9700_w12_qp_21
A paper of Biology, 9700
Questions:
5
Year:
2012
Paper:
2
Variant:
1
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1
is a drawing made from an electron micrograph of a mammalian liver cell. F E D C B G glycogen granules A Complete the table by naming the structures B to G and stating one function of each. The first one (A) has been completed for you. name of organelle function A cell surface membrane controls movement of substances into and out of the cell B C D E F G For Examiner’s Use As shown in , liver cells contain many storage granules of glycogen. Describe the molecular structure of glycogen and explain how this structure makes it suitable for storage.
2. Biological molecules  →  2.2. Carbohydrates and lipids
12. Energy and respiration  →  12.2. Respiration
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2
For Examiner’s Use Thale cress, Arabidopsis thaliana, is used to study the roles of genes and proteins in plants. The cell membranes of the root hairs of A. thaliana contain proteins called aquaporins that allow the movement of water between the soil and the cytoplasm as shown in . cell wall soil cytoplasm aquaporin water molecule With reference to : explain how water is absorbed by root hairs of A. thaliana state why aquaporins are necessary in cell surface membranes. For Examiner’s Use Describe the pathway taken by water from the cytoplasm of the root hair cell to a xylem vessel in the centre of the root. For Examiner’s Use An investigation was carried out to find the effect of an enzyme in A. thaliana on the composition of the cuticle. The enzyme is involved in the production of lipid that accumulates in the cuticle. Plants were discovered with a mutation of the gene that codes for the enzyme. Some of these mutant plants (Group A) were grown in pots and their rate of transpiration was determined over three days. They were compared with control plants (Group B) in which the gene was switched on and the enzyme present. The results are shown in . 12.00 00.00 rate of transpiration / g h–1 g dry mass–1 12.00 00.00 time / hours 12.00 00.00 dark dark dark light light A B Key: mutant plants (A) control plants (B) With reference to , explain: why the rate of transpiration is higher during the day than at night in both groups of plants For Examiner’s Use how the results show that the cuticle is less effective in the mutant plants.
7. Transport in plants  →  7.2. Transport mechanisms
4. Cell membranes and transport  →  4.2. Movement into and out of cells
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3
For Examiner’s Use Bone marrow contains stem cells that divide by mitosis to form blood cells. Each time a stem cell divides it forms a replacement stem cell and a cell that develops into a blood cell. shows changes in the mass of DNA in a human stem cell from the bone marrow during three cell cycles. K mass of DNA per cell time L With reference to , state: what happens to bring about the changes in the mass of DNA per cell at K and at L K L how many blood cells are formed from the stem cell in the time shown what happens to the number of chromosomes in the stem cell. For Examiner’s Use Stem cells in bone marrow give rise to phagocytes, B-lymphocytes and T-lymphocytes. Describe how a red blood cell develops from a stem cell. During an immune response, cells divide by mitosis. Describe how mitosis is involved in an immune response. Describe the modes of action of T-lymphocytes during an immune response.
5. The mitotic cell cycle  →  5.1. Replication and division of nuclei and cells
11. Immunity  →  11.1. The immune system
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4
For Examiner’s Use Lancaster Sound in the Canadian Arctic is a very productive marine environment and supports large populations of sea birds and marine mammals. Studies of the area have shown the importance of Arctic cod, Boreogadus saida, in the flow of energy to marine birds, such as guillemots and fulmars, and marine mammals, such as narwhals and belugas. Arctic cod forms the main, or only, source of food for many such animals. The flow of energy through the food web in Lancaster Sound is shown in . gull polar bear human guillemot narwhal Arctic cod copepods amphipods arrow worms walrus bivalve molluscs algae kelp phytoplankton detritus harp seal fulmar Note: detritus is dead and decaying matter ringed seal beluga Name the trophic levels occupied by the following organisms in the food web in : kelp arrow worms narwhals. For Examiner’s Use The population of polar bears in the Lancaster Sound area is quite small in comparison to populations of animals that feed on Arctic cod. Using only the information shown in , explain why the population of polar bears is small. Populations of many fish species are under threat of extinction as a result of over-fishing. Explain the likely consequences of over-fishing of Arctic cod.
18. Classification, biodiversity and conservation  →  18.3. Conservation
18. Classification, biodiversity and conservation  →  18.2. Biodiversity
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5
For Examiner’s Use Mammals have closed, double circulatory systems. Explain what are meant by the terms closed and double as applied to mammalian circulatory systems. closed double shows a longitudinal section through a mammalian heart. Use label lines and the letters P, Q, R and S to label the following on : P the right atrium Q a semilunar valve R a blood vessel that carries deoxygenated blood S the position of Purkyne tissue For Examiner’s Use Catheters are small tubes that are inserted into blood vessels. A catheter was inserted into an artery in the arm and then moved into the aorta and then into the left ventricle during a diagnostic investigation. The catheter contained a device to measure the blood pressure in the aorta and in the left ventricle. The results are shown in . time / s blood pressure / kPa Calculate the heart rate during the period of the investigation. Show your working. answer Describe and explain the differences in pressure as the catheter moves from the aorta into the left ventricle. For Examiner’s Use is an X-ray showing narrowing in the blood vessels supplying muscles in the heart. A catheter is used to insert a dye into the blood vessels so that they appear clearly in the X-ray. The arrows indicate where there is narrowing of the blood vessels. Name the blood vessels shown in . State the likely effect of narrowing of these blood vessels. Suggest ways in which the condition shown in may be treated.
8. Transport in mammals  →  8.1. The circulatory system
8. Transport in mammals  →  8.3. The heart
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