Topic 1: Cell biology

Unicellular and multicellular organisms share the same functions of life. Outline four functions of life.

Using the scale bar, determine the diameter of the nucleus of the cell on the left, giving the units.

Deduce the magnification of the image.

Label the area where cellulose is found in the micrograph of a plant cell.

[Source: BIOPHOTO ASSOCIATES/Getty Images]

Outline the reasons for differences between the proteomes of cells within a multicellular organism.

Which graph represents the change in cell surface area to volume ratio with increasing cell diameter?

[Source: © International Baccalaureate Organization 2019]

The images show a sequence of changes in an organism.

The electron micrograph shows a thin section through a plant mesophyll cell.

Calculate the magnification of the image, showing your working.

. . . . . . . . . . . . . . . . . . . . x

What function is performed by the part of the cell shown in the electron micrograph?

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

A. Locomotion

B. Synthesis of proteins

C. Movement of chromosomes

D. Breakdown of cellular organelles

Three cell types are shown in the micrographs.

[Source: left: UCSF School of Medicine, Courtesy of Prof. D Schmucker. middle: Professor Roger Meicenheimer, Miami University, Department of Botany. right: Courtesy of visualhistology.com.]

What feature distinguishes striated muscle fibres from the three cell types shown in the images?

A. Mitochondria

B. Nucleoid regions

C. Multinucleate structure

D. Membrane-bound organelles

Outline reasons for the therapeutic use of stem cells.

Calculate the maximum diameter of the stem cell cluster on the micrograph, showing your working and giving the units.

..........

Outline reasons for the therapeutic use of stem cells.

What life function is illustrated?

A.  Nutrition

B.  Homeostasis

C.  Endocytosis

D.  Response

Explain how observation of the fossil record provides evidence for evolution.

Onion (Allium cepa) epidermis was placed in pure water and observed with a light microscope using high magnification.

What would happen to these cells if they were transferred to a hypertonic solution?

A.  Cells would gain mass.

B.  Cells would take in water by osmosis and swell.

C.  Cells would burst open, releasing their content.

D.  Cell membranes would detach from walls at some points.

Onion (Allium cepa) epidermis was placed in pure water and observed with a light microscope using high magnification.

What would happen to these cells if they were transferred to a hypertonic solution?

A.  Cells would gain mass.

B.  Cells would take in water by osmosis and swell.

C.  Cells would burst open, releasing their content.

D.  Cell membranes would detach from walls at some points.

The electron micrograph shows a thin section through a plant mesophyll cell.

Calculate the magnification of the image, showing your working.

. . . . . . . . . . . . . . . . . . . . x

Calculate the magnification of the image, showing your working.

. . . . . . . . . . . . . . . . . . . . x

What function is performed by the part of the cell shown in the electron micrograph?

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

A. Locomotion

B. Synthesis of proteins

C. Movement of chromosomes

D. Breakdown of cellular organelles

Three cell types are shown in the micrographs.

[Source: left: UCSF School of Medicine, Courtesy of Prof. D Schmucker. middle: Professor Roger Meicenheimer, Miami University, Department of Botany. right: Courtesy of visualhistology.com.]

What feature distinguishes striated muscle fibres from the three cell types shown in the images?

A. Mitochondria

B. Nucleoid regions

C. Multinucleate structure

D. Membrane-bound organelles

Outline reasons for the therapeutic use of stem cells.

Outline reasons for the therapeutic use of stem cells.

Calculate the maximum diameter of the stem cell cluster on the micrograph, showing your working and giving the units.

..........

Calculate the maximum diameter of the stem cell cluster on the micrograph, showing your working and giving the units.

..........

Outline reasons for the therapeutic use of stem cells.

Outline reasons for the therapeutic use of stem cells.

What life function is illustrated?

A.  Nutrition

B.  Homeostasis

C.  Endocytosis

D.  Response

Explain how observation of the fossil record provides evidence for evolution.

Explain how observation of the fossil record provides evidence for evolution.

Onion (Allium cepa) epidermis was placed in pure water and observed with a light microscope using high magnification.

What would happen to these cells if they were transferred to a hypertonic solution?

A.  Cells would gain mass.

B.  Cells would take in water by osmosis and swell.

C.  Cells would burst open, releasing their content.

D.  Cell membranes would detach from walls at some points.

Onion (Allium cepa) epidermis was placed in pure water and observed with a light microscope using high magnification.

What would happen to these cells if they were transferred to a hypertonic solution?

A.  Cells would gain mass.

B.  Cells would take in water by osmosis and swell.

C.  Cells would burst open, releasing their content.

D.  Cell membranes would detach from walls at some points.

Unicellular and multicellular organisms share the same functions of life. Outline four functions of life.

Unicellular and multicellular organisms share the same functions of life. Outline four functions of life.

Using the scale bar, determine the diameter of the nucleus of the cell on the left, giving the units.

Deduce the magnification of the image.

