two amino acids?

(Total 1 mark)

106.	What is a polysome?
A.	A ribosome that is synthesizing proteins from several mRNA molecules at the same time
B.	A ribosome that is synthesizing different proteins for secretion
C.	Several ribosomes using a mRNA molecule to synthesize protein at the same time
D.	Several ribosomes that are synthesizing different proteins for use in the cytoplasm
(Total 1 mark)

107.	What does oxidation involve?
A.	A loss of electrons
B.	A gain of electrons
C.	A loss of oxygen
D.	A gain of hydrogen
(Total 1 mark)

108.	What is required for ATP synthesis in mitochondria?
A.	Active pumping of protons into the matrix
B.	Diffusion of protons out of the matrix
C.	Accumulation of protons in the intermembrane space
D.	Accumulation of protons in the matrix
(Total 1 mark)

109.	What happens in the light-independent reactions of photosynthesis?
A.	Splitting of water molecules
B.	ATP synthesis
C.	Reduction of NADP
D.	Reduction of CO2
(Total 1 mark)

110.	Which two tissues of a leaf are photosynthetic?
A.	Upper epidermis and palisade mesophyll
B.	Palisade mesophyll and spongy mesophyll
C.	Spongy mesophyll and xylem
D.	Upper epidermis and xylem
(Total 1 mark)

111.	Gibberellin promotes both seed germination and plant growth. Researchers hypothesize that the gene GID1 in rice (Oryza sativa) codes for the production of a cell receptor for gibberellin.
The mutant variety gid1-1 for that gene leads to rice plants with a severe dwarf phenotype and infertile flowers when homozygous recessive. It is suspected that homozygous recessive gid1-1 plants fail to degrade the protein SLR1 which, when present, inhibits the action of gibberellin. The graphs show the action of gibberellin on the leaves and α-amylase activity of wild-type rice plants (WT) and their gid1-1 mutants.

	[Adapted by permission from Macmillan Ltd, Ueguchi-Tanaka, M et al. 2005.  “Gibberellin-insensitive dwarf1 encodes a soluble receptor for gibberellins”. Nature. Vol 437. Pp 693–698. Copyright (2005).]
 
(a)	(i)	State which variety of rice fails to respond to gibberellin treatment.
...........................................................................................................................
(1)
 
(ii)	The activity of α-amylase was tested at successive concentrations of gibberellin.
Determine the increment in gibberellin concentration that produces the greatest change in α-amylase activity in wild-type rice plants (WT).
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
 
(iii)	Outline the role of α-amylase during the germination of seeds.
...........................................................................................................................
...........................................................................................................................
(1)
 
(b)	Discuss the consequence of crossing gid1-1 heterozygous rice plants amongst themselves for food production.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
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......................................................................................................................................
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(3)
 
	Most rice varieties are intolerant to sustained submergence under water and will usually die within a week. Researchers have hypothesized that the capacity to survive when submerged is related to the presence of three genes very close to each other on rice chromosome number 9; these genes were named Sub1A, Sub1B and Sub1C. The photograph below of part of a gel shows relative amounts of messenger RNA produced from these three genes by the submergence-intolerant variety, O. sativa japonica, and by the submergence-tolerant variety, O. sativa indica, at different times of a submergence period, followed by a recovery period out of water.

	[Adapted by permission from Macmillan Publishers Ltd, Xu et al. 2006. Nature. Vol 442. Pp 705–708. Copyright 2006. http://www.nature.com/]
 
(c)	(i)	Determine which gene produced the most mRNA on the first day of the submergence period for variety O. sativa japonica.
...........................................................................................................................
(1)
 
(ii)	Outline the difference in mRNA production for the three genes during the submergence period for variety O. sativa indica.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(d)	Using only this data, deduce which gene confers submersion resistance to rice plants.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
	The OsGI gene causes long-day flowering and the effect of its overexpression has been observed in a transgenic variety of rice. Some wild-type rice (WT) and transgenic plants were exposed to long days (14 hours of light per day) and others to short days (9 hours of light per day).
	The shades of grey represent the genotypes of the transgenic plants, where:

	[Adapted by permission from Macmillan Ltd, Ueguchi-Tanaka, M et al. 2005.  “Gibberellin-insensitive dwarf1 encodes a soluble receptor for gibberellins”. Nature. Vol 437. Pp 693–698. Copyright (2005).]

