Cell Structure (AQA A Level Biology): Exam Questions

Figure 1 shows part of a prokaryotic cell.

Name the structures labelled R and S in Figure 1.

Name the structures labelled P and Q in Figure 1.

Phospholipids and glycoproteins are two biological molecules found in prokaryotic cells.

(i) Name the structure(s) (P, Q, R or S) in which phospholipids are the main biological molecule found.

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(ii) Name the structure(s) (P, Q, R or S) in which glycoproteins are the main biological molecule found.

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In certain conditions some prokaryotic cells can divide every 25 minutes.

Assuming that each cell divides every 25 minutes, calculate the number of cells that will be present after 3.75 hours if the starting population contains 2.45 × 10³ cells. Assume that no cells die during this time.

Figure 1 shows a diagram of an animal cell.

Name the organelles labelled F and H.

Name two structures present in plant cells that are not present in animal cells.

A scientist used the method below to prepare a sample of organelle F from muscle cells: 

1. Place muscle tissue in a solution that is ice-cold, buffered and has the same water potential as the muscle tissue

2. Place the muscle tissue and solution into a blender; blend for 3 minutes

3. Filter the blended mixture

4. Centrifuge the filtrate at a low speed; a pellet should be seen at the bottom of the centrifuge tube

5. Pour off the liquid from the first centrifuge tube into a second centrifuge tube

6. Centrifuge this liquid at a high speed; the pellet that forms contains organelle F

Explain why the solution used in step 1 had to be ice-cold and have the same water potential as the muscle tissue. 

Explain why the muscle tissue and solution first had to be blended, and why the resulting mixture then had to be filtered (steps 2 and 3).

Figure 1 shows a plant cell organelle, as seen under an electron microscope.

Name the structures labelled J and K.

Describe the function of the organelle shown in Figure 1.

Describe how a sample of the organelle in Figure 1 could be obtained from leaf tissue using cell fractionation techniques.

Table 1 below shows features of a mitochondrion and a chloroplast.

Table 1

Complete the table with ticks (✓) where a feature is present.

Figure 1 shows a drawing of part of an animal cell as seen through an electron microscope.

Name the organelles labelled L and M.

Suggest why the shapes of the two organelles labelled O in Figure 1 appear different.

Give the function of organelle M in Figure 1.

Large numbers of organelle O are found in the small intestine epithelial cells. Explain why these cells are adapted in this way.

Figure 1 shows a diagram of an organism called Chlamydomonas that lives in freshwater.

Name two features of the Chlamydomonas cell that are not found in animal cells. 

Use Figure 1 to explain three adaptations of Chlamydomonas that enable this organism to maintain a high rate of photosynthesis.

A scientist used an optical microscope to observe Chlamydomonas.

Name two eukaryotic cellular structures that cannot be identified using an optical microscope.

Using your knowledge of osmosis, suggest why Chlamydomonas uses starch as a carbohydrate store.

A biologist prepared a sample of organelles extracted from an animal cell. The following method was used:

1. An ice-cold, buffered solution with the same water potential as the cells was added to the liver tissue

2. The liver and solution were homogenised in a blender

3. The homogenate was filtered

4. The filtered liquid was centrifuged at low speed

5. The liquid above the pellet was decanted into a second centrifuge tube and spun at a higher speed to obtain a sample of mitochondria

Name the organelle that made up most of the first pellet after centrifuging at a low speed (step 4).

The second centrifuge tube was spun at a higher speed to obtain a sample of mitochondria (step 5).

Suggest why it was spun at a higher speed.

Explain how the inner mitochondrial membrane is adapted to its function.

Name three eukaryotic cell structures that cannot be studied using an optical microscope.

Structures V to Z are organelles within a plant cell.

• V - nucleus

• W - chloroplast

• X - Golgi apparatus

• Y - mitochondrion

• Z - cell wall

Complete Table 1 by writing the correct letter next to each statement.

Table 1

Mammals feed their young with milk that is synthesised and expressed by mammary gland cells. These gland cells have evolved to contain large numbers of mitochondria and Golgi bodies. The milk contains a high concentration of protein to feed an infant’s growth.

Explain how these adaptations could aid the synthesis and expression of milk.

State the contents and function of the mitochondrial matrix.

Scientists investigated the effect of an exercise programme on the number of mitochondria and the area of the inner mitochondrial membranes in skeletal muscle.

They took samples of muscle from a large number of volunteers before and after the exercise programme. From each sample, they cut thin sections and used these to determine the mean number of mitochondria per μm² and the mean area of inner mitochondrial membranes.

The results are shown in Table 1 below.

Table 1

Use the data in Table 1 to suggest the effect of the exercise programme on the mitochondria.

Bacteriophages are viruses that kill bacteria. Researchers investigated the use of bacteriophages to alleviate the symptoms of bacterial lung infections. They inoculated the lungs of rats with a pathogenic bacterium. The rats were then divided into two groups; J and K:

• The rats in group J were untreated

• The rats in group K were given bacteriophage treatment by means of an inhaled aerosol spray

After 5 days the researchers extracted fluid from the lungs of the rats and counted the number of live bacteria in the fluid. Figure 1 below shows the mean results for each group. The ranges are shown for each group.

Analyse the effectiveness of the bacteriophage in treating the lung infection in rats.

Identify the statement below that is correct for the structures of both the bacteriophage and the bacterium.

In some cases the researchers needed to carry out a serial dilution of the sample before performing a count of the bacteria.

Use data from Figure 1 to explain the researchers’ choices to perform serial dilutions in some cases but not for others.

Figure 1 below shows a diagram of a cholera bacterium.

Name W and X and state their function.

Name four structures that are present in an epithelial cell from the small intestine but not present in a cholera bacterium.

Cholera bacteria can be viewed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). 

State one advantage of using a TEM and one advantage of using an SEM.

An outbreak of cholera occurred in London in 1849. Figure 2 below shows the relationship between the number of deaths from cholera and the height at which people lived above sea level.

Describe the results shown in Figure 2.