Topic 3: Genetics

Some regions of DNA act as telomeres or produce tRNA. State one other function of DNA sequences that do not code for protein.

Some regions of DNA act as telomeres or produce tRNA. State one other function of DNA sequences that do not code for protein.

Some regions of DNA act as telomeres or produce tRNA. State one other function of DNA sequences that do not code for protein.

The image shows a karyogram.

The image shows a karyogram.

Distinguish between sex-linked genes and genes with linked loci.

Distinguish between sex-linked genes and genes with linked loci.

Distinguish between sex-linked genes and genes with linked loci.

Outline how it can be shown that the genes for shell base colour (Cc) and presence or absence of bands (Bb) are linked.

Outline how it can be shown that the genes for shell base colour (Cc) and presence or absence of bands (Bb) are linked.

Outline how it can be shown that the genes for shell base colour (Cc) and presence or absence of bands (Bb) are linked.

Explain the process of genetically modifying bacteria.

Explain the process of genetically modifying bacteria.

Explain the process of genetically modifying bacteria.

The genes for cystic fibrosis and blood group are not linked. Two parents are heterozygous for cystic fibrosis. One parent has blood group O and the other has blood group AB. Using a Punnett square, determine the probability that their child will have both cystic fibrosis and blood group A.

The genes for cystic fibrosis and blood group are not linked. Two parents are heterozygous for cystic fibrosis. One parent has blood group O and the other has blood group AB. Using a Punnett square, determine the probability that their child will have both cystic fibrosis and blood group A.

The genes for cystic fibrosis and blood group are not linked. Two parents are heterozygous for cystic fibrosis. One parent has blood group O and the other has blood group AB. Using a Punnett square, determine the probability that their child will have both cystic fibrosis and blood group A.

Nail patella syndrome is a rare disease that causes abnormalities of the nails and some bones. Its alleles are linked to the blood group alleles on the same chromosome. The pedigree chart shows the inheritance of these two characteristics over three generations.

[Source: Copyright © 1998. Phillip McClean]

Which descendant represents a recombinant phenotype?

Nail patella syndrome is a rare disease that causes abnormalities of the nails and some bones. Its alleles are linked to the blood group alleles on the same chromosome. The pedigree chart shows the inheritance of these two characteristics over three generations.

[Source: Copyright © 1998. Phillip McClean]

Which descendant represents a recombinant phenotype?

The image shows chromosomes from an insect (2 n = 8).

Which pair of chromosomes are the sex chromosomes of this insect species?

A.  c and e

B.  a and h

C.  f and h

D.  a and e

The image shows the results of Griffith’s experiment with S and R strains of Streptococcus pneumoniae in mice (Mus musculus).

What is an explanation for the results?

A.  Mice vary in their resistance to bacteria.

B.  The R strain and S strain mated.

C.  R strain bacteria are more heat-stable than S strain.

D.  DNA was transferred from heat-killed S cells to R cells.

The image shows the results of Griffith’s experiment with S and R strains of Streptococcus pneumoniae in mice (Mus musculus).

What is an explanation for the results?

A.  Mice vary in their resistance to bacteria.

B.  The R strain and S strain mated.

C.  R strain bacteria are more heat-stable than S strain.

D.  DNA was transferred from heat-killed S cells to R cells.

The image shows chromosomes from an insect (2 n = 8).

Which pair of chromosomes are the sex chromosomes of this insect species?

A.  c and e

B.  a and h

C.  f and h

D.  a and e

Ampicillin (Amp) is an antibiotic. A plasmid carrying a gene for Amp resistance was used to transform bacteria in a tube of broth. A control tube without plasmid was also produced. The results were plated as shown. Which plate has only colonies of transformed bacteria?

Ampicillin (Amp) is an antibiotic. A plasmid carrying a gene for Amp resistance was used to transform bacteria in a tube of broth. A control tube without plasmid was also produced. The results were plated as shown. Which plate has only colonies of transformed bacteria?

Outline the conclusions that can be drawn from the data in the graph for the group of aphids fed for three generations on transgenic thale cress plants (T).

The system of sex determination in chimpanzees (Pan troglodytes) is the same as in other mammals. A chimpanzee has 48 chromosomes in the nuclei of its body cells.

What can be deduced from this information?

A. The sex of the chimpanzee

B. The number of genes in each chromosome

C. Whether non-disjunction has occurred

D. The number of autosomes in a diploid cell

The system of sex determination in chimpanzees (Pan troglodytes) is the same as in other mammals. A chimpanzee has 48 chromosomes in the nuclei of its body cells.

What can be deduced from this information?

A. The sex of the chimpanzee

B. The number of genes in each chromosome

C. Whether non-disjunction has occurred

D. The number of autosomes in a diploid cell

Outline the conclusions that can be drawn from the data in the graph for the group of aphids fed for three generations on transgenic thale cress plants (T).

