Home / iGCSE Biology (0610)-21.3 Genetic modification – iGCSE Style Questions Paper 2

iGCSE Biology (0610)-21.3 Genetic modification – iGCSE Style Questions Paper 2

IGCSE Biology (0610) Practice Questions Paper 2 - All Chapters

Question

Some processes involved in the production of human insulin by genetic modification are listed.

1. insertion of the human insulin gene DNA into a cut bacterial plasmid

2. bacteria containing recombinant plasmids multiply and make human insulin

3. human insulin gene DNA is isolated using restriction enzymes

4. recombinant plasmids are inserted into bacteria

What is the sequence of these processes in genetic modification?

(A) $1 \rightarrow 3 \rightarrow 2 \rightarrow 4$
(B) $1 \rightarrow 4 \rightarrow 3 \rightarrow 2$
(C) $3 \rightarrow 1 \rightarrow 4 \rightarrow 2$
(D) $3 \rightarrow 2 \rightarrow 1 \rightarrow 4$
▶️ Answer/Explanation
To produce insulin, the specific gene must first be isolated from human DNA using restriction enzymes (Step 3). Once isolated, this gene is inserted into a bacterial plasmid to create a recombinant DNA molecule (Step 1). This recombinant plasmid is then transferred into a host bacterium (Step 4). Finally, these modified bacteria are grown in large quantities so they can multiply and express the gene to synthesize human insulin (Step 2). This logical progression follows the sequence $3 \rightarrow 1 \rightarrow 4 \rightarrow 2$.
✅ Answer: (C)
Question

The diagram shows a bacterial cell that is used in genetic modification.

Which labelled structure makes the bacterium useful for genetic modification?

▶️ Answer/Explanation
Solution

Ans: C

Plasmids (C) are small, circular DNA molecules in bacteria that can be easily modified to carry foreign genes. They replicate independently and are key tools in genetic engineering. The other structures (cell wall, flagellum, ribosome) don’t directly facilitate genetic modification.

Question

The stages describe how genetic modification can be used to produce human insulin from bacteria.

  1. Cut bacterial plasmid DNA with restriction enzymes.
  2. Extract the gene for insulin from human DNA with restriction enzymes.
  3. Insert the recombinant plasmids into bacteria.
  4. Join human DNA to bacterial plasmid DNA using DNA ligase.
  5. Replicate bacteria containing recombinant plasmids.

Which sequence will lead to the production of human insulin by bacteria?

▶️ Answer/Explanation
Solution

Ans: A

The correct sequence for genetic modification to produce human insulin is:

  1. Cut plasmid DNA (Step 1)
  2. Extract insulin gene (Step 2)
  3. Join DNA using ligase (Step 4)
  4. Insert into bacteria (Step 3)
  5. Replicate bacteria (Step 5)

This matches sequence A (1 → 2 → 4 → 3 → 5) in the diagram.

Why this order? The plasmid must first be prepared (1), then the gene isolated (2), combined (4), inserted (3), and finally the bacteria grown (5) to produce insulin.

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