Using the scale bar, determine the diameter of the nucleus of the cell on the left, giving the units.

Deduce the magnification of the image.

Label the area where cellulose is found in the micrograph of a plant cell.

[Source: BIOPHOTO ASSOCIATES/Getty Images]

Label the area where cellulose is found in the micrograph of a plant cell.

[Source: BIOPHOTO ASSOCIATES/Getty Images]

Outline the reasons for differences between the proteomes of cells within a multicellular organism.

Outline the reasons for differences between the proteomes of cells within a multicellular organism.

Which graph represents the change in cell surface area to volume ratio with increasing cell diameter?

[Source: © International Baccalaureate Organization 2019]

The images show a sequence of changes in an organism.

The image shows an electron micrograph of a cell.

[Source: Junqueira’s Basic Histology, 15th edition, by Anthony L. Mescher, McGraw-Hill publisher.]

Which organelles correspond to the labels in the electron micrograph of this cell?

Outline the function of the structure labelled III.

The structure of prokaryotic cells has been investigated using electron microscopy. Draw a labelled diagram to show prokaryotic cell structure.

Calculate the actual width along line A-B of the parenchyma cell shown.

The image shows an electron micrograph of part of a cell.

[Source: Dr. Eldon Newcomb – Emeritis Professor at The University of Wisconsin – Madison.]

Which features do the two structures labelled X and Y have in common?

A. They are surrounded by a double membrane.

B. They contain 70S ribosomes.

C. They contain naked DNA.

D. They are only found in leaf cells.

The image shows a phagocytic white blood cell as seen with a transmission electron microscope.

[Source: http://www.wikidoc.org/index.php/File:Monocyte_TEM_0002.jpg, by Cafer Zorkun is licensed
under the Creative Commons Attribution/Share-Alike License]

Which features can be found both within this cell and in a photosynthetic bacterium?

A. Chloroplasts

B. Multiple nuclei

C. 70S ribosomes

D. Lysosomes

The magnification of the micrograph is 2000×.

[Source: https://upload.wikimedia.org/wikipedia/commons/6/6c/HeLa_cells_stained_with_Hoechst_33258.jpg
by TenOfAllTrades.]

What is the maximum diameter of the nucleus in the cell labelled X?

A. 10 μm

B. 10 nm

C. 20 μm

D. 20 nm

Draw the ultrastructure of a prokaryotic cell based on electron micrographs.

Outline how the structures labelled X and Y are adapted to carry out the function of the mitochondrion.

X:

Y:

State two structural similarities between mitochondria and chloroplasts.

1.

2.

Outline the structures in M. tuberculosis that are not present in a human cell.

The image shows an electron micrograph of virus particles known to infect the bacterium Vibrio parahaemolyticus, which is associated with gastroenteritis, wound infections and septicemia in humans and animals.

[Source: Lin, Y. and Lin, C., 2012. Transmission electron micrograph of phage ϕpp2 particles with several structural proteins. [micrograph] (BMC Genomics, 13:224).]

What does a virus have in common with a living cell?

A. 70S ribosomes

B. Genetic material

C. Reproduction by binary fission

D. Anaerobic respiration

The images of the radiolarian, a single-celled marine organism, were produced using a light microscope (left) and a scanning electron microscope (right).

The micrograph of a section through a plant stem shows at least ten different types of cells.

[Source: Joan Carles Juarez / Shutterstock.com.]

What explains the differences between these cells?

A. Only one gene is expressed in each cell type.

B. Different genes are expressed in each cell type.

C. Only useful genes remain in the DNA of each cell type.

D. Changes in the DNA sequence take place when these cells develop.

Distinguish between the structure of chromosomes in prokaryotes and eukaryotes.

The diagram shows a prokaryotic cell.

[Source: © Rice University. 1999–2023 Figure 4.5 Prokaryotic cell. [image online] Available at: https://openstax.org/apps/archive/20220815.182343/resources/50163f8ff80f335574f41bfc10cc49a1e87cf9df [Accessed 13 January 2023].]

What are the structures labelled Y and Z?

Using the data in the stacked column graph, describe the features that characterize the B2 enterotype.

Describe the organelles and other structures in animal cells that are visible in electron micrographs.

Explain how the pancreas cell carries out its function, with reference to three organelles visible in the diagram.

Draw the ultrastructure of a prokaryotic cell based on electron micrographs.

Draw the ultrastructure of a prokaryotic cell based on electron micrographs.

Outline how the structures labelled X and Y are adapted to carry out the function of the mitochondrion.

X:

Y:

Outline how the structures labelled X and Y are adapted to carry out the function of the mitochondrion.

X:

Y:

State two structural similarities between mitochondria and chloroplasts.

1.

2.

State two structural similarities between mitochondria and chloroplasts.

1.

2.

Outline the structures in M. tuberculosis that are not present in a human cell.

Outline the structures in M. tuberculosis that are not present in a human cell.