Outline the conclusions that can be drawn from the data in the graph for the group of aphids fed for three generations on transgenic thale cress plants (T).

At which stage of meiosis are bivalents formed?

A. Interphase

B. Prophase I

C. Prophase II

D. Metaphase II

At which stage of meiosis are bivalents formed?

A. Interphase

B. Prophase I

C. Prophase II

D. Metaphase II

Creeper in chickens is a condition in which the chickens are born with very short legs. The creeper allele (C) is dominant over the normal allele (c). Embryos which are homozygous for the dominant allele fail to develop into viable chickens and die before they hatch. What phenotypic ratio would you expect in the live offspring of a cross between two creeper chickens?

A. All creeper

B. 1 creeper; 2 normal

C. 2 creeper; 1 normal

D. 3 creeper; 1 normal

Which statement correctly describes genome and proteome?

A. Only the genome but not the proteome can be analysed using gel electrophoresis.

B. The genome and the proteome are the same in all tissues in an organism.

C. In cells of different tissues, the genome is the same while the proteome varies.

D. Only mutations in the proteome but not in the genome cause any variability.

Which statement correctly describes genome and proteome?

A. Only the genome but not the proteome can be analysed using gel electrophoresis.

B. The genome and the proteome are the same in all tissues in an organism.

C. In cells of different tissues, the genome is the same while the proteome varies.

D. Only mutations in the proteome but not in the genome cause any variability.

Creeper in chickens is a condition in which the chickens are born with very short legs. The creeper allele (C) is dominant over the normal allele (c). Embryos which are homozygous for the dominant allele fail to develop into viable chickens and die before they hatch. What phenotypic ratio would you expect in the live offspring of a cross between two creeper chickens?

A. All creeper

B. 1 creeper; 2 normal

C. 2 creeper; 1 normal

D. 3 creeper; 1 normal

Which pedigree chart is consistent with the inheritance of red-green colour blindness?

[Source: © International Baccalaureate Organization 2019]

Which pedigree chart is consistent with the inheritance of red-green colour blindness?

[Source: © International Baccalaureate Organization 2019]

The graph shows the incidence of trisomy resulting from non-disjunction in pregnancies at different maternal ages.

[Source: Center for Disease Control]

What can be inferred from the graph?

A. The incidence of three copies of a chromosome increases directly in proportion with the age of the mother.

B. The incidence of three sets of chromosomes increases from age 20.

C. The incidence of three copies of a chromosome increases the most from age 35.

D. The incidence of three sets of chromosomes increases the most from age 30.

Two restriction endonucleases (EcoRI and BamHI) were used to cut a DNA sample into smaller fragments. These were then subjected to gel electrophoresis and the results are shown. The lengths of the DNA fragments are measured in kilobases (kb). One kilobase is 1000 DNA bases.

[Source: © International Baccalaureate Organization 2019]

Which statement is supported by the data?

A. The DNA sample is approximately 16 kb in size.

B. Each endonuclease produces a 2 kb fragment.

C. Both endonucleases produce the same number of fragments.

D. The fragments produced using both endonucleases are all different from those produced by the individual endonucleases.

The graph shows the incidence of trisomy resulting from non-disjunction in pregnancies at different maternal ages.

[Source: Center for Disease Control]

What can be inferred from the graph?

A. The incidence of three copies of a chromosome increases directly in proportion with the age of the mother.

B. The incidence of three sets of chromosomes increases from age 20.

C. The incidence of three copies of a chromosome increases the most from age 35.

D. The incidence of three sets of chromosomes increases the most from age 30.

Two restriction endonucleases (EcoRI and BamHI) were used to cut a DNA sample into smaller fragments. These were then subjected to gel electrophoresis and the results are shown. The lengths of the DNA fragments are measured in kilobases (kb). One kilobase is 1000 DNA bases.

[Source: © International Baccalaureate Organization 2019]

Which statement is supported by the data?

A. The DNA sample is approximately 16 kb in size.

B. Each endonuclease produces a 2 kb fragment.

C. Both endonucleases produce the same number of fragments.

D. The fragments produced using both endonucleases are all different from those produced by the individual endonucleases.

The pedigree chart shows a family affected by cystic fibrosis.

[Source: © International Baccalaureate Organization 2019]

What is the genotype of the affected boy’s father?

A. AA only

B. Either AA or Aa

C. Aa only

D. aa only

The pedigree chart shows a family affected by cystic fibrosis.

[Source: © International Baccalaureate Organization 2019]

What is the genotype of the affected boy’s father?

A. AA only

B. Either AA or Aa

C. Aa only

D. aa only

Genetically modified maize, called Bt maize, is thought to be affecting the monarch butterfly (Danaus plexippus) in the USA. What is the reason for this?

