0610_s17_qp_42
A paper of Biology, 0610
Questions:
6
Year:
2017
Paper:
4
Variant:
2

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Acid rain has negative effects on many ecosystems. Describe the negative effects of acid rain on freshwater ecosystems, such as streams, rivers and lakes. Two groups of students were asked to investigate the effects of acid rain on the germination of pine tree seeds. Both groups of students decided to use sulfuric acid rather than hydrochloric acid to represent acid rain in their investigation. Suggest why. State how the students could have measured the pH of the sulfuric acid. The students provided the environmental conditions that seeds need to germinate. State two of these environmental conditions. One group of students recorded the change in temperature as the seeds germinated in five insulated flasks, labelled A to E. Suggest why germinating seeds increase in temperature. The students sterilised the seeds before their investigation. Their teacher told them to use a sterilising solution to wash the seeds because steam would kill the seeds and prevent the seeds from germinating. Explain why steam sterilisation would prevent seed germination. The results from this group of students are shown in Table 5.1. Table 5.1 flask pH group 1 temperature of seeds after 72 hours / °C A 2.0 20.6 B 3.5 20.3 C 4.0 21.2 D 5.5 34.1 E 7.0 46.2 Describe the results obtained by group 1. The second group of students placed 100 seeds in each of five Petri dishes, labelled 1 to 5. Group 2 used the same range of pH values as group 1. They recorded the percentage of seeds that had germinated after 72 hours. Their results are shown in Table 5.2. Table 5.2 Petri dish pH group 2 percentage of seeds germinated after 72 hours 2.0 3.5 4.0 5.5 7.0 The teacher thought that group 2 had forgotten to add the sulfuric acid to one of their Petri dishes. Suggest which Petri dish was not set up correctly.
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