Additional higher level

Describe the production of hybridoma cells.

Describe the production of hybridoma cells.

Describe the production of hybridoma cells.

Describe the role of ADH in human osmoregulation.

Describe the role of ADH in human osmoregulation.

Describe the role of ADH in human osmoregulation.

Describe the process of photolysis in photosynthesis.

Concerns have been raised about the effect of rising pollution levels on sperm production in men. To investigate the possible effects of pollution on spermatogenesis, sperm samples from men of similar ages were collected in Kolkata in the 1980s and 2000s. The box plot represents the mean and range of sperm counts in the 1980s and 2000s.

[Source: Republished with permission of Elsevier Science and Technology Journals, from ‘Semen quality and age-specific changes: A study between two decades on 3729 male partners of couples with normal sperm count and attending an andrology laboratory for infertility-related problems in an Indian city’, Dyutiman Mukhopadhyay, Alex C. Varghese, Manisha Pal, Sudip K. Banerjee, Asok K. Bhattacharyya, Rakesh K. Sharma, and Ashok Agarwal, Fertility and Sterility, 93 (7), 2009; permission conveyed through Copyright Clearance Center, Inc]

A hypothesis has been suggested that pollution may have a negative effect on spermatogenesis. Evaluate whether the data support this hypothesis.

Concerns have been raised about the effect of rising pollution levels on sperm production in men. To investigate the possible effects of pollution on spermatogenesis, sperm samples from men of similar ages were collected in Kolkata in the 1980s and 2000s. The box plot represents the mean and range of sperm counts in the 1980s and 2000s.

[Source: Republished with permission of Elsevier Science and Technology Journals, from ‘Semen quality and age-specific changes: A study between two decades on 3729 male partners of couples with normal sperm count and attending an andrology laboratory for infertility-related problems in an Indian city’, Dyutiman Mukhopadhyay, Alex C. Varghese, Manisha Pal, Sudip K. Banerjee, Asok K. Bhattacharyya, Rakesh K. Sharma, and Ashok Agarwal, Fertility and Sterility, 93 (7), 2009; permission conveyed through Copyright Clearance Center, Inc]

A hypothesis has been suggested that pollution may have a negative effect on spermatogenesis. Evaluate whether the data support this hypothesis.

Concerns have been raised about the effect of rising pollution levels on sperm production in men. To investigate the possible effects of pollution on spermatogenesis, sperm samples from men of similar ages were collected in Kolkata in the 1980s and 2000s. The box plot represents the mean and range of sperm counts in the 1980s and 2000s.

[Source: Republished with permission of Elsevier Science and Technology Journals, from ‘Semen quality and age-specific changes: A study between two decades on 3729 male partners of couples with normal sperm count and attending an andrology laboratory for infertility-related problems in an Indian city’, Dyutiman Mukhopadhyay, Alex C. Varghese, Manisha Pal, Sudip K. Banerjee, Asok K. Bhattacharyya, Rakesh K. Sharma, and Ashok Agarwal, Fertility and Sterility, 93 (7), 2009; permission conveyed through Copyright Clearance Center, Inc]

A hypothesis has been suggested that pollution may have a negative effect on spermatogenesis. Evaluate whether the data support this hypothesis.

Describe the process of photolysis in photosynthesis.

Describe the process of photolysis in photosynthesis.

Describe the process of crossing over.

The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.

Describe the process of crossing over.

The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.

The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.

Describe the process of crossing over.

Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.

Compare and contrast the processes of spermatogenesis and oogenesis.

Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.

Compare and contrast the processes of spermatogenesis and oogenesis.

Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.

Compare and contrast the processes of spermatogenesis and oogenesis.

Nitrogen is part of many important substances in living organisms.

Distinguish between transcription and translation.

Which letter (A–D) indicates where a new nucleotide would attach?

Which letter (A–D) indicates where a new nucleotide would attach?

Nitrogen is part of many important substances in living organisms.

Distinguish between transcription and translation.

Nitrogen is part of many important substances in living organisms.

Distinguish between transcription and translation.

Nitrogen is part of many important substances in living organisms.

Explain how insects excrete nitrogenous wastes.

Nitrogen is part of many important substances in living organisms.

Explain how insects excrete nitrogenous wastes.

Nitrogen is part of many important substances in living organisms.

Explain how insects excrete nitrogenous wastes.

Plants have widespread influences, from food chains to climate change.

Draw a labelled diagram of the internal structure of a seed.

Mucus traps pathogenic bacteria. Mucus also attracts viruses that attack pathogenic bacteria.

[Source: EYE OF SCIENCE/SCIENCE PHOTO LIBRARY]

What part of the immune system do these viruses resemble in their function?

A. Antigens

B. Antibodies

C. Memory cells

D. Antibiotics

Mucus traps pathogenic bacteria. Mucus also attracts viruses that attack pathogenic bacteria.

[Source: EYE OF SCIENCE/SCIENCE PHOTO LIBRARY]

What part of the immune system do these viruses resemble in their function?

A. Antigens

B. Antibodies

C. Memory cells

D. Antibiotics

Plants have widespread influences, from food chains to climate change.

Draw a labelled diagram of the internal structure of a seed.

The image shows a portion of a cell containing a mitochondrion.

[Source: ‘TEM of a mitochondrion’ by Prof. R. Bellairs. Credit: Prof. R. Bellairs. CC BY 4.0.]

Where do glycolysis and electron transport occur?

The image shows a portion of a cell containing a mitochondrion.

[Source: ‘TEM of a mitochondrion’ by Prof. R. Bellairs. Credit: Prof. R. Bellairs. CC BY 4.0.]

Where do glycolysis and electron transport occur?

Plants have widespread influences, from food chains to climate change.

Draw a labelled diagram of the internal structure of a seed.

Plants have widespread influences, from food chains to climate change.

Explain the process of water uptake and transport by plants.

Plants have widespread influences, from food chains to climate change.

Explain the process of water uptake and transport by plants.

Plants have widespread influences, from food chains to climate change.

Explain the process of water uptake and transport by plants.

Which letter identifies phloem?

[Source: E R DEGGINGER/Getty Images]

Which letter identifies phloem?

[Source: E R DEGGINGER/Getty Images]

Compare and contrast the location of ATP synthase and the movement of protons during aerobic cell respiration and photosynthesis.

Compare and contrast the location of ATP synthase and the movement of protons during aerobic cell respiration and photosynthesis.

In a plant, what tissue(s) is/are specially adapted to transport sucrose?

In a plant, what tissue(s) is/are specially adapted to transport sucrose?

Compare and contrast the location of ATP synthase and the movement of protons during aerobic cell respiration and photosynthesis.

What structure is indicated by the arrows?

[Source: Courtesy Roger Craig, University of Massachusetts]

A. One muscle fibre

B. One sarcomere

C. One myofibril

D. One Z line

What structure is indicated by the arrows?

[Source: Courtesy Roger Craig, University of Massachusetts]

A. One muscle fibre

B. One sarcomere

C. One myofibril

D. One Z line

The diagram shows the female reproductive system.

[Source: © International Baccalaureate Organization 2017]

Which structures do K and L identify?

The diagram shows the female reproductive system.

[Source: © International Baccalaureate Organization 2017]

Which structures do K and L identify?

What could account for this distribution of height in a population?

[Source: Graph adapted from Six Minutes http://sixminutes.dlugan.com/good-public-speaker-average/]

A. Gene linkage

B. Dominant alleles

C. Independent assortment

D. Multiple genes

Calculate the difference (in mm²) in the mean leaf area of L6 at the start of stage 4 between the leaves of plants grown in long days and short days.

What could account for this distribution of height in a population?

[Source: Graph adapted from Six Minutes http://sixminutes.dlugan.com/good-public-speaker-average/]

A. Gene linkage

B. Dominant alleles

C. Independent assortment

D. Multiple genes

Outline how plants make use of the different wavelengths of light.

Calculate the difference (in mm²) in the mean leaf area of L6 at the start of stage 4 between the leaves of plants grown in long days and short days.

Outline how plants make use of the different wavelengths of light.

Outline how plants make use of the different wavelengths of light.

Calculate the difference (in mm²) in the mean leaf area of L6 at the start of stage 4 between the leaves of plants grown in long days and short days.

Explain how organic compounds are transported within plants.

Explain how organic compounds are transported within plants.

Explain how organic compounds are transported within plants.

Outline the roles of estrogen and progesterone in females during human reproduction.

Suggest reasons for the difference in end of day starch concentrations in stage 2 (S2) for the plants grown in long days and short days.