(e)	(i)	State the overall effect of overexpression of the OsGI gene in plants treated with short-day light.
...........................................................................................................................
...........................................................................................................................
(1)
 
(ii)	Compare the results between the plants treated with short-day light and the plants treated with long-day light.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(iii)	State, giving one reason taken from the data opposite, if unmodified rice is a short-day plant or a long-day plant.
...........................................................................................................................
...........................................................................................................................
(1)

(f)	Discuss, using only the data opposite, if OsGI+ and OsGI– behave as codominant alleles.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(g)	Evaluate, using all the data, how modified varieties of rice could be used to overcome food shortages in some countries.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 19 marks)

112.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	State four functions of proteins, giving a named example of each.
(4)
 
(b)	Outline the structure of ribosomes.
(6)
 
(c)	Explain the process of transcription leading to the formation of mRNA.
(8)
(Total 20 marks)

113.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram of the ultrastructure of Escherichia coli as an example of a prokaryote.
(4)
 
(b)	Describe the events that occur in the four phases of mitosis in animals.
(6)
 
(c)	Explain the process of aerobic cell respiration after glycolysis has occurred.
(8)
(Total 20 marks)

114.	Superoxide dismutase is an enzyme used by cells to protect themselves against oxidative damage. These enzymes can have different metals as part of their structure.
	A study to compare two dismutases from Escherichia coli bacteria and two dismutases from eukaryotic cells was undertaken. The following enzymes were used:
•	E. coli dismutase with iron (Fe)
•	E. coli dismutase with manganese (Mn)
•	eukaryotic mitochondrial dismutase with manganese (Mn)
•	eukaryotic cytoplasmic dismutase with copper-zinc (Cu-Zn).
	The following shows part of the amino acid sequences of these enzymes. Boxes enclose identical amino acids in the sequence of the two E. coli and mitochondrial dismutases.

	[Steinman, H M and Hill, R L. 1973. “Sequence homologies among bacterial and mitochondrial superoxide dismutases”. PNAS. Vol 70, issue 12. Pp 3725–3729. Used with the permission of the authors.]
 
(a)	State how many amino acids are in the same position in the E. coli (Fe), E. coli (Mn) and the mitochondrial dismutase sequences shown.
......................................................................................................................................
(1)
 
(b)	State the amino acids which are present in the same position in at least one bacterial dismutase and in both eukaryotic dismutases.
......................................................................................................................................
(1)

(c)	Compare the E. coli (Mn) and the mitochondrial dismutases.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(d)	Using the diagram, suggest whether the evolution of bacterial dismutase and cytoplasmic dismutase is convergent or divergent.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(1)

(e)	The sequences of the two bacterial dismutases and the mitochondrial dismutase show a high degree of homology. Discuss how this supports the endosymbiotic theory for the origin of mitochondria.
......................................................................................................................................
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(2)
(Total 7 marks)

115.	Which diagram represents the polarity of a water molecule?

(Total 1 mark)

116.	Which of these molecules is a disaccharide?
A.	Galactose
B.	Sucrose
C.	Cellulose
D.	Ribose
(Total 1 mark)

117.	What is a codon?
A.	A sequence of nucleotides on rRNA that corresponds to an amino acid
B.	A sequence of nucleotides on mRNA that corresponds to an amino acid
C.	A sequence of nucleotides on tRNA that corresponds to an amino acid
D.	A sequence of nucleotides on DNA that corresponds to an amino acid
(Total 1 mark)

118.	What happens as an enzyme becomes denatured?
A.	The enzyme works faster.
B.	The enzyme works slower.
C.	The enzyme can perform a new role.
D.	The enzyme can make the reverse reaction proceed faster.
(Total 1 mark)

119.	What happens during the pathway of glycolysis?
A.	Glucose is broken down into pyruvate.
B.	Carbon dioxide is produced.
C.	More ATP is consumed than is produced.
D.	Lactic acid is produced.
(Total 1 mark)

