1.	Which of the following statements about homologous chromosomes is correct?
A.	Each gene is at the same locus on both chromosomes.
B.	They are two identical copies of a parent chromosome which are attached to one another at the centromere.
C.	They always produce identical phenotypes.
D.	They are chromosomes that have identical genes and alleles.
(Total 1 mark)

2.	What happens in crossing over?
A.	Exchange of genetic material between homologous chromosomes
B.	Exchange of genes during metaphase of mitosis
C.	Random distribution of chromosomes during meiosis
D.	Homologous chromosomes fail to separate during meiosis
(Total 1 mark)

3.	The pedigree chart below shows the blood types of three members of a family.
		
	Which could be the blood types of individuals 1 and 2?

	Individual 1	Individual 2	
A.	A	AB	
B.	AB	B	
C.	O	B	
D.	B	A	
(Total 1 mark)

4.	Which of the following types of information are needed to construct a karyotype?
I.	Size of the chromosomes
II.	Gene mutations of the chromosomes
III.	Age of the individual
A.	I only
B.	II only
C.	I and II only
D.	I, II and III
(Total 1 mark)

5.	A woman who is a carrier for hemophilia and a man who does not have hemophilia have a child.
What is the probability that the child will have hemophilia?

	If it is a girl	If it is a boy	
A.	0%	50%	
B.	0%	0%	
C.	50%	50%	
D.	50%	0%	
(Total 1 mark)

6.	Which enzymes are needed to produce recombinant plasmids to be used in gene transfer?
A.	DNA polymerase and DNA ligase
B.	DNA polymerase and restriction enzyme (endonuclease)
C.	Transcriptase and RNA polymerase
D.	Restriction enzyme (endonuclease) and DNA ligase
(Total 1 mark)

7.	A human cell has between 20 000 and 25 000 genes whereas an E. coli cell has approximately 4000 genes. Which of the following statements is true?
A.	The human genome is larger than the E. coli genome.
B.	There are more genes on each human chromosome than on the E. coli chromosome.
C.	The human cell and the E. coli cell produce approximately the same variety of proteins.
D.	The DNA in both organisms is associated with histones (proteins).
(Total 1 mark)

8.	In the following diagram, which pair represents homologous chromosomes?
		
A.	1 and 2
B.	3 and 4
C.	2 and 5
D.	4 and 6
(Total 1 mark)

9.	A parent organism of unknown genotype is mated in a test cross. Half of the offspring have the same phenotype as the parent. What can be concluded from this result?
A.	The parent of unknown genotype is heterozygous.
B.	The parent of unknown genotype is homozygous dominant.
C.	The parent of unknown genotype is homozygous recessive.
D.	The parent of known genotype is heterozygous.
(Total 1 mark)

10.	Rhesus factor is an antigen present on the surface of red blood cells of Rhesus positive individuals.
Rhesus positive (Rh+ ) is dominant to Rhesus negative (Rh– ). A mother with Rhesus negative blood gives birth to a baby with Rhesus positive blood and there are concerns that subsequent pregnancies will trigger an immune response.
	What are the genotypes of the mother and her first baby?

	Genotype of mother	Genotype of first baby	
A.	Rh– Rh–	Rh– Rh–	
B.	Rh– Rh–	Rh+ Rh–	
C.	Rh– Rh–	Rh+ Rh+	
D.	Rh+ Rh–	Rh+ Rh+	
(Total 1 mark)

11.	Rhesus factor is an antigen present on the surface of red blood cells of Rhesus positive individuals.
Rhesus positive (Rh+ ) is dominant to Rhesus negative (Rh– ). A mother with Rhesus negative blood gives birth to a baby with Rhesus positive blood and there are concerns that subsequent pregnancies will trigger an immune response.
	What is a possible explanation for why subsequent pregnancies could trigger an immune response?
A.	Exposure to the Rh+ antigen in the first pregnancy triggered the development of antibodies that could attack the blood of a future Rh+ baby.
B.	Exposure to the Rh+ antigen in the first pregnancy triggered the development of specific phagocytes that could attack the blood of a future Rh+ baby.
C.	The mother has developed passive immunity to the Rh+ factor.
D.	The mother’s immune system has been weakened by pregnancy.
(Total 1 mark)

