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5.1 Inheritance

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Question 19

A student clones a carrot plant using a tissue culture technique.

She uses a sterile scalpel to cut small pieces of root tissue, called explants. This is the method she follows:

  1. Disinfect the laboratory bench with 70% ethanol and sterilise all equipment.
  2. Place a small section of carrot root on a clean white tile.
  3. Use a scalpel to carefully slice the carrot into small 3–5 mm3\text{--}5\text{ mm}3–5 mm pieces (explants).
  4. Record the initial total mass of the explants.
a.

(i) Suggest why the student uses a sharp scalpel rather than a standard kitchen knife to cut the explants. (ii) State one safety precaution the student should take when using the scalpel. (iii) The explants, which initially have no roots or leaves, are placed on a sterile nutrient agar plate containing water, minerals, and sucrose. Explain why the agar must contain water, minerals, and sucrose.

[4]
b.

(i) The student places the nutrient agar plate in a warm incubator under a continuous light source. Explain how this setup helps the explants grow and develop into healthy clones.

[2]
c.

The total mass of the carrot explants at the start of the experiment was 16 g. After two weeks, the total mass of the explants was 35 g.

Calculate the percentage increase in the mass of the explants. Give your answer to 1 decimal place.

[3]
d.

Explain why it is more difficult to clone adult animals than it is to clone plants from plant tissue.

[2]
Markscheme

5.1 Inheritance Questions

  1. GCSE
  2. /Biology
  3. /5.1 Inheritance

97 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.

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