A. The monarch butterfly feeds on maize nectar, which contains Bt toxin.

B. The monarch caterpillar feeds on maize leaves, which contain Bt toxin.

C. Bt toxin kills the plants that the monarch caterpillar usually eats.

D. Bt toxin is in maize pollen, which blows on to plants that the monarch caterpillar eats.

Genetically modified maize, called Bt maize, is thought to be affecting the monarch butterfly (Danaus plexippus) in the USA. What is the reason for this?

A. The monarch butterfly feeds on maize nectar, which contains Bt toxin.

B. The monarch caterpillar feeds on maize leaves, which contain Bt toxin.

C. Bt toxin kills the plants that the monarch caterpillar usually eats.

D. Bt toxin is in maize pollen, which blows on to plants that the monarch caterpillar eats.

Each gene is activated by one or more of the treatments. From the gel electrophoresis data, discuss the impact of the herbivorous mite infestation on gene activation compared to treatment with C1 and C2.

Each gene is activated by one or more of the treatments. From the gel electrophoresis data, discuss the impact of the herbivorous mite infestation on gene activation compared to treatment with C1 and C2.

Each gene is activated by one or more of the treatments. From the gel electrophoresis data, discuss the impact of the herbivorous mite infestation on gene activation compared to treatment with C1 and C2.

State the proportion of the ancestral allele for the gene GS3 in the O. rufipogon-III population.

State the proportion of the ancestral allele for the gene GS3 in the O. rufipogon-III population.

State the proportion of the ancestral allele for the gene GS3 in the O. rufipogon-III population.

A pregnant woman had fetal cells removed by chorionic villus sampling and tested. The following karyogram was produced.

[Source: Mediscan / Alamy Stock Photo]

What does this show?

A. The child is female with Down syndrome.

B. The child is female without Down syndrome.

C. The child is male with Down syndrome.

D. The child is male without Down syndrome.

A pregnant woman had fetal cells removed by chorionic villus sampling and tested. The following karyogram was produced.

[Source: Mediscan / Alamy Stock Photo]

What does this show?

A. The child is female with Down syndrome.

B. The child is female without Down syndrome.

C. The child is male with Down syndrome.

D. The child is male without Down syndrome.

The pedigree chart shows the inheritance of hemophilia in some of the descendants of Queen Victoria. Which letter points to a family member certain to be heterozygous?

[Source: © International Baccalaureate Organization 2019]

The pedigree chart shows the inheritance of hemophilia in some of the descendants of Queen Victoria. Which letter points to a family member certain to be heterozygous?

[Source: © International Baccalaureate Organization 2019]

A pair of alleles controls the secretion of antigens corresponding to blood group in saliva. Examine the pedigree chart.

[Source: © International Baccalaureate Organization 2019]

Based on this pedigree chart, which best describes the allele conferring antigen secretion in saliva?

A. Dominant

B. Recessive

C. Sex-linked

D. Co-dominant

A pair of alleles controls the secretion of antigens corresponding to blood group in saliva. Examine the pedigree chart.

[Source: © International Baccalaureate Organization 2019]

Based on this pedigree chart, which best describes the allele conferring antigen secretion in saliva?

A. Dominant

B. Recessive

C. Sex-linked

D. Co-dominant

In DNA profiling, short tandem repeats (STRs) of DNA are used, as these vary a great deal between individuals. Some skin cells were retrieved from a crime scene. Three STR sections of the DNA from these cells, from the victim and from a suspect, were analysed and the results are shown in the table.

What can be concluded from the gel electrophoresis data?

A. The suspect was at the crime scene.

B. The victim has the band moving the least distance.

C. The suspect and the victim have bands moving the same distance.

D. The skin cells have the band moving the greatest distance.

In DNA profiling, short tandem repeats (STRs) of DNA are used, as these vary a great deal between individuals. Some skin cells were retrieved from a crime scene. Three STR sections of the DNA from these cells, from the victim and from a suspect, were analysed and the results are shown in the table.

What can be concluded from the gel electrophoresis data?

A. The suspect was at the crime scene.

B. The victim has the band moving the least distance.

C. The suspect and the victim have bands moving the same distance.

D. The skin cells have the band moving the greatest distance.

Testing the chromosomes of a girl with Turner syndrome produced the following karyogram.

[Source: Turner’s syndrome karyotype 45,XO. This female lacks the second X chromosome present in the
normal karyotype. Symptoms include short stature, neck webbing, elbow deformity, widely spaced nipples with shield chest, primary amenorrhea, sexual infantilism and sterility. The ovaries are reduced to fibrous streaks. Also known as XO syndrome or ovarian short-stature syndrome. Credit: Wessex Reg. Genetics Centre. Attribution 4.0 International (CC BY 4.0).]