12.	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.
...........................................................................................................................
(1)
 
(ii)	State the population in which the allele frequencies were closest to 0.5.
...........................................................................................................................
(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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)	mean surface sea temperature in June and the frequency of the PanIA allele.
...........................................................................................................................
...........................................................................................................................
(1)
 
(d)	Suggest how natural selection could have caused the relationships shown in the graphs.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(f)	Using the data in this question, predict the effects of global warming on cod fish populations.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 11 marks)

13.	(a)	State the name of the technique that is used to separate fragments of DNA according to their size, during DNA profiling.
......................................................................................................................................
(1)
 
(b)	The diagram below represents the results of a paternity investigation. Track A is the profile of the mother of a child, track B is the profile of the child and track C is the profile of a man who might be the father.

	Explain, using evidence from the diagram, whether this man is the father or not.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 4 marks)

14.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Embryos that are produced by in vitro fertilization can be screened for genetic disease.
Outline the process of in vitro fertilization, including one example of a situation when it is used.
(9)
 
(b)	Explain, using an example, how females but not males can be carriers of some recessive alleles.
(4)
 
(c)	Explain the causes and consequences of sickle-cell anemia.
(5)
(Total 20 marks)

15.	The karyotype below shows the chromosomes from a person with Down syndrome.

	[Source: U.S. Department of Energy Human Genome Program (genomics.energy.gov, genomicscience.energy.gov)]
 
(a)	State the evidence provided by the karyotype that shows this person has Down syndrome.
......................................................................................................................................
(1)
 
(b)	Outline how Down syndrome occurs due to meiosis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(c)	Determine, giving a reason, the sex of the person in the karyotype.
......................................................................................................................................
......................................................................................................................................
(1)
 
(d)	Explain briefly why males are more likely to inherit colour blindness than females.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)

16.	What is the difference between the alleles of a gene?
A.	Their position on the chromosome
B.	Their amino acid sequence
C.	Their pentose sugars
D.	Their base sequence
(Total 1 mark)

17.	A new allele that provides herbicide resistance is identified in soybean plants. The allele is dominant.
Which of the following would be carried out in a herbicide-resistant plant to find out if it is homozygous or heterozygous for the gene?
A.	Gel electrophoresis
B.	Karyotyping
C.	Test cross
D.	DNA profiling
(Total 1 mark)

18.	The diagram below shows chromosomes during meiosis.
		
	How many chromosomes and chiasmata are visible?

	Chromosomes	Chiasmata	
A.	4	4	
B.	2	4	
C.	2	2	
D.	4	2	
(Total 1 mark)

19.	Genes A and B are located on the same chromosome. If two individuals with the genotype shown below are crossed, which genotype could be formed?
		
A.	
B.	
C.	
D.	
(Total 1 mark)

20.	The ACHOO syndrome is an inherited condition that leads to sneezing in response to bright light and is hypothesized to be inherited in an autosomal (not sex-linked) dominant fashion. The following is a pedigree chart that shows three generations from one family.
		
	[Source: “Autosomal dominant pedigree chart. In Autosomal Dominance the chance of receiving and expressing a particular gene is 50% regardless of the sex of parent or child.” Jerome Walker. 22 July 2006.]
	What evidence from the pedigree chart confirms that the ACHOO syndrome is not X-linked dominant?
A.	Four females in the pedigree chart are affected and X-linked conditions do not affect females.
B.	There is an affected male in generation II.
C.	There is an affected female in generation II.
D.	If the condition is X-linked dominant, the affected mother in generation II could not produce an unaffected son.
(Total 1 mark)

21.	The ACHOO syndrome is an inherited condition that leads to sneezing in response to bright light and is hypothesized to be inherited in an autosomal (not sex-linked) dominant fashion. The following is a pedigree chart that shows three generations from one family.
		