The image shows an electron micrograph of virus particles known to infect the bacterium Vibrio parahaemolyticus, which is associated with gastroenteritis, wound infections and septicemia in humans and animals.

[Source: Lin, Y. and Lin, C., 2012. Transmission electron micrograph of phage ϕpp2 particles with several structural proteins. [micrograph] (BMC Genomics, 13:224).]

What does a virus have in common with a living cell?

A. 70S ribosomes

B. Genetic material

C. Reproduction by binary fission

D. Anaerobic respiration

The images of the radiolarian, a single-celled marine organism, were produced using a light microscope (left) and a scanning electron microscope (right).

The micrograph of a section through a plant stem shows at least ten different types of cells.

[Source: Joan Carles Juarez / Shutterstock.com.]

What explains the differences between these cells?

A. Only one gene is expressed in each cell type.

B. Different genes are expressed in each cell type.

C. Only useful genes remain in the DNA of each cell type.

D. Changes in the DNA sequence take place when these cells develop.

Distinguish between the structure of chromosomes in prokaryotes and eukaryotes.

Distinguish between the structure of chromosomes in prokaryotes and eukaryotes.

The diagram shows a prokaryotic cell.

[Source: © Rice University. 1999–2023 Figure 4.5 Prokaryotic cell. [image online] Available at: https://openstax.org/apps/archive/20220815.182343/resources/50163f8ff80f335574f41bfc10cc49a1e87cf9df [Accessed 13 January 2023].]

What are the structures labelled Y and Z?

Using the data in the stacked column graph, describe the features that characterize the B2 enterotype.

Using the data in the stacked column graph, describe the features that characterize the B2 enterotype.

Describe the organelles and other structures in animal cells that are visible in electron micrographs.

Describe the organelles and other structures in animal cells that are visible in electron micrographs.

Explain how the pancreas cell carries out its function, with reference to three organelles visible in the diagram.

Explain how the pancreas cell carries out its function, with reference to three organelles visible in the diagram.

The image shows an electron micrograph of a cell.

[Source: Junqueira’s Basic Histology, 15th edition, by Anthony L. Mescher, McGraw-Hill publisher.]

Which organelles correspond to the labels in the electron micrograph of this cell?

Outline the function of the structure labelled III.

Outline the function of the structure labelled III.

The structure of prokaryotic cells has been investigated using electron microscopy. Draw a labelled diagram to show prokaryotic cell structure.

The structure of prokaryotic cells has been investigated using electron microscopy. Draw a labelled diagram to show prokaryotic cell structure.

Calculate the actual width along line A-B of the parenchyma cell shown.

Calculate the actual width along line A-B of the parenchyma cell shown.

The image shows an electron micrograph of part of a cell.

[Source: Dr. Eldon Newcomb – Emeritis Professor at The University of Wisconsin – Madison.]

Which features do the two structures labelled X and Y have in common?

A. They are surrounded by a double membrane.

B. They contain 70S ribosomes.

C. They contain naked DNA.

D. They are only found in leaf cells.

The image shows a phagocytic white blood cell as seen with a transmission electron microscope.

[Source: http://www.wikidoc.org/index.php/File:Monocyte_TEM_0002.jpg, by Cafer Zorkun is licensed
under the Creative Commons Attribution/Share-Alike License]

Which features can be found both within this cell and in a photosynthetic bacterium?

A. Chloroplasts

B. Multiple nuclei

C. 70S ribosomes

D. Lysosomes

The magnification of the micrograph is 2000×.

[Source: https://upload.wikimedia.org/wikipedia/commons/6/6c/HeLa_cells_stained_with_Hoechst_33258.jpg
by TenOfAllTrades.]

What is the maximum diameter of the nucleus in the cell labelled X?

A. 10 μm

B. 10 nm

C. 20 μm

D. 20 nm

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw an annotated diagram of the fluid mosaic model of membrane structure.

Using the scale bar, calculate the magnification of the image.

Label the model A diagram to show a region of protein.

Label the model B diagram to show a phospholipid.

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

The Davson–Danielli model of membrane structure proposed that membranes were composed of a phospholipid bilayer that lies between two layers of globular proteins, as shown in this diagram.

[Source: Cornell, B. 2016. https://ib.bioninja.com.au/standard-level/topic-1-cell-biology/13-membrane-structure/membrane-models.html]

What evidence supported this model?

A. An electron micrograph that showed two dark lines with a lighter band in between

B. Freeze-fracture electron microscopy

C. Evidence that all membranes are identical

D. The hydrophobic regions of protein would be in contact with water

The image shows part of a mammalian cell.

[Source: Louisa Howard, Katherine Connollly - Dartmouth Electron Microscope Facility. Available at:
https://en.wikipedia.org/wiki/File:Microvilli.jpg.] 

What is the specialized function of this mammalian cell?

A. Locomotion

B. Absorption

C. Reception of stimuli

D. Gas exchange

The Davson-Danielli model of membrane structure was proposed in the 1930s. When electron micrographs of membranes were first produced, they were used as evidence for this model. The micrograph shows two adjacent membranes (indicated with arrows).

