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3.3 Maintaining internal environments

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Question 3
F

The kidneys control the amount of water in the body.

A man collected all his urine on two different days.

  • On day 1, the weather was cool.
  • On day 2, the weather was very hot.
  • He drank the same volume of water on both days.

The Table shows the results.

Table

Day 1 (cool)Day 2 (very hot)
Volume of water drunk in cm3\text{cm}^3cm320002000
Volume of urine produced in cm3\text{cm}^3cm31500600
Concentration of urea in urine in g\text{g}g per dm3\text{dm}^3dm31230
a.

Calculate the percentage decrease in the volume of urine from day 1 to day 2.

[2]
b.

Explain why the man produced a smaller volume of urine on day 2.

[3]
c.

Show that the man excreted the same mass of urea on both days.

[2]
d.

Water is also lost from the body in urine and sweat.

Give one other way that water is lost from the body.

[1]
Markscheme

3.3 Maintaining internal environments Questions

  1. GCSE
  2. /Biology
  3. /3.3 Maintaining internal environments

72 exam-style questions on OCR GCSE Biology 3.3 Maintaining internal environments, covering 3.3.1 Importance of a constant internal environment, 3.3.2 The skin and body temperature, 3.3.3 Insulin and blood sugar, 3.3.4 Glucagon and blood sugar, 3.3.5 Type 1 and type 2 diabetes, 3.3.6 Osmotic changes in body fluids, 3.3.7 Kidneys and water balance, 3.3.8 Structure of the kidney and tubule, 3.3.9 ADH and kidney tubule permeability, and 3.3.10 Responses to temperature and osmotic challenges. Each one has a worked solution and a mark scheme showing where the marks go.

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