120.	What is light energy used for during photosynthesis?
A.	To produce carbon dioxide
B.	To produce water molecules
C.	To produce ATP
D.	To break down sugar molecules
(Total 1 mark)

121.	Which molecule is shown below?
		
A.	Glucose
B.	Galactose
C.	Ribose
D.	Sucrose
(Total 1 mark)

122.	Blood is a water-based transport medium. Which property of water makes it a good transport medium?
A.	High specific heat
B.	Transparency
C.	Versatility as a solvent
D.	It has its greatest density at 4°C
(Total 1 mark)

123.	What is replicated by a semi-conservative process?
A.	Messenger RNA (mRNA) only
B.	Messenger RNA (mRNA) and transfer RNA (tRNA) only
C.	Messenger RNA (mRNA), transfer RNA (tRNA) and DNA only
D.	DNA only
(Total 1 mark)

124.	Which of the following processes produces CO2?
I.	Glycolysis
II.	Alcohol (ethanol) fermentation
III.	Lactic acid production
A.	I only
B.	II only
C.	I and II only
D.	I, II and III
(Total 1 mark)

125.	Which of the following colours of light is absorbed the most by chlorophyll?
A.	Blue
B.	Green
C.	Yellow
D.	Orange
(Total 1 mark)

126.	(a)	Define active site.
......................................................................................................................................
......................................................................................................................................
(1)

(b)	Explain enzyme-substrate specificity.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
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(3)
(Total 4 marks)

127.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram to show how two nucleotides are joined together in a single strand of DNA.
(3)
(b)	Outline a basic technique for gene transfer.
(6)
(c)	Explain the process of translation.
(9)
(Total 20 marks)

128.	(a)	State the property of stem cells that makes them useful in medical treatment.
......................................................................................................................................
......................................................................................................................................
(1)
 
(b)	Explain how multicellular organisms develop specialized tissues.
......................................................................................................................................
......................................................................................................................................
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......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Outline some of the outcomes of the sequencing of the human genome.
......................................................................................................................................
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(3)
(Total 6 marks)

129.	Glucose has an important regulatory function in carbohydrate metabolism in yeast (Saccharomyces cerevisiae). The enzyme α-glucosidase catalyses the breakdown of maltose to two glucose molecules. The activity of yeast α-glucosidase was measured in cells which were grown in three different media containing : 2 % maltose, 2 % glucose and 1 % of both.
		
	[Boris U. Stambuk. 1999. “A simple experiment illustrating metabolic regulation: induction versus repression of yeast α-glucosidase”. Biochemical Education. Vol 27, issue 3. Pp 177–180.]
 
(a)	Calculate the difference in α-glucosidase activity at two hours in yeast grown with 2 % maltose compared to yeast grown with 1 % of both.

......................................................................................................................................
(1)
 
(b)	Distinguish between α-glucosidase activity in yeast incubated only with glucose and yeast incubated only with maltose.
......................................................................................................................................
......................................................................................................................................
(1)

(c)	Suggest the effect of incubating the yeast cells with both maltose and glucose in terms of metabolic pathways.
......................................................................................................................................
......................................................................................................................................
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......................................................................................................................................
(3)
 
(d)	Outline the metabolism of glucose during glycolysis.
......................................................................................................................................
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(2)
(Total 7 marks)

130.	(a)	(i)	Explain the primary structure of proteins and secondary structure of proteins.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
 
(ii)	Using named examples, distinguish between fibrous protein and globular protein.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(b)	State one difference between oxidation and reduction.
......................................................................................................................................
(1)
(Total 6 marks)

131.	(a)	State the location in the chloroplast of the following reactions of photosynthesis.
Light-independent reactions: .......................................................................................
Light-dependent reactions: ..........................................................................................
(2)
 
(b)	Explain what happens to the electrons in the light-dependent reactions of photosynthesis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
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......................................................................................................................................
(3)
(Total 5 marks)

132.	In the model of the DNA molecule shown below, which arrows point to covalent bonds?
		
A.	I, II and III only
B.	II, III and IV only
C.	I, III and IV only
D.	I, II and IV only
(Total 1 mark)

133.	The antisense strand on the DNA molecule coding for three codons of a gene is
		TATCGCACG
	What are the anticodons of the three tRNA molecules that correspond to this sequence?
A.	UAU, CGC and ACG
B.	ATA, GCG and TGC
C.	AUA, GCG and UGC
D.	TAT, CGC and ACG
(Total 1 mark)