[Source: DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY.]

Explain how the appearance of membranes in electron micrographs was used as evidence to support the Davson-Danielli model.

Which feature(s) allow(s) transport of glucose in blood plasma?

I. It is hydrophobic.

II. It is polar.

III. Its solubility is low at 37 °C.

A. I only

B. II only

C. I and II only

D. II and III only

Outline four different processes, with examples, that allow substances to pass through the plasma membrane.

Annotate the diagram to illustrate the amphipathic nature of phospholipids.

In 1925, Gorter and Grendel carried out an experiment to study the structure of cell membranes in different mammals. The total surface area of red blood cells was measured in a sample and compared to the surface area formed by a single layer of lipid extracted from cell membranes and floated on water.

Which diagram best illustrates Gorter and Grendel’s conclusion drawn from this experiment?

[Source: Gorter, E. and Grendel, F., 1925. On bimolecular layers of lipoids on the chromocytes of the blood. Journal of Experimental Medicine 41(4), pp. 439–443.]

Scenedesmus is a microscopic, unicellular green alga. However, it often exists as multicellular colonies of cells.

[Source: www.mikro-foto.de 2010. Scenedesmus, a green algae. [image online] Available at:
https://commons.wikimedia.org/wiki/File:Mikrofoto.de-alge2.jpg [Accessed 13 January 2023]. Source adapted.]

The magnification of the image is 500×. What is the length of one cell?

A.  10 nm

B.  50 μm

C.  20 μm

D.  10 mm

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

Outline how the amphipathic properties of phospholipids play a role in membrane structure.

The Davson–Danielli model of membrane structure proposed that membranes were composed of a phospholipid bilayer that lies between two layers of globular proteins, as shown in this diagram.

[Source: Cornell, B. 2016. https://ib.bioninja.com.au/standard-level/topic-1-cell-biology/13-membrane-structure/membrane-models.html]

What evidence supported this model?

A. An electron micrograph that showed two dark lines with a lighter band in between

B. Freeze-fracture electron microscopy

C. Evidence that all membranes are identical

D. The hydrophobic regions of protein would be in contact with water

The image shows part of a mammalian cell.

[Source: Louisa Howard, Katherine Connollly - Dartmouth Electron Microscope Facility. Available at:
https://en.wikipedia.org/wiki/File:Microvilli.jpg.] 

What is the specialized function of this mammalian cell?

A. Locomotion

B. Absorption

C. Reception of stimuli

D. Gas exchange

The Davson-Danielli model of membrane structure was proposed in the 1930s. When electron micrographs of membranes were first produced, they were used as evidence for this model. The micrograph shows two adjacent membranes (indicated with arrows).

[Source: DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY.]

Explain how the appearance of membranes in electron micrographs was used as evidence to support the Davson-Danielli model.

The Davson-Danielli model of membrane structure was proposed in the 1930s. When electron micrographs of membranes were first produced, they were used as evidence for this model. The micrograph shows two adjacent membranes (indicated with arrows).

[Source: DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY.]

Explain how the appearance of membranes in electron micrographs was used as evidence to support the Davson-Danielli model.

Which feature(s) allow(s) transport of glucose in blood plasma?

I. It is hydrophobic.

II. It is polar.

III. Its solubility is low at 37 °C.

A. I only

B. II only

C. I and II only

D. II and III only

Outline four different processes, with examples, that allow substances to pass through the plasma membrane.

Outline four different processes, with examples, that allow substances to pass through the plasma membrane.

Annotate the diagram to illustrate the amphipathic nature of phospholipids.

Annotate the diagram to illustrate the amphipathic nature of phospholipids.

In 1925, Gorter and Grendel carried out an experiment to study the structure of cell membranes in different mammals. The total surface area of red blood cells was measured in a sample and compared to the surface area formed by a single layer of lipid extracted from cell membranes and floated on water.

Which diagram best illustrates Gorter and Grendel’s conclusion drawn from this experiment?

[Source: Gorter, E. and Grendel, F., 1925. On bimolecular layers of lipoids on the chromocytes of the blood. Journal of Experimental Medicine 41(4), pp. 439–443.]

Scenedesmus is a microscopic, unicellular green alga. However, it often exists as multicellular colonies of cells.

[Source: www.mikro-foto.de 2010. Scenedesmus, a green algae. [image online] Available at:
https://commons.wikimedia.org/wiki/File:Mikrofoto.de-alge2.jpg [Accessed 13 January 2023]. Source adapted.]

The magnification of the image is 500×. What is the length of one cell?

A.  10 nm

B.  50 μm

C.  20 μm

D.  10 mm

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane.

Draw an annotated diagram of the fluid mosaic model of membrane structure.

Draw an annotated diagram of the fluid mosaic model of membrane structure.

Using the scale bar, calculate the magnification of the image.

Using the scale bar, calculate the magnification of the image.