The condition can result from non-disjunction occurring in anaphase I of meiosis in an egg cell. Two cells result from the first division, one of which would lead to Turner syndrome. Which chromosomes will be in the other cell (polar body) at the end of meiosis I?

A. 44 autosomes and X

B. 44 autosomes and XX

C. 22 autosomes and X

D. 22 autosomes and XX

Testing the chromosomes of a girl with Turner syndrome produced the following karyogram.

[Source: Turner’s syndrome karyotype 45,XO. This female lacks the second X chromosome present in the
normal karyotype. Symptoms include short stature, neck webbing, elbow deformity, widely spaced nipples with shield chest, primary amenorrhea, sexual infantilism and sterility. The ovaries are reduced to fibrous streaks. Also known as XO syndrome or ovarian short-stature syndrome. Credit: Wessex Reg. Genetics Centre. Attribution 4.0 International (CC BY 4.0).]

The condition can result from non-disjunction occurring in anaphase I of meiosis in an egg cell. Two cells result from the first division, one of which would lead to Turner syndrome. Which chromosomes will be in the other cell (polar body) at the end of meiosis I?

A. 44 autosomes and X

B. 44 autosomes and XX

C. 22 autosomes and X

D. 22 autosomes and XX

Outline the inheritance of blood types in the ABO blood system in humans.

A two-cell sea urchin (Echinoidea) embryo was physically separated by scientists into two cells. Each cell, through further embryonic development, became an adult sea urchin.

[Source: Clker-Free-Vector-Images/Pixabay.]

What is the relationship between the two adult sea urchins?

A. They are equivalent to non-identical twins.

B. Half of the genes would be the same.

C. Both adults would have haploid cells.

D. They are clones.

Outline what occurs in cells in the first division of meiosis.

Outline what occurs in cells in the first division of meiosis.

Outline what occurs in cells in the first division of meiosis.

Outline the inheritance of blood types in the ABO blood system in humans.

Discuss the process, including potential risks and benefits, of using bacteria to genetically modify plant crop species.

A two-cell sea urchin (Echinoidea) embryo was physically separated by scientists into two cells. Each cell, through further embryonic development, became an adult sea urchin.

[Source: Clker-Free-Vector-Images/Pixabay.]

What is the relationship between the two adult sea urchins?

A. They are equivalent to non-identical twins.

B. Half of the genes would be the same.

C. Both adults would have haploid cells.

D. They are clones.

Outline the inheritance of blood types in the ABO blood system in humans.

Outline the process of DNA profiling.

Discuss the process, including potential risks and benefits, of using bacteria to genetically modify plant crop species.

Discuss the process, including potential risks and benefits, of using bacteria to genetically modify plant crop species.

Outline the process of DNA profiling.

Outline the process of DNA profiling.

Outline how sperm are produced from diploid cells in the testis and how this production can be sustained over many decades of adult life.

Distinguish between the outcomes of a cell dividing either by mitosis or meiosis.

Distinguish between the outcomes of a cell dividing either by mitosis or meiosis.

Distinguish between the outcomes of a cell dividing either by mitosis or meiosis.

Outline how sperm are produced from diploid cells in the testis and how this production can be sustained over many decades of adult life.

The electron micrograph shows a section through a plant cell.

[Source: Photo © E. Newcomb.]

In which structure(s) is the genome of the cell contained?

A. Z only

B. X, Y and Z only

C. W and X only

D. X and Y only

Outline how sperm are produced from diploid cells in the testis and how this production can be sustained over many decades of adult life.

Describe the structure of the DNA molecule.

The electron micrograph shows a section through a plant cell.

[Source: Photo © E. Newcomb.]

In which structure(s) is the genome of the cell contained?

A. Z only

B. X, Y and Z only

C. W and X only

D. X and Y only

Describe the structure of the DNA molecule.

Describe the structure of the DNA molecule.

The image shows tetrads in the anther of a lily. A tetrad is a group of four cells, produced when one mother cell divides by meiosis. The tetrad indicated by the arrow contains a total of 48 chromosomes.

[Source: [Tetrad], 2012. [image online] Available at: https://www.iasprr.org/old/iasprr-pix/lily/tetrad.jpg [accessed: 4 April 2019]. Photo courtesy of Professor Scott D. Russell.]

What is the diploid number of the plant?

A. 12

B. 24

C. 48

D. 96

The image shows tetrads in the anther of a lily. A tetrad is a group of four cells, produced when one mother cell divides by meiosis. The tetrad indicated by the arrow contains a total of 48 chromosomes.

[Source: [Tetrad], 2012. [image online] Available at: https://www.iasprr.org/old/iasprr-pix/lily/tetrad.jpg [accessed: 4 April 2019]. Photo courtesy of Professor Scott D. Russell.]

What is the diploid number of the plant?

