A wildlife researcher compares arctic foxes in summer and winter. In winter their fur is thicker and they reduce the blood flow to skin on their feet when s...
Question 1 Report
A wildlife researcher compares arctic foxes in summer and winter. In winter their fur is thicker and they reduce the blood flow to skin on their feet when standing on snow. In summer, the same species sheds much of its insulating coat. The researcher notes that an animal must balance the benefit of retaining thermal energy against the risk that tissues near the skin receive too little oxygen in very cold conditions. Blood transports oxygen and glucose to cells, but it can also carry thermal energy around the body.
(a) Identify the change in blood vessels that reduces blood flow to the skin. [1]
(b) Explain how thick winter fur helps the fox in cold air. [2]
(c) Explain why blood flow to the feet cannot be reduced completely for a long time. [2]
(d) Give one advantage of shedding fur in summer. [1]
Answer Details
(a) Vasoconstriction [1] (b) Fur traps air [1]; trapped air is a poor conductor so reduces thermal energy loss [1] (c) Cells in the feet need oxygen/glucose delivered by blood [1]; and waste products such as carbon dioxide must be removed / cells could be damaged without a supply [1] (d) Reduces overheating / allows heat loss more easily [1]
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