Label the model A diagram to show a region of protein.

Label the model B diagram to show a phospholipid.

Label the model A diagram to show a region of protein.

Label the model B diagram to show a phospholipid.

Analyse the graph to obtain two conclusions about the concentration of sodium–potassium pumps.

Muscle fibres are stimulated to contract by the binding of acetylcholine to receptors in their membranes and the subsequent depolarization.

Suggest a reason for increasing the concentration of sodium–potassium pumps in the membranes of diaphragm muscle fibres.

Data was collected on rabbit red blood cells that were exposed to sodium chloride (NaCl) and scorpion venom. Under some osmotic conditions red blood cells swell and burst, releasing hemoglobin (hemolysis). The graph shows the response of red blood cells to different concentrations of sodium chloride, with and without scorpion venom.

[Source: Adapted from Mirakabadi A Z, et al., (2006), J. Venom. Anim. Toxins incl. Trop. Dis., 12 (1), pages 67–77 (London: BioMed Central)]

Outline the effect of the venom on the hemolysis of red blood cells.

Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.

Which process(es) occur(s) by osmosis?

I. Uptake of water by cells in the wall of the intestine

II. Loss of water from a plant cell in a hypertonic environment

III. Evaporation of water from sweat on the skin surface

A. I only

B. I and II only

C. II and III only

D. I, II and III

The table shows concentrations of potassium ions and sodium ions inside and outside human cells.

[Source: © International Baccalaureate Organization 2019]

What explains these concentrations?

A. Potassium ions diffuse in and sodium ions diffuse out.

B. Sodium ions diffuse in and potassium ions diffuse out.

C. Active transport pumps sodium ions in and potassium ions out.

D. Active transport pumps sodium ions out and potassium ions in.

Using the graph, estimate isotonic sucrose solutions for potato tissue and carrot tissue.

Potato:

Carrot:

The diagram shows a section through a membrane. What are the modes of transport in the diagram?

[Source: © International Baccalaureate Organization 2020.]

The diagrams represent cells with the same concentration of dissolved substances in their cytoplasm. If all the cells were placed in the same hypertonic sucrose solution, which cell would show the greatest rate of change in the concentration of its cytoplasm?

Describe transport across cell membranes by osmosis.

The image shows human red blood cells.

[Source: someoneice/123rf.com.]

Outline what will happen to human red blood cells if transferred to distilled water.

In an experiment on osmosis, red blood cells were immersed in a salt solution for two hours. The micrographs show the appearance of these cells before and after immersion in the salt solution.

Which feature(s) allow(s) transport of glucose in blood plasma?

I. It is hydrophobic.

II. It is polar.

III. Its solubility is low at 37 °C.

A. I only

B. II only

C. I and II only

D. II and III only

Red blood cells from a small mammal were immersed in NaCl (sodium chloride) solutions of different concentrations for 2 hours. The graph shows the percentage of hemolysed (ruptured) red blood cells at each concentration.

Draw one phospholipid molecule on the diagram to show a possible position in the membrane.

Explain how vesicles are used by cells to move materials.

The light micrograph shows the structure of blood vessels in a muscle.

_{[Source: Calvo, J.L., n.d. [image online] Available at: https://www.shutterstock.com/image-photo/muscular-artery-veinnervebundles-
surrounded-785176687 [Accessed 12 January 2022].]}

Which blood vessel is shown by X?

A.  A vein

B.  An artery

C.  An arteriole

D.  A capillary

Using the graph, estimate isotonic sucrose solutions for potato tissue and carrot tissue.

Potato:

Carrot:

Using the graph, estimate isotonic sucrose solutions for potato tissue and carrot tissue.

Potato:

Carrot:

The diagram shows a section through a membrane. What are the modes of transport in the diagram?

[Source: © International Baccalaureate Organization 2020.]

The diagrams represent cells with the same concentration of dissolved substances in their cytoplasm. If all the cells were placed in the same hypertonic sucrose solution, which cell would show the greatest rate of change in the concentration of its cytoplasm?

Describe transport across cell membranes by osmosis.

Describe transport across cell membranes by osmosis.

The image shows human red blood cells.

[Source: someoneice/123rf.com.]

Outline what will happen to human red blood cells if transferred to distilled water.

The image shows human red blood cells.

[Source: someoneice/123rf.com.]

Outline what will happen to human red blood cells if transferred to distilled water.

In an experiment on osmosis, red blood cells were immersed in a salt solution for two hours. The micrographs show the appearance of these cells before and after immersion in the salt solution.

Which feature(s) allow(s) transport of glucose in blood plasma?

I. It is hydrophobic.

II. It is polar.

III. Its solubility is low at 37 °C.

A. I only

B. II only

C. I and II only

D. II and III only

Red blood cells from a small mammal were immersed in NaCl (sodium chloride) solutions of different concentrations for 2 hours. The graph shows the percentage of hemolysed (ruptured) red blood cells at each concentration.

