AS & A Level Biology - 9700 Paper 2 2013 Winter Zone 2

Fig. 1.1 is a diagram of a transverse section through a vein.


(a) Calculate the actual diameter of the vein marked by the line X–Y.
Show your working and give your answer in millimetres (mm).
answer ................................. mm [2]

(b) The presence of a valve would help to confirm that the blood vessel in Fig. 1.1 is a vein and not an artery.
Describe three structural features of the blood vessel shown in Fig. 1.1 that would help to identify it as a vein and not as an artery.
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(c) Explain how the following structural features of a capillary are related to its function.
(i) The capillary wall is composed of a single layer of squamous epithelial cells.
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(ii) The diameter of the capillary lumen is approximately 8μm.
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(d) The inner lining of arteries and veins is composed of a layer of epithelial cells supported by a layer of elastic and connective tissue. The epithelial cells are capable of cell division by mitosis.
(i) State the role of mitosis in cell division of epithelial cells.
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(ii) Explain why the epithelial cells undergo mitosis and not meiosis.
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(e) Fig. 1.2 is a diagram of a cell in late prophase of mitosis.


Complete Fig. 1.3 to show the same cell in the anaphase stage of mitosis.

(a) Features of chitin and keratin are shown in the boxes in Fig. 2.1.

Write, in each box, the biological molecules from the list below that have the same feature.
Each box may contain one, or more than one, biological molecule. The first box has been completed as an example.
amylopectin
cellulose
collagen
haemoglobin
mRNA
triglyceride [5]

(b) Chitin and the products of chitin hydrolysis have many useful medical and environmental applications. Chitinase enzymes can be used commercially to hydrolyse chitin. Enzyme stability and activity are important considerations in technological applications of chitinase.

Fig. 2.2 is a graph showing the effects of temperature on chitinase extracted from a soil bacterium.

The relative activity of the enzyme was measured at different temperatures, with 100% representing maximum enzyme activity.

(i) With reference to Fig. 2.2, state the optimum temperature for the chitinase enzyme.
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Fig. 2.3 is a graph showing how temperature affects the stability of chitinase. The activity of the enzyme was measured over a time period of 72 hours at each of five different temperatures.

(ii) With reference to Fig. 2.2 and Fig. 2.3, describe and discuss the effect of temperature on chitinase activity and stability.
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(a) Explain the need for transport systems in plants. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [3] (b) Fig. 3.1 is a drawing of a transverse section through part of the stem of a dicotyledonous plant. Cell A and cell B are involved in the transport of dissolved organic molecules. (i) Name cell A and cell B. cell A ....................................................................................................................................... cell B ....................................................................................................................................... [1] (ii) With reference to Fig. 3.1, explain how the different structures of cell types A and B are related to their function. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [5] (c) Complete Table 3.1 to state four differences between transport systems in mammals and in plants. [Table_1] transport system in mammals | transport system in plants ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [4]

Staphylococcus aureus is a bacterium that is the cause of many different infectious diseases.
(a) Fig. 4.1 is a diagram of S. aureus.

(i) Cell structures, such as mitochondria, endoplasmic reticula (ER), Golgi apparatus, lysosomes and chloroplasts are found only in eukaryotic cells. These are not present in Fig. 4.1.
With reference to Fig. 4.1, describe other features that support the fact that S. aureus is a prokaryote.
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(ii) State the main difference in the composition of the plant cell wall compared to the bacterial cell wall.
plant cell wall ................................................................................................................................
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(b) Bacterial cells behave in a similar way to plant cells when immersed in solutions of different water potential.
Suggest and explain what would happen to bacteria placed in a solution with a water potential more negative than their cell contents.
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(c) Some strains of S. aureus have become resistant to one or more of the antibiotics used to treat infections.
The mechanisms of antibiotic resistance involve proteins, for example:
• enzymes to breakdown antibiotics
• membrane proteins that inactivate antibiotics
• membrane proteins that pump out antibiotics.
Explain why antibiotic resistance arises as a result of mutation.
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(a) Explain the ecological terms population and community, using examples given in the passage.

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(b) Suggest why the sloth and its fur can be described as a small ecosystem.
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(a) Nicotine, in cigarette smoke, is highly addictive. A nicotine vaccine has been developed to try and reduce the effects of addiction. The vaccine stimulates an immune response to produce antibodies that bind to the nicotine molecule. Fig. 6.1 is a diagram of an antibody molecule.

On Fig. 6.1:
• label three structural features that enable an antibody molecule to carry out its function.
• next to each label, state the function of the feature.


Fig. 6.1
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(b) Nicotine has an effect on the cardiovascular system, such as making platelets sticky, so causing blood to clot. This increases the risk of thrombosis and reduces blood flow.

Outline other effects of nicotine on the cardiovascular system.
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