Outline the roles of estrogen and progesterone in females during human reproduction.

Outline the roles of estrogen and progesterone in females during human reproduction.

Suggest reasons for the difference in end of day starch concentrations in stage 2 (S2) for the plants grown in long days and short days.

Explain the production and role of antibodies in defense against bacterial pathogens in humans.

Suggest reasons for the difference in end of day starch concentrations in stage 2 (S2) for the plants grown in long days and short days.

Explain the production and role of antibodies in defense against bacterial pathogens in humans.

Explain the production and role of antibodies in defense against bacterial pathogens in humans.

Explain the process of muscle contraction.

Explain the process of muscle contraction.

Explain the process of muscle contraction.

Evaluate the limitations of using a potometer in the investigation you suggested in (a).

Evaluate the limitations of using a potometer in the investigation you suggested in (a).

Evaluate the limitations of using a potometer in the investigation you suggested in (a).

In which image are polysomes visible? (The images do not have the same magnification)

In which image are polysomes visible? (The images do not have the same magnification)

Outline the role of tRNA activating enzymes in translation.

Outline the role of tRNA activating enzymes in translation.

Outline the role of tRNA activating enzymes in translation.

The micrograph shows the cross-section of the vascular tissue in a dicotyledonous root. Which letter identifies phloem sieve tubes?

[Source: Wendy Paul]

The micrograph shows the cross-section of the vascular tissue in a dicotyledonous root. Which letter identifies phloem sieve tubes?

[Source: Wendy Paul]

The image shows seedlings that have been exposed to unidirectional light.

[Source: The Micro Gardener (https://themicrogardener.com/prevent-fix-leggy-seedlings/)]

Which statement explains the growth towards the light source?

A. Light causes auxin to inhibit cell division in the shoot meristem.

B. Light causes auxin to promote cell division in the shoot meristem.

C. Auxin is concentrated in the side of the shoot with light and inhibits cell elongation.

D. Auxin is concentrated in the side of the shoot without light and promotes cell elongation.

The image shows seedlings that have been exposed to unidirectional light.

[Source: The Micro Gardener (https://themicrogardener.com/prevent-fix-leggy-seedlings/)]

Which statement explains the growth towards the light source?

A. Light causes auxin to inhibit cell division in the shoot meristem.

B. Light causes auxin to promote cell division in the shoot meristem.

C. Auxin is concentrated in the side of the shoot with light and inhibits cell elongation.

D. Auxin is concentrated in the side of the shoot without light and promotes cell elongation.

The diagram shows two states of skeletal muscle, relaxed and contracted.

[Source: Provophys/Wikipedia. File licensed under CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)]

Which process is part of muscle contraction?

A. Myosin filaments cause the actin filaments to shorten.

B. Ca²⁺ from the sarcoplasmic reticulum binds to the myosin heads.

C. ATP provides energy for the movement of the myosin heads.

D. Ca²⁺ binds to tropomyosin and uncovers troponin.

The diagram shows two states of skeletal muscle, relaxed and contracted.

[Source: Provophys/Wikipedia. File licensed under CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)]

Which process is part of muscle contraction?

A. Myosin filaments cause the actin filaments to shorten.

B. Ca²⁺ from the sarcoplasmic reticulum binds to the myosin heads.

C. ATP provides energy for the movement of the myosin heads.

D. Ca²⁺ binds to tropomyosin and uncovers troponin.

Label a peptide bond in the diagram of a polypeptide.

Label a peptide bond in the diagram of a polypeptide.

Label a peptide bond in the diagram of a polypeptide.

The image shows a light micrograph of tissue stained with a dye that binds to the nucleic acids in a cell.

[Source: by Jose Luis Calvo/Shutterstock]

What is the major purpose of the tissue depicted in the image?

A. Absorption of digested food

B. Production of insulin

C. Spermatogenesis

D. Fertilization

The image shows a light micrograph of tissue stained with a dye that binds to the nucleic acids in a cell.

[Source: by Jose Luis Calvo/Shutterstock]

What is the major purpose of the tissue depicted in the image?

A. Absorption of digested food

B. Production of insulin

C. Spermatogenesis

D. Fertilization

The diagram shows the arrangement of introns and exons in a segment of pre-mRNA. Pre-mRNA is immature mRNA containing introns and exons.

Which is a mature mRNA molecule derived from the pre-mRNA by splicing?

[Source: © International Baccalaureate Organization 2019]

Hershey and Chase used a bacteriophage (a virus that infects bacteria) to investigate the chemical nature of genes. The diagram shows a bacteriophage.

The diagram shows the arrangement of introns and exons in a segment of pre-mRNA. Pre-mRNA is immature mRNA containing introns and exons.

Which is a mature mRNA molecule derived from the pre-mRNA by splicing?

[Source: © International Baccalaureate Organization 2019]

The image shows a polysome in a bacterial cell.

[Source: © International Baccalaureate Organization 2019]

How many genes have been transcribed?

A. 1

B. 2

C. 3

D. 4 

Hershey and Chase used a bacteriophage (a virus that infects bacteria) to investigate the chemical nature of genes. The diagram shows a bacteriophage.

The image shows a polysome in a bacterial cell.

[Source: © International Baccalaureate Organization 2019]

How many genes have been transcribed?

A. 1

B. 2

C. 3

D. 4 

The first enzyme in the metabolic pathway that produces isoleucine is threonine deaminase. Which graph illustrates the relationship between threonine deaminase activity and threonine concentration?

[Source: © International Baccalaureate Organization 2019]

The first enzyme in the metabolic pathway that produces isoleucine is threonine deaminase. Which graph illustrates the relationship between threonine deaminase activity and threonine concentration?

[Source: © International Baccalaureate Organization 2019]

The electron micrograph shows a section through part of an animal cell.

[Source: https://en.wikipedia.org/wiki/Mitochondrion#/media/File:Mitochondria,mammalian_lung_-TEM.jpg,
by Louisa Howard.]

Which process is occurring on the structures labelled X?

A. The Krebs cycle

B. The link reaction

C. Glycolysis

D. Phosphorylation of ADP

The electron micrograph shows a section through part of an animal cell.

[Source: https://en.wikipedia.org/wiki/Mitochondrion#/media/File:Mitochondria,mammalian_lung_-TEM.jpg,
by Louisa Howard.]

Which process is occurring on the structures labelled X?

A. The Krebs cycle

B. The link reaction

C. Glycolysis

D. Phosphorylation of ADP

Label region X and structure Y on the diagram of the kidney.

[Source: PeterHermesFurian/iStock]

Label region X and structure Y on the diagram of the kidney.

[Source: PeterHermesFurian/iStock]

Label region X and structure Y on the diagram of the kidney.

[Source: PeterHermesFurian/iStock]

The diagram shows compounds in the Krebs cycle labelled as X, Y and Z.

[Source: © International Baccalaureate Organization 2019]

How many carbon atoms are there in Y and in the acetyl group of acetyl CoA?

The diagram shows compounds in the Krebs cycle labelled as X, Y and Z.

[Source: © International Baccalaureate Organization 2019]

How many carbon atoms are there in Y and in the acetyl group of acetyl CoA?

The image shows a cross-section of a flower.

[Source: © International Baccalaureate Organization 2019]

Where does production of haploid gametes occur?

A. I and II only

B. III and IV only

C. I and III only

D. II and IV only

The cheetah (Acinonyx jubatus) is a large cat found in Africa. It has been discovered that organs could be transferred between any two individuals without rejection of the organ.

What is the probable reason for this?

A. Cheetahs have poor reproductive success.

B. Cheetahs have high heterozygosity.

C. Cheetahs have a large gene pool.

D. Cheetahs have a small gene pool.

The image shows a cross-section of a flower.

[Source: © International Baccalaureate Organization 2019]

Where does production of haploid gametes occur?

A. I and II only

B. III and IV only

C. I and III only

D. II and IV only

The cheetah (Acinonyx jubatus) is a large cat found in Africa. It has been discovered that organs could be transferred between any two individuals without rejection of the organ.

What is the probable reason for this?

A. Cheetahs have poor reproductive success.

B. Cheetahs have high heterozygosity.

C. Cheetahs have a large gene pool.

D. Cheetahs have a small gene pool.

Describe the role of oxygen in aerobic cell respiration.

The image shows part of a section through the stem of a non-woody plant.