Analyse the graph to obtain two conclusions about the concentration of sodium–potassium pumps.

Muscle fibres are stimulated to contract by the binding of acetylcholine to receptors in their membranes and the subsequent depolarization.

Suggest a reason for increasing the concentration of sodium–potassium pumps in the membranes of diaphragm muscle fibres.

Analyse the graph to obtain two conclusions about the concentration of sodium–potassium pumps.

Muscle fibres are stimulated to contract by the binding of acetylcholine to receptors in their membranes and the subsequent depolarization.

Suggest a reason for increasing the concentration of sodium–potassium pumps in the membranes of diaphragm muscle fibres.

Draw one phospholipid molecule on the diagram to show a possible position in the membrane.

Draw one phospholipid molecule on the diagram to show a possible position in the membrane.

Explain how vesicles are used by cells to move materials.

Explain how vesicles are used by cells to move materials.

The light micrograph shows the structure of blood vessels in a muscle.

_{[Source: Calvo, J.L., n.d. [image online] Available at: https://www.shutterstock.com/image-photo/muscular-artery-veinnervebundles-
surrounded-785176687 [Accessed 12 January 2022].]}

Which blood vessel is shown by X?

A.  A vein

B.  An artery

C.  An arteriole

D.  A capillary

Data was collected on rabbit red blood cells that were exposed to sodium chloride (NaCl) and scorpion venom. Under some osmotic conditions red blood cells swell and burst, releasing hemoglobin (hemolysis). The graph shows the response of red blood cells to different concentrations of sodium chloride, with and without scorpion venom.

[Source: Adapted from Mirakabadi A Z, et al., (2006), J. Venom. Anim. Toxins incl. Trop. Dis., 12 (1), pages 67–77 (London: BioMed Central)]

Outline the effect of the venom on the hemolysis of red blood cells.

Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.

Data was collected on rabbit red blood cells that were exposed to sodium chloride (NaCl) and scorpion venom. Under some osmotic conditions red blood cells swell and burst, releasing hemoglobin (hemolysis). The graph shows the response of red blood cells to different concentrations of sodium chloride, with and without scorpion venom.

[Source: Adapted from Mirakabadi A Z, et al., (2006), J. Venom. Anim. Toxins incl. Trop. Dis., 12 (1), pages 67–77 (London: BioMed Central)]

Outline the effect of the venom on the hemolysis of red blood cells.

Describe how the variables would be controlled in an experiment to estimate the osmolarity of plant tissue.

Which process(es) occur(s) by osmosis?

I. Uptake of water by cells in the wall of the intestine

II. Loss of water from a plant cell in a hypertonic environment

III. Evaporation of water from sweat on the skin surface

A. I only

B. I and II only

C. II and III only

D. I, II and III

The table shows concentrations of potassium ions and sodium ions inside and outside human cells.

[Source: © International Baccalaureate Organization 2019]

What explains these concentrations?

A. Potassium ions diffuse in and sodium ions diffuse out.

B. Sodium ions diffuse in and potassium ions diffuse out.

C. Active transport pumps sodium ions in and potassium ions out.

D. Active transport pumps sodium ions out and potassium ions in.

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

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

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

Describe the endosymbiotic theory.

In the chimpanzee (Pan troglodytes), the haploid number of chromosomes is 24. How many sister chromatids are present in the G2 phase of a somatic cell, such as a cell in the bone marrow of the chimpanzee?

A. 12

B. 24

C. 48

D. 96

Describe two pieces of evidence that show that eukaryotic cells originated by endosymbiosis.

Describe the endosymbiotic theory.

Describe the endosymbiotic theory.

In the chimpanzee (Pan troglodytes), the haploid number of chromosomes is 24. How many sister chromatids are present in the G2 phase of a somatic cell, such as a cell in the bone marrow of the chimpanzee?

A. 12

B. 24

C. 48

D. 96

Describe two pieces of evidence that show that eukaryotic cells originated by endosymbiosis.

Describe two pieces of evidence that show that eukaryotic cells originated by endosymbiosis.

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

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

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

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

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

Which diagram(s) represent(s) processes used in asexual reproduction?

A. I only

B. I and II only

C. II only

D. I, II and III

The concentrations of cyclins rise and fall in cells at certain times.

[Source: https://en.wikipedia.org/wiki/Cyclin#/media/File:Cyclin_Expression.svg]

What times are these?

A. Day and night

B. Seasons of the year

C. Stages of mitosis and interphase

D. Developmental stages in the life cycle

The image shows cells in the different stages of mitosis. Which cell is in telophase?

[Source: © The Trustees of Indiana University]

The image shows a micrograph of a cell.

[Source: © 2014, https://commons.wikimedia.org/wiki/File:Mitosis_(261_13)_Pressed;_root_meristem_of_onion_(cells_
in_prophase,_metaphase,_anaphase,_telophase).jpg by Doc. RNDr. Josef Reischig, CSc.]

What explains the appearance of the cell in the micrograph?