134.	What is the function of the tRNA activating enzyme?
A.	It links tRNA to ribosomes.
B.	It links tRNA to mRNA.
C.	It links tRNA to a specific amino acid.
D.	It links an amino acid on one tRNA to an amino acid on another tRNA.
(Total 1 mark)

135.	Which best describes the tertiary structure of a protein?
A.	The interaction of polypeptide subunits and prosthetic groups
B.	Interactions forming hydrogen bonds between the amino acids
C.	The sequence of amino acids in the polypeptide chain
D.	The structure formed from interactions between the amino acid side groups
(Total 1 mark)

136.	Where is carbon dioxide produced in the mitochondrion?
		
(Total 1 mark)

137.	In the mitochondrial electron transport chain, what is the last electron acceptor?
A.	CO2
B.	H2O
C.	O2
D.	NAD
(Total 1 mark)

138.	Where are complex carbohydrates made in the chloroplast?
A.	In the intermembrane space
B.	In the stroma
C.	On the inner membrane
D.	In the thylakoid space
(Total 1 mark)

139.	Which of the following graphs represents the effect of changing light intensity on the rate of oxygen production by a green plant?

(Total 1 mark)

140.	Which of the following is true about a polar amino acid and cellulose?
A.	Both are polysaccharides.
B.	Both contain nitrogen.
C.	Both are hydrophobic.
D.	Both contain hydrogen atoms.
(Total 1 mark)

141.	What conclusion can be drawn from examining the action spectrum for a green plant shown below?
		
A.	Yellow light is the most effective at promoting photosynthesis.
B.	Every colour of light is equally effective at promoting photosynthesis.
C.	Light of wavelength 550 nm is least effective at promoting photosynthesis.
D.	Light in the green range is the most effective at promoting photosynthesis.
(Total 1 mark)

142.	Where in the cell does the Calvin cycle take place?
A.	Stroma of chloroplast
B.	Mitochondrial matrix
C.	Cytoplasm
D.	Inside thylakoid
(Total 1 mark)

143.	Blood is a water-based transport medium. Which property of water makes it a good transport medium?
A.	High specific heat
B.	Transparency
C.	Versatility as a solvent
D.	It has its greatest density at 4°C
(Total 1 mark)

144.	What is the distinction between highly repetitive DNA sequences and single-copy genes?
A.	The highly repetitive sequences have greater amounts of guanine.
B.	The highly repetitive sequences have greater amounts of cytosine.
C.	The highly repetitive sequences are not transcribed.
D.	The highly repetitive sequences are not replicated.
(Total 1 mark)

145.	Which of the following statements is true about enzymes?
A.	They are used up in the reactions they catalyse.
B.	Allosteric inhibitors bind to the active site.
C.	They lower the energy of activation for a reaction.
D.	They supply the energy of activation for a reaction.
(Total 1 mark)

146.	Which of the following is not a function performed by a membrane protein?
A.	Hormone binding sites
B.	Cell adhesion
C.	Enzyme synthesis
D.	Pumps for active transport
(Total 1 mark)

147.	Which chemical is shown in the diagram below?
		
A.	Monosaccharide
B.	Triglyceride
C.	Fatty acid
D.	Amino acid
(Total 1 mark)

148.	Genetic engineering allows genes for resistance to pest organisms to be inserted into various crop plants. Bacteria such as Bacillus thuringiensis (Bt) produce proteins that are highly toxic to specific pests.
	Stem borers are insects that cause damage to maize crops. In Kenya, a study was carried out to see which types of Bt genes and their protein products would be most efficient against three species of stem borer. The stem borers were allowed to feed on nine types of maize (A–I), modified with Bt genes. The graph below shows the leaf areas damaged by the stem borers after feeding on maize leaves for five days.