William Bateson and Reginald Punnett used the sweet pea (Lathyrus odoratus) in genetics studies in the early 20^th century. Pure-breeding plants that produced purple flowers and long pollen grains were crossed with pure-breeding plants that produced red flowers and round pollen grains. The resulting offspring all produced purple flowers and long pollen grains. Two of the F₁ generation plants were crossed. The table shows the ratio of phenotypes in the F₂ generation. 

What is an explanation for these experimental results?

A. Purple flowers and long pollen grains are dominant and the alleles have assorted independently.

B. The genes for flower colour and pollen shape are linked and all plants producing long pollen grains are recombinants.

C. The genes for flower colour and pollen shape are linked and all plants producing red flowers are recombinants.

D. Plants producing purple flowers and round pollen grains arose through crossing over.

The image shows part of a section through the stem of a non-woody plant.

William Bateson and Reginald Punnett used the sweet pea (Lathyrus odoratus) in genetics studies in the early 20^th century. Pure-breeding plants that produced purple flowers and long pollen grains were crossed with pure-breeding plants that produced red flowers and round pollen grains. The resulting offspring all produced purple flowers and long pollen grains. Two of the F₁ generation plants were crossed. The table shows the ratio of phenotypes in the F₂ generation. 

What is an explanation for these experimental results?

A. Purple flowers and long pollen grains are dominant and the alleles have assorted independently.

B. The genes for flower colour and pollen shape are linked and all plants producing long pollen grains are recombinants.

C. The genes for flower colour and pollen shape are linked and all plants producing red flowers are recombinants.

D. Plants producing purple flowers and round pollen grains arose through crossing over.

Describe the role of oxygen in aerobic cell respiration.

Describe the role of oxygen in aerobic cell respiration.

The diagram shows the chromosomes derived from a single homologous pair following meiosis in a diploid cell.

Which diagram represents the homologous pair from which these chromosomes were derived?

[Source: © International Baccalaureate Organization 2019]

The diagram shows the chromosomes derived from a single homologous pair following meiosis in a diploid cell.

Which diagram represents the homologous pair from which these chromosomes were derived?

[Source: © International Baccalaureate Organization 2019]

The table shows the results of blood type tests on samples from four individuals. Which row represents an individual who can accept transfusions from people with blood type AB?

[Source: © International Baccalaureate Organization 2019]

The image is a cross section through an Ammophila leaf, which grows on coastal sand dunes.

[Source: Charles Good: The Ohio State University at Lima]

What feature suggests that Ammophila is a xerophyte?

A. The leaf surface area is increased.

B. The rolled leaf reduces the upper epidermis area.

C. The rolled leaf protects the lower epidermis from the wind.

D. The lower epidermis can transpire more easily.

The table shows the results of blood type tests on samples from four individuals. Which row represents an individual who can accept transfusions from people with blood type AB?

[Source: © International Baccalaureate Organization 2019]

The image is a cross section through an Ammophila leaf, which grows on coastal sand dunes.

[Source: Charles Good: The Ohio State University at Lima]

What feature suggests that Ammophila is a xerophyte?

A. The leaf surface area is increased.

B. The rolled leaf reduces the upper epidermis area.

C. The rolled leaf protects the lower epidermis from the wind.

D. The lower epidermis can transpire more easily.

The photomicrograph shows a section through the top of a plant shoot.

[Source: Charles Good: The Ohio State University at Lima]

What are the structures labelled X and Y?

The image shows a transverse section through a collecting duct in a vertebrate kidney.

[Source: Professor Peter Takizawa, Yale University]

How is the movement of materials across the wall of the collecting duct affected by the release of ADH from the pituitary gland?

A. There is increased movement of water in the direction of arrow I.

B. There is increased movement of sodium in the direction of arrow I.

C. There is increased movement of water in the direction of arrow II.

D. There is increased movement of sodium in the direction of arrow II.

The photomicrograph shows a section through the top of a plant shoot.

[Source: Charles Good: The Ohio State University at Lima]

What are the structures labelled X and Y?

The image shows a transverse section through a collecting duct in a vertebrate kidney.

[Source: Professor Peter Takizawa, Yale University]

How is the movement of materials across the wall of the collecting duct affected by the release of ADH from the pituitary gland?

A. There is increased movement of water in the direction of arrow I.

B. There is increased movement of sodium in the direction of arrow I.

C. There is increased movement of water in the direction of arrow II.

D. There is increased movement of sodium in the direction of arrow II.

DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.

Label with an R the tissue where the red dye would appear.

DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.

DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.

Label with an R the tissue where the red dye would appear.

Label with an R the tissue where the red dye would appear.

Label with a C the tissue where organic compounds are transported.

Label with a C the tissue where organic compounds are transported.

Label with a C the tissue where organic compounds are transported.

Suggest reasons for the high percentage of fatal cases at Ebola treatment centres.

Suggest reasons for the high percentage of fatal cases at Ebola treatment centres.

Suggest reasons for the high percentage of fatal cases at Ebola treatment centres.

The mean stomatal density for the lower epidermis of P. decandrum was around 600 per mm². Predict how the stomatal density for the upper epidermis would compare.

The mean stomatal density for the lower epidermis of P. decandrum was around 600 per mm². Predict how the stomatal density for the upper epidermis would compare.

The mean stomatal density for the lower epidermis of P. decandrum was around 600 per mm². Predict how the stomatal density for the upper epidermis would compare.

State the name of the process which occurs in the chloroplasts of Chlorella, that uses CO₂.

State the name of the process which occurs in the chloroplasts of Chlorella, that uses CO₂.

State the name of the process which occurs in the chloroplasts of Chlorella, that uses CO₂.

The colours of the indicator in the jars ranged from yellow to purple after five hours.

Predict the distribution of indicator colours in jars 1 to 9.

The colours of the indicator in the jars ranged from yellow to purple after five hours.

Predict the distribution of indicator colours in jars 1 to 9.

The colours of the indicator in the jars ranged from yellow to purple after five hours.

Predict the distribution of indicator colours in jars 1 to 9.

Explain the scientific reasoning for your hypothesis.

Explain the scientific reasoning for your hypothesis.

Explain the scientific reasoning for your hypothesis.

Explain how polypeptides are produced by the process of translation.

Explain how polypeptides are produced by the process of translation.

Explain how polypeptides are produced by the process of translation.

Describe the processes that cause water to move from the roots of plants to their leaves.

Draw a half-view of an animal-pollinated flower.

Draw a half-view of an animal-pollinated flower.

Draw a half-view of an animal-pollinated flower.

The diagram shows the three-dimensional structure of tRNA.

[Source: Structure reproduced with the kind permission of N.R. Voss.]

What can attach to the region marked X?

A. mRNA

B. An amino acid

C. An anticodon

D. The P site of the ribosome

The diagram shows the three-dimensional structure of tRNA.

[Source: Structure reproduced with the kind permission of N.R. Voss.]

What can attach to the region marked X?

A. mRNA

B. An amino acid

C. An anticodon

D. The P site of the ribosome

Describe the processes that cause water to move from the roots of plants to their leaves.

The diagram shows a section through a thylakoid. Electrons move from X to Y.

[Source: Courtesy Alyse Da Quynh.]

What do the letters X, Y and Z represent?

Describe the processes that cause water to move from the roots of plants to their leaves.

Explain the role of the kidney in osmoregulation.

In the diagram of a ribosome, which letter indicates the P site?

[Source: iStock.com/ttsz]

The diagram shows a section through a thylakoid. Electrons move from X to Y.

[Source: Courtesy Alyse Da Quynh.]

What do the letters X, Y and Z represent?

Explain the role of the kidney in osmoregulation.

In the diagram of a ribosome, which letter indicates the P site?

[Source: iStock.com/ttsz]

Explain the role of the kidney in osmoregulation.

Describe the changes that occur in gene pools during speciation.

The grey line in each of the graphs below represents the rate of reaction catalysed by an uninhibited enzyme as substrate concentration is increased.

Which graph shows expected results if a competitive inhibitor was added to the reaction?

[Source: © International Baccalaureate Organization 2019]

The grey line in each of the graphs below represents the rate of reaction catalysed by an uninhibited enzyme as substrate concentration is increased.

Which graph shows expected results if a competitive inhibitor was added to the reaction?

[Source: © International Baccalaureate Organization 2019]

The diagram shows the link reaction between glycolysis and the Krebs cycle.

[Source: © International Baccalaureate Organization 2019]

Which type of reaction is occurring?

A. Pyruvate is carboxylated.

B. CO2 is oxidized.

C. NAD+ is reduced.

D. Pyruvate is phosphorylated.

Describe the changes that occur in gene pools during speciation.