A. 12

B. 24

C. 48

D. 96

John Cairns used the technique of autoradiography to produce photographs of DNA from the bacterium E. coli.

[Source: © Cold Spring Harbor Laboratory Press. Autoradiography of bacterium E. coli DNA - micrograph, The Chromosome of
Escherichia coli Cairns, J.P., 1963. Cold Spring Harbor Symposia, Quantitative Biology, 28(44).]

Which conclusion was drawn from his experiments?

A. The DNA in all organisms is circular.

B. DNA in E. coli naturally contains thymidine.

C. DNA replication is conservative.

D. The DNA in E. coli is 900 μm in length.

John Cairns used the technique of autoradiography to produce photographs of DNA from the bacterium E. coli.

[Source: © Cold Spring Harbor Laboratory Press. Autoradiography of bacterium E. coli DNA - micrograph, The Chromosome of
Escherichia coli Cairns, J.P., 1963. Cold Spring Harbor Symposia, Quantitative Biology, 28(44).]

Which conclusion was drawn from his experiments?

A. The DNA in all organisms is circular.

B. DNA in E. coli naturally contains thymidine.

C. DNA replication is conservative.

D. The DNA in E. coli is 900 μm in length.

Explain the need for halving the chromosome number during a sexual life cycle and how this is done.

Explain the need for halving the chromosome number during a sexual life cycle and how this is done.

Explain the need for halving the chromosome number during a sexual life cycle and how this is done.

Draw a Punnett square to show all the possible genotypes of Queen Victoria’s children.

Draw a Punnett square to show all the possible genotypes of Queen Victoria’s children.

Draw a Punnett square to show all the possible genotypes of Queen Victoria’s children.

A nucleus was removed from a cell of sheep P and fused with a denucleated egg cell of sheep Q. This was transplanted into the uterus of sheep R, which gave birth to Dolly.

[Source: Photo courtesy of The Roslin Institute, The University of Edinburgh, Roslin, Scotland, UK, n.d. Dolly the Sheep
in a field at The Roslin Institute. [image online] Available at: https://www.livescience.com/57961-dolly-the-sheepannouncement-
20-year-anniversary.html [Accessed 23 March 2020].]

Which describes Dolly?

A. A clone of sheep P, because Dolly was formed from the nucleus of its udder cell

B. A clone of sheep Q, because Dolly was formed from one of its egg cells

C. A clone of sheep R, because Dolly developed in its uterus

D. Not a proper clone, as more than one sheep was involved in the development

A nucleus was removed from a cell of sheep P and fused with a denucleated egg cell of sheep Q. This was transplanted into the uterus of sheep R, which gave birth to Dolly.

[Source: Photo courtesy of The Roslin Institute, The University of Edinburgh, Roslin, Scotland, UK, n.d. Dolly the Sheep
in a field at The Roslin Institute. [image online] Available at: https://www.livescience.com/57961-dolly-the-sheepannouncement-
20-year-anniversary.html [Accessed 23 March 2020].]

Which describes Dolly?

A. A clone of sheep P, because Dolly was formed from the nucleus of its udder cell

B. A clone of sheep Q, because Dolly was formed from one of its egg cells

C. A clone of sheep R, because Dolly developed in its uterus

D. Not a proper clone, as more than one sheep was involved in the development

Suggest possible benefits and risks of using genetic modification to develop varieties of crop plant with traits such as drought resistance.

Suggest possible benefits and risks of using genetic modification to develop varieties of crop plant with traits such as drought resistance.

Explain the reasons for none of the females in the pedigree chart having hemophilia.

Suggest possible benefits and risks of using genetic modification to develop varieties of crop plant with traits such as drought resistance.

Explain the reasons for none of the females in the pedigree chart having hemophilia.

Explain the reasons for none of the females in the pedigree chart having hemophilia.

The karyogram shown belongs to a human being.

[Source: Reproduced from Tennakoon J, Kandasamy Y, Alcock G, Koh TH. Edwards syndrome with double trisomy. Singapore Med J. 2008 Jul;49(7):e190-1. PMID: 18695855.]

What can be deduced from this karyogram?

A. The person is a male with Down syndrome.

B. The person is a female with Down syndrome.

C. The person is a male with a genetic disorder.

D. The person is a female with a missing chromosome.

The karyogram shown belongs to a human being.

[Source: Reproduced from Tennakoon J, Kandasamy Y, Alcock G, Koh TH. Edwards syndrome with double trisomy. Singapore Med J. 2008 Jul;49(7):e190-1. PMID: 18695855.]

What can be deduced from this karyogram?

A. The person is a male with Down syndrome.

B. The person is a female with Down syndrome.

C. The person is a male with a genetic disorder.

D. The person is a female with a missing chromosome.

A cloning method used for livestock involves in vitro fertilization (IVF) with selected male and female gametes. The diagram shows the steps followed after in vitro fertilization.