	[Source: “Autosomal dominant pedigree chart. In Autosomal Dominance the chance of receiving and expressing a particular gene is 50% regardless of the sex of parent or child.” Jerome Walker. 22 July 2006.]
	If the ACHOO syndrome is inherited as an autosomal dominant condition, what is the probability that a heterozygous father and an unaffected mother produce an unaffected child?
A.	0%
B.	25%
C.	50%
D.	100%
(Total 1 mark)

22.	Which of the following would be possible only if the ACHOO syndrome is inherited as autosomal recessive?
		
	[Source: “Autosomal dominant pedigree chart. In Autosomal Dominance the chance of receiving and expressing a particular gene is 50% regardless of the sex of parent or child.” Jerome Walker. 22 July 2006.]
A.	Two unaffected parents have a child with the condition.
B.	At least one parent has to be affected to produce children that have the condition.
C.	An affected and an unaffected parent have an affected child.
D.	Two unaffected parents have no affected children.
(Total 1 mark)

23.	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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 5 marks)

24.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Describe the causes of Down syndrome.
(5)
 
(b)	Describe how human skin colour is determined genetically.
(5)
 
(c)	Explain the causes of sickle-cell anemia.
(8)
(Total 20 marks)

25.	What is a suspected heterozygous individual crossed with in a test cross?
A.	Homozygous dominant
B.	Homozygous recessive
C.	Heterozygous dominant
D.	Heterozygous recessive
(Total 1 mark)

26.	What are homologous chromosomes?
A.	Identical chromosomes
B.	Non-identical chromosomes with different genes
C.	Non-identical chromosomes with the same genes in the same sequence but not necessarily the same alleles
D.	Non-identical chromosomes with the same genes in a different sequence and not necessarily the same alleles
(Total 1 mark)

27.	Which processes involved in cloning an animal are indicated by the letters X and Y?

	X	Y	
A.	differentiated cell removed from animal	nucleus removed from unfertilized egg cell	
B.	sex cell removed from animal	nucleus removed from differentiated animal cell	
C.	sex cell removed from animal	nucleus removed from unfertilized egg cell	
D.	differentiated cell removed from animal	nucleus removed from differentiated animal cell	
(Total 1 mark)

28.	What type of inheritance is shown in this pedigree chart?
		
A.	X-linked dominant
B.	Y-linked dominant
C.	X-linked recessive
D.	Y-linked recessive
(Total 1 mark)

29.	Which of the following is the cause of sickle-cell anemia?
A.	Tryptophan is replaced by leucine.
B.	Leucine is replaced by valine.
C.	Glutamic acid is replaced by valine.
D.	Lysine is replaced by glutamic acid.
(Total 1 mark)

30.	What does the karyotype below correspond to?
		
A.	A normal male
B.	A normal female
C.	A female with Down syndrome
D.	A male with Down syndrome
(Total 1 mark)

31.	A man of blood group A and a woman of blood group B have a child. If both are heterozygous for the gene, what are the chances of them having a child with blood group B?
A.	0%
B.	25%
C.	50%
D.	75%
(Total 1 mark)

32.	Which disease is an example of sex-linked (X-linked) inheritance?
A.	AIDS
B.	Down syndrome
C.	Sickle-cell anemia
D.	Hemophilia
(Total 1 mark)

33.	The diagram below represents the results obtained in a DNA profile from a crime scene.
		
	Suspect 2 is most likely to be the criminal because the band pattern coincides with that of the crime scene sample. What do these bands represent?
A.	DNA fragments
B.	Genes
C.	Chromosomes
D.	Chromatids
(Total 1 mark)

34.	What is a genetic test cross?
A.	Testing a suspected homozygote by crossing it with a known heterozygote
B.	Testing a suspected heterozygote by crossing it with a known heterozygote
C.	Testing a suspected homozygote by crossing it with a known homozygous dominant
D.	Testing a suspected heterozygote by crossing it with a known homozygous recessive
(Total 1 mark)

35.	(a)	Gene transfer to bacteria often involves small circles of DNA into which genes can be inserted. State the name of a small circle of DNA, used for DNA transfer, in bacteria.
......................................................................................................................................
(1)

(b)	The diagram below shows a cut circle of DNA into which a gene is being inserted. Before it can be transferred into a bacterium, the ring must be altered, using an enzyme.
		
