C. Interaction and interdependence

With reference to the diagram, identify one example of catabolism.

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.

The graph of the effect of pH on immobilized lipase activity does not allow for the determination of optimum pH precisely. Explain how a more exact value for the optimum pH could be determined.

The graph shows the results of an investigation into the activity of turnip peroxidase. The accumulation of the product of the reaction catalysed by the enzyme is shown at different pH values.

[Source: © International Baccalaureate Organization 2019]

Based on the data in the graph, what is most probably the optimum pH for turnip peroxidase?

A. Between 3 and 5

B. Between 10 and 11

C. Between 7 and 8

D. Between 9 and 10

Explain the decrease in activity of the enzyme on either side of the optimum temperature.

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]

Outline, using graphs, the effect of different factors that influence enzyme activity.

State a role of the active site of an enzyme.

Outline one factor that could affect the activity of Rubisco.

The graph shows the activity of an enzyme at different temperatures.

[Source: © International Baccalaureate Organization 2019]

What does the dashed line in the graph represent?

A. Increasing temperature increases substrate concentration.

B. Increasing temperature affects the active site.

C. Increasing temperature increases the rate of reaction.

D. Increasing temperature decreases the movement of particles.

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]

Distinguish between competitive and non-competitive enzyme inhibition.

Explain the role of lactose in the expression of the gene for lactase production.

The activity of amylase from two bacterial species and a fungus was measured at different pH levels and constant temperature. The results are shown in the graph.

[Source: Held, P., 2012. Enzymatic Digestion of Polysaccharides. Part II: Optimization of Polymer Digestion and Glucose Production in Microplates. Available at: https://www.agilent.com/cs/library/applications/enzymatic-digestion-of-polysaccharides-part-II-5994-3304EN-agilent.pdf.]

Which statement about the effect of pH on amylase can be concluded?

A.  A. oryzae amylase has the highest optimum pH.

B.  A change in pH affects amylase most in B. licheniformis.

C.  The optimum pH is 6 in B. subtilis.

D.  Amylase activity at pH 8 is the lowest in B. licheniformis.

Explain the regulation of metabolic pathways by end-product inhibition.

Predict what effect arginase has on the activation energy of this reaction.

Explain how temperature affects enzymes.

State the effect that immobilizing the enzyme had on the relative activity of the enzyme.

Using the information in the graph, describe how the experiment could be extended to determine the optimum temperature for immobilized HRP.

State the purpose of lime water in flask B.

Identify the independent variable.

Through a series of enzymatic reactions, the amino acid threonine is converted to isoleucine. The graph shows the rate of reaction of threonine deaminase according to the concentration of its substrate threonine, with and without the presence of isoleucine.

^{[Source: Calhoun, D.H., Rimernian, R.A. and Hatfield, G.W., 1973.
Threonine Deaminase from Escherichia coli.
I. Purification and Properties. The Journal Of Biological Chemistry,
248(10), pp. 3511–3516. Open Access.]}

What can be seen from these results?

A.  Threonine deaminase only works in the presence of isoleucine.

B.  Isoleucine inhibits threonine deaminase at low concentrations of threonine.

C.  Production of isoleucine is inhibited at high concentration of threonine.

D.  End-product inhibition controls the production of threonine deaminase.

In the grass plant Halopyrum mucronatum, the enzyme amylase breaks bonds in polysaccharides during germination. The graph shows how the activity of the enzyme varies with the concentration of polysaccharide.

_{[Source: Material from: Siddiqui, Z.S. and Khan, M.A., The role of enzyme amylase in two germinating seed morphs of
Halopyrum mucronatum (L.) Stapf. in saline and non-saline environment, published 2011, Acta Physiologiae
Plantarum, reproduced with permission of SNCSC.]}

What is the reason for the curve levelling off?

A.  There is insufficient substrate for the enzyme to act on.

B.  The product acts as an enzyme inhibitor.

C.  The enzymes have all been consumed in the reaction.

D.  All the enzyme active sites are occupied by substrate.

In the grass plant Halopyrum mucronatum, the enzyme amylase breaks bonds in polysaccharides during germination. The graph shows how the activity of the enzyme varies with the concentration of polysaccharide.

_{[Source: Material from: Siddiqui, Z.S. and Khan, M.A., The role of enzyme amylase in two germinating seed morphs of
Halopyrum mucronatum (L.) Stapf. in saline and non-saline environment, published 2011, Acta Physiologiae
Plantarum, reproduced with permission of SNCSC.]}

What is the reason for the curve levelling off?

A.  There is insufficient substrate for the enzyme to act on.

B.  The product acts as an enzyme inhibitor.

C.  The enzymes have all been consumed in the reaction.

D.  All the enzyme active sites are occupied by substrate.

With reference to the diagram, identify one example of catabolism.

With reference to the diagram, identify one example of catabolism.

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.

The graph of the effect of pH on immobilized lipase activity does not allow for the determination of optimum pH precisely. Explain how a more exact value for the optimum pH could be determined.

The graph shows the results of an investigation into the activity of turnip peroxidase. The accumulation of the product of the reaction catalysed by the enzyme is shown at different pH values.

[Source: © International Baccalaureate Organization 2019]

Based on the data in the graph, what is most probably the optimum pH for turnip peroxidase?

A. Between 3 and 5

B. Between 10 and 11

C. Between 7 and 8

D. Between 9 and 10

Explain the decrease in activity of the enzyme on either side of the optimum temperature.

Explain the decrease in activity of the enzyme on either side of the optimum temperature.

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]

Outline, using graphs, the effect of different factors that influence enzyme activity.

Outline, using graphs, the effect of different factors that influence enzyme activity.

State a role of the active site of an enzyme.

Outline one factor that could affect the activity of Rubisco.

State a role of the active site of an enzyme.

Outline one factor that could affect the activity of Rubisco.

The graph shows the activity of an enzyme at different temperatures.

[Source: © International Baccalaureate Organization 2019]

What does the dashed line in the graph represent?

A. Increasing temperature increases substrate concentration.

B. Increasing temperature affects the active site.

C. Increasing temperature increases the rate of reaction.

D. Increasing temperature decreases the movement of particles.

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]

Distinguish between competitive and non-competitive enzyme inhibition.

Distinguish between competitive and non-competitive enzyme inhibition.

Explain the role of lactose in the expression of the gene for lactase production.

Explain the role of lactose in the expression of the gene for lactase production.

The activity of amylase from two bacterial species and a fungus was measured at different pH levels and constant temperature. The results are shown in the graph.

[Source: Held, P., 2012. Enzymatic Digestion of Polysaccharides. Part II: Optimization of Polymer Digestion and Glucose Production in Microplates. Available at: https://www.agilent.com/cs/library/applications/enzymatic-digestion-of-polysaccharides-part-II-5994-3304EN-agilent.pdf.]

Which statement about the effect of pH on amylase can be concluded?

A.  A. oryzae amylase has the highest optimum pH.

B.  A change in pH affects amylase most in B. licheniformis.

C.  The optimum pH is 6 in B. subtilis.

D.  Amylase activity at pH 8 is the lowest in B. licheniformis.

Explain the regulation of metabolic pathways by end-product inhibition.