A. The cell is dying.

B. The DNA is replicating.

C. The cell is in metaphase.

D. The cell is in telophase.

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]

The diagram shows a stage in cell division.

[Source: © International Baccalaureate Organization 2019]

What is the stage shown?

A. Anaphase I of mitosis

B. Anaphase II of mitosis

C. Anaphase I of meiosis

D. Anaphase II of meiosis

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]

In the micrograph, which letter points to a cell in anaphase?

[Source: Berkshire Community College Bioscience Image Library,
https://commons.wikimedia.org/wiki/File:Mitotic_Stages_in_Apical_Meristem_of_Allium_Root_Tip_(36762516673).jpg,
licensed under Creative Commons CC0 1.0 Universal Public Domain Dedication]

Describe what happens to the membranes of an animal cell during mitosis.

By referring to both graphs, evaluate the hypothesis that vinblastine targets cells in mitosis and prevents them from completing the process.

Some anticancer drugs inhibit mitosis by blocking the formation of the spindle. Suggest one other way in which vinblastine could block mitosis.

Discuss one advantage and one disadvantage of using plant tissue to investigate drugs intended to treat cancer in humans.

Advantage:

Disadvantage:

State processes occurring during interphase.

Using the letter C, label the stage on the diagram where chromosome supercoiling occurs.

Using the letter M, label the stage on the diagram where sister chromatids migrate to opposite poles.

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

The mitotic index is an important prognostic tool for predicting the response of cancer cells to chemotherapy. Outline how the mitotic index is calculated.

The graph shows the mitotic index in the roots of lentil plants at different distances from the end of the root.

[Source: Physiologia Plantarum, Volume 105, Issue 1, January 1999, Pages 171–178, Effect of microgravity on the cell cycle
in the lentil root F. Yu, D. Driss-Ecole, J. Rembur, V. Legué, G. Perbal Wiley Online Library: https://onlinelibrary.wiley.
com/doi/abs/10.1034/j.1399-3054.1999.105125.x]

What can be deduced from the graph?

A. As the distance from the end of the root increases, more cells are undergoing mitosis.

B. At 0.5 mm from the end of the root, most of the cells are in prophase.

C. There were fewer cells observed at 1.5 mm than at 0.5 mm.

D. As the distance from the end of the root increases, the percentage of cells in interphase increases.

In the chimpanzee (Pan troglodytes), the haploid number of chromosomes is 24. How many sister chromatids are present in the G2 phase of a somatic cell, such as a cell in the bone marrow of the chimpanzee?

A. 12

B. 24

C. 48

D. 96

In which stage of the cell cycle are chromosomes duplicated?

Identify, with a reason, the stage shown at X.

Calculate the length of the entire cell labelled Y, showing your working.

State the role of cyclins in the cell cycle.

The micrograph shows some onion (Allium cepa) cells undergoing mitosis.

[Source: Reischig, J., 2014. [Onion cells]. [image online] Available at: https://commons.wikimedia.org/wiki/File:Mitosis_(261_14)_Pressed;_root_
meristem_of_onion_(cells_in_prophase,_anaphase).jpg [Accessed 27 October 2021].]

What is the mitotic index, taking into account all visible nuclei?

A.  0.1

B.  0.2

C.  0.4

D.  0.6

Explain how changes to the cell cycle can result in tumour formation.

The image shows a cell from the root tip of an onion (Allium cepa) (2n = 16) during late prophase of mitosis.

_{[Source: Davidson, M.W. and Molecular Expressions at Florida State University, n.d. Late prophase. [image online]
Available at: https://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html [Accessed 5 October 2021].]}

How many chromatids are present in the cell?

A.  8

B.  16

C.  32

D.  64

Outline the sequence of events that occurs during mitosis.

The image shows a cell from the root tip of an onion (Allium cepa) (2n = 16) during late prophase of mitosis.

_{[Source: Davidson, M.W. and Molecular Expressions at Florida State University, n.d. Late prophase. [image online]
Available at: https://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html [Accessed 5 October 2021].]}

How many chromatids are present in the cell?

A.  8

B.  16

C.  32

D.  64

In the micrograph, which letter points to a cell in anaphase?

[Source: Berkshire Community College Bioscience Image Library,
https://commons.wikimedia.org/wiki/File:Mitotic_Stages_in_Apical_Meristem_of_Allium_Root_Tip_(36762516673).jpg,
licensed under Creative Commons CC0 1.0 Universal Public Domain Dedication]

Describe what happens to the membranes of an animal cell during mitosis.

Describe what happens to the membranes of an animal cell during mitosis.

By referring to both graphs, evaluate the hypothesis that vinblastine targets cells in mitosis and prevents them from completing the process.

Some anticancer drugs inhibit mitosis by blocking the formation of the spindle. Suggest one other way in which vinblastine could block mitosis.

Discuss one advantage and one disadvantage of using plant tissue to investigate drugs intended to treat cancer in humans.

