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People produce sweat when they are hot - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Question 7
People produce sweat when they are hot. Sweat consists of substances dissolved in water. Figure 16 shows the concentration of dissolved substances in the sweat of t... show full transcript
Worked Solution & Example Answer:People produce sweat when they are hot - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Step 1
(i) Calculate the ratio of the concentration of urea in the sweat of patient A to the concentration of urea in the sweat of patient B.
Answer
To calculate the ratio, we first take the concentration of urea in patient A, which is 8.0 mmol per dm², and the concentration in patient B, which is 32.0 mmol per dm². The ratio can be expressed as:
Thus, the simplest form of the ratio is 1:4.
Step 2
(ii) Describe how urea is produced in the body.
Answer
Urea is produced in the body during the process of deamination. This occurs when excess amino acids are broken down. The amino group from amino acids is removed and converted to ammonia, which is further converted to urea in the liver. Urea is then excreted from the body through urine.
Step 3
Step 4
Step 5
(ii) Explain how structures in the skin help to reduce body temperature during hot weather.
Answer
Several structures in the skin contribute to reducing body temperature during hot weather:
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Sweat Glands: These glands produce sweat, which spreads out onto the surface of the skin. As the sweat evaporates, it cools the body, helping to lower the temperature.
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Hair and Muscles: In hot conditions, the erector muscles relax, causing the hairs to lie flat. This reduces insulation, allowing heat to escape more easily.
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Capillaries: Blood vessels, particularly capillaries, dilate (widen) near the surface of the skin, increasing blood flow. This allows more heat to be released from the blood to the external environment, enhancing cooling via radiation and convection.
These mechanisms work together to effectively manage body temperature and prevent overheating.