Explain the regulation of metabolic pathways by end-product inhibition.

Predict what effect arginase has on the activation energy of this reaction.

Predict what effect arginase has on the activation energy of this reaction.

Explain how temperature affects enzymes.

Explain how temperature affects enzymes.

State the effect that immobilizing the enzyme had on the relative activity of the enzyme.

Using the information in the graph, describe how the experiment could be extended to determine the optimum temperature for immobilized HRP.

State the purpose of lime water in flask B.

Identify the independent variable.

Through a series of enzymatic reactions, the amino acid threonine is converted to isoleucine. The graph shows the rate of reaction of threonine deaminase according to the concentration of its substrate threonine, with and without the presence of isoleucine.

^{[Source: Calhoun, D.H., Rimernian, R.A. and Hatfield, G.W., 1973.
Threonine Deaminase from Escherichia coli.
I. Purification and Properties. The Journal Of Biological Chemistry,
248(10), pp. 3511–3516. Open Access.]}

What can be seen from these results?

A.  Threonine deaminase only works in the presence of isoleucine.

B.  Isoleucine inhibits threonine deaminase at low concentrations of threonine.

C.  Production of isoleucine is inhibited at high concentration of threonine.

D.  End-product inhibition controls the production of threonine deaminase.

In the grass plant Halopyrum mucronatum, the enzyme amylase breaks bonds in polysaccharides during germination. The graph shows how the activity of the enzyme varies with the concentration of polysaccharide.

_{[Source: Material from: Siddiqui, Z.S. and Khan, M.A., The role of enzyme amylase in two germinating seed morphs of
Halopyrum mucronatum (L.) Stapf. in saline and non-saline environment, published 2011, Acta Physiologiae
Plantarum, reproduced with permission of SNCSC.]}

What is the reason for the curve levelling off?

A.  There is insufficient substrate for the enzyme to act on.

B.  The product acts as an enzyme inhibitor.

C.  The enzymes have all been consumed in the reaction.

D.  All the enzyme active sites are occupied by substrate.

In the grass plant Halopyrum mucronatum, the enzyme amylase breaks bonds in polysaccharides during germination. The graph shows how the activity of the enzyme varies with the concentration of polysaccharide.

_{[Source: Material from: Siddiqui, Z.S. and Khan, M.A., The role of enzyme amylase in two germinating seed morphs of
Halopyrum mucronatum (L.) Stapf. in saline and non-saline environment, published 2011, Acta Physiologiae
Plantarum, reproduced with permission of SNCSC.]}

What is the reason for the curve levelling off?

A.  There is insufficient substrate for the enzyme to act on.

B.  The product acts as an enzyme inhibitor.

C.  The enzymes have all been consumed in the reaction.

D.  All the enzyme active sites are occupied by substrate.

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.

The graph shows the results of an experimental investigation that compared the rates at which lactose, glucose and galactose are broken down in the process of anaerobic cellular respiration by the yeast Torulopsis cremoris.

State one process that produces ATP.

Outline the use of ATP. 

Yeast cells, Saccharomyces cerevisiae, were incubated with and without glucose at three different temperatures for a period of four minutes, during which the rate of CO₂ production was measured with a CO₂ sensor.

[Source: © International Baccalaureate Organization 2019]

What conclusion can be drawn from the results of this experiment?

A. Yeast uses lipids rather than glucose in respiration at low temperatures.

B. Addition of glucose has a greater impact on rates of cell respiration at lower temperatures.

C. Rates of cell respiration increase with temperature.

D. More glucose is produced at higher temperatures.

Describe anaerobic respiration in humans and in yeast.

Using the following table, compare and contrast anaerobic cell respiration in yeasts and in humans. The first row has been completed as an example.

Which equation is an example of decarboxylation?

A. Pyruvate $\to$ Acetyl CoA + CO₂

B. CO₂ + H₂O H₂CO₃

C. CH₄ + 2O₂ CO₂ + 2H₂O

D.

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

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 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

Rotenone is a naturally occurring toxin that blocks the electron transport chain in insects and fish. Outline the consequences of exposure to a toxin like rotenone for cell respiration.

Rotenone is a naturally occurring toxin that blocks the electron transport chain in insects and fish. Outline the consequences of exposure to a toxin like rotenone for cell respiration.

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.

The graph shows the results of an experimental investigation that compared the rates at which lactose, glucose and galactose are broken down in the process of anaerobic cellular respiration by the yeast Torulopsis cremoris.

State one process that produces ATP.

Outline the use of ATP. 

State one process that produces ATP.

Outline the use of ATP. 

Yeast cells, Saccharomyces cerevisiae, were incubated with and without glucose at three different temperatures for a period of four minutes, during which the rate of CO₂ production was measured with a CO₂ sensor.

[Source: © International Baccalaureate Organization 2019]

What conclusion can be drawn from the results of this experiment?

A. Yeast uses lipids rather than glucose in respiration at low temperatures.

B. Addition of glucose has a greater impact on rates of cell respiration at lower temperatures.

C. Rates of cell respiration increase with temperature.

D. More glucose is produced at higher temperatures.

Describe anaerobic respiration in humans and in yeast.

Describe anaerobic respiration in humans and in yeast.

Using the following table, compare and contrast anaerobic cell respiration in yeasts and in humans. The first row has been completed as an example.

Using the following table, compare and contrast anaerobic cell respiration in yeasts and in humans. The first row has been completed as an example.

Which equation is an example of decarboxylation?

A. Pyruvate $\to$ Acetyl CoA + CO₂

B. CO₂ + H₂O H₂CO₃

C. CH₄ + 2O₂ CO₂ + 2H₂O

D.

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 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 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

Rotenone is a naturally occurring toxin that blocks the electron transport chain in insects and fish. Outline the consequences of exposure to a toxin like rotenone for cell respiration.

Rotenone is a naturally occurring toxin that blocks the electron transport chain in insects and fish. Outline the consequences of exposure to a toxin like rotenone for cell respiration.

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

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.

Explain the scientific reasoning for your hypothesis.

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

[Source: © International Baccalaureate Organization 2019]

In 1882, Engelmann investigated photosynthesis by shining light of varying wavelength on a green alga. He observed where aerobic bacteria accumulated.

[Source: Republished with permission of Oxford University Press, from Plant Physiology and Development, Sixth Edition by
Lincoln Taiz, Eduardo Zeiger, Ian M. Møller, and Angus Murphy, 2015. Permission conveyed through Copyright
Clearance Center, Inc.]

What can be deduced from this experiment?

A. Only parts of the chloroplast contained chlorophyll.

B. The distribution of bacteria indicates the action spectrum of photosynthesis.

C. Most oxygen is released from the algae in green light.

D. Chloroplasts reflect blue and red light.

The amount of food passing into food chains can be affected by the rate of photosynthesis. Explain the effect of one limiting factor on photosynthesis.

Describe the control for this experiment.

