2. Which letter on the logarithmic scale corresponds to the size of a typical prokaryote?

3. Which calculation is used to find the actual length of an organelle from an image?

4. Which statement is correct?

5. The diagram shows a typical animal cell.

Which features are also found in both plant cells and prokaryotic cells?

key:
√= present, x= absent

6. A student carried out the Benedict’s test on four different concentrations of glucose solution and then recorded the time taken for the first appearance of a colour change (the end-point).

The student found it difficult to identify the first appearance of a colour change and consistently timed each solution for two seconds after it had appeared. This introduced a source of error into the experiment.

Which statements about this error are correct?

1 The effect of the error will be reduced if the student performs three repeats at each concentration of glucose.

2 The error will prevent the student from identifying which solution has the highest concentration of glucose.

3 The error is systematic as the student consistently timed each solution for two seconds after the end-point.

7. Which row is correct for each of the molecules?

8. The diagram shows how the β-glucose units of cellulose are linked to each other.

What is the significance of the fact that the OH groups on carbon 2 in adjacent glucose molecules are on opposite sides of the molecule?

9. Threonylvaline is a dipeptide formed from the two amino acids, threonine and valine. A peptide bond forms between the carboxyl group of threonine and the amine group of valine.

The side-chains (R groups) of the two amino acids are shown.

Which molecular structure is threonylvaline?

10. Which feature explains why haemoglobin is soluble?

11. An investigation into the rate of an enzyme-catalysed reaction was carried out. During the investigation the concentration of the substrate was kept higher than the concentration of the enzyme.

During this investigation, which change in the variables would always lead to an increase in the rate of the reaction?

1 increase in enzyme concentration

2 increase in pH

3 increase in temperature

12. The enzymes glucokinase in the liver and hexokinase in the brain both catalyse the phosphorylation of glucose:

glucose + ATP → glucose phosphate + ADP

The activity of each enzyme was measured at different concentrations of glucose. The graph shows the results.

What describes the different activities of the two enzymes?

13. The value  $K_m$   is the substrate concentration at which the rate of an enzyme-catalysed reaction is half its maximum rate,  $\frac{V_{\max}}{2}$  
The  $K_m$   was measured in the presence of a competitive inhibitor and in the presence of a non-competitive inhibitor. 

What could be the value of  $K_m$   with inhibitor compared to the value of Km with no inhibitor?

14. Which molecules, found in cell surface membranes, help the immune system to identify cells?

1 cholesterol

2 glycolipids

3 glycoproteins

4 proteins

15. The following are all processes by which substances can enter a cell.

1 endocytosis

2 facilitated diffusion

3 osmosis

Which processes are passive?

16. Equal volumes of five concentrations of sodium chloride solution were placed into five containers. An identical piece of plant tissue was placed into each container and left for 48 hours.

The plant tissues were removed and the volumes of the sodium chloride solution were accurately measured. The results are shown below.

Which statements explain the results from 0.80 to 1.00 mol dm–3 sodium chloride?

1 There was no net movement of water into or out of the plant tissues.

2 The plant root tissues had a water potential of zero.

3 The plant tissues were fully plasmolysed.

17. Chromosome telomeres are essential for DNA replication and are not completely replaced during mitosis.

Substance X completely replaces telomeres during mitosis.

What will be the effect of growing cells with and without substance X?

18. Gene mutations in either the BRCA1 or the BRCA2 genes are responsible for the majority of hereditary breast cancer in humans.

The proteins produced by the two genes migrate to the nucleus where they interact with other proteins, such as those produced by the tumour suppressor gene, p53, and the DNA repair gene, RAD51.

Which combination of gene activity is most likely to result in breast cancer? key: √= gene produces normal protein, x= gene produces abnormal protein or no protein.

19. The information describes some events of mitosis.

1 chromosomes undergo condensation and spiralisation

2 centromeres are pulled by shortening of spindle fibres

3 sister chromatids are orientated across the centre of the cell

4 centrioles separate from each other

5 spindle fibres disperse

Which row correctly identifies the stages of mitosis in which these events occur?

20. Which diagram shows a correct ring structure and named nucleic acid base?

21. The diagram shows the nucleotide sequence of a small section of a gene which is transcribed.

GCGCGCGGCCGC

The table shows the amino acids coded for by 10 mRNA codons.

What is the order of the four amino acids in the polypeptide translated from this small section of a gene?

22. The following events occur during transcription.

1 Bonds break between complementary bases.

2 Bonds form between complementary bases.

3 Sugar-phosphate bonds form.

4 Free nucleotides pair with complementary nucleotides.

Before the mRNA molecule leaves the nucleus, which events will have occurred twice?

23. Which statements about water movement in plants are correct?

1 Water cannot pass through cellulose.

2 Water cannot pass through lignin.

3 Water cannot pass through the Casparian strip.

24. The diagrams show transverse sections of parts of a plant.

In the transverse sections, which tissues transport water and which tissues transport sucrose?

25. Which diagram represents the effect of atmospheric humidity on the rate of transpiration?

26. Which parts of a plant have plasmodesmata?

1 companion cells

2 phloem sieve tube elements

3 root hair cell

27. The following are all structural components of blood vessels.

1 collagen fibres

2 elastic fibres

3 endothelial cells

4 smooth muscle cells

Which row shows the components in an artery and a vein?

28. Scientists have shown that the oxygen dissociation curves for haemoglobin of smaller mammals are to the right of those of larger mammals.

What does this suggest about the haemoglobin of smaller mammals?

29. Which row could be correct for the average blood pressure in different parts of the human

circulatory system?

30. Which statements are correct?

1 The activity of carbonic anhydrase increases the hydrogen ion concentration in blood passing through active tissue.

2 Carbon dioxide can react with haemoglobin in red blood cells to form carboxyhaemoglobin.

3 When haemoglobin binds with the hydrogen ion its affinity for oxygen decreases.

31. The diagram shows pressure changes during the cardiac cycle.

Which arrow indicates atrial systole?

32. The image shown is a photomicrograph of a transverse section of part of the gas exchange system.

What describes the image?

33. The table lists some of the effects of smoking.

Which row shows the effect of nicotine and carbon monoxide?

34. Which statement about chronic obstructive pulmonary disease (COPD) is correct?

35. Which row is correct?

36. What do pathogens of HIV / AIDS, malaria and TB have in common? key: √= present in each causative agent, x= not present in each causative agent

37. Which factor might have contributed to the spread of HIV / AIDS?

38. Which event will occur following antigen-antibody binding?

39. Which statements about macrophages are correct?

1 More are found in tissues such as the lungs, than in the blood.

2 They have a role in antigen presentation.

3 They can engulf pathogens, dust particles and damaged body cells.

40. The graph shows the antibody concentration in blood following vaccination and a booster vaccination 28 days later.

Which statements about the changes in antibody concentration are correct?

1 Antibody concentration falls after the primary response because antibodies are

broken down and are no longer being produced.

2 The secondary response is more rapid due to memory B cells produced from activated B cells in the primary response.

3 The secondary response lasts longer than the primary response because memory B cells live longer than plasma B cells.