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9700_s20_qp_11
A paper of Biology, 9700
Questions:
40
Year:
2020
Paper:
1
Variant:
1
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3
A student examined a slide of human blood with a light microscope and made a careful drawing of the different cell types. The student used an eyepiece graticule so that the relative sizes of the different cell types were drawn accurately. In the drawing: ● red blood cells were 7 mm in diameter ● lymphocytes were 6 mm in diameter ● neutrophils were 14 mm in diameter. What is the linear magnification of the drawing?
1. Cell structure  →  1.1. The microscope in cell studies
8. Transport in mammals  →  8.1. The circulatory system
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4
The diagram shows a graduated slide, with divisions of 0.1 mm viewed using an eyepiece graticule. 90 100 Pollen grains were grown in a sugar solution and viewed using the eyepiece graticule. Diagram 1 shows the pollen grains at the start. Diagram 2 shows the pollen grains after four hours. 90 100 90 100 at start after 4 hours diagram 1 diagram 2 pollen tube What is the growth rate of the pollen tubes?
13. Photosynthesis  →  13.2. Investigation of limiting factors
1. Cell structure  →  1.1. The microscope in cell studies
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8
The diagrams show short sections of some common polysaccharides and modified polysaccharides. CH2OH H H H H OH H OH H CH2OH NHCOCH3 H NHCOCH3 H H O O O H O H O CH2OH H H H OH H OH H CH2OH OH H OH H O O O H O H O CH2OH H H H H OH OH H O CH2OH H H OH OH H O O H O H O The polysaccharides can be described as: ● F is composed of β-glucose monomers with 1,4 glycosidic bonds ● G is composed of α-glucose monomers with 1,4 glycosidic bonds ● H is composed of N-acetylglucosamine monomers with β-1,4 glycosidic bonds. Which row correctly matches the numbered diagrams to the descriptions of the polysaccharides?
2. Biological molecules  →  2.2. Carbohydrates and lipids
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22
Scientists grew bacteria in a medium containing heavy nitrogen, 15N, as the only source of nitrogen. After many generations, all of the bacterial DNA contained heavy nitrogen. These bacteria were then moved from the heavy nitrogen medium into a medium with only light nitrogen, 14N. Some bacteria were collected from each of the next three generations and their DNA was analysed. Hybrid DNA contains both heavy and light nitrogen. Which row shows the correct DNA of the first and third generations?
19. Genetic technology  →  19.1. Principles of genetic technology
6. Nucleic acids and protein synthesis  →  6.1. Structure of nucleic acids and replication of DNA
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30
The statements list some of the events in the cardiac cycle. They are not in the correct order. The impulse travels through Purkyne tissue. A wave of excitation sweeps across the atria. The atrioventricular node delays the impulse for a fraction of a second. The sinoatrial node contracts. The wave of excitation sweeps upwards from the base of the ventricles. The ventricles contract. The atria contract. Which statement describes the third of these events to occur in the cardiac cycle?
8. Transport in mammals  →  8.3. The heart
15. Control and coordination  →  15.1. Control and coordination in mammals
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38
The antibiotic teixobactin was discovered in January 2015. Teixobactin kills some bacteria such as Staphylococcus and Mycobacterium. Most antibiotics work by binding to proteins. Teixobactin binds to lipids that are used in the synthesis of bacterial cell walls. This means that it is unlikely that bacteria will quickly develop resistance to teixobactin. Which statements explain why bacteria are unlikely to quickly develop resistance to teixobactin?
10. Infectious diseases  →  10.2. Antibiotics
17. Selection and evolution  →  17.2. Natural and artificial selection
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