Outline how the carbon dioxide could be removed from the water used to irrigate the plant.

Suggest how a plastic bag placed around the plant pot prevents carbon dioxide from reaching the plant’s leaves.

A chromatograph was made of the photosynthetic pigments of a leaf of the plant.

[Source: Adapted from “Diversity of Photosynthetic Pigments” by Alexander F. Motten in Tested Studies for
Laboratory Teaching, Volume 16 of the Association for Biology Laboratory Education and used by permission of the
author.]

Outline what measurements would be taken to identify pigment X.

The graph shows the effect of increasing light intensity on the rate of CO₂ uptake by a species of green plant maintained in conditions of constant temperature and CO₂ concentration.

[Source: © International Baccalaureate Organization 2019]

Which statement is consistent with the graph?

A. Photosynthesis stops at high light intensity.

B. Rates of photosynthesis increase with temperature.

C. Cell respiration leads to net production of CO₂ at low light intensity.

D. There is a negative correlation between CO₂ uptake and light intensity.

Outline how photosynthesis produces glucose.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

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?

The graph shows the absorption spectra of chlorophyll a and chlorophyll b.

[Source: adapted from F. P. Zscheile and C. L. Comar, 'Influence of Preparative Procedure on the Purity of Chlorophyll
Components as Shown by Absorption Spectra.' Int. J. Plant Sciences, Volume 102, Number 3, Mar., 1941, pp. 463–481.
Used with the kind permission of University of Chicago Press.]

What can be concluded from the graph?

A. Both chlorophyll a and chlorophyll b absorb a large amount of green light

B. Chlorophyll b absorbs red light more efficiently than blue light

C. Other pigments must absorb light between blue and red in the spectrum

D. Chlorophyll a and chlorophyll b have different absorption peaks

Describe how leaf cells make use of light energy.

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

Explain the role of hydrogen ions used in photosynthesis.

State one function of Rubisco.

The graph shows atmospheric oxygen levels over time.

About 2.5 billion years ago, a significant rise in atmospheric oxygen occurred. What was the cause of this rise?

A. Photosynthesis by non-vascular land plants

B. Photosynthesis by vascular land plants

C. Oxygen produced by photosynthetic bacteria being released from the ocean into the atmosphere

D. Volcanic activity

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

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.

Explain the differences in the water loss rate in dark and light conditions.

The micrograph shows part of a chloroplast.

_{[Source: Newcomb, E., n.d. [Detail of a chloroplast]. [image online] Available at: https://search.library.wisc.edu/digital/
AHDTZ7JMHZ5VSU8C [Accessed 1 October 2021] © Board of Regents of the University of Wisconsin System.
Licensed under the Creative Commons Attribution 4.0 International. https://creativecommons.org/licenses/by/4.0/
deed.en.]}

What reaction takes place in region P?

A.  Carboxylation of ribulose bisphosphate

B.  Photolysis of water molecules

C.  Generation of ATP by ATP synthase

D.  Reduction of NAD in Photosystem I

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

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.

Explain the scientific reasoning for your hypothesis.

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

[Source: © International Baccalaureate Organization 2019]

In 1882, Engelmann investigated photosynthesis by shining light of varying wavelength on a green alga. He observed where aerobic bacteria accumulated.

[Source: Republished with permission of Oxford University Press, from Plant Physiology and Development, Sixth Edition by
Lincoln Taiz, Eduardo Zeiger, Ian M. Møller, and Angus Murphy, 2015. Permission conveyed through Copyright
Clearance Center, Inc.]

What can be deduced from this experiment?

A. Only parts of the chloroplast contained chlorophyll.

B. The distribution of bacteria indicates the action spectrum of photosynthesis.

C. Most oxygen is released from the algae in green light.

D. Chloroplasts reflect blue and red light.

The amount of food passing into food chains can be affected by the rate of photosynthesis. Explain the effect of one limiting factor on photosynthesis.

The amount of food passing into food chains can be affected by the rate of photosynthesis. Explain the effect of one limiting factor on photosynthesis.

Describe the control for this experiment.

Outline how the carbon dioxide could be removed from the water used to irrigate the plant.

Suggest how a plastic bag placed around the plant pot prevents carbon dioxide from reaching the plant’s leaves.

A chromatograph was made of the photosynthetic pigments of a leaf of the plant.

[Source: Adapted from “Diversity of Photosynthetic Pigments” by Alexander F. Motten in Tested Studies for
Laboratory Teaching, Volume 16 of the Association for Biology Laboratory Education and used by permission of the
author.]

Outline what measurements would be taken to identify pigment X.

The graph shows the effect of increasing light intensity on the rate of CO₂ uptake by a species of green plant maintained in conditions of constant temperature and CO₂ concentration.

[Source: © International Baccalaureate Organization 2019]

Which statement is consistent with the graph?

A. Photosynthesis stops at high light intensity.

B. Rates of photosynthesis increase with temperature.

C. Cell respiration leads to net production of CO₂ at low light intensity.

D. There is a negative correlation between CO₂ uptake and light intensity.

Outline how photosynthesis produces glucose.

Outline how photosynthesis produces glucose.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

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?

The graph shows the absorption spectra of chlorophyll a and chlorophyll b.

[Source: adapted from F. P. Zscheile and C. L. Comar, 'Influence of Preparative Procedure on the Purity of Chlorophyll
Components as Shown by Absorption Spectra.' Int. J. Plant Sciences, Volume 102, Number 3, Mar., 1941, pp. 463–481.
Used with the kind permission of University of Chicago Press.]

What can be concluded from the graph?

A. Both chlorophyll a and chlorophyll b absorb a large amount of green light

B. Chlorophyll b absorbs red light more efficiently than blue light

C. Other pigments must absorb light between blue and red in the spectrum

D. Chlorophyll a and chlorophyll b have different absorption peaks

Describe how leaf cells make use of light energy.

Describe how leaf cells make use of light energy.

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 role of hydrogen ions used in photosynthesis.

Explain the role of hydrogen ions used in photosynthesis.

State one function of Rubisco.

State one function of Rubisco.

The graph shows atmospheric oxygen levels over time.

About 2.5 billion years ago, a significant rise in atmospheric oxygen occurred. What was the cause of this rise?

A. Photosynthesis by non-vascular land plants

B. Photosynthesis by vascular land plants

C. Oxygen produced by photosynthetic bacteria being released from the ocean into the atmosphere

D. Volcanic activity

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

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.

Explain the differences in the water loss rate in dark and light conditions.

The micrograph shows part of a chloroplast.

_{[Source: Newcomb, E., n.d. [Detail of a chloroplast]. [image online] Available at: https://search.library.wisc.edu/digital/
AHDTZ7JMHZ5VSU8C [Accessed 1 October 2021] © Board of Regents of the University of Wisconsin System.
Licensed under the Creative Commons Attribution 4.0 International. https://creativecommons.org/licenses/by/4.0/
deed.en.]}

What reaction takes place in region P?