Describe the changes that occur in gene pools during speciation.

The diagram shows a section through a seminiferous tubule.

[Source: © International Baccalaureate Organization 2020.]

Which labelled cells are diploid and haploid, respectively?

The diagram shows the link reaction between glycolysis and the Krebs cycle.

[Source: © International Baccalaureate Organization 2019]

Which type of reaction is occurring?

A. Pyruvate is carboxylated.

B. CO2 is oxidized.

C. NAD+ is reduced.

D. Pyruvate is phosphorylated.

Which structure in the chloroplast diagram is adapted to carry out chemiosmosis?

[Source: © International Baccalaureate Organization 2019]

Which structure in the chloroplast diagram is adapted to carry out chemiosmosis?

[Source: © International Baccalaureate Organization 2019]

In the micrograph of a plant stem, which letter indicates the xylem?

[Source: adapted from Kelvinsong/https://creativecommons.org/licenses/by/3.0/deed.en]

In the micrograph of a plant stem, which letter indicates the xylem?

[Source: adapted from Kelvinsong/https://creativecommons.org/licenses/by/3.0/deed.en]

The diagram shows a section through a seminiferous tubule.

[Source: © International Baccalaureate Organization 2020.]

Which labelled cells are diploid and haploid, respectively?

The graph shows three hormones circulating during pregnancy in the rat, with birth occurring at 22 days.

[Source: Dr Paul Kenyon University of Plymouth (retired).]

What are hormones X and Z?

The graph shows three hormones circulating during pregnancy in the rat, with birth occurring at 22 days.

[Source: Dr Paul Kenyon University of Plymouth (retired).]

What are hormones X and Z?

Which equation is an example of decarboxylation?

A. Pyruvate $\to$ Acetyl CoA + CO₂

B. CO₂ + H₂O H₂CO₃

C. CH₄ + 2O₂ CO₂ + 2H₂O

D.

Which equation is an example of decarboxylation?

A. Pyruvate $\to$ Acetyl CoA + CO₂

B. CO₂ + H₂O H₂CO₃

C. CH₄ + 2O₂ CO₂ + 2H₂O

D.

The diagram shows a section through the seminiferous tubules. What is the cell labelled X?

[Source: © International Baccalaureate Organization 2019]

A. Spermatid that will differentiate into sperm

B. Primary spermatocyte that will undergo meiosis to form secondary spermatocytes

C. Sertoli cell that provides nutrients

D. Stem cell that will divide by mitosis to form spermatogonia

The diagram shows a section through the seminiferous tubules. What is the cell labelled X?

[Source: © International Baccalaureate Organization 2019]

A. Spermatid that will differentiate into sperm

B. Primary spermatocyte that will undergo meiosis to form secondary spermatocytes

C. Sertoli cell that provides nutrients

D. Stem cell that will divide by mitosis to form spermatogonia

On the diagram, label the testa and the radicle.

On the diagram, label the testa and the radicle.

On the diagram, label the testa and the radicle.

Autosomal genes are located in chromosomes that are not sex chromosomes. The inheritance of autosomal genes is affected by whether the genes are linked or unlinked. Explain the two types of inheritance, using the example of parents that are heterozygous for two genes A and B.

In fruit flies (Drosophila melanogaster), grey bodies (b⁺) are dominant to black bodies (b) and normal wings (vg⁺) are dominant to vestigial wings (vg). Homozygous vestigial winged, black bodied flies were crossed with individuals that were heterozygous for both traits. 2300 individuals were counted and the phenotypes observed were recorded as shown.

965 normal wings, grey bodies
944 vestigial wings, black bodies
206 vestigial wings, grey bodies
185 normal wings, black bodies

Which statement is valid?

A. The predicted phenotypic ratio was 9:3:3: 1.

B. There is independent assortment of wings but not body colour.

C. The expected number of vestigial winged, grey bodied flies was 575.

D. The traits are on different chromosomes.

In fruit flies (Drosophila melanogaster), grey bodies (b⁺) are dominant to black bodies (b) and normal wings (vg⁺) are dominant to vestigial wings (vg). Homozygous vestigial winged, black bodied flies were crossed with individuals that were heterozygous for both traits. 2300 individuals were counted and the phenotypes observed were recorded as shown.

965 normal wings, grey bodies
944 vestigial wings, black bodies
206 vestigial wings, grey bodies
185 normal wings, black bodies

Which statement is valid?

A. The predicted phenotypic ratio was 9:3:3: 1.

B. There is independent assortment of wings but not body colour.

C. The expected number of vestigial winged, grey bodied flies was 575.

D. The traits are on different chromosomes.

Autosomal genes are located in chromosomes that are not sex chromosomes. The inheritance of autosomal genes is affected by whether the genes are linked or unlinked. Explain the two types of inheritance, using the example of parents that are heterozygous for two genes A and B.

Autosomal genes are located in chromosomes that are not sex chromosomes. The inheritance of autosomal genes is affected by whether the genes are linked or unlinked. Explain the two types of inheritance, using the example of parents that are heterozygous for two genes A and B.

The diagram represents a sarcomere. Which structure is myosin?

[Source: MPI of Molecular Plant Physiology. [Sarcomere]. [diagram online] Available at: http://www.macroevolution.net/sarcomere.html [accessed 4 April 2019]. Source adapted.]

The diagram represents a sarcomere. Which structure is myosin?

[Source: MPI of Molecular Plant Physiology. [Sarcomere]. [diagram online] Available at: http://www.macroevolution.net/sarcomere.html [accessed 4 April 2019]. Source adapted.]

Explain the role of hydrogen ions used in photosynthesis.

Explain the role of hydrogen ions used in photosynthesis.

Explain the role of hydrogen ions used in photosynthesis.

The pregnancy test for humans is based on detection of the hormone HCG. What is the reason for detection of this hormone indicating pregnancy?

A. HCG is involved in milk production.

B. HCG production is blocked by negative feedback during menstruation.

C. HCG is produced by an embryo.

D. HCG is released during the acrosome reaction.

Describe how the structure of the chloroplast is adapted to its function in photosynthesis.

The pregnancy test for humans is based on detection of the hormone HCG. What is the reason for detection of this hormone indicating pregnancy?

A. HCG is involved in milk production.

B. HCG production is blocked by negative feedback during menstruation.

C. HCG is produced by an embryo.

D. HCG is released during the acrosome reaction.

Describe how the structure of the chloroplast is adapted to its function in photosynthesis.

Describe how the structure of the chloroplast is adapted to its function in photosynthesis.

The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either ³²P or ³⁵S. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.

[Source: Republished with permission of ROCKEFELLER UNIVERSITY PRESS, from Independent functions of protein and nucleic acid in growth of bacteriophage. Hershey, A.D. and Chase, M., 1952. (Journal of General Physiology, 36(1), p.47). Society of General Physiologists, Rockefeller Institute for Medical Research, Rockefeller Institute; permission conveyed through Copyright Clearance Center, Inc.]

What do curves X and Y represent?

Rosalind Franklin produced X-ray diffraction images of DNA.

[Source: © King’s College, London. KCL Department of Biophysics KDBP/1/1.]

Which previously unknown aspect of DNA was deduced from these images?

A. Chromosomes are made of DNA.

B. Deoxyribose sugar is attached to a phosphate group.

C. The base A pairs with T and C with G.

D. The DNA molecule is a double helix.

Compare and contrast mitochondria and chloroplasts in terms of the substrates they use and the products they produce. 

Rosalind Franklin produced X-ray diffraction images of DNA.

[Source: © King’s College, London. KCL Department of Biophysics KDBP/1/1.]

Which previously unknown aspect of DNA was deduced from these images?

A. Chromosomes are made of DNA.

B. Deoxyribose sugar is attached to a phosphate group.

C. The base A pairs with T and C with G.

D. The DNA molecule is a double helix.

What is the difference between the DNA of adult identical (monozygotic) twins?

A. Order of genes

B. Sequence of nucleotides

C. Methylation pattern

D. Ratio of complementary base pairs

The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either ³²P or ³⁵S. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.

[Source: Republished with permission of ROCKEFELLER UNIVERSITY PRESS, from Independent functions of protein and nucleic acid in growth of bacteriophage. Hershey, A.D. and Chase, M., 1952. (Journal of General Physiology, 36(1), p.47). Society of General Physiologists, Rockefeller Institute for Medical Research, Rockefeller Institute; permission conveyed through Copyright Clearance Center, Inc.]

