Oxford AQA IGCSE · Biology (9201)

Genetic variation: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Genetic variation.

10 questions28 marksFree, no account

Question 1

1 mark

Which of the following best describes a gene?

Question 2

1 mark

In genetic engineering, enzymes are used to 'cut out' a required gene from an organism's chromosome. What is typically used as a vector to insert this gene into the required cells?

Question 3

1 mark

In adult cell cloning, the nucleus from an adult body cell is inserted into an unfertilised egg cell. What is the role of the electric shock applied during this process?

Question 4

1 mark

In the genetic diagram provided, which shows a cross between a parent who is heterozygous for polydactyly (\(Dd\)) and a parent who is homozygous recessive (\(dd\)), what is the probability that their child will inherit the condition?

Question 5

1 mark

The family tree diagram shows the inheritance of cystic fibrosis, a recessive disorder (\(f\)). Two parents who do not have the disorder have a daughter who is affected. What are the genotypes of these two parents?

Question 6

2 marks

In human body cells, which specific pair of chromosomes determines that an individual is female?

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Question 7

3 marks

Define the term heterozygous in the context of an individual's alleles for a specific gene.

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Question 8

5 marks

A man has the sex genotype \( XY \). Explain why his sperm cells will not all carry the same sex chromosome.

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Question 9

5 marks

In humans, the allele for cystic fibrosis is recessive (f) and the allele for normal mucus production is dominant (F).
(a) A man and a woman are both carriers of the cystic fibrosis allele. Use a Punnett square to show the possible genotypes of their children.
(b) Determine the probability that their first child will have cystic fibrosis.
(c) Define the term 'heterozygous'.

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Question 10

8 marks

DNA is a polymer made up of two strands forming a double helix.
(a) Describe the relationship between DNA, genes, and chromosomes.
(b) DNA contains a sequence of bases. Explain how this sequence of bases determines the specific proteins made in a cell.
(c) polydactyly is a condition where a person has extra fingers or toes, caused by a dominant allele (D). If a father is heterozygous (Dd) and the mother is homozygous recessive (dd), calculate the percentage chance that their offspring will inherit the condition. Provide a genetic diagram to support your answer.

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