B3 - Genetics

Question 1

Name the structure in the cell that contains DNA. (1)

Answer 1

Nucleus. (1)

Question 2

What is the term to describe the number of chromosomes in an egg or sperm cell? (1)

Answer 2

Haploid. (1)

Question 3

Why do you filter the mixture when extracting DNA? (1)

Answer 3

To remove insoluble material. (1)

Question 4

what is the role of ethanol in DNA extraction? (1)

Answer 4

To precipitate the DNA. (1)

Question 5

Describe the structure of DNA. (3)

Answer 5

• Double Helix (1)
• Sugar phosphate backbone (1)
• Complementary bases (1)

Question 6

Explain how two parents with a dominant phenotype can produce offspring expressing a recessive characteristic. (2)

Answer 6

Both parents must be heterozygous for the recessive allele (1) The offspring inherits a recessive allele from each parent (1)

Question 7

Describe the causes of variation in a population. (2)

Answer 7

• genetic variation (1)

- environmental variation (1)

Question 8

Explain how a gene mutation can produce a different protein. (2)

Answer 8

A change in base that causes a change in amino acid. (1)

Question 9

Name the base pairs in DNA. (1)

Answer 9

Thymine with Adenine (A with T)

Cytosine with Guanine (C with G) (1)

Question 10

Name the bonds joining two strands of a DNA molecule together. (1)

Answer 10

Weak hydrogen bonds. (1)