What do curves X and Y represent?

What is a feature of transcription in the single-celled organism shown in the electron micrograph?

[Source: George E. Palade Electron Microscopy Slide Collection Harvey Cushing/John Hay Whitney Medical Library Yale University Library.]

A. mRNA splicing

B. Removal of introns

C. Codon-anticodon binding

D. Synthesis of RNA in a 5′ to 3′ direction

What is a feature of transcription in the single-celled organism shown in the electron micrograph?

[Source: George E. Palade Electron Microscopy Slide Collection Harvey Cushing/John Hay Whitney Medical Library Yale University Library.]

A. mRNA splicing

B. Removal of introns

C. Codon-anticodon binding

D. Synthesis of RNA in a 5′ to 3′ direction

Compare and contrast mitochondria and chloroplasts in terms of the substrates they use and the products they produce. 

What is the difference between the DNA of adult identical (monozygotic) twins?

A. Order of genes

B. Sequence of nucleotides

C. Methylation pattern

D. Ratio of complementary base pairs

What is the primary function of the free ribosomes shown in the electron micrograph?

What is the primary function of the free ribosomes shown in the electron micrograph?

Compare and contrast mitochondria and chloroplasts in terms of the substrates they use and the products they produce. 

Outline how the compounds produced by chloroplasts are distributed throughout the plant.

Some bacteria can synthesize the amino acid isoleucine from threonine, a process involving five enzymes (E₁ to E₅) and four intermediary products (P, Q, R and S). The production of isoleucine is controlled by end-product inhibition.

Which statement describes this end-product inhibition?

A. If isoleucine accumulates, it inhibits the production of P.

B. End-product inhibition causes a build-up of intermediary products.

C. Isoleucine inhibits E₅, so no more isoleucine is produced.

D. Isoleucine affects the structure of threonine.

Outline how the compounds produced by chloroplasts are distributed throughout the plant.

The Hill reaction occurs when isolated chloroplasts are exposed to sunlight in the presence of DCPIP. DCPIP replaces NADP as the final electron acceptor for the light-dependent reactions of photosynthesis. What are products of the Hill reaction?

A. H₂O and ATP

B. ATP and CO₂

C. O₂ and ATP

D. C₆H₁₂O₆ and O₂

Some bacteria can synthesize the amino acid isoleucine from threonine, a process involving five enzymes (E₁ to E₅) and four intermediary products (P, Q, R and S). The production of isoleucine is controlled by end-product inhibition.

Which statement describes this end-product inhibition?

A. If isoleucine accumulates, it inhibits the production of P.

B. End-product inhibition causes a build-up of intermediary products.

C. Isoleucine inhibits E₅, so no more isoleucine is produced.

D. Isoleucine affects the structure of threonine.

Outline how the compounds produced by chloroplasts are distributed throughout the plant.

Plasma cells secrete antibodies against specific antigens. Outline how plasma cells become activated.

The Hill reaction occurs when isolated chloroplasts are exposed to sunlight in the presence of DCPIP. DCPIP replaces NADP as the final electron acceptor for the light-dependent reactions of photosynthesis. What are products of the Hill reaction?

A. H₂O and ATP

B. ATP and CO₂

C. O₂ and ATP

D. C₆H₁₂O₆ and O₂

Plasma cells secrete antibodies against specific antigens. Outline how plasma cells become activated.

The apparatus in the diagram was used to assess the effects of factors on transpiration rates.

[Source: Republished with permission of Springer-Verlag from Experimentelle Pflanzenphysiologie: Band 2, Peter Schopfer, 1st edition, 1st Jan 1989; permission conveyed through Copyright Clearance Center, Inc.]

Which factor would be a controlled variable in an experiment designed to assess the effects of temperature on transpiration rate?

A. The opening and closing of stomata

B. The intensity of light striking the plant

C. The height of the water in the reservoir

D. The evaporation of water from the leaves

Plasma cells secrete antibodies against specific antigens. Outline how plasma cells become activated.

A hybridoma is a cell produced by the fusion of a plasma cell with a tumour cell. Explain the advantages of using hybridoma cells in the production of monoclonal antibodies.

The apparatus in the diagram was used to assess the effects of factors on transpiration rates.

[Source: Republished with permission of Springer-Verlag from Experimentelle Pflanzenphysiologie: Band 2, Peter Schopfer, 1st edition, 1st Jan 1989; permission conveyed through Copyright Clearance Center, Inc.]

Which factor would be a controlled variable in an experiment designed to assess the effects of temperature on transpiration rate?

A. The opening and closing of stomata

B. The intensity of light striking the plant

C. The height of the water in the reservoir

D. The evaporation of water from the leaves

A hybridoma is a cell produced by the fusion of a plasma cell with a tumour cell. Explain the advantages of using hybridoma cells in the production of monoclonal antibodies.

A hybridoma is a cell produced by the fusion of a plasma cell with a tumour cell. Explain the advantages of using hybridoma cells in the production of monoclonal antibodies.

State one use of monoclonal antibodies.

The image shows part of a section through the stem of a non-woody plant. Where does transport of sucrose occur?

[Source: Courtesy of Kelly Cude, PhD, Professor Biological Sciences, College of the Canyons.]

State one use of monoclonal antibodies.

A plant is allowed to photosynthesize in an atmosphere containing radioactive ¹⁴C. Where in the plant stem would radioactive sugars be found?

[Source: sinhyu/123rf.com.]

The image shows part of a section through the stem of a non-woody plant. Where does transport of sucrose occur?

[Source: Courtesy of Kelly Cude, PhD, Professor Biological Sciences, College of the Canyons.]

State one use of monoclonal antibodies.

Outline how the hormone auxin controls phototropism in plant shoots.

A plant is allowed to photosynthesize in an atmosphere containing radioactive ¹⁴C. Where in the plant stem would radioactive sugars be found?

[Source: sinhyu/123rf.com.]

The diagram shows a plant shoot and the direction of the light which the shoot received.

[Source: USDA-NRCS PLANTS Database. Available at: https://commons.wikimedia.org/wiki/File:Alnus_seedling_drawing.png
[Accessed 30 November 2021].]

What are the direction of movement and the effect of auxin in the tip of a plant shoot when receiving light from one side?

Outline how the hormone auxin controls phototropism in plant shoots.

The diagram shows a plant shoot and the direction of the light which the shoot received.

[Source: USDA-NRCS PLANTS Database. Available at: https://commons.wikimedia.org/wiki/File:Alnus_seedling_drawing.png
[Accessed 30 November 2021].]

What are the direction of movement and the effect of auxin in the tip of a plant shoot when receiving light from one side?

The graph shows how the mass of a bean seed from which all water has been removed (dry mass) changes during germination.

What can be deduced from the graph?

A. The plant loses more water during period X than during period Y.

B. During period Y, photosynthesis occurs but not respiration.

C. During period Y, more CO₂ is fixed in photosynthesis than is released by cell respiration.

D. The seeds were not exposed to the correct temperature for germination during period X.

Outline how the hormone auxin controls phototropism in plant shoots.

Explain the factors that affect the rate of enzyme-controlled reactions in cells.

The graph shows how the mass of a bean seed from which all water has been removed (dry mass) changes during germination.

What can be deduced from the graph?

A. The plant loses more water during period X than during period Y.

B. During period Y, photosynthesis occurs but not respiration.

C. During period Y, more CO₂ is fixed in photosynthesis than is released by cell respiration.

D. The seeds were not exposed to the correct temperature for germination during period X.

Explain the factors that affect the rate of enzyme-controlled reactions in cells.

The graph shows the relationship between mass at birth and the percentage that die shortly after birth for Scottish Blackface lambs.

[Source: Dwyer, C.M., Conington, J., Corbiere, F., Holmoy, I.H., Muri, K., Nowak, R., Rooke, J., Vipond, J. and Gautier,
J.-M., 2016. Invited review: Improving neonatal survival in small ruminants: science into practice. Animal, 10(3),
pp. 449–459.]

What type of selection for the lambs is shown in the graph?

A. Disruptive selection, as there is a drop in mortality at intermediate birth masses

B. Stabilizing selection, as lambs with low or high birth mass are less likely to survive

C. Directional selection, as lambs with a high birth mass have high mortality

D. There is no evidence in the graph of selection, as survival frequency is not shown

The graph shows changes in the concentration of an antibody in the blood of an individual subjected to two separate infections at time X and time Y.

The graph shows changes in the concentration of an antibody in the blood of an individual subjected to two separate infections at time X and time Y.