	Outline what must be done next to complete the process of gene insertion into the DNA circle, including the name of the enzyme that is used.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(c)	Discuss the potential benefit and possible harm of one named example of gene transfer between species.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 6 marks)

36.	(a)	Define the term allele as used in genetics.
......................................................................................................................................
(1)
 
(b)	List the possible genotypes for blood group B.
......................................................................................................................................
(1)

(c)	Label the diagram below which shows a basic gene transfer.

I. ..................................................................................................................................
II. .................................................................................................................................
III. ................................................................................................................................
IV. ................................................................................................................................
(2)
 
(d)	State two general types of enzymes used in gene transfer.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 5 marks)

37.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Describe the movement of energy and nutrients in an ecosystem.
(6)
(b)	Explain how sexual reproduction can eventually lead to evolution in offspring.
(8)
(c)	Using simple external recognition features, distinguish between the plant phyla bryophyta and angiospermophyta.
(4)
(Total 20 marks)

38.	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)

39.	Which of the following genotypes is possible in the offspring of a homozygous male with blood group A and a female with blood group B?
A.	IAIA
B.	IAi
C.	ii
D.	IBi
(Total 1 mark)

40.	A test cross resulted in these recombinants:
	
	Which of the following was the parental test cross?
A.	
B.	
C.	
D.	
(Total 1 mark)

41.	What kind of inheritance does skin colour represent?
A.	Sex-linked (X-linked)
B.	Multiple alleles
C.	Systemic
D.	Polygenic
(Total 1 mark)

42.	Which are the possible recombinants in a dihybrid test cross involving the linked genes ?
A.	
B.	
C.	
D.	
(Total 1 mark)

43.	The diagram below shows a pair of chromosomes during meiosis in a cell in the human testis.
The position of the alleles of some genes is indicated.

(a)	Deduce, with reasons for your answer, whether the chromosomes are
(i)	autosomes or sex chromosomes.
...........................................................................................................................
...........................................................................................................................
(1)
 
(ii)	homologous or non-homologous.
...........................................................................................................................
...........................................................................................................................
(1)
 
(b)	State the stage of meiosis of a cell if it contains pairs of chromosomes as shown in the diagram.
......................................................................................................................................
(1)
 
(c)	At the end of meiosis, each of the chromatids shown in the diagram will be in a different haploid cell. The diagrams below represent the chromatids inside the haploid cells.
Determine the combinations of alleles that would be present on each chromatid. Use the diagrams to indicate your answer.

(2)
 
(d)	State the pattern of inheritance shown by the three genes.
......................................................................................................................................
(1)
(Total 6 marks)

44.	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)

45.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw a labelled diagram of a mature sperm.
(5)
 
(b)	Outline the formation of chiasmata during crossing over.
(5)
 
(c)	Explain how an error in meiosis can lead to Down syndrome.
(8)
(Total 20 marks)

46.	A cell in the testis of a male chimpanzee (Pan troglodytes) contains 48 chromosomes. It is about to undergo meiosis. How many molecules of DNA will be present in the nucleus of the sperm cells just after meiosis?
A.	96
B.	48
C.	24
D.	12
(Total 1 mark)

47.	What is chorionic villus sampling?
A.	Sampling cells from the placenta
B.	Sampling cells from the fetal digestive system
C.	Sampling fetal cells from the amniotic fluid
D.	Sampling stem cells from the umbilical cord
(Total 1 mark)

48.	How can fragments of DNA be separated?
A.	Using polymerase chain reaction (PCR)
B.	Using gel electrophoresis
C.	Using gene transfer
D.	Using gene cloning
(Total 1 mark)

49.	Why can DNA profiling be used to determine paternity?
A.	Genes of children are exactly the same as their father’s.
B.	Half the genes of children are the same as their father’s.
C.	The father passes on all of his genes to each of his children.
D.	The father passes on a fraction of his genes equal to the number of his children.
(Total 1 mark)

50.	Which of the following will promote variation in a species?
I.	Meiosis
II.	Fertilization
III.	Natural selection
A.	I only
B.	II only
C.	I and II only
D.	I, II and III
(Total 1 mark)

51.	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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 17 marks)

52.	The following sequence of pictures, made using an electronic imaging technique, shows a cell undergoing division.

	[Adapted by permission from Macmillan Publishers Ltd, Fuller, B G et al. 2008. “Midzone activation of aurora B in anaphase produces an intracellular phosphorylation gradient”. Nature. Vol 453.]