A.  Carboxylation of ribulose bisphosphate

B.  Photolysis of water molecules

C.  Generation of ATP by ATP synthase

D.  Reduction of NAD in Photosystem I

The diagram shows the synaptic transmission of nerve impulses by the neurotransmitter acetylcholine. 

[Source: Zhang, X. A Mathematical Model of a Neuron with Synapses based on Physiology. Nat Prec (2008).
https://doi.org/10.1038/npre.2008.1703.1 available at https://www.nature.com/articles/npre.2008.1703.1
Source adapted.]

What is the fate of acetylcholine immediately after binding to the receptor?

A. It is pumped into the postsynaptic neuron.

B. It diffuses into the presynaptic neuron.

C. It is broken down in the synaptic cleft.

D. It binds to another receptor in the postsynaptic neuron.

State one function of epinephrine in the human body.

Identify the structure labelled X.

Outline how the neuron is stimulated to release the neurotransmitter.

The diagram shows the synaptic transmission of nerve impulses by the neurotransmitter acetylcholine. 

[Source: Zhang, X. A Mathematical Model of a Neuron with Synapses based on Physiology. Nat Prec (2008).
https://doi.org/10.1038/npre.2008.1703.1 available at https://www.nature.com/articles/npre.2008.1703.1
Source adapted.]

What is the fate of acetylcholine immediately after binding to the receptor?

A. It is pumped into the postsynaptic neuron.

B. It diffuses into the presynaptic neuron.

C. It is broken down in the synaptic cleft.

D. It binds to another receptor in the postsynaptic neuron.

State one function of epinephrine in the human body.

State one function of epinephrine in the human body.

Identify the structure labelled X.

Outline how the neuron is stimulated to release the neurotransmitter.

Identify the structure labelled X.

Outline how the neuron is stimulated to release the neurotransmitter.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Using the data, outline the different use of thiamethoxam in North and South America.

Identify the total percentage of honey samples contaminated with neonicotinoid pesticides in the continent with the lowest overall levels of contamination.

. . . . . . . . . . . . %

Deduce the conclusions that can be drawn from the data in the graph.

Suggest a reason for the effect of a diet reduced in acetylcholine on the larval survival rate.

Compare and contrast the effect of clothianidin and thiacloprid treatments on the concentration of acetylcholine in royal jelly.

Explain how neonicotinoids affect synaptic transmission in insects.

Outline how depolarization of the membrane of an axon occurs.

Explain how acetylcholine initiates an action potential in a postsynaptic membrane.

Explain the propagation of nerve impulses along the membrane of a neuron.

The diagram shows a motor neuron.

[Source: © International Baccalaureate Organization 2019]

What are the biochemical nature and function of the myelin sheath?

A. The myelin sheath is mainly protein which allows growth of the axon.

B. The myelin sheath is mainly protein which acts as membrane carriers.

C. The myelin sheath is mainly lipid which allows saltatory conduction.

D. The myelin sheath is mainly lipid which provides an energy source.

The diagram shows a graph of an action potential.

The diagram shows a neural synapse in the central nervous system of a honey bee (Apis mellifera).

[Source: © International Baccalaureate Organization 2019]

How do neonicotinoid pesticides cause paralysis and death of honey bees?

A. They destroy I.

B. They bind to II.

C. They inhibit the release of III.

D. They block the activity of IV.

The electron micrograph shows a transverse section through a myelinated neuron.

Explain the action of neonicotinoid pesticides in insects.

Describe what occurs in a neuron when an action potential is propagated along the axon.

Outline the role of membrane proteins in the movement of specific ions at specific times in the transmission of nerve impulses.

Explain how communication between neurons during synaptic transmission is achieved through neurotransmitters.

Outline the role of membrane proteins in the movement of specific ions at specific times in the transmission of nerve impulses.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

State the approximate value of the membrane potential at X.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the movements in ions that occur during time t.

Explain how a nerve impulse is passed on to other neurons.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

Using the data, outline the different use of thiamethoxam in North and South America.

Identify the total percentage of honey samples contaminated with neonicotinoid pesticides in the continent with the lowest overall levels of contamination.

. . . . . . . . . . . . %

Deduce the conclusions that can be drawn from the data in the graph.

Suggest a reason for the effect of a diet reduced in acetylcholine on the larval survival rate.

Compare and contrast the effect of clothianidin and thiacloprid treatments on the concentration of acetylcholine in royal jelly.

Explain how neonicotinoids affect synaptic transmission in insects.

Using the data, outline the different use of thiamethoxam in North and South America.

Identify the total percentage of honey samples contaminated with neonicotinoid pesticides in the continent with the lowest overall levels of contamination.

. . . . . . . . . . . . %

Deduce the conclusions that can be drawn from the data in the graph.

Suggest a reason for the effect of a diet reduced in acetylcholine on the larval survival rate.

Compare and contrast the effect of clothianidin and thiacloprid treatments on the concentration of acetylcholine in royal jelly.

Explain how neonicotinoids affect synaptic transmission in insects.

Outline how depolarization of the membrane of an axon occurs.

Explain how acetylcholine initiates an action potential in a postsynaptic membrane.

Outline how depolarization of the membrane of an axon occurs.

Explain how acetylcholine initiates an action potential in a postsynaptic membrane.

Explain the propagation of nerve impulses along the membrane of a neuron.

Explain the propagation of nerve impulses along the membrane of a neuron.

The diagram shows a motor neuron.

[Source: © International Baccalaureate Organization 2019]

What are the biochemical nature and function of the myelin sheath?

A. The myelin sheath is mainly protein which allows growth of the axon.

B. The myelin sheath is mainly protein which acts as membrane carriers.

C. The myelin sheath is mainly lipid which allows saltatory conduction.

D. The myelin sheath is mainly lipid which provides an energy source.

The diagram shows a graph of an action potential.

The diagram shows a neural synapse in the central nervous system of a honey bee (Apis mellifera).

[Source: © International Baccalaureate Organization 2019]

How do neonicotinoid pesticides cause paralysis and death of honey bees?

A. They destroy I.

B. They bind to II.

C. They inhibit the release of III.

D. They block the activity of IV.

The electron micrograph shows a transverse section through a myelinated neuron.

Explain the action of neonicotinoid pesticides in insects.

Explain the action of neonicotinoid pesticides in insects.

Describe what occurs in a neuron when an action potential is propagated along the axon.

Describe what occurs in a neuron when an action potential is propagated along the axon.

Outline the role of membrane proteins in the movement of specific ions at specific times in the transmission of nerve impulses.

Outline the role of membrane proteins in the movement of specific ions at specific times in the transmission of nerve impulses.

Explain how communication between neurons during synaptic transmission is achieved through neurotransmitters.

State the trend in relative brain mass in primates other than humans according to their time of divergence from humans.

Suggest one reason that the relative brain mass of Homo is different from Parapithecus and Australopithecus.

Deduce, with a reason, whether the relative brain mass is a good indicator of brain development.

Outline the extension of the stem in plants.

The image shows the changes in heart rate of an athlete during exercise.

