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3.3 Maintaining internal environments

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Question 15
H

A student investigates the effect of different concentrations of sodium chloride solution on red blood cells.

  • She adds the same volume of blood to the same volume of each solution.
  • After 30 minutes, she looks at a sample of each mixture using a light microscope.
  • She calculates the percentage of red blood cells that have burst.

The Table shows her results.

Table

Concentration of sodium chloride solution in %\%%Percentage of red blood cells that have burst
0.0100
0.298
0.460
0.612
0.80
1.00
a.

Explain why all the red blood cells burst in the 0.0% sodium chloride solution.

[3]
b.

The student says:

'The concentration of sodium chloride in blood plasma is 0.4%.'

Evaluate the student's claim using data from the Table.

[2]
c.

Predict and explain what would happen to red blood cells placed in a 3.0% sodium chloride solution.

[2]
d.

Suggest how the student could find the lowest concentration at which no cells burst more precisely.

[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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