(a)	State the stage of mitosis typified by image II.
......................................................................................................................................
(1)
 
(b)	List two processes that involve mitosis.
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	State the process that results in tumour (cancer) formation or development.
......................................................................................................................................
(1)
 
(d)	Explain, using one example, how non-disjunction in meiosis can lead to changes in chromosome number.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)

53.	Which processes result in recombination?

	Meiosis	Crossing over	Independent assortment	Mutation	
A.	yes	yes	yes	no	
B.	yes	no	yes	no	
C.	yes	yes	no	yes	
D.	no	no	no	yes	
(Total 1 mark)

54.	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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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)

55.	What is the set of alleles that an individual possesses?
A.	A gene
B.	A genotype
C.	A genome
D.	A genus
(Total 1 mark)

56.	Which phase of cell division is photographed in order to make a karyotype?
A.	Anaphase of mitosis
B.	Anaphase I of meiosis
C.	Metaphase of mitosis
D.	Metaphase II of meiosis
(Total 1 mark)

57.	What evidence is given in the pedigree chart below to establish that the condition is caused by a dominant allele?

A.	Two unaffected parents have unaffected children.
B.	Two affected parents have affected children.
C.	An affected parent and an unaffected parent have affected children.
D.	Two affected parents have an unaffected child.
(Total 1 mark)

58.	Which process is used in polymerase chain reaction (PCR)?
A.	Transcription
B.	Translation
C.	Replication
D.	Mutation
(Total 1 mark)

59.	What conclusion can be made from the following evidence from an analysis of DNA fragments?
		
A.	Both children are related to both parents.
B.	Child I is related to the man but child II is not.
C.	Both children are unrelated to either of the parents.
D.	Child II is related to the man but child I is not.
(Total 1 mark)

60.	If the haploid number of a species is 14, how many chromatids will there be in metaphase I in a dividing diploid cell?
A.	7
B.	14
C.	28
D.	56
(Total 1 mark)

61.	Which enzymes are needed to incorporate genes into plasmids to create recombinant plasmids?
A.	DNA polymerase and ligase
B.	DNA polymerase and restriction enzymes
C.	Restriction enzymes and ligase
D.	Helicase and restriction enzymes
(Total 1 mark)

62.	What could be achieved by DNA profiling using gel electrophoresis?
A.	The chromosome number of an organism could be counted.
B.	It could be shown that human tissue found at the site of a crime did not come from a person suspected of having committed the crime.
C.	A karyotype could be produced.
D.	Extinct species of living organisms could be brought back to life.
(Total 1 mark)

63.	If an organism that is homozygous recessive for a trait is crossed with a heterozygote, what is the chance of getting a homozygous recessive phenotype in the first generation?
A.	0%
B.	25%
C.	50%
D.	100%
(Total 1 mark)

64.	What is placed into the uterus after the process of in vitro fertilization (IVF)?
A.	Eggs
B.	Sperm
C.	Embryos
D.	Fetuses
(Total 1 mark)

65.	What can be concluded from the karyotype provided below?
		
[Source: www.ds-health.com/trisomy.htm]
A.	There was non-disjunction during meiosis in the mother.
B.	There was non-disjunction during meiosis in the father.
C.	The fetus is male.
D.	The fetus is female.
(Total 1 mark)

66.	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: adapted from S Mugo, et al., (2005), African Journal of Biotechnology, 4(13), pages 1490–1504]

(a)	(i)	State what would be used as the control in this experiment.
...........................................................................................................................
...........................................................................................................................
(1)
 
(ii)	Calculate the percentage difference in leaf area damaged by Sesamia calamistis between the control and maize type H. Show your working.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
 
(b)	Outline the effects of the three species of stem borer on Bt maize type A.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(c)	Evaluate the efficiency of the types of Bt maize studied, in controlling the three species of stem borers.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
	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 3 groups of 12 adult 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. © Elsevier. Reproduced with permission]