[Source: Liddle, P.F., 2010. Heart Rate Variability (HRV) during exercise. [online] Available at: https://canute1.wordpress.com/2010/07/ [Accessed 1 August 2019].]

What is likely to have occurred between 0 and 4 minutes and between 24 and 28 minutes?

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

Outline how the hormone auxin controls phototropism in plant shoots.

Compare and contrast hormonal and nervous communication.

Outline how the shrew labelled P differs from the normal relationship between BCH and brain mass.

State the season when shrew brain mass is greatest.

Compare and contrast the results for winter and spring.

State the activity and season that occupied the greatest mean percentage of observation time.

Calculate the percentage of containers that contained food.

Outline a reason that the path length was standardized.

Compare and contrast the results for trials 2 and 9.

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?

How is involuntary peristalsis in the intestine directly controlled in humans?

A.  By the endocrine system

B.  By the central nervous system (CNS)

C.  By the sympathetic nervous system

D.  By the enteric nervous system (ENS)

Explain how breathing is controlled by the brain.

How is involuntary peristalsis in the intestine directly controlled in humans?

A.  By the endocrine system

B.  By the central nervous system (CNS)

C.  By the sympathetic nervous system

D.  By the enteric nervous system (ENS)

How is involuntary peristalsis in the intestine directly controlled in humans?

A.  By the endocrine system

B.  By the central nervous system (CNS)

C.  By the sympathetic nervous system

D.  By the enteric nervous system (ENS)

State the trend in relative brain mass in primates other than humans according to their time of divergence from humans.

Suggest one reason that the relative brain mass of Homo is different from Parapithecus and Australopithecus.

Deduce, with a reason, whether the relative brain mass is a good indicator of brain development.

Outline the extension of the stem in plants.

Outline the extension of the stem in plants.

The image shows the changes in heart rate of an athlete during exercise.

[Source: Liddle, P.F., 2010. Heart Rate Variability (HRV) during exercise. [online] Available at: https://canute1.wordpress.com/2010/07/ [Accessed 1 August 2019].]

What is likely to have occurred between 0 and 4 minutes and between 24 and 28 minutes?

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

Outline how the hormone auxin controls phototropism in plant shoots.

Compare and contrast hormonal and nervous communication.

Outline how the hormone auxin controls phototropism in plant shoots.

Compare and contrast hormonal and nervous communication.

Outline how the shrew labelled P differs from the normal relationship between BCH and brain mass.

State the season when shrew brain mass is greatest.

Compare and contrast the results for winter and spring.

State the activity and season that occupied the greatest mean percentage of observation time.

Calculate the percentage of containers that contained food.

Outline a reason that the path length was standardized.

Compare and contrast the results for trials 2 and 9.

Outline how the shrew labelled P differs from the normal relationship between BCH and brain mass.

State the season when shrew brain mass is greatest.

Compare and contrast the results for winter and spring.

State the activity and season that occupied the greatest mean percentage of observation time.

Calculate the percentage of containers that contained food.

Outline a reason that the path length was standardized.

Compare and contrast the results for trials 2 and 9.

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?

How is involuntary peristalsis in the intestine directly controlled in humans?

A.  By the endocrine system

B.  By the central nervous system (CNS)

C.  By the sympathetic nervous system

D.  By the enteric nervous system (ENS)

Explain how breathing is controlled by the brain.

The blood of two men was tested and the results are shown. Anti-D refers to the rhesus blood group. Clotting indicates that antigens associated with a particular factor or blood group are present in a blood sample.

[Source: © International Baccalaureate Organization 2019]

The man who tested positive for anti-D was then tested for ABO blood group. These results were obtained.

[Source: © International Baccalaureate Organization 2019]

What ABO blood group does the man testing positive for anti-D have?

A. A

B. B

C. AB

D. O

The diagram shows the major events involved in the formation of a blood clot.

[Source: © International Baccalaureate Organization 2019]

What is Factor Y?

A. Fibrin

B. Prothrombin

C. Fibrinogen

D. Thrombin

The graph shows the results of measuring two factors in the blood of patients with HIV/AIDS.

[Source: Courtesy ACRIA.]

What do X and Y represent?

Explain the development of antibiotic resistance in terms of natural selection.

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

Explain how cells and cell components in the blood defend the body against infectious disease.

Explain how blood clotting occurs and the consequence for a person who has hemophilia.

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

Explain the role of cells in the defence against infectious disease.

Explain the production of antibodies when a patient is infected with the TB bacterium.

Describe the risk to the human population of indiscriminate use of antibiotics.

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 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 production of antibodies in humans.

Despite continuous scientific research into the control of pathogens, it has proved very difficult to eliminate them. What is/are the reason(s) for this?

I.   Development of antibiotic resistance in viruses

II.  Development of antibiotic resistance in bacteria

III. Mutations of pathogens

A.  II only

B.  I and II only

C.  II and III only

D.  I, II and III

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

Melatonin controls circadian rhythms and is involved in the sleep-wake cycle. The pineal gland, which secretes melatonin, is inhibited by light. The graph shows a normal cycle where bedtime is around 10pm.

Using data from the graph, what might be the effect(s) of screen light from a laptop, tablet or phone at bedtime?

I.   Delay in melatonin production

II.  Lower peak concentration of melatonin

III. Peak of melatonin earlier in the evening

A.  I only

B.  III only

C.  II and III only

D.  I, II and III

Explain how natural selection could increase the prevalence of an antibiotic resistance gene in a species of soil bacterium.

There are viruses in soils that are pathogens of animals. Outline a reason for antibiotics in soil not eliminating these viruses.

Explain the reasons for antibiotics secreted into soil not harming insects or other animals in the soil.

Outline the conclusions that can be drawn from the graph showing data for PCV and S. pneumoniae.

Suggest reasons for the difference between the data for S. pneumoniae and H. influenzae.

Using the data in the violin plots, deduce the age range at which children are most likely to develop ARI due to S. pneumoniae.

Suggest reasons for the difference between the fraction attributed to S. pneumoniae in all cases of ARI and in cases where antibiotics were used to treat the infection.

When there is no vaccination, the estimated number of cases for lower-middle income countries is larger than in either low income or upper-middle income countries. Suggest one reason for this.

Using the data, predict the effect of universal PCV vaccination in LMICs.

Outline likely health benefits of universal PCV vaccination of children, other than reducing the incidence of ARI.

Estimate the median number of bacterial cells per gram of feces in the R enterotype.

The blood of two men was tested and the results are shown. Anti-D refers to the rhesus blood group. Clotting indicates that antigens associated with a particular factor or blood group are present in a blood sample.

[Source: © International Baccalaureate Organization 2019]

The man who tested positive for anti-D was then tested for ABO blood group. These results were obtained.

[Source: © International Baccalaureate Organization 2019]

What ABO blood group does the man testing positive for anti-D have?

A. A

B. B

C. AB

D. O

The diagram shows the major events involved in the formation of a blood clot.

[Source: © International Baccalaureate Organization 2019]

What is Factor Y?

A. Fibrin

B. Prothrombin

C. Fibrinogen

D. Thrombin

The graph shows the results of measuring two factors in the blood of patients with HIV/AIDS.