[Source: Aldona Griskeviciene / Shutterstock.com.]

What does X represent?

A. A group of eggs

B. An embryo

C. A follicle

D. A group of zygotes

A family has a history of hemophilia that is caused by a sex-linked recessive allele. A woman from this family is a carrier and marries a man who does not have the allele. Showing your working, determine the probability of their children having the disease.

A cloning method used for livestock involves in vitro fertilization (IVF) with selected male and female gametes. The diagram shows the steps followed after in vitro fertilization.

[Source: Aldona Griskeviciene / Shutterstock.com.]

What does X represent?

A. A group of eggs

B. An embryo

C. A follicle

D. A group of zygotes

A family has a history of hemophilia that is caused by a sex-linked recessive allele. A woman from this family is a carrier and marries a man who does not have the allele. Showing your working, determine the probability of their children having the disease.

A family has a history of hemophilia that is caused by a sex-linked recessive allele. A woman from this family is a carrier and marries a man who does not have the allele. Showing your working, determine the probability of their children having the disease.

Outline the role of tRNA in hemoglobin synthesis.

Outline the role of tRNA in hemoglobin synthesis.

Outline the role of tRNA in hemoglobin synthesis.

Draw the symbol for individual X on the diagram.

Describe how DNA profiling can be used to establish paternity.

Describe how DNA profiling can be used to establish paternity.

Describe how DNA profiling can be used to establish paternity.

Explain Cairns’s technique to measure the length of the DNA molecule.

Explain Cairns’s technique to measure the length of the DNA molecule.

Explain Cairns’s technique to measure the length of the DNA molecule.

Draw the symbol for individual X on the diagram.

Amniocentesis and chorionic villus sampling (CVS) are used to test for fetal abnormalities. Which statement is a valid comparison between the two tests?

A.  CVS is performed later in pregnancy but has more risk of miscarriage than amniocentesis.

B.  Amniocentesis is performed earlier in pregnancy but has more risk of miscarriage than CVS.

C.  CVS is performed earlier in pregnancy but has more risk of miscarriage than amniocentesis.

D.  Amniocentesis is performed later in pregnancy but has more risk of miscarriage than CVS.

Draw the symbol for individual X on the diagram.

Calculate the probability of male Y having an allele for the disorder.

Calculate the probability of male Y having an allele for the disorder.

Amniocentesis and chorionic villus sampling (CVS) are used to test for fetal abnormalities. Which statement is a valid comparison between the two tests?

A.  CVS is performed later in pregnancy but has more risk of miscarriage than amniocentesis.

B.  Amniocentesis is performed earlier in pregnancy but has more risk of miscarriage than CVS.

C.  CVS is performed earlier in pregnancy but has more risk of miscarriage than amniocentesis.

D.  Amniocentesis is performed later in pregnancy but has more risk of miscarriage than CVS.

Calculate the probability of male Y having an allele for the disorder.

Explain how a single base substitution mutation in DNA can cause a change to a protein.

A couple have four children whose blood groups are A, B and AB. What is the likely combination of the parents’ genotypes?

A.  I^Ai and I^Bi

B.  I^Ai and I^BI^B

C.  I^AI^B and ii

D.  I^AI^A and I^BI^B

Explain how a single base substitution mutation in DNA can cause a change to a protein.

Explain how a single base substitution mutation in DNA can cause a change to a protein.

Identify the stage of meiosis shown where exchange of genetic material occurs.

A couple have four children whose blood groups are A, B and AB. What is the likely combination of the parents’ genotypes?

A.  I^Ai and I^Bi

B.  I^Ai and I^BI^B

C.  I^AI^B and ii

D.  I^AI^A and I^BI^B

Identify the stage of meiosis shown where exchange of genetic material occurs.

Identify the stage of meiosis shown where exchange of genetic material occurs.

A total of 271 164 people were tested for blood groups in Mexico. The pie chart summarizes the ABO blood group distribution.

^{[Source: Canizalez-Román, A. et al., 2018. Blood Groups Distribution and Gene Diversity
of the ABO and Rh (D) Loci in the Mexican Population.
BioMed Research International, (Article ID 1925619).
http://dx.doi.org/10.1155/2018/1925619. Public domain.]}

What can be concluded from the ABO blood group distribution in Mexico?

A.  Allele frequencies are not the same for all blood group alleles.

B.  The majority of the Mexican population shows a co-dominant phenotype.

C.  Most of the Mexican population can receive blood from all blood groups.

D.  Only 2 % of the Mexican population have a heterozygous genotype for blood groups.

A short sequence of amino acids (represented by letters) in cytochrome c is shown for six vertebrates. Letters in bold indicate identical amino acids for all species.

Which statement refers to this section of cytochrome c?