(d)	Calculate the change in mean mass of female rats fed on Bt maize from day 14 to 42.
......................................................................................................................................
......................................................................................................................................
(1)
 
(e)	Describe the change in mean mass for the female rats during the 90-day experiment.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(f)	Evaluate the use of Bt maize as a food source compared to the other diets tested.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 13 marks)

67.	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)

68.	(a)	Explain how materials are moved across membranes of cells by active transport.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)

(b)	Explain the effects of pH on enzyme catalysed reactions.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
 
(c)	Distinguish between the process of anaerobic respiration in yeast and humans.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 7 marks)

69.	Red-green colour blindness is a sex-linked condition. Which of the following always shows normal vision?
A.	A homozygous male
B.	A homozygous female
C.	A heterozygous male
D.	A heterozygous female
(Total 1 mark)

70.	What are the fundamental structural units of eukaryotic chromosomes?
A.	Nucleosomes
B.	Centromeres
C.	Histones
D.	Nucleoids
(Total 1 mark)

71.	When do chiasmata form in meiosis?
A.	During prophase I
B.	During metaphase I
C.	During anaphase I
D.	During prophase II
(Total 1 mark)

72.	Which of the following processes result in the production of recombinants?
I.	Crossing over between linked genes
II.	Reassortment of non-linked genes
III.	Mutation
A.	I only
B.	I and II only
C.	I and III only
D.	I, II and III
(Total 1 mark)

73.	What do all human males inherit from their mother?
I.	An X chromosome
II.	A Y chromosome
III.	Mitochondrial DNA
A.	I and II only
B.	II only
C.	I and III only
D.	I, II and III
(Total 1 mark)

74.	What could be achieved by DNA profiling using gel electrophoresis?
A.	The chromosome number of an organism could be counted.
B.	It could be shown that human tissue found at the site of a crime did not come from a person suspected of having committed the crime.
C.	A karyotype could be produced.
D.	Extinct species of living organisms could be brought back to life.
(Total 1 mark)

75.	Which of the following conclusions did Mendel make from his experiments?
A.	Dominant genes are more frequent than recessive genes.
B.	Genes are composed of DNA.
C.	Genes for two different characteristics are inherited separately.
D.	Segregation occurs through meiosis.
(Total 1 mark)

76.	
In fruit flies (Drosophila melanogaster) grey body is dominant to black body and normal wings are dominant to vestigial wings.	
	If a heterozygous grey fruit fly is mated with a black-bodied fruit fly, what proportion of the offspring would be black?
A.	0%
B.	25%
C.	50%
D.	100%
(Total 1 mark)

77.	
In fruit flies (Drosophila melanogaster) grey body is dominant to black body and normal wings are dominant to vestigial wings.	
	Male flies, heterozygous for both grey body and normal wings, were mated with black-bodied, vestigial-winged females. 2000 offspring were counted. The resulting percentage of each type of offspring is shown in the table below.

Resulting offspring	Frequency	
Grey body, normal wings	40%	
Black body, vestigial wings	40%	
Grey body, vestigial wings	10%	
Black body, normal wings	10%	
	What conclusion can be drawn from the information given above?
A.	The genes assort independently.
B.	A mistake has been made.
C.	The genes are linked.
D.	The genes are on separate chromosomes.
(Total 1 mark)

78.	Which of the following chemicals is a component of eukaryotic chromosomes?
A.	Protein
B.	Triglyceride
C.	Fatty acid
D.	RNA
(Total 1 mark)

79.	This question refers to the following karyotype.
		
[Source: www.ds-health.com/trisomy.htm]
	What procedure(s) could have been involved in the creation of the karyotype?
I.	Chorionic villus sampling
II.	DNA profiling
III.	Amniocentesis
A.	I only
B.	II only
C.	I and III only
D.	I, II and III
(Total 1 mark)

80.	Which of the following is an inherited disease that is due to a base substitution mutation in a gene?
A.	Trisomy 21
B.	Sickle cell anemia
C.	AIDS
D.	Type II diabetes
(Total 1 mark)

81.	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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(b)	Discuss which species of stem borer was most successfully controlled by the genetic engineering of the maize plants.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(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)

82.	(a)	In some maize plants the seed is enclosed in a green sheath called a tunica.
The allele (T) for this is dominant to the allele (t) for normal, unenclosed seeds.
The endosperm of the seed can be starchy (allele E) or sugary (allele e). The genes for these two characteristics are linked. The table below shows the outcome of crosses between a plant heterozygous for both characteristics and one that is homozygous recessive for both characteristics.