[Source: Courtesy ACRIA.]

What do X and Y represent?

Explain the development of antibiotic resistance in terms of natural selection.

Explain the development of antibiotic resistance in terms of natural selection.

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

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

Explain how cells and cell components in the blood defend the body against infectious disease.

Explain how cells and cell components in the blood defend the body against infectious disease.

Explain how blood clotting occurs and the consequence for a person who has hemophilia.

Explain how blood clotting occurs and the consequence for a person who has hemophilia.

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.

Explain the role of cells in the defence against infectious disease.

Explain the role of cells in the defence against infectious disease.

Explain the production of antibodies when a patient is infected with the TB bacterium.

Describe the risk to the human population of indiscriminate use of antibiotics.

Explain the production of antibodies when a patient is infected with the TB bacterium.

Describe the risk to the human population of indiscriminate use of antibiotics.

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 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 production of antibodies in humans.

Explain the production of antibodies in humans.

Despite continuous scientific research into the control of pathogens, it has proved very difficult to eliminate them. What is/are the reason(s) for this?

I.   Development of antibiotic resistance in viruses

II.  Development of antibiotic resistance in bacteria

III. Mutations of pathogens

A.  II only

B.  I and II only

C.  II and III only

D.  I, II and III

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

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

Melatonin controls circadian rhythms and is involved in the sleep-wake cycle. The pineal gland, which secretes melatonin, is inhibited by light. The graph shows a normal cycle where bedtime is around 10pm.

Using data from the graph, what might be the effect(s) of screen light from a laptop, tablet or phone at bedtime?

I.   Delay in melatonin production

II.  Lower peak concentration of melatonin

III. Peak of melatonin earlier in the evening

A.  I only

B.  III only

C.  II and III only

D.  I, II and III

Explain how natural selection could increase the prevalence of an antibiotic resistance gene in a species of soil bacterium.

There are viruses in soils that are pathogens of animals. Outline a reason for antibiotics in soil not eliminating these viruses.

Explain the reasons for antibiotics secreted into soil not harming insects or other animals in the soil.

Explain how natural selection could increase the prevalence of an antibiotic resistance gene in a species of soil bacterium.

There are viruses in soils that are pathogens of animals. Outline a reason for antibiotics in soil not eliminating these viruses.

Explain the reasons for antibiotics secreted into soil not harming insects or other animals in the soil.

Outline the conclusions that can be drawn from the graph showing data for PCV and S. pneumoniae.

Suggest reasons for the difference between the data for S. pneumoniae and H. influenzae.

Using the data in the violin plots, deduce the age range at which children are most likely to develop ARI due to S. pneumoniae.

Suggest reasons for the difference between the fraction attributed to S. pneumoniae in all cases of ARI and in cases where antibiotics were used to treat the infection.

When there is no vaccination, the estimated number of cases for lower-middle income countries is larger than in either low income or upper-middle income countries. Suggest one reason for this.

Using the data, predict the effect of universal PCV vaccination in LMICs.

Outline likely health benefits of universal PCV vaccination of children, other than reducing the incidence of ARI.

Outline the conclusions that can be drawn from the graph showing data for PCV and S. pneumoniae.

Suggest reasons for the difference between the data for S. pneumoniae and H. influenzae.

Using the data in the violin plots, deduce the age range at which children are most likely to develop ARI due to S. pneumoniae.

Suggest reasons for the difference between the fraction attributed to S. pneumoniae in all cases of ARI and in cases where antibiotics were used to treat the infection.

When there is no vaccination, the estimated number of cases for lower-middle income countries is larger than in either low income or upper-middle income countries. Suggest one reason for this.

Using the data, predict the effect of universal PCV vaccination in LMICs.

Outline likely health benefits of universal PCV vaccination of children, other than reducing the incidence of ARI.

Estimate the median number of bacterial cells per gram of feces in the R enterotype.

Estimate the median number of bacterial cells per gram of feces in the R enterotype.

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.

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.

Outline a method that could have been used in this study to measure the numbers of sea urchins per 0.25 m².

E. modestus is an invasive barnacle while the others are native species. Analyse the data to show how it supports this statement.

Explain the factors that can contribute to the exponential growth phase in a sigmoid population curve.

Explain the technique used to estimate the population size of a named species of organism that is able to move.

The garden snail, Helix aspersa, is a herbivore.

[Source: Sinan Önder /https://www.pexels.com/photo/animal-close-up-crawling-garden-243128/]

Explain how the population of snails in an ecosystem could be estimated by capture-mark-release-recapture, identifying the limitations in the method.

Explain what is meant by competitive exclusion, with respect to a named example of an invasive species.

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.

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Explain how the population of fish in a pond could be estimated using the capture-mark-release-recapture method.

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

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.

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.

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.

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.

Outline a method that could have been used in this study to measure the numbers of sea urchins per 0.25 m².

E. modestus is an invasive barnacle while the others are native species. Analyse the data to show how it supports this statement.

Explain the factors that can contribute to the exponential growth phase in a sigmoid population curve.

Explain the technique used to estimate the population size of a named species of organism that is able to move.

The garden snail, Helix aspersa, is a herbivore.

[Source: Sinan Önder /https://www.pexels.com/photo/animal-close-up-crawling-garden-243128/]

Explain how the population of snails in an ecosystem could be estimated by capture-mark-release-recapture, identifying the limitations in the method.

Explain what is meant by competitive exclusion, with respect to a named example of an invasive species.

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.

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Black walnut (Juglans nigra) secretes the chemical juglone into the soil surrounding its roots. Juglone inhibits cell respiration in other species of plants. What does this example illustrate?

A.  Mutualism

B.  Intraspecific competition

C.  Allelopathy

D.  Parasitism

Explain how the population of fish in a pond could be estimated using the capture-mark-release-recapture method.

State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.

The crustacean and the jellyfish obtain carbon compounds by feeding. State one source of carbon for marine organisms, other than feeding.

In the diagram, which of the processes labelled A to D transfers the largest mass of carbon per year in a woodland ecosystem?

[Source: © International Baccalaureate Organization 2019]

Distinguish between the transfers of energy and inorganic nutrients in ecosystems.

Describe how autotrophs absorb light energy

The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

[Source: © International Baccalaureate Organization 2019]

Which organism is a tertiary consumer?

A. Organism T

B. Organism U

C. Organism W

D. Organism Y

A pyramid of energy represents the amount of energy taken in by each trophic level per unit time and per unit area. Discuss the advantages and disadvantages of the use of pyramids of energy as models of energy flow in an ecosystem.

The image shows an example of a soil food web.

[Source: Anon., n.d. The Soil Food Web. [image online] Available at: https://www.nrcs.usda.gov/wps/portal/nrcs/
photogallery/soils/health/biology/gallery/?cid=1788&position=Promo [Accessed 11 March 2020].]

Draw a food chain from this food web, showing at least three organisms.

Explain the reasons for food chains rarely containing more than four or five trophic levels.