	[Source: S Mugo et al., Figure 3 from “Developing Bt maize for resource-poor farmers—Recent advances in the IRMA project”, African Journal of Biotechnology (2005), volume 4, number 13, pp. 1490-1504]

(a)	Calculate the percentage difference in leaf area damaged by Sesamia calamistis between the control and maize type H. Show your working.
......................................................................................................................................
......................................................................................................................................
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(2)
 
(b)	Discuss which species of stem borer was most successfully controlled by the genetic engineering of the maize plants.
......................................................................................................................................
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(3)

	Before the use of genetically modified maize as a food source, risk assessment must be carried out. A 90-day study was carried out in which adult male and female rats were fed either:
•	seeds from a Bt maize variety
•	seeds from the original non-Bt maize variety
•	commercially prepared rat food.
	All the diets had similar nutritional qualities.

	[Source: Linda A. Malley et al. 2007. “Subchronic feeding study of DAS-59122-7 maize grain in Sprague-Dawley rats”. Food and Chemical Toxicology. Vol 45, issue 7. Pp 1277–1292]
 
(c)	Calculate the change in mean mass of male and of female rats fed on Bt maize from day 14 to 42.
......................................................................................................................................
......................................................................................................................................
(2)

(d)	Evaluate the use of Bt maize as a food source on the growth of the rats.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(e)	Comment on the use of Bt maize as a food source compared to the other diets tested.
......................................................................................................................................
......................................................................................................................................
(1)

	Studies have shown that Bt proteins are released by plant roots and remain in the soil.
One study looked at the biomass of microorganisms in soil surrounding the roots of:
•	Bt maize
•	non-Bt maize
•	non-Bt maize with an insecticide (I).
	The graph below shows the biomass of microorganisms at two different times in the growth cycle of the plants (Flower and Harvest). Error bars represent standard error of the mean.
		
	[Source: Devare, M et al. “Neither transgenic Bt maize (MON863) nor tefluthrin insecticide adversely affect soil microbial activity or biomass: A 3-year field analysis”. Soil Biology and Biochemistry. Vol 39, issue 6. Pp 2038–2047. © Elsevier. Reproduced with permission.]
 
(f)	State one role of bacteria in a soil ecosystem.
......................................................................................................................................
......................................................................................................................................
(1)

(g)	Compare the biomass of microbes in the soils surrounding the roots of Bt maize and non-Bt maize.
......................................................................................................................................
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......................................................................................................................................
(2)
 
(h)	The researchers’ original hypothesis stated that microorganisms would be negatively affected by the Bt protein released by the plant roots. Discuss whether the data supports the hypothesis.
......................................................................................................................................
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(2)

	Bt proteins act as toxins to insects, primarily by destroying epithelial cells in the insect’s digestive system. Below is the three-dimensional structure of one such protein.
		
	[Reprinted from Mario Soberón. 2007. “Mode of action of mosquitocidal Bacillus thuringiensis toxins”. Toxicon. Vol 49, issue 5. Pp 597–600. Copyright (2007), with permission from Elsevier and the International Society on Toxicology.]
 
(i)	(i)	State the type of structure shown in the region marked A in the diagram above.
...........................................................................................................................
(1)
 
(ii)	Outline how this structure is held together.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(iii)	Region A inserts into the membrane. Deduce, with a reason, the nature of the amino acids that would be expected to be found in this region.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 20 marks)

149.	(a)	Draw a labelled diagram of the structure of a chloroplast as seen with an electron microscope.
(4)
 
(b)	Describe how water is carried by the transpiration stream.
(7)
 
(c)	Explain how flowering is controlled in long-day and short-day plants.
(7)
(Total 18 marks)

150.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Distinguish between RNA and DNA.
(3)
(b)	Explain the process of DNA replication.
(8)
(c)	Outline how enzymes catalyse reactions.
(7)
(Total 20 marks)

151.	(a)	Draw a labelled diagram showing two different complementary pairs of nucleotides in a molecule of DNA.