Phenotype	Number	
Tunica present, starchy	326	
Unenclosed seeds, starchy	111	
Tunica present, sugary	118	
Unenclosed seeds, sugary	295	
 
(i)	State the genotype of the heterozygous parent using the correct notation.
...........................................................................................................................
...........................................................................................................................
(1)

(ii)	Identify which individuals are recombinants in this cross.
...........................................................................................................................
...........................................................................................................................
(1)
 
(iii)	Explain what has occurred to cause these results.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)

(b)	Maize belongs to the group of plants known as angiospermophyta. Distinguish between angiospermophytes and bryophytes.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)

83.	(a)	Outline a possible cause of Down syndrome.
(4)
 
(b)	Outline the processes involved in oogenesis within the human ovary.
(8)
 
(c)	Discuss the ethical issues surrounding IVF.
(6)
(Total 18 marks)

84.	(a)	Define the term polygenic inheritance.
......................................................................................................................................
......................................................................................................................................
(1)
 
(b)	Explain, using a named example, how polygenic inheritance gives rise to continuous variation.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
 
(c)	Describe the inheritance of colour blindness in humans.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 6 marks)

85.	What is the cause of sickle-cell anemia?
A.	A change to the base sequence of a hemoglobin gene
B.	Mosquitoes acting as the vector for malaria
C.	Iron deficiency due to the malaria parasite
D.	Production of more white blood cells than red blood cells by bone marrow
(Total 1 mark)

86.	The blood groups of a mother and four children are indicated on the pedigree chart below.
		
	What are the possible blood groups of the father?
A.	Group A only
B.	Group A or B only
C.	Group AB only
D.	Group A, B or AB only
(Total 1 mark)

87.	Boys can inherit the recessive allele (c) that causes red-green colour blindness from their mother, not from their father. The allele for normal red and green vision is C. Which of the following genotypes are possible in men?
A.	c only
B.	C or c only
C.	CC or cc only
D.	CC, Cc or cc only
(Total 1 mark)

88.	A small amount of a suspect’s DNA is obtained from a crime scene. What techniques would be used to carry out DNA profiling?
A.	Gel electrophoresis and paternity testing
B.	Paternity testing and the polymerase chain reaction (PCR)
C.	Polymerase chain reaction (PCR) and gel electrophoresis
D.	Test crossing and pedigree analysis
(Total 1 mark)

89.	The Human Genome Project allowed the first accurate estimates of the number of different genes in the human genome. What was a typical estimate, based on the results of the Human Genome Project?
A.	46
B.	64
C.	25 000
D.	1 000 000
(Total 1 mark)

90.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Describe karyotyping and one application of its use.
(4)
(b)	Describe a technique used for gene transfer.
(5)
(c)	Using a named example, discuss the benefits and harmful effects of genetic modification.
(9)
(Total 20 marks)

91.	What type of enzyme could be used to cut a DNA molecule as indicated by the dotted line on the diagram below?
		
A.	DNA ligase
B.	DNA polymerase
C.	Helicase
D.	Restriction enzyme
(Total 1 mark)

92.	The diagram below shows a pair of chromosomes immediately after pairing in prophase I of meiosis in a cell. What combinations of alleles are possible in haploid cells produced by meiosis in this cell?