Calculate the percentage increase in the use of liquid fuels from 1950 to 1975.

%

Referring to the data, compare and contrast the changes in the use of the different fuels between 1950 and 1975.

The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

[Source: © International Baccalaureate Organization 2019]

Which organism is a tertiary consumer?

A. Organism T

B. Organism U

C. Organism W

D. Organism Y

Models are used as representations of the real world. Evaluate the use of food webs to represent ecological communities.

State two causes of the decrease of biomass along food chains in terrestrial ecosystems.

The table shows the global carbon budget over two decades; the years 1990 to 1999 and 2000 to 2009.

[Source: © International Baccalaureate Organization 2019]

Using the table, explain causes of the changes in carbon flux over the two decades.

The diagram shows the carbon flux in gigatonnes per year between some of the Earth’s global reservoirs.

[Source: Figure 7.3 and Table 7.1 from Denman, K.L., G. Brasseur, A. Chidthaisong, P. Ciais, P.M. Cox, R.E. Dickinson, D.
Hauglustaine, C. Heinze, E. Holland, D. Jacob, U. Lohmann, S Ramachandran, P.L. da Silva Dias, S.C. Wofsy and
X. Zhang, 2007: Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt,
M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.]

What can be deduced from the information in the diagram?

A. Arrows S are mainly due to respiration of marine plants and animals.

B. Photosynthesis is a component of both arrows Q and S.

C. Every day, more carbon is removed from the ocean than is added.

D. Ocean carbon is stored as dissolved calcium carbonate.

Outline energy flow through a community in a natural ecosystem.

Explain the transformations of carbon compounds in the carbon cycle.

Explain what information a pyramid of energy provides about an ecological community.

The diagram shows the flow of energy through an ecosystem in ${\text{kJ\hspace{0.05em}m}}^{–2}{\text{\hspace{0.05em}y}}^{–1}.$

State the mean annual decline in insect biomass.

Calculate the number of Coleoptera species that would be expected to exist after one year from a starting number of 400$$000 species, assuming the mean rate of decline.

Compare and contrast the results for the 1:1 and the 1:10 P:L diets.

Suggest a reason that the mass of protein and lipid mixture eaten at 25:1 is lower than at 50:1.

Suggest with a reason which P:L diet is closest to the normal diet of these bumblebees.

Outline how energy flows in an ecosystem.

Describe how plants affect the amount of carbon dioxide in the atmosphere.

Carbon sinks are any reservoirs that absorb and store carbon dioxide from the atmosphere. Which process increases the size of the carbon sink in oceans?

A.  Photosynthesis

B.  Respiration

C.  Ocean acidification

D.  Decomposition

The diagram shows part of the carbon cycle involving methane.

[Source: NASA GISS, n.d. Rough schematic of methane sources and sinks. [diagram online] Available at:
https://www.giss.nasa.gov/research/features/200409_methane/ [Accessed 26 October 2021].]

Which conditions favour methane production in W, X and Y?

A.  Presence of eubacteria and organic matter

B.  Presence of archaeans and waterlogged soil

C.  Presence of eubacteria and waterlogged soil

D.  Presence of archaeans and oxygen

The Silver Springs feed into the Silver River in Florida. The diagram shows a pyramid of energy for the Silver Springs ecosystem. The units are kJ m^–2 y^–1.

[Source: © International Baccalaureate Organization 2019]

What do level I and level III represent in the pyramid of energy?

Outline the stages of the carbon cycle that involve plants or materials made by plants.

Explain what information is needed to find the trophic level of pangolins.

Describe processes in the carbon cycle that produce or use carbon dioxide.

Explain what information is needed to find the trophic level of pangolins.

Identify the trophic level of sea lions. [

Humans have persecuted predators such as coyotes (Canis latrans), causing severe reduction in the number of large carnivores throughout the world. The diagram represents part of a food web in Texas, USA.

_{[Source: Coyote: https://commons.wikimedia.org/wiki/File:2009-Coyote-Yosemite.jpg. CC-BY-SA 3.0; Yathin S. Krishnappa, Jan.
2009, Coyote from Yosemite National Park, California in snow.]
[Source: Fox: https://commons.wikimedia.org/wiki/File:Foxes_of_Island_Beach_State_Park_New_Jersey_(16324545492).jpg.
CC-Attribution 2.0; Anthony Quintano, Jan. 2015, Foxes of Island Beach State Park New Jersey.]
[Source: Rodent/Brown Rat: https://commons.wikimedia.org/wiki/File:Rattus_norvegicus_-_Brown_rat_02.jpg. CC-BY-SA-4.0
Zeynel Cebeci, May 2020; Brown Rat, Adana, Turkey.]
[Source: Lagomorph: https://commons.wikimedia.org/wiki/File:Eastern_Cottontail.JPG. CC 3.0. Taken by Gareth Rasberry,
Huntington Beach State Park, Murrells Inlet, South Carolina, USA.]
[Source: Nest Eggs: https://commons.wikimedia.org/wiki/File:Eastern_Phoebe-nest-Brown-headed-Cowbird-egg.jpg. CC 3.0.
Galawebdesign, June 2007, Eastern Phoebe (Sayornis phoebe) nest with one Brown-headed Cowbird (Molothrus ater)
egg.]}

What is a possible outcome for the lagomorph population in this ecosystem if coyote numbers were controlled by killing them to reduce losses of domestic livestock?

A.  Decrease because there are fewer predators

B.  Increase because there are fewer foxes to eat them

C.  Decrease because there are more rodents for foxes to eat

D.  Increase because, although there are more foxes, there are also more rodents

State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.

The crustacean and the jellyfish obtain carbon compounds by feeding. State one source of carbon for marine organisms, other than feeding.

State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.

The crustacean and the jellyfish obtain carbon compounds by feeding. State one source of carbon for marine organisms, other than feeding.

In the diagram, which of the processes labelled A to D transfers the largest mass of carbon per year in a woodland ecosystem?

[Source: © International Baccalaureate Organization 2019]

Distinguish between the transfers of energy and inorganic nutrients in ecosystems.

Describe how autotrophs absorb light energy

Distinguish between the transfers of energy and inorganic nutrients in ecosystems.

Describe how autotrophs absorb light energy

The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

[Source: © International Baccalaureate Organization 2019]

Which organism is a tertiary consumer?

A. Organism T

B. Organism U

C. Organism W

D. Organism Y

A pyramid of energy represents the amount of energy taken in by each trophic level per unit time and per unit area. Discuss the advantages and disadvantages of the use of pyramids of energy as models of energy flow in an ecosystem.

The image shows an example of a soil food web.

[Source: Anon., n.d. The Soil Food Web. [image online] Available at: https://www.nrcs.usda.gov/wps/portal/nrcs/
photogallery/soils/health/biology/gallery/?cid=1788&position=Promo [Accessed 11 March 2020].]

Draw a food chain from this food web, showing at least three organisms.

Explain the reasons for food chains rarely containing more than four or five trophic levels.

The image shows an example of a soil food web.