(4)
 
(b)	Outline the structure of nucleosomes.
......................................................................................................................................
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(2)

(c)	Explain primary structures and tertiary structures of an enzyme.
......................................................................................................................................
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(3)
(Total 9 marks)

152.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram showing the tissues present in a dicotyledonous leaf.
(4)
(b)	Outline the light-dependent reactions of photosynthesis.
(6)
(c)	Explain the effect of light intensity and temperature on the rate of photosynthesis.
(8)
(Total 20 marks)

153.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram showing the ultra-structure of a liver cell.
(4)
(b)	Distinguish between prokaryotic cells and eukaryotic cells.
(6)
(c)	Explain prokaryotic DNA replication.
(8)
(Total 20 marks)

154.	Which of the following chemical elements are part of biochemical molecules in living organisms?
A.	nitrogen, sulfur, phosphorus and iron
B.	lead, oxygen, carbon and phosphorus
C.	helium, carbon, sulfur and nitrogen
D.	silicon, helium, oxygen and iron
(Total 1 mark)

155.	Which of the following is an organic compound made by all plants?
A.	Carbon dioxide
B.	DNA
C.	Lactose
D.	Oxygen
(Total 1 mark)

156.	Which of the following graphs shows the relationship between substrate concentration and enzyme activity with a fixed concentration of enzyme?

(Total 1 mark)

157.	Oxygen is produced during photosynthesis. What is the source of this oxygen inside the plant?
A.	Air spaces in the leaf
B.	Carbon dioxide
C.	Glucose
D.	Water
(Total 1 mark)

158.	(a)	State the type of bonds that
(i)	connect base pairs in a DNA molecule.
...........................................................................................................................
(1)

(ii)	link DNA nucleotides into a single strand.
...........................................................................................................................
(1)
 
(b)	Distinguish between DNA and RNA nucleotides by giving two differences in the chemical structure of the molecules.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Explain the role of transfer RNA (tRNA) in the process of translation.
......................................................................................................................................
......................................................................................................................................
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......................................................................................................................................
(2)
(Total 6 marks)

159.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram to show the fluid mosaic structure of a plasma membrane, indicating the hydrophilic and hydrophobic regions.
(5)
 
(b)	Distinguish between active and passive movements of materials across plasma membranes, using named examples.
(4)
 
(c)	Explain how the properties of water are significant to living organisms.
(9)
(Total 20 marks)

160.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram to show the human ventilation system.
(4)
 
(b)	Outline anaerobic cell respiration in plant cells.
(5)
 
(c)	Explain the concept of homeostasis, using the control of blood sugar as an example.
(9)
(Total 20 marks)

161.	The graph below shows the results of an experiment to determine the effect of salt (NaCl) concentration on photosynthesis of the freshwater green alga Chlorella vulgaris. The experiment attempted to determine the effect of salt concentration on the light-dependent reactions overall and separately on photosystem I and photosystem II.

	[Source: M M El-Sheekh, “Inhibition of the water splitting system by sodium chloride stress in the green alga Chlorella vulgaris”, Brazilian Journal of Plant Physiology, Volume 16, Issue 1, Figure 1, (2004)]
 
(a)	Describe the effect of salt concentration on the activity of the light-dependent reactions overall.
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(1)
 
(b)	Compare the effect of increasing salt concentration on photosystem I with the effect on photosystem II.
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(1)

(c)	When salt concentration is increased, some algal cells increase their rates of cyclic photophosphorylation. Deduce the reasons for this.
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(2)
 
(d)	Using the graph, predict the effect of high salt concentration on the growth of Chlorella vulgaris. Give a reason for your answer.
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(2)
(Total 6 marks)

162.	(a)	State one example of a fibrous protein.
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(1)
 
(b)	Distinguish between the secondary structure and tertiary structure of proteins.
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(3)
 
(c)	Explain what is meant by allosteric inhibition.
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(3)
(Total 7 marks)

163.	(a)	State the location of high proton concentration caused by electron transport in the mitochondrion.
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(1)

(b)	Outline the role of oxygen in cellular respiration.
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(2)
 
(c)	Explain how any two structural features of the mitochondrion are related to its function.
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(2)
(Total 5 marks)

164.	Which of the following chemical elements are part of biochemical molecules in living organisms?
A.	nitrogen, sulfur, phosphorus and iron
B.	lead, oxygen, carbon and phosphorus
C.	helium, carbon, sulfur and nitrogen
D.	silicon, helium, oxygen and iron
(Total 1 mark)

165.	The diagram below represents part of the DNA molecule.
		
	What are the parts labelled I, II and III?

