Edexcel GCSE Biology

Required practicals — biology

Edexcel GCSE Biology revision on Required practicals — biology. Aligned to the Pearson Edexcel GCSE Biology 1BI0 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

Question 1

In the microscopy practical, why must the onion epidermis layer be extremely thin?
- A) To prevent cell wall decay
- B) To allow light penetration
- C) To stop water evaporation
- D) To keep cells in position
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Answer: To allow light penetration

Light microscopes work by passing light through a specimen. If the layer is too thick, the light cannot penetrate, resulting in a dark image where no cellular detail is visible.
Question 2

During the osmosis potato practical, why is the potato cylinder surface dried with a paper towel before weighing?
- A) To remove surface moisture
- B) To improve water absorption
- C) To reduce potato mass error
- D) To prevent bacterial growth
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Answer: To remove surface moisture

This is a control variable to ensure that the change in mass measured is due to osmosis occurring within the cells, not water clinging to the outside of the cylinder. Failing to dry the potato creates an inconsistent starting mass.
Question 3

In the enzyme activity practical, which chemical is used to indicate the presence of starch?
- A) Benedict reagent
- B) Iodine solution
- C) Biuret reagent
- D) Ethanol emulsion
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Answer: Iodine solution

Iodine is the specific reagent used to test for starch. Benedict's tests for reducing sugars, while Biuret tests for proteins, meaning the other options are incorrect for this specific procedure.

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