Explain the factors that affect the rate of enzyme-controlled reactions in cells.

Distinguish between the xylem and phloem of plants.

The diagram shows structures involved in contraction of a sarcomere.

The diagram shows structures involved in contraction of a sarcomere.

What function is maintained as a result of the release of HCG?

A. Production of milk by the mammary glands

B. Release of oxytocin by the posterior pituitary gland

C. Production of FSH by the anterior pituitary gland

D. Production of progesterone by the ovary

What function is maintained as a result of the release of HCG?

A. Production of milk by the mammary glands

B. Release of oxytocin by the posterior pituitary gland

C. Production of FSH by the anterior pituitary gland

D. Production of progesterone by the ovary

The graph shows the relationship between mass at birth and the percentage that die shortly after birth for Scottish Blackface lambs.

[Source: Dwyer, C.M., Conington, J., Corbiere, F., Holmoy, I.H., Muri, K., Nowak, R., Rooke, J., Vipond, J. and Gautier,
J.-M., 2016. Invited review: Improving neonatal survival in small ruminants: science into practice. Animal, 10(3),
pp. 449–459.]

What type of selection for the lambs is shown in the graph?

A. Disruptive selection, as there is a drop in mortality at intermediate birth masses

B. Stabilizing selection, as lambs with low or high birth mass are less likely to survive

C. Directional selection, as lambs with a high birth mass have high mortality

D. There is no evidence in the graph of selection, as survival frequency is not shown

The diagram shows a method for the production of monoclonal antibodies.

The diagram shows a method for the production of monoclonal antibodies.

The image shows part of a myofibril from a relaxed muscle fibre.

[Source: Sarcomere. Sameerb. Available at https://commons.wikimedia.org/wiki/File:Sarcomere.gif
[Accessed 30 November 2021].]

What occurs during muscle contraction?

A. Myosin binding sites are blocked.

B. The bands labelled Y get shorter.

C. The bands labelled X get shorter.

D. Calcium ions bind to myosin.

The image shows part of a myofibril from a relaxed muscle fibre.

[Source: Sarcomere. Sameerb. Available at https://commons.wikimedia.org/wiki/File:Sarcomere.gif
[Accessed 30 November 2021].]

What occurs during muscle contraction?

A. Myosin binding sites are blocked.

B. The bands labelled Y get shorter.

C. The bands labelled X get shorter.

D. Calcium ions bind to myosin.

Distinguish between the xylem and phloem of plants.

Where in the nephron is most glucose reabsorbed?

[Source: National Institute of Diabetes and Digestive and Kidney Diseases, n.d. [Nephron]. [diagram online] Available at:
https://www.niddk.nih.gov/news/media-library/9164 [Accessed 23 March 2020].]

Where in the nephron is most glucose reabsorbed?

[Source: National Institute of Diabetes and Digestive and Kidney Diseases, n.d. [Nephron]. [diagram online] Available at:
https://www.niddk.nih.gov/news/media-library/9164 [Accessed 23 March 2020].]

The micrograph shows part of a human sperm cell. Which region of the cell is responsible for the greatest production of ATP?

The micrograph shows part of a human sperm cell. Which region of the cell is responsible for the greatest production of ATP?

Distinguish between the xylem and phloem of plants.

Explain how the light-independent reactions of photosynthesis rely on the light-dependent reactions.

Explain how the light-independent reactions of photosynthesis rely on the light-dependent reactions.

Explain how the light-independent reactions of photosynthesis rely on the light-dependent reactions.

Explain the production of antibodies in humans.

Explain the production of antibodies in humans.

Explain the production of antibodies in humans.

Distinguish between competitive and non-competitive enzyme inhibition.

Explain gene linkage and its effects on inheritance.

Explain gene linkage and its effects on inheritance.

Explain gene linkage and its effects on inheritance.

Distinguish between competitive and non-competitive enzyme inhibition.

Explain the mechanism that prevents polyspermy during fertilization.

Distinguish between competitive and non-competitive enzyme inhibition.

This DNA sequence was used to synthesize a polypeptide.

DNA (sense strand): 3′ T A C T G A 5′

DNA (template strand): 5′ A T G A C T 3′

Which are the bases of the tRNA (anticodons)?

A. T A C   T G A

B. U A C   U G A

C. A U G   A C U

D. A T G   A C T

Explain the mechanism that prevents polyspermy during fertilization.

Explain the mechanism that prevents polyspermy during fertilization.

Describe the secondary structure of proteins.

This DNA sequence was used to synthesize a polypeptide.

DNA (sense strand): 3′ T A C T G A 5′

DNA (template strand): 5′ A T G A C T 3′

Which are the bases of the tRNA (anticodons)?

A. T A C   T G A

B. U A C   U G A

C. A U G   A C U

D. A T G   A C T

Describe the secondary structure of proteins.

Describe the secondary structure of proteins.

Explain how some plant species are able to respond to changes in their abiotic environment and flower at a precise time of the year.

Explain how some plant species are able to respond to changes in their abiotic environment and flower at a precise time of the year.

Explain how some plant species are able to respond to changes in their abiotic environment and flower at a precise time of the year.

Outline the extension of the stem in plants.

Outline the extension of the stem in plants.

Outline the extension of the stem in plants.

The diagram shows the structure of a nucleosome.

The diagram shows the structure of a nucleosome.

Draw labelled diagrams to show the structure of RNA nucleotides and how they are linked together to form a molecule of RNA.

Draw labelled diagrams to show the structure of RNA nucleotides and how they are linked together to form a molecule of RNA.

Draw labelled diagrams to show the structure of RNA nucleotides and how they are linked together to form a molecule of RNA.

Explain transcription.

Explain transcription.

Explain transcription.

The diagram shows the structure of E. coli ribonuclease HI, a bacterial protein consisting of one polypeptide chain.

The diagram shows the structure of E. coli ribonuclease HI, a bacterial protein consisting of one polypeptide chain.

Describe how changes in weather conditions affect the transport and loss of water in plants.

Describe how changes in weather conditions affect the transport and loss of water in plants.

Describe how changes in weather conditions affect the transport and loss of water in plants.

The picture shows lentils sprouts growing towards a light source from the left.

Explain how water balance is restored in mammals when they are dehydrated.

The picture shows lentils sprouts growing towards a light source from the left.

Explain how water balance is restored in mammals when they are dehydrated.

Explain how water balance is restored in mammals when they are dehydrated.

When a cell divides by meiosis, chiasmata can be observed. Which are features of chiasmata?

I. They are points of attachment between chromatids of non-homologous chromosomes.

II. They occur during meiosis I.

III. They increase stability of bivalents.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

When a cell divides by meiosis, chiasmata can be observed. Which are features of chiasmata?

I. They are points of attachment between chromatids of non-homologous chromosomes.

II. They occur during meiosis I.

III. They increase stability of bivalents.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

Describe how monoclonal antibodies are produced.

Three-spined stickleback fish (Gasterosteus aculeatus) vary in the number of armour plates. The graph shows the frequency of individuals with low, partial or complete plating in a three-spined stickleback population living in Kennedy Lake, Vancouver Island, Canada.

[Source: Reprinted from Current Biology, 24, Marchinko, K.B., Matthews, B., Arnegard, M.E., Rogers, S.M. and Schluter, D., Maintenance of a Genetic Polymorphism with Disruptive Natural Selection in Stickleback.
2014.  pp.1289–1292 with permission from Elsevier.]

Which type of natural selection could result in this pattern of variation in the population?

A. Disruptive

B. Directional

C. Stabilizing

D. Convergent

Describe how monoclonal antibodies are produced.

Describe how monoclonal antibodies are produced.

Three-spined stickleback fish (Gasterosteus aculeatus) vary in the number of armour plates. The graph shows the frequency of individuals with low, partial or complete plating in a three-spined stickleback population living in Kennedy Lake, Vancouver Island, Canada.

[Source: Reprinted from Current Biology, 24, Marchinko, K.B., Matthews, B., Arnegard, M.E., Rogers, S.M. and Schluter, D., Maintenance of a Genetic Polymorphism with Disruptive Natural Selection in Stickleback.
2014.  pp.1289–1292 with permission from Elsevier.]

Which type of natural selection could result in this pattern of variation in the population?

A. Disruptive

B. Directional

C. Stabilizing

D. Convergent

Explain the role of the electron transport chain in the generation of ATP by cell respiration.

The electron micrograph shows sarcomeres in myofibrils of striated muscle during muscle contraction. The lines P–Q and R–S show two regions of one sarcomere.