Advantage:

Disadvantage:

State processes occurring during interphase.

Using the letter C, label the stage on the diagram where chromosome supercoiling occurs.

Using the letter M, label the stage on the diagram where sister chromatids migrate to opposite poles.

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

The mitotic index is an important prognostic tool for predicting the response of cancer cells to chemotherapy. Outline how the mitotic index is calculated.

State processes occurring during interphase.

Using the letter C, label the stage on the diagram where chromosome supercoiling occurs.

Using the letter M, label the stage on the diagram where sister chromatids migrate to opposite poles.

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

The mitotic index is an important prognostic tool for predicting the response of cancer cells to chemotherapy. Outline how the mitotic index is calculated.

The graph shows the mitotic index in the roots of lentil plants at different distances from the end of the root.

[Source: Physiologia Plantarum, Volume 105, Issue 1, January 1999, Pages 171–178, Effect of microgravity on the cell cycle
in the lentil root F. Yu, D. Driss-Ecole, J. Rembur, V. Legué, G. Perbal Wiley Online Library: https://onlinelibrary.wiley.
com/doi/abs/10.1034/j.1399-3054.1999.105125.x]

What can be deduced from the graph?

A. As the distance from the end of the root increases, more cells are undergoing mitosis.

B. At 0.5 mm from the end of the root, most of the cells are in prophase.

C. There were fewer cells observed at 1.5 mm than at 0.5 mm.

D. As the distance from the end of the root increases, the percentage of cells in interphase increases.

In the chimpanzee (Pan troglodytes), the haploid number of chromosomes is 24. How many sister chromatids are present in the G2 phase of a somatic cell, such as a cell in the bone marrow of the chimpanzee?

A. 12

B. 24

C. 48

D. 96

In which stage of the cell cycle are chromosomes duplicated?

Identify, with a reason, the stage shown at X.

Calculate the length of the entire cell labelled Y, showing your working.

State the role of cyclins in the cell cycle.

Identify, with a reason, the stage shown at X.

Calculate the length of the entire cell labelled Y, showing your working.

State the role of cyclins in the cell cycle.

The micrograph shows some onion (Allium cepa) cells undergoing mitosis.

[Source: Reischig, J., 2014. [Onion cells]. [image online] Available at: https://commons.wikimedia.org/wiki/File:Mitosis_(261_14)_Pressed;_root_
meristem_of_onion_(cells_in_prophase,_anaphase).jpg [Accessed 27 October 2021].]

What is the mitotic index, taking into account all visible nuclei?

A.  0.1

B.  0.2

C.  0.4

D.  0.6

Which diagram(s) represent(s) processes used in asexual reproduction?

A. I only

B. I and II only

C. II only

D. I, II and III

The concentrations of cyclins rise and fall in cells at certain times.

[Source: https://en.wikipedia.org/wiki/Cyclin#/media/File:Cyclin_Expression.svg]

What times are these?

A. Day and night

B. Seasons of the year

C. Stages of mitosis and interphase

D. Developmental stages in the life cycle

Explain how changes to the cell cycle can result in tumour formation.

Explain how changes to the cell cycle can result in tumour formation.

The image shows a cell from the root tip of an onion (Allium cepa) (2n = 16) during late prophase of mitosis.

_{[Source: Davidson, M.W. and Molecular Expressions at Florida State University, n.d. Late prophase. [image online]
Available at: https://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html [Accessed 5 October 2021].]}

How many chromatids are present in the cell?

A.  8

B.  16

C.  32

D.  64

Outline the sequence of events that occurs during mitosis.

Outline the sequence of events that occurs during mitosis.

The image shows a cell from the root tip of an onion (Allium cepa) (2n = 16) during late prophase of mitosis.

_{[Source: Davidson, M.W. and Molecular Expressions at Florida State University, n.d. Late prophase. [image online]
Available at: https://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html [Accessed 5 October 2021].]}

How many chromatids are present in the cell?

A.  8

B.  16

C.  32

D.  64

The image shows cells in the different stages of mitosis. Which cell is in telophase?

[Source: © The Trustees of Indiana University]

The image shows a micrograph of a cell.

[Source: © 2014, https://commons.wikimedia.org/wiki/File:Mitosis_(261_13)_Pressed;_root_meristem_of_onion_(cells_
in_prophase,_metaphase,_anaphase,_telophase).jpg by Doc. RNDr. Josef Reischig, CSc.]

What explains the appearance of the cell in the micrograph?

A. The cell is dying.

B. The DNA is replicating.

C. The cell is in metaphase.

D. The cell is in telophase.

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]

The diagram shows a stage in cell division.

[Source: © International Baccalaureate Organization 2019]

What is the stage shown?

A. Anaphase I of mitosis

B. Anaphase II of mitosis

C. Anaphase I of meiosis

D. Anaphase II of meiosis

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]

Identify the stage of mitosis labelled X in the image, giving a reason.

[Source: Copyright 2002, The Trustees of Indiana University]