[Source: Anon., n.d. The Soil Food Web. [image online] Available at: https://www.nrcs.usda.gov/wps/portal/nrcs/
photogallery/soils/health/biology/gallery/?cid=1788&position=Promo [Accessed 11 March 2020].]

Draw a food chain from this food web, showing at least three organisms.

Explain the reasons for food chains rarely containing more than four or five trophic levels.

Calculate the percentage increase in the use of liquid fuels from 1950 to 1975.

%

Referring to the data, compare and contrast the changes in the use of the different fuels between 1950 and 1975.

The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

[Source: © International Baccalaureate Organization 2019]

Which organism is a tertiary consumer?

A. Organism T

B. Organism U

C. Organism W

D. Organism Y

Models are used as representations of the real world. Evaluate the use of food webs to represent ecological communities.

State two causes of the decrease of biomass along food chains in terrestrial ecosystems.

The table shows the global carbon budget over two decades; the years 1990 to 1999 and 2000 to 2009.

[Source: © International Baccalaureate Organization 2019]

Using the table, explain causes of the changes in carbon flux over the two decades.

State two causes of the decrease of biomass along food chains in terrestrial ecosystems.

The table shows the global carbon budget over two decades; the years 1990 to 1999 and 2000 to 2009.

[Source: © International Baccalaureate Organization 2019]

Using the table, explain causes of the changes in carbon flux over the two decades.

The diagram shows the carbon flux in gigatonnes per year between some of the Earth’s global reservoirs.

[Source: Figure 7.3 and Table 7.1 from Denman, K.L., G. Brasseur, A. Chidthaisong, P. Ciais, P.M. Cox, R.E. Dickinson, D.
Hauglustaine, C. Heinze, E. Holland, D. Jacob, U. Lohmann, S Ramachandran, P.L. da Silva Dias, S.C. Wofsy and
X. Zhang, 2007: Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt,
M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.]

What can be deduced from the information in the diagram?

A. Arrows S are mainly due to respiration of marine plants and animals.

B. Photosynthesis is a component of both arrows Q and S.

C. Every day, more carbon is removed from the ocean than is added.

D. Ocean carbon is stored as dissolved calcium carbonate.

Outline energy flow through a community in a natural ecosystem.

Outline energy flow through a community in a natural ecosystem.

Explain the transformations of carbon compounds in the carbon cycle.

Explain the transformations of carbon compounds in the carbon cycle.

Explain what information a pyramid of energy provides about an ecological community.

The diagram shows the flow of energy through an ecosystem in ${\text{kJ\hspace{0.05em}m}}^{–2}{\text{\hspace{0.05em}y}}^{–1}.$

State the mean annual decline in insect biomass.

Calculate the number of Coleoptera species that would be expected to exist after one year from a starting number of 400$$000 species, assuming the mean rate of decline.

Compare and contrast the results for the 1:1 and the 1:10 P:L diets.

Suggest a reason that the mass of protein and lipid mixture eaten at 25:1 is lower than at 50:1.

Suggest with a reason which P:L diet is closest to the normal diet of these bumblebees.

State the mean annual decline in insect biomass.

Calculate the number of Coleoptera species that would be expected to exist after one year from a starting number of 400$$000 species, assuming the mean rate of decline.

Compare and contrast the results for the 1:1 and the 1:10 P:L diets.

Suggest a reason that the mass of protein and lipid mixture eaten at 25:1 is lower than at 50:1.

Suggest with a reason which P:L diet is closest to the normal diet of these bumblebees.

Outline how energy flows in an ecosystem.

Describe how plants affect the amount of carbon dioxide in the atmosphere.

Outline how energy flows in an ecosystem.

Describe how plants affect the amount of carbon dioxide in the atmosphere.

Carbon sinks are any reservoirs that absorb and store carbon dioxide from the atmosphere. Which process increases the size of the carbon sink in oceans?

A.  Photosynthesis

B.  Respiration

C.  Ocean acidification

D.  Decomposition

The diagram shows part of the carbon cycle involving methane.

[Source: NASA GISS, n.d. Rough schematic of methane sources and sinks. [diagram online] Available at:
https://www.giss.nasa.gov/research/features/200409_methane/ [Accessed 26 October 2021].]

Which conditions favour methane production in W, X and Y?

A.  Presence of eubacteria and organic matter

B.  Presence of archaeans and waterlogged soil

C.  Presence of eubacteria and waterlogged soil

D.  Presence of archaeans and oxygen

The Silver Springs feed into the Silver River in Florida. The diagram shows a pyramid of energy for the Silver Springs ecosystem. The units are kJ m^–2 y^–1.

[Source: © International Baccalaureate Organization 2019]

What do level I and level III represent in the pyramid of energy?

Outline the stages of the carbon cycle that involve plants or materials made by plants.

Outline the stages of the carbon cycle that involve plants or materials made by plants.

Explain what information is needed to find the trophic level of pangolins.

Explain what information is needed to find the trophic level of pangolins.

Describe processes in the carbon cycle that produce or use carbon dioxide.

Describe processes in the carbon cycle that produce or use carbon dioxide.

Explain what information is needed to find the trophic level of pangolins.

Explain what information is needed to find the trophic level of pangolins.

Identify the trophic level of sea lions. [

Humans have persecuted predators such as coyotes (Canis latrans), causing severe reduction in the number of large carnivores throughout the world. The diagram represents part of a food web in Texas, USA.

_{[Source: Coyote: https://commons.wikimedia.org/wiki/File:2009-Coyote-Yosemite.jpg. CC-BY-SA 3.0; Yathin S. Krishnappa, Jan.
2009, Coyote from Yosemite National Park, California in snow.]
[Source: Fox: https://commons.wikimedia.org/wiki/File:Foxes_of_Island_Beach_State_Park_New_Jersey_(16324545492).jpg.
CC-Attribution 2.0; Anthony Quintano, Jan. 2015, Foxes of Island Beach State Park New Jersey.]
[Source: Rodent/Brown Rat: https://commons.wikimedia.org/wiki/File:Rattus_norvegicus_-_Brown_rat_02.jpg. CC-BY-SA-4.0
Zeynel Cebeci, May 2020; Brown Rat, Adana, Turkey.]
[Source: Lagomorph: https://commons.wikimedia.org/wiki/File:Eastern_Cottontail.JPG. CC 3.0. Taken by Gareth Rasberry,
Huntington Beach State Park, Murrells Inlet, South Carolina, USA.]
[Source: Nest Eggs: https://commons.wikimedia.org/wiki/File:Eastern_Phoebe-nest-Brown-headed-Cowbird-egg.jpg. CC 3.0.
Galawebdesign, June 2007, Eastern Phoebe (Sayornis phoebe) nest with one Brown-headed Cowbird (Molothrus ater)
egg.]}

What is a possible outcome for the lagomorph population in this ecosystem if coyote numbers were controlled by killing them to reduce losses of domestic livestock?

A.  Decrease because there are fewer predators

B.  Increase because there are fewer foxes to eat them

C.  Decrease because there are more rodents for foxes to eat

D.  Increase because, although there are more foxes, there are also more rodents