[Source: Republished with permission of Elsevier - Health Sciences Division from Cell by Don W. Fawcett 1981 ; permission conveyed through Copyright Clearance Center, Inc.]

How would regions P–Q and R–S change when the muscle relaxes?

There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.

The electron micrograph shows sarcomeres in myofibrils of striated muscle during muscle contraction. The lines P–Q and R–S show two regions of one sarcomere.

[Source: Republished with permission of Elsevier - Health Sciences Division from Cell by Don W. Fawcett 1981 ; permission conveyed through Copyright Clearance Center, Inc.]

How would regions P–Q and R–S change when the muscle relaxes?

Explain the role of the electron transport chain in the generation of ATP by cell respiration.

Explain the role of the electron transport chain in the generation of ATP by cell respiration.

The micrograph shows a glomerulus and Bowman’s capsule, where ultrafiltration takes place in the kidney.

[Source: MICROSCAPE/SCIENCE PHOTO LIBRARY.]

What facilitates the formation of glomerular filtrate?

A. Many fenestrations in walls of capillaries in the glomerulus

B. High pressure in the Bowman’s capsule

C. ADH secreted by the pituitary gland

D. Osmosis caused by a high concentration of urea in the blood

There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.

There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.

The micrograph shows a glomerulus and Bowman’s capsule, where ultrafiltration takes place in the kidney.

[Source: MICROSCAPE/SCIENCE PHOTO LIBRARY.]

What facilitates the formation of glomerular filtrate?

A. Many fenestrations in walls of capillaries in the glomerulus

B. High pressure in the Bowman’s capsule

C. ADH secreted by the pituitary gland

D. Osmosis caused by a high concentration of urea in the blood

Explain the reasons for variation in human height.

Explain the reasons for variation in human height.

Explain the reasons for variation in human height.

Explain how speciation occurs, including the different processes of isolation and selection.

Explain how speciation occurs, including the different processes of isolation and selection.

Explain how speciation occurs, including the different processes of isolation and selection.

To calculate chi-squared, expected values must first be calculated. Assuming that there is no association between the two species, calculate the expected number of quadrats in which both species would be present, showing your working.

To calculate chi-squared, expected values must first be calculated. Assuming that there is no association between the two species, calculate the expected number of quadrats in which both species would be present, showing your working.

To calculate chi-squared, expected values must first be calculated. Assuming that there is no association between the two species, calculate the expected number of quadrats in which both species would be present, showing your working.

Humans need to balance water and solute concentrations and also excrete nitrogenous wastes. Explain how the different parts of the kidney carry out these processes.

Humans need to balance water and solute concentrations and also excrete nitrogenous wastes. Explain how the different parts of the kidney carry out these processes.

Humans need to balance water and solute concentrations and also excrete nitrogenous wastes. Explain how the different parts of the kidney carry out these processes.

State the number of degrees of freedom for this test to determine the critical value of chi-squared.

State the number of degrees of freedom for this test to determine the critical value of chi-squared.

State the number of degrees of freedom for this test to determine the critical value of chi-squared.

When the data in the table were used to calculate chi-squared, the calculated value was 0.056. The critical value is 3.84. Explain the conclusion that can be drawn from the calculated and critical values for chi-squared.

When the data in the table were used to calculate chi-squared, the calculated value was 0.056. The critical value is 3.84. Explain the conclusion that can be drawn from the calculated and critical values for chi-squared.

When the data in the table were used to calculate chi-squared, the calculated value was 0.056. The critical value is 3.84. Explain the conclusion that can be drawn from the calculated and critical values for chi-squared.

Describe adaptations in mammals living in desert ecosystems to maintain osmolarity in their bodies.

Describe adaptations in mammals living in desert ecosystems to maintain osmolarity in their bodies.

Describe adaptations in mammals living in desert ecosystems to maintain osmolarity in their bodies.

Suggest how the graph would differ for a human during a long period of inactivity.

Suggest how the graph would differ for a human during a long period of inactivity.

Suggest how the graph would differ for a human during a long period of inactivity.

Outline how the muscle attachment of insects differs from humans.

Outline how the muscle attachment of insects differs from humans.

Explain the reason that Morgan’s results did not agree with expected Mendelian ratios in a dihybrid cross.

Outline how the muscle attachment of insects differs from humans.

Explain the reason that Morgan’s results did not agree with expected Mendelian ratios in a dihybrid cross.

Explain the reason that Morgan’s results did not agree with expected Mendelian ratios in a dihybrid cross.

The diagram illustrates some of the processes involved in DNA replication.

[Source: Rohrmann, G., 2019. AcMNPV DNA replication. [diagram online] Available at:
https://www.ncbi.nlm.nih.gov/books/NBK543453/figure/ch05.F1/ [Accessed 26 October 2021].]

What is shown in the diagram?

A.  DNA polymerase bonding nucleotides in a 3’ to 5’ direction

B.  Single-stranded DNA-binding proteins on the old strands

C.  Gyrase reforming the double helix

D.  DNA ligase joining Okazaki fragments in the leading strand

The diagram illustrates some of the processes involved in DNA replication.

[Source: Rohrmann, G., 2019. AcMNPV DNA replication. [diagram online] Available at:
https://www.ncbi.nlm.nih.gov/books/NBK543453/figure/ch05.F1/ [Accessed 26 October 2021].]

What is shown in the diagram?

A.  DNA polymerase bonding nucleotides in a 3’ to 5’ direction

B.  Single-stranded DNA-binding proteins on the old strands

C.  Gyrase reforming the double helix

D.  DNA ligase joining Okazaki fragments in the leading strand

What occurs in the light-independent reactions of photosynthesis?

A.  Glycerate 3-phosphate is reduced to triose phosphate.

B.  Ribulose bisphosphate is regenerated using reduced NADP.

C.  Ribulose bisphosphate is oxidized to two molecules of glycerate 3-phosphate.

D.  Both ATP and NADP are used to produce triose phosphate.

What occurs in the light-independent reactions of photosynthesis?

A.  Glycerate 3-phosphate is reduced to triose phosphate.

B.  Ribulose bisphosphate is regenerated using reduced NADP.

C.  Ribulose bisphosphate is oxidized to two molecules of glycerate 3-phosphate.

D.  Both ATP and NADP are used to produce triose phosphate.

The apparatus is set up to measure the rate of transpiration. As transpiration occurs from the leafy shoot, water is drawn through the apparatus and is measured by timing the movement of the air bubble along the capillary tube.

Which variable(s) must be controlled if transpiration rates are compared in different plant species?

I.   Total leaf surface area

II.  Volume of water in the reservoir

III. Room temperature

A.  I only

B.  III only

C.  I and III only

D.  I, II and III

The apparatus is set up to measure the rate of transpiration. As transpiration occurs from the leafy shoot, water is drawn through the apparatus and is measured by timing the movement of the air bubble along the capillary tube.

Which variable(s) must be controlled if transpiration rates are compared in different plant species?

I.   Total leaf surface area

II.  Volume of water in the reservoir

III. Room temperature

A.  I only

B.  III only

C.  I and III only

D.  I, II and III

A hummingbird is shown visiting a large flower.

[Source: Nussbaumer, R./Naturepl.com, n.d. Black chinned hummingbird (Archilochus alexandri). Available at:
https://www.naturepl.com/stock-photo/black-chinned-hummingbird-archilochus-alexandri-male-feeding-at-sageflower/search/detail-0_01140572.html.]

What makes this a mutualistic relationship?

A.  The bird feeds on nectar and transfers pollen to the stamen of a flower of the same species.

B.  The bird obtains nutrients and the plant is assisted with pollination for sexual reproduction.

C.  The bird requires pollen as a protein source and, while obtaining this, disperses seeds for the plant.

D.  The bird transfers pollen to the stigma of flowers of a different species while feeding.

A hummingbird is shown visiting a large flower.

[Source: Nussbaumer, R./Naturepl.com, n.d. Black chinned hummingbird (Archilochus alexandri). Available at:
https://www.naturepl.com/stock-photo/black-chinned-hummingbird-archilochus-alexandri-male-feeding-at-sageflower/search/detail-0_01140572.html.]

What makes this a mutualistic relationship?

A.  The bird feeds on nectar and transfers pollen to the stamen of a flower of the same species.

B.  The bird obtains nutrients and the plant is assisted with pollination for sexual reproduction.

C.  The bird requires pollen as a protein source and, while obtaining this, disperses seeds for the plant.

D.  The bird transfers pollen to the stigma of flowers of a different species while feeding.

Movement of insects requires muscles in antagonistic pairs. The diagram shows an insect leg with muscles labelled X and Y.

