18. Variation and selection
A section of Biology, 0610
Listing 10 of 190 questions
For Examiner's Use shows Soay sheep on St. Kilda, a group of small remote islands off the coast of Scotland. These islands experience extreme conditions of cold, wind and rain. Sheep were introduced to the islands thousands of years ago and the Soay sheep are descended from them. The islands of St. Kilda have been uninhabited by people since 1930. The sheep are now left unfarmed and in their natural state. The populations of Soay sheep on St. Kilda show much more variation in their phenotype than modern breeds of sheep. Explain, by using an example from , what is meant by variation in their phenotype. For Examiner's Use Scientists have recorded the numbers of Soay sheep and lambs on St. Kilda for many years. Each year between 1985 and 1996, the lambs (young sheep) were caught, marked and weighed. In some years, the total number of sheep on St. Kilda was lower than in other years. shows the frequency of lambs of different body mass in years when the total number of sheep was low and years when the total number was high. frequency of lambs 3–4 5–6 7–8 9–10 11–12 body mass / kg low population years 13–14 15–16 17–18 19–20 21–22 frequency of lambs 3–4 5–6 7–8 9–10 11–12 body mass / kg high population years 13–14 15–16 17–18 19–20 21–22 key lambs that died lambs that survived for at least a year For Examiner's Use Population size has a great effect on the survival of lambs on St. Kilda. Describe the evidence from that supports this statement. Suggest an explanation for the effect that you have described. Soay sheep are adapted to the extreme conditions experienced on St. Kilda. Explain how natural selection could account for the adaptive features of Soay sheep.
0610_w13_qp_32
THEORY
2013
Paper 3, Variant 2
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An adaptive feature helps an organism survive in its environment. Adaptive features are inherited. contains diagrams of three animals. For each animal, select one adaptive feature visible in and briefly suggest how it helps the animal to survive. An example has been done for you. not drawn to scale animal C red deer adaptive feature: antlers on head help in survival: used for defence against predators animal D saltwater crocodile adaptive feature: help in survival: shows a giraffe and an okapi. The long neck is an adaptive feature for giraffes. It helps them feed on leaves that other animals like the okapi cannot reach. Giraffes developed long necks by the process of natural selection.
0610_s17_qp_31
THEORY
2017
Paper 3, Variant 1
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shows a photograph of Ursus maritimus (polar bear). Polar bears live in and around the Arctic Circle, surviving in extremely cold conditions. Describe and explain one visible adaptive feature that enables the polar bear to survive in a cold environment. feature explanation Polar bears have adapted over time to live in the cold arctic environment through a process called natural selection. Describe the process of natural selection. Polar bears are an endangered species. Suggest reasons why polar bears have become endangered and how they could be conserved.
0610_s17_qp_32
THEORY
2017
Paper 3, Variant 2
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Questions Discovered
190