	I	II	III	
A.	hydrogen bond	base	deoxyribose	
B.	hydrogen bond	deoxyribose	phosphate group	
C.	covalent bond	base	deoxyribose	
D.	covalent bond	deoxyribose	phosphate group	
(Total 1 mark)

166.	What principle is necessary to preserve the sequence of DNA during replication?
A.	Base pairing is complementary.
B.	One gene codes for one polypeptide.
C.	Substrates are specific to enzymes.
D.	The genetic code is universal.
(Total 1 mark)

167.	What happens during translation?
A.	Copying of DNA to produce DNA
B.	Copying of DNA to produce mRNA
C.	Copying of DNA to produce tRNA
D.	Polypeptide synthesis
(Total 1 mark)

168.	Which equation shows a chemical reaction that occurs during anaerobic cell respiration?

(Total 1 mark)

169.	The diagram below shows part of a DNA molecule that is being replicated.

	Where would DNA polymerase link the next nucleotide during replication?
A.	I
B.	II
C.	III
D.	IV
(Total 1 mark)

170.	The graph below shows energy changes during a chemical reaction that occurs without a catalyst.
What would change if the reaction was catalysed by an enzyme?
		
A.	The initial energy level (I) would be higher, speeding up the reaction.
B.	The maximum energy level (II) would be higher, speeding up the reaction.
C.	The maximum energy level (II) would be lower, speeding up the reaction.
D.	The final energy level (III) would be lower, speeding up the reaction.
(Total 1 mark)

171.	What is the role of NADH + H+ in aerobic cell respiration?
A.	To transfer hydrogen to the electron transport chain
B.	To reduce intermediates in the Krebs cycle
C.	To accept electrons from the electron transport chain
D.	To combine with oxygen to produce water
(Total 1 mark)

172.	What reaction, involving glycerate 3-phosphate, is part of the light-independent reactions of photosynthesis?
A.	Glycerate 3-phosphate is carboxylated using carbon dioxide.
B.	Two glycerate 3-phosphates are linked together to form one hexose phosphate.
C.	Glycerate 3-phosphate is reduced to triose phosphate.
D.	Five glycerate 3-phosphates are converted to three ribulose 5-phosphates.
(Total 1 mark)

173.	What is the advantage of having a small volume inside the thylakoids of the chloroplast?
A.	High proton concentrations are rapidly developed.
B.	High electron concentrations are rapidly developed.
C.	Photosynthetic pigments are highly concentrated.
D.	Enzymes of the Calvin cycle are highly concentrated.
(Total 1 mark)

174.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Outline the thermal, cohesive and solvent properties of water.
(5)
 
(b)	Outline adaptations of xerophytes.
(4)
 
(c)	Explain the role of the kidney in maintaining water balance in humans.
(9)
(Total 20 marks)

175.	Carbon, hydrogen, nitrogen and sulphur are elements found in living cells. Which is the least common?
A.	Carbon
B.	Hydrogen
C.	Nitrogen
D.	Sulphur
(Total 1 mark)

176.	Which of the following terms correctly describe the molecule below?

I.	Monosaccharide
II.	Ribose
III.	Carbohydrate
A.	I only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

177.	A certain gene in a bacterium codes for a polypeptide that is 120 amino acids long. How many nucleotides are needed in the mRNA to code for this polypeptide?
A.	30
B.	40
C.	360
D.	480
(Total 1 mark)

178.	What enzyme is used in transcription but not in translation?
A.	DNA polymerase
B.	Helicase
C.	Protease
D.	RNA polymerase
(Total 1 mark)

179.	Humans can respire aerobically and anaerobically. Which are products of both aerobic cell respiration and anaerobic cell respiration in humans?
A.	Pyruvate and ATP
B.	Pyruvate and lactate
C.	ATP and carbon dioxide
D.	Lactate and carbon dioxide
(Total 1 mark)

180.	Which two colours of light does chlorophyll absorb most?
A.	Red and yellow
B.	Green and blue
C.	Red and green
D.	Red and blue
(Total 1 mark)

181.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw and label a diagram of the digestive system.
(4)
(b)	Discuss factors that affect enzyme activity.
(9)
(c)	Outline one industrial use of lactase.
(5)
(Total 20 marks)

182.	Inflammation of human tissues often causes pain. Cyclooxygenases (COX) are a group of enzymes that play a role in causing inflammation. Analgesics are drugs that can reduce pain. The graph below shows how increasing concentrations of the analgesic drug dipyrone, affects the activity of three different cyclooxygenases, COX-1, COX-2 and COX-3.
	