[Source: Johnson, S.K., n.d. [Insect leg]. [diagram online] Available at: http://www.susankjohnson.com/portfolio.shtml
[Accessed 26 October 2021].]

What actions in the human arm are equivalent to muscle X contracting and muscle Y relaxing?

A.  triceps contracts, biceps relaxes, arm extends

B.  biceps contracts, triceps relaxes, arm flexes

C.  triceps contracts, biceps relaxes, arm flexes

D.  biceps contracts, triceps relaxes, arm extends

Movement of insects requires muscles in antagonistic pairs. The diagram shows an insect leg with muscles labelled X and Y.

[Source: Johnson, S.K., n.d. [Insect leg]. [diagram online] Available at: http://www.susankjohnson.com/portfolio.shtml
[Accessed 26 October 2021].]

What actions in the human arm are equivalent to muscle X contracting and muscle Y relaxing?

A.  triceps contracts, biceps relaxes, arm extends

B.  biceps contracts, triceps relaxes, arm flexes

C.  triceps contracts, biceps relaxes, arm flexes

D.  biceps contracts, triceps relaxes, arm extends

A person with failing kidneys is often treated with dialysis several times a week. This is done either by passing blood through a dialysis machine or by using the peritoneum, the lining of the abdomen, as shown in the diagram.

[Source: National Kidney Foundation, n.d. Peritoneal dialysis. [diagram online] Available at:
https://www.kidney.org/content/what-peritoneal-dialysis [Accessed 26 October 2021].]

Dialysis fluid is similar to normal blood plasma. What would be in solution in the dialysis fluid?

A.  Sugar, salts and urea

B.  Salts and urea only

C.  Sugar only

D.  Sugar and salts only

A person with failing kidneys is often treated with dialysis several times a week. This is done either by passing blood through a dialysis machine or by using the peritoneum, the lining of the abdomen, as shown in the diagram.

[Source: National Kidney Foundation, n.d. Peritoneal dialysis. [diagram online] Available at:
https://www.kidney.org/content/what-peritoneal-dialysis [Accessed 26 October 2021].]

Dialysis fluid is similar to normal blood plasma. What would be in solution in the dialysis fluid?

A.  Sugar, salts and urea

B.  Salts and urea only

C.  Sugar only

D.  Sugar and salts only

Outline how nucleosomes affect the transcription of DNA.

Outline how nucleosomes affect the transcription of DNA.

Outline how nucleosomes affect the transcription of DNA.

State one reason that identical twins may show different methylation patterns as they grow older.

State one reason that identical twins may show different methylation patterns as they grow older.

State one reason that identical twins may show different methylation patterns as they grow older.

State the region of the kidney in which the loop of Henle is situated.

State the region of the kidney in which the loop of Henle is situated.

State the region of the kidney in which the loop of Henle is situated.

Explain the role of the hormone ADH in osmoregulation.

Explain the role of the hormone ADH in osmoregulation.

Explain the role of the hormone ADH in osmoregulation.

Outline two adaptations for water conservation in leaves of desert plants.

Outline two adaptations for water conservation in leaves of desert plants.

Outline two adaptations for water conservation in leaves of desert plants.

Explain how cells in the bloodstream cause a specific immune response.

Explain how cells in the bloodstream cause a specific immune response.

Explain how cells in the bloodstream cause a specific immune response.

Describe how ATP is produced by Photosystem II in the light-dependent stage of photosynthesis.

Describe how ATP is produced by Photosystem II in the light-dependent stage of photosynthesis.

Describe how ATP is produced by Photosystem II in the light-dependent stage of photosynthesis.

Explain how carbohydrates are transported from plant leaves.

Explain how carbohydrates are transported from plant leaves.

Explain how carbohydrates are transported from plant leaves.

Describe polyploidy and how it can lead to speciation.

Describe polyploidy and how it can lead to speciation.

Describe polyploidy and how it can lead to speciation.

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.

Explain the conclusion that can be drawn from Cross 1.

Explain the conclusion that can be drawn from Cross 1.

State the name and function of structures I and II.

Structure I name and function: 

Structure II name and function:

State the name and function of structures I and II.

Structure I name and function: 

Structure II name and function:

State the name and function of structures I and II.

Structure I name and function: 

Structure II name and function:

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.

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.

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.

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 stem of a young plant is cut through and the cut end is immersed in water containing a red dye. The plant continues to transpire as normal. In what region of the stem would the red colour be visible soon after immersion?

_{[Source: Berkshire Community College Bioscience Image Library, 2014. Herbaceous Dicot Stem: Vascular Bundles Young
Helianthus. [image online] Available at: https://www.flickr.com/photos/146824358@N03/36834307513 [Accessed
4 October 2021]. Public domain.]}

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 stem of a young plant is cut through and the cut end is immersed in water containing a red dye. The plant continues to transpire as normal. In what region of the stem would the red colour be visible soon after immersion?

_{[Source: Berkshire Community College Bioscience Image Library, 2014. Herbaceous Dicot Stem: Vascular Bundles Young
Helianthus. [image online] Available at: https://www.flickr.com/photos/146824358@N03/36834307513 [Accessed
4 October 2021]. Public domain.]}

Dolly the sheep was the first mammal to be cloned from an adult somatic cell.

_{[Source: Squidonius, Public domain, via Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Dolly_clone.svg.]}

Which DNA did Dolly inherit?

A.  Nuclear and mitochondrial DNA from the surrogate ewe

B.  Nuclear and mitochondrial DNA from the Finn-Dorset

C.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the Finn-Dorset

D.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the surrogate ewe

Dolly the sheep was the first mammal to be cloned from an adult somatic cell.

_{[Source: Squidonius, Public domain, via Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Dolly_clone.svg.]}

Which DNA did Dolly inherit?

A.  Nuclear and mitochondrial DNA from the surrogate ewe

B.  Nuclear and mitochondrial DNA from the Finn-Dorset

C.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the Finn-Dorset

D.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the surrogate ewe

How do DNA and messenger RNA (mRNA) molecules differ in eukaryotes?

A.  mRNA is twice the size of DNA and is formed from four different bases.

B.  DNA contains ribose while mRNA contains deoxyribose.

C.  mRNA has the same bases as DNA but contains ribose.

D.  DNA has two strands while mRNA has only one.

Dolly the sheep was the first mammal to be cloned from an adult somatic cell.

_{[Source: Squidonius, Public domain, via Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Dolly_clone.svg.]}

Which DNA did Dolly inherit?

A.  Nuclear and mitochondrial DNA from the surrogate ewe

B.  Nuclear and mitochondrial DNA from the Finn-Dorset

C.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the Finn-Dorset

D.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the surrogate ewe

Dolly the sheep was the first mammal to be cloned from an adult somatic cell.

_{[Source: Squidonius, Public domain, via Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Dolly_clone.svg.]}

Which DNA did Dolly inherit?

A.  Nuclear and mitochondrial DNA from the surrogate ewe

B.  Nuclear and mitochondrial DNA from the Finn-Dorset

C.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the Finn-Dorset

D.  Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the surrogate ewe

How do DNA and messenger RNA (mRNA) molecules differ in eukaryotes?

A.  mRNA is twice the size of DNA and is formed from four different bases.

B.  DNA contains ribose while mRNA contains deoxyribose.

C.  mRNA has the same bases as DNA but contains ribose.

D.  DNA has two strands while mRNA has only one.

The image of the X-ray diffraction of calf thymus DNA was obtained by R. Franklin and R. Gosling in 1953.

^{[Source: Franklin, R.E. and Gosling, R.G., 1953. [image online]
Available at: https://scripts.iucr.org/cgi-bin/paper?a00979.
[Accessed 8 March 2022].]}

What does this image show about the structure of DNA?

A.  It is associated with histones.

B.  It has a helical shape.

C.  It contains deoxyribose.

D.  It contains four nitrogenous bases.

The image of the X-ray diffraction of calf thymus DNA was obtained by R. Franklin and R. Gosling in 1953.

^{[Source: Franklin, R.E. and Gosling, R.G., 1953. [image online]
Available at: https://scripts.iucr.org/cgi-bin/paper?a00979.
[Accessed 8 March 2022].]}

What does this image show about the structure of DNA?

A.  It is associated with histones.

B.  It has a helical shape.

C.  It contains deoxyribose.

D.  It contains four nitrogenous bases.