Supplying the Cell (OCR GCSE Combined Science A (Gateway): Biology)

A scientist clones a cauliflower plant.

He uses small pieces of the cauliflower plant called explants.

This is the method the scientist uses to get the explants:

• Place the equipment in a beaker of bleach and swab the bench with 70% alcohol.

• Collect a small piece of cauliflower and place on a white tile.

• Use a scalpel to cut the piece of cauliflower lengthways into small 3–5mm pieces called explants.

• Measure the mass of the explants.

(i) Suggest why the scientist uses a scalpel rather than a kitchen knife.

 [1]

(ii) Write down one safety precaution that the scientist should take when using a scalpel.

[1]

(iii) The explants are then prepared for cloning by placing on an agar jelly plate.

Agar jelly contains water, sugars and minerals.

When the explants are placed on the agar jelly plate they have no roots or leaves.

Explain why the explants must be placed on the agar jelly plate.

 [2]

To grow the explants, the scientist places the agar jelly plate in a warm room near to a window.

(i) Explain why this will help the explants grow and develop into clones.

 [2]

(ii) Using a heated cabinet with light bulbs inside the cabinet would improve this method. Explain why.

 [2]

(iii) The scientist examines the agar jelly plate regularly.

Growth of the explants is visible in the plate within 10 days and parts of the explants are turning green.

What conclusion can be made about why the explants have parts that are turning green?

 [1]

The mass of the explants at the start was 15g.

After 10 days the mass of the explants was 28g.

Calculate the percentage increase in mass of the explants.

Give your answer to 1 decimal place.

Percentage increase = .................................... % 

The cells in cauliflower explants behave the same way as embryonic stem cells do in animals.

Explain why it is more difficult to clone adult animals than to clone cauliflower.