9700_w14_qp_23
A paper of Biology, 9700
Questions:
6
Year:
2014
Paper:
2
Variant:
3
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1
is a photomicrograph of plant root cells near the growing tip. Some of the cells are undergoing mitosis. A C 20 +m B D State one feature, visible in , which indicates that the section is taken from plant tissue and not animal tissue. State the letter, A to D, of the cell in which is in: prophase anaphase. Describe two events occurring in cell B. 1. 2. Describe the role of mitosis in a growing plant root tip. Mutations can sometimes occur in cells which are rapidly dividing. Outline how a mutation can cause an altered polypeptide to be produced. Calculate the magnification of . Show your working and give your answer to the nearest whole number. magnification ×
5. The mitotic cell cycle  →  5.2. Chromosome behaviour in mitosis
16. Inheritance  →  16.1. Passage of information from parents to offspring
1. Cell structure  →  1.2. Cells as the basic units of living organisms
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2
shows a food chain in a freshwater ecosystem. diatom water flea pond skater northern pike heron The diatom is an autotroph. Explain what is meant by the term autotroph. Describe the role of the water flea in the food chain shown in . Suggest why the heron population is much smaller than the population of the water flea. a shows a pond skater walking on the surface of the water. b shows a northern pike. These are not shown to the same scale. a b Both animals live in northern countries of the world, where temperatures often drop below 0 °C. Describe the importance of water as an environment for the pond skater and the northern pike. The mud at the bottom of the freshwater ecosystem contains dead organic material and also supports the growth of water plants. Outline how nitrogen from the dead organic material is made available to the growing plants.
18. Classification, biodiversity and conservation  →  18.2. Biodiversity
4. Cell membranes and transport  →  4.2. Movement into and out of cells
13. Photosynthesis  →  13.2. Investigation of limiting factors
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3
Measles is an infectious disease for which vaccines have been developed. The commonly used vaccine consists of an attenuated form of the virus. The measles vaccine is normally given to children when they are about one year old, followed by a booster dose when they are about four years old. Explain how this vaccine can provide long-term immunity against measles. shows the number of reported cases of measles and the percentage of the population vaccinated worldwide between 1980 and 2002. number of cases key: percentage of population vaccinated 500 000 1 000 000 1 500 000 number of cases percentage of population vaccinated 2 000 000 2 500 000 3 000 000 3 500 000 4 000 000 4 500 000 year Describe the trends shown in : between 1980 and 1990 between 1990 and 2002. The measles virus has a unique protein on its surface called MV-H which can bind to a protein called CD-46 on the surface of human cells. This allows the measles virus to infect these cells. Suggest how the two proteins, MV-H and CD-46, can bind to each other.
11. Immunity  →  11.2. Antibodies and vaccination
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4
is a computer-generated image of the enzyme hexokinase binding with its substrate, glucose. The product of the enzyme-catalysed reaction is glucose-6-phosphate. glucose hexokinase Hexokinase binds with glucose using the induced fit mechanism. Describe how an enzyme-substrate complex forms by this mechanism. Suggest how enzymes which use the induced fit mechanism can be less affected by competitive inhibitors than those which use the lock and key mechanism. When a solution of the enzyme hexokinase is heated to 45 °C for 10 minutes, the quantity of product formed decreases by 50% compared to a sample kept between 30 °C and 40 °C. Explain this result. Glucose can enter cells by active transport or facilitated diffusion. Glucose-6-phosphate is a charged, polar molecule and cannot move out of cells. State two differences between active transport and facilitated diffusion. 1. 2. Suggest why glucose-6-phosphate cannot move out of cells.
3. Enzymes  →  3.1. Mode of action of enzymes
3. Enzymes  →  3.2. Factors that affect enzyme action
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5
shows a section of lung tissue from a smoker. The image magnification is ×10. X In a smoker, the walls between the gas exchange structures in the lungs can break down, resulting in the damaged features visible in . One of these damaged features is labelled X. Name the gas exchange structures which are damaged in . Name the smoking-related disease resulting in the damaged feature labelled X in . Smoking-related diseases may increase the risk of infectious diseases of the gas exchange system. Describe and explain how smoking can increase the risk of these infections. From one cigarette, a smoker will inhale between 14 and 20 mg of carbon monoxide. Describe the effects of carbon monoxide on haemoglobin.
9. Gas exchange  →  9.1. The gas exchange system
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6
Table 6.1 contains some information about xylem vessels and phloem sieve tube elements in plants. Table 6.1 features xylem vessels phloem sieve tube elements living cells yes substances transported dissolved sugars and amino acids direction of flow of substances one direction, roots to leaves permeability of cell walls to water not permeable cell wall material Complete Table 6.1. State one use for magnesium ions in plants.
7. Transport in plants  →  7.1. Structure of transport tissues
7. Transport in plants  →  7.2. Transport mechanisms
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