At a sports clinic, Fig. 1 shows two runners completing the same hill route. One runner has trained regularly at high altitude, while the other has not. The...
Question 1 Report
At a sports clinic, Fig. 1 shows two runners completing the same hill route. One runner has trained regularly at high altitude, while the other has not. Their leg muscles are both made of cells containing inherited genes, but training can change the size and efficiency of muscles. The coach warns that a runner's performance is not caused by a single gene. Food intake, oxygen availability, motivation and practice can all affect the result. The clinic is comparing inherited and environmental sources of variation.
(a) Identify one environmental cause of variation in running performance shown in Fig. 1. [1]
(b) Explain why training does not change the alleles a runner passes to offspring. [2]
(c) Give one inherited characteristic that could affect running performance. [1]
(d) Suggest why comparing only two runners gives weak evidence. [2]
Answer Details
(a) Training / oxygen availability at altitude / diet [1] (b) Training affects body cells, such as muscle cells [1]; it does not alter DNA in gametes / sex cells [1] (c) Any one: muscle fibre type / height / lung capacity potential / inherited body build [1] (d) Individual differences may be due to chance [1]; more runners / repeats are needed for a reliable conclusion [1]
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