A.  The DNA base sequences for human and rhesus monkey are different.

B.  The most DNA base changes are between humans and snapping turtles.

C.  The largest number of amino acid differences is two.

D.  The amino acid at position 32 is the most variable.

A short sequence of amino acids (represented by letters) in cytochrome c is shown for six vertebrates. Letters in bold indicate identical amino acids for all species.

Which statement refers to this section of cytochrome c?

A.  The DNA base sequences for human and rhesus monkey are different.

B.  The most DNA base changes are between humans and snapping turtles.

C.  The largest number of amino acid differences is two.

D.  The amino acid at position 32 is the most variable.

Explain the conclusion that can be drawn from Cross 1.

Explain the conclusion that can be drawn from Cross 1.

A total of 271 164 people were tested for blood groups in Mexico. The pie chart summarizes the ABO blood group distribution.

^{[Source: Canizalez-Román, A. et al., 2018. Blood Groups Distribution and Gene Diversity
of the ABO and Rh (D) Loci in the Mexican Population.
BioMed Research International, (Article ID 1925619).
http://dx.doi.org/10.1155/2018/1925619. Public domain.]}

What can be concluded from the ABO blood group distribution in Mexico?

A.  Allele frequencies are not the same for all blood group alleles.

B.  The majority of the Mexican population shows a co-dominant phenotype.

C.  Most of the Mexican population can receive blood from all blood groups.

D.  Only 2 % of the Mexican population have a heterozygous genotype for blood groups.

Explain the conclusion that can be drawn from Cross 1.

Explain the conclusion that can be drawn from Cross 1.

Explain the conclusion that can be drawn from Cross 1.

Explain the conclusion that can be drawn from Cross 1.

The pedigree chart shows the inheritance of three generations of Duane syndrome, a condition caused by a dominant allele that affects alignment of the eyes.

_{[Source: Yang, M.-M., Ho, M. et al., 2013. Pedigree of a Chinese family with Duane retraction syndrome. [diagram online]
Available at: https://www.researchgate.net/figure/Pedigree-of-a-Chinese-family-with-Duane-retraction-syndrome-
Squares-men-circles_fig1_236921765 [Accessed 5 October 2021]. Public domain.]}

If individuals II:1 and II:2 had a third child, what is the probability that the child would have Duane syndrome?

A.  25 %

B.  50 %

C.  75 %

D.  100 %

The pedigree chart shows the inheritance of three generations of Duane syndrome, a condition caused by a dominant allele that affects alignment of the eyes.

_{[Source: Yang, M.-M., Ho, M. et al., 2013. Pedigree of a Chinese family with Duane retraction syndrome. [diagram online]
Available at: https://www.researchgate.net/figure/Pedigree-of-a-Chinese-family-with-Duane-retraction-syndrome-
Squares-men-circles_fig1_236921765 [Accessed 5 October 2021]. Public domain.]}

If individuals II:1 and II:2 had a third child, what is the probability that the child would have Duane syndrome?

A.  25 %

B.  50 %

C.  75 %

D.  100 %

The pedigree chart shows the inheritance of three generations of Duane syndrome, a condition caused by a dominant allele that affects alignment of the eyes.

_{[Source: Yang, M.-M., Ho, M. et al., 2013. Pedigree of a Chinese family with Duane retraction syndrome. [diagram online]
Available at: https://www.researchgate.net/figure/Pedigree-of-a-Chinese-family-with-Duane-retraction-syndrome-
Squares-men-circles_fig1_236921765 [Accessed 5 October 2021]. Public domain.]}

If individuals II:1 and II:2 had a third child, what is the probability that the child would have Duane syndrome?

A.  25 %

B.  50 %

C.  75 %

D.  100 %

The pedigree chart shows the inheritance of three generations of Duane syndrome, a condition caused by a dominant allele that affects alignment of the eyes.

_{[Source: Yang, M.-M., Ho, M. et al., 2013. Pedigree of a Chinese family with Duane retraction syndrome. [diagram online]
Available at: https://www.researchgate.net/figure/Pedigree-of-a-Chinese-family-with-Duane-retraction-syndrome-
Squares-men-circles_fig1_236921765 [Accessed 5 October 2021]. Public domain.]}

If individuals II:1 and II:2 had a third child, what is the probability that the child would have Duane syndrome?

A.  25 %

B.  50 %

C.  75 %

D.  100 %

State how many chromosomes there would be in male or female gametes of L. purpureus.

State how many chromosomes there would be in male or female gametes of L. purpureus.

State how many chromosomes there would be in male or female gametes of L. purpureus.

Outline the sequence of events that occurs during mitosis.

Scientists sequenced the genes in each chromosome of chimpanzees (Pan troglodytes) and humans (Homo sapiens). The graph shows the mean divergence between the genes of these species by chromosome.

