3. Movement into and out of cells
A section of Biology, 0610
Listing 10 of 315 questions
For Examiner's Use After an accident at a nuclear power plant in 1986, particles containing radioactive strontium were carried like dust in the atmosphere. These landed on grassland in many European countries. When sheep fed on the grass they absorbed the strontium and used it in a similar way to calcium. Explain where in the sheep you might expect the radioactive strontium to become concentrated. Suggest the possible effects of the radiation, given off by the strontium, on cells in the body of the sheep.
0610_w08_qp_2
THEORY
2008
Paper 2, Variant 0
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For Examiner's Use A shows a buttercup, Ranunculus cymbalaria. B shows details of a flower of the same plant. A B Explain, using only features visible in , why Ranunculus cymbalaria is classified as a dicotyledonous plant rather than as a monocotyledonous plant. For Examiner's Use shows a transverse section through a buttercup root at the end of the cold winter (W) and at the end of the warm, moist summer (S). At the end of the winter, the cells contain very few starch grains. At the end of the summer, most of the root cells contain many starch grains. W S Suggest why there are few starch grains in the cells of W compared with a large number of starch grains in the cells of S. Describe how enzymes in root cells synthesise starch. For Examiner's Use As temperature is increased, for example from 10 oC to 30 oC, enzyme activity increases. Explain how increasing temperature affects enzyme activity.
0610_w10_qp_32
THEORY
2010
Paper 3, Variant 2
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For Examiner's Use Explain how water is absorbed by plant roots. Young plants were grown in pots of sand for four weeks. Some plants were watered with distilled water at pH 7.0 (no salts). Most pots were watered with solutions containing different concentrations of salt (sodium chloride) at pH 7.0. The plants were kept at 20 oC. The growth of the plants was measured after four weeks. The growth of the plants is shown in as percentages of the growth of the plants watered with distilled water. concentration of sodium chloride / arbitrary units growth as percentages of the growth of the plants given distilled water For Examiner's Use Describe the results shown in . You will gain credit for using the figures in the graph to support your answer. Explain the difference in growth between the plants watered with low concentrations and those watered with high concentrations of salt solution. For Examiner's Use The pH of soils influences the availability of ions to plants. shows the availability of ions in soils of different pH. 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 availability of each ion magnesium potassium phosphate nitrate iron sulfate Name the ion that is least available in soils of pH 4.0 and in soils of pH 11.0. pH 4.0 pH 11.0 For Examiner's Use Plants grown in soils of pH 10 may show symptoms of deficiency. They are stunted and their leaves are yellow. Explain how deficiencies of magnesium ions and nitrate ions lead to the symptoms described. magnesium ions nitrate ions
0610_w11_qp_33
THEORY
2011
Paper 3, Variant 3
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Questions Discovered
315