(Total 1 mark)

93.	How many autosomes are there in a human sperm?
A.	1
B.	22
C.	23
D.	46
(Total 1 mark)

94.	What is polygenic inheritance?
A.	A character that is controlled by two or more genes
B.	A character that is controlled by more than two copies of a gene
C.	Inheriting more than two alleles of a gene
D.	Inheriting a linked group of genes
(Total 1 mark)

95.	In the red squirrel (Tamiasciurus hudsonicus), the allele for grey fur colour (G) is dominant to the allele for red fur colour (g) and the allele for a fluffy tail (F) is dominant to hairless tail (f).
(a)	The genes described above form a linkage group. Define linkage group.
......................................................................................................................................
......................................................................................................................................
(1)
 
(b)	A cross is made between squirrels of the following genotypes.
		
	Using a similar format, identify the genotypes of offspring which are recombinants.

......................................................................................................................................
(2)

(c)	Explain how the recombinants are formed during meiosis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
 
(d)	Explain the role of transfer RNA (tRNA) in the process of translation.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 8 marks)

96.	How are plasmids used in biotechnology?
A.	For respiration in prokaryotes
B.	For photosynthesis in eukaryotes
C.	For protein synthesis in prokaryotes and eukaryotes
D.	For gene transfer
(Total 1 mark)

97.	The diagram below shows the cell of an organism going through the first division of meiosis.

How many different combinations are possible for these chromosomes in the haploid cells formed by meiosis?
A.	2
B.	6
C.	8
D.	9
(Total 1 mark)

98.	If the amount of DNA in a haploid gamete is represented by ´, what is the net quantity of DNA in a cell from the same organism at the start of meiosis?
A.	0.5 ´
B.	´
C.	2 ´
D.	4 ´
(Total 1 mark)

99.	A parent organism of unknown genotype is mated in a test cross. Half of the offspring have the same phenotype as the parent. What can be concluded from this result?
A.	The parent is homozygous dominant for the trait.
B.	The trait being inherited is polygenic.
C.	The parent is heterozygous for the trait.
D.	The parent is homozygous recessive for the trait.
(Total 1 mark)

100.	If a man has blood group O and a woman has blood group AB, what is the probability that their child will be blood group O?
A.	0%
B.	25%
C.	50%
D.	100%
(Total 1 mark)

101.	(a)	State two procedures used for the preparation of a DNA profile.
.....................................................................................................................................
.....................................................................................................................................
(1)
 
	The following part of a DNA profile was used as evidence in a criminal investigation. DNA profiles of two suspects labelled S1 and S2 were compared to the DNA profile taken from the scene of the crime labelled E.

[Source: Solomon and Berg, (1995), The World of Biology, Saunders Harcourt Brace College, Publishers Orlando, page 238]
 
(b)	Analyse the profiles to determine which suspect was present at the crime scene.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 3 marks)

102.	(a)	List two roles of testosterone in males.
1.	..........................................................................................................................
2.	..........................................................................................................................
(1)
 
(b)	A boy inherited red-green colour-blindness from one of his grandfathers. Deduce, giving your reasons, which of his two grandfathers was also colour-blind.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 4 marks)

103.	Up to two additional marks are available for the construction of your answers.
(2)
	(a)	Draw and label a diagram of the molecular structure of DNA.
(4)
(b)	Explain the consequences of a base substitution mutation in relation to the processes of transcription and translation.
(8)
(c)	Outline the evidence for evolution provided by homologous structures.
(6)
(Total 20 marks)

104.	(a)	Explain one use of reverse transcriptase in biotechnology.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
 
(b)	List two commercial production processes that rely on the activity of Saccharomyces.
1. .................................................................................................................................
2. .................................................................................................................................
(2)
(Total 5 marks)

105.	(a)	State the two classes of compounds that compose chromosomes in animal cells.
.....................................................................................................................................
.....................................................................................................................................
(1)

(b)	Outline how meiotic division results in almost an infinite genetic variation in the gametes produced.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)

(c)	In a species of plant, tall is dominant to short and the production of round seeds is dominant to that of wrinkled seeds. The alleles are unlinked.
	A plant heterozygous for both characteristics is crossed with a plant homozygous for tall with wrinkled seeds.
Use the letters:
T—allele for tall
t — allele for short
R — allele for round seed
r—allele for wrinkled seed.
Determine the phenotypes and genotypes of the offspring of this cross.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
 
(d)	State how chromosome number can increase in human beings.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 6 marks)