_{[Source: Material from: Mikkelsen, T.S. et al, Initial sequence of the chimpanzee genome and 
comparison with the human genome, 2005 Nature, reproduced with permission of SNCSC.]}

What can be deduced from this data?

A.  Autosomes are more similar than Y chromosomes.

B.  There is the same number of chromosomes in humans and chimpanzees.

C.  Humans are more closely related to chimpanzees than to other species.

D.  Smaller chromosomes are more similar than larger chromosomes.

Scientists sequenced the genes in each chromosome of chimpanzees (Pan troglodytes) and humans (Homo sapiens). The graph shows the mean divergence between the genes of these species by chromosome.

_{[Source: Material from: Mikkelsen, T.S. et al, Initial sequence of the chimpanzee genome and 
comparison with the human genome, 2005 Nature, reproduced with permission of SNCSC.]}

What can be deduced from this data?

A.  Autosomes are more similar than Y chromosomes.

B.  There is the same number of chromosomes in humans and chimpanzees.

C.  Humans are more closely related to chimpanzees than to other species.

D.  Smaller chromosomes are more similar than larger chromosomes.

Outline the sequence of events that occurs during mitosis.

Outline the sequence of events that occurs during mitosis.

Scientists sequenced the genes in each chromosome of chimpanzees (Pan troglodytes) and humans (Homo sapiens). The graph shows the mean divergence between the genes of these species by chromosome.

_{[Source: Material from: Mikkelsen, T.S. et al, Initial sequence of the chimpanzee genome and 
comparison with the human genome, 2005 Nature, reproduced with permission of SNCSC.]}

What can be deduced from this data?

A.  Autosomes are more similar than Y chromosomes.

B.  There is the same number of chromosomes in humans and chimpanzees.

C.  Humans are more closely related to chimpanzees than to other species.

D.  Smaller chromosomes are more similar than larger chromosomes.

Scientists sequenced the genes in each chromosome of chimpanzees (Pan troglodytes) and humans (Homo sapiens). The graph shows the mean divergence between the genes of these species by chromosome.

_{[Source: Material from: Mikkelsen, T.S. et al, Initial sequence of the chimpanzee genome and 
comparison with the human genome, 2005 Nature, reproduced with permission of SNCSC.]}

What can be deduced from this data?

A.  Autosomes are more similar than Y chromosomes.

B.  There is the same number of chromosomes in humans and chimpanzees.

C.  Humans are more closely related to chimpanzees than to other species.

D.  Smaller chromosomes are more similar than larger chromosomes.

The micrograph shows a cross section of a lily (Lilium longiflorum) anther.

^{[Source: Sinhyu / iStock.]}

What can be found in X?

A.  Haploid nuclei produced by meiosis

B.  Diploid nuclei produced by fertilization

C.  Haploid nuclei produced by mitosis

D.  Diploid nuclei produced by pollination

The micrograph shows a cross section of a lily (Lilium longiflorum) anther.

^{[Source: Sinhyu / iStock.]}

What can be found in X?

A.  Haploid nuclei produced by meiosis

B.  Diploid nuclei produced by fertilization

C.  Haploid nuclei produced by mitosis

D.  Diploid nuclei produced by pollination

DNA methylation profiles in zebrafish (Danio rerio) gametes were determined. The methylated areas were divided into three groups according to the amount of methylation: high, medium and low methylation.

^{[Source: Potok, M.E., Nix, D.A., Parnell, T.J. and Cairns, B.R., 2013.
Reprogramming the Maternal Zebrafish Genome afterFertilization to
Match the Paternal Methylation Pattern.
Cell, [e-journal] 153(4), pp. 759–772. http://dx.doi.org/10.1016/j.
cell.2013.04.030.]}

Methylation of DNA in sperm and egg is removed immediately after fertilization. What is the reason for this?

A.  Methylation allows RNA polymerase to join the promoter.

B.  It is needed to form homologous pairs of chromosomes.

C.  It allows expression of genes linked to early development.

D.  Transcription of promoters only occurs in methylated genes.

DNA methylation profiles in zebrafish (Danio rerio) gametes were determined. The methylated areas were divided into three groups according to the amount of methylation: high, medium and low methylation.

^{[Source: Potok, M.E., Nix, D.A., Parnell, T.J. and Cairns, B.R., 2013.
Reprogramming the Maternal Zebrafish Genome afterFertilization to
Match the Paternal Methylation Pattern.
Cell, [e-journal] 153(4), pp. 759–772. http://dx.doi.org/10.1016/j.
cell.2013.04.030.]}

Methylation of DNA in sperm and egg is removed immediately after fertilization. What is the reason for this?

A.  Methylation allows RNA polymerase to join the promoter.

B.  It is needed to form homologous pairs of chromosomes.

C.  It allows expression of genes linked to early development.

D.  Transcription of promoters only occurs in methylated genes.