[Source: Adapted from N V Chandrasekharan, et al, (2002), Proceedings of the National Academy of Sciences, USA, 99, (21),
pages 13926-13931]
 
(a)	Outline the relationship between dipyrone concentration and COX-3 activity.
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(2)

(b)	Deduce whether dipyrone is an inhibitor of COX-2.
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(2)
 
(c)	Evaluate the potential of dipyrone as an analgesic using the data in the graph.
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(2)
(Total 6 marks)

183.	(a)	List two examples of fibrous proteins.
1. .................................................................................................................................
2. .................................................................................................................................
(1)

(b)	(i)	State one protein involved in oxidative phosphorylation.
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(1)
 
(ii)	Outline the role of this protein in oxidative phosphorylation.
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(2)
(Total 4 marks)

184.	(a)	Explain why carbon dioxide concentration is a limiting factor of photosynthesis.
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(3)

(b)	Explain the relationship between the structure of the chloroplast and its function.
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(3)
 
(c)	State two products of the light-dependent reactions.
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(2)
(Total 8 marks)

185.	The diagram shows part of a molecule produced by replication of DNA. What is the significance of the shaded and the unshaded regions?

A.	The shaded parts are DNA and the unshaded parts are mRNA.
B.	The shaded parts contain adenine and thymine and the unshaded parts contain guanine and cytosine.
C.	The shaded part is a codon and unshaded part is an anticodon.
D.	One of the parts has been newly synthesized and the other was part of a pre-existing DNA molecule.
(Total 1 mark)

186.	If mRNA has a codon CAU, what is the corresponding anticodon on the tRNA molecule?
A.	CAT
B.	GUA
C.	CAU
D.	GTA
(Total 1 mark)

187.	Which graph shows the relationship between the substrate concentration and the rate of an enzyme controlled reaction?

(Total 1 mark)

188.	What are pyrimidines in DNA?
A.	Types of nucleotides
B.	Types of base pairs
C.	Types of sugars
D.	Types of bases
(Total 1 mark)

189.	Which enzyme removes the RNA primer during replication?
A.	RNA primase
B.	DNA polymerase I
C.	DNA ligase
D.	Helicase
(Total 1 mark)

190.	Consider the metabolic pathway shown below.
	
If there is end-product inhibition, which product would inhibit which enzyme?
	Product	Enzyme	
A.	X	4	
B.	W	3	
C.	W	2	
D.	Z	1	
(Total 1 mark)

191.	What is the net production of ATP, per molecule of glucose during the fermentation of glucose to lactate?
A.	36 molecules
B.	4 molecules
C.	2 molecules
D.	None
(Total 1 mark)

192.	The diagram below summarizes the light-dependent reactions in photosynthesis. What is occurring at X?

A.	ADP + phosphate ® ATP
B.	NADP+®NADPH + H+
C.	H2O ® O2– + 2H+
D.	NADPH + H+ ® NADP+
(Total 1 mark)

193.	What is the first identifiable product of carbon dioxide fixation in photosynthesis?
A.	Ribulose bisphosphate (RuBP)
B.	Glycerate3-phosphate (GP)
C.	Triose phosphate (TP)
D.	Acetyl CoA
(Total 1 mark)

194.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram showing the structure of a plasma membrane.
(4)
(b)	Outline the role of chlorophyll and the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis.
(6)
(c)	Explain the production of energy during aerobic respiration from pyruvate that has been produced by glycolysis.
(8)
(Total 20 marks)

195.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram showing the structure of the digestive system.
(4)
(b)	Outline the need for enzymatic hydrolysis in the digestive process.
(6)
(c)	Explain how the kidney prevents the body from losing important materials absorbed from the digestive system.
(8)
(Total 20 marks)