Past paper questions

Question 1

Describe the changes that occur in the eye when a bright light is directed into the eye

Answer 1

The pupil gets smaller, and the iris changes shape to reduce the amount of light let it

Question 2

Describe two processes that occur in the cell during prophase

Answer 2

1. The nucleus membrane breaks down
2. The chromosomes condense

Question 3

Describe how you would adjust a microscope to view a slide at a magnification of x400

Answer 3

Change the objective lens to x40
Change the eye piece lens to x10

Question 4

Benefits and Risks of using stem cells to treat illnesses

Answer 4

Benefits: Can differentiate and become specialised
- They replace damaged cells
- They reduce symptoms

Risks: New cells may not function properly
- If the stem cells continue to divide it may cause cancer
- The stem cells may reject

Question 5

What is one method that can be used to date a fossil

Answer 5

The location in the rock layer

Question 6

Explain how to genetically modify a bacterial cell to produce chymosin

Answer 6

• Get the chymosin gene using a restrictive enzyme.
• Cut open the plasmid using the restrictive enzyme
• Add the chymosin gene to the sticky ends using the enzyme ligase
• Reinsert the plasmid back into the bacterial cell

Question 7

Explain why alleles can produce proteins with different structures

Answer 7

Alleles are caused by mutations in the DNA
The mRNA strand has a different sequence,
therefore it codes for a different amino acid
And the protein folds with a different structure