Genetic Diversity arises from result of mutation or during meiosis

Question 1

What is a substitution mutation?

Answer 1

When a nucleotide in DNA sequence is replaced by another. More likely to be quiet mutation, meaning no change occurs in amino acid sequence

Question 2

What is a deletion mutation?

Answer 2

When nucleotide in DNA sequence is lost. More likely to be harmful & significant, as it leads to frame shift which means entire amino acid sequence will be different

Question 3

What is a Mutagenic agent?

Answer 3

Factors that increase rate of gene mutation. X-rays, UV light, gamma rays, certain chemicals (e.g. in alcohol & tobacco)

Question 4

What is polyploidy chromosome mutation?

Answer 4

Where an individual has three or more sets of chromosomes instead of two

Question 5

What is chromosome non-disjunction?

Answer 5

When chromosomes fail to separate correctly in meiosis, resulting in gametes with one more or less chromosome than normal

Question 6

What is meiosis

Answer 6

Form of cell division that produces four genetically different haploid cells (cells with half no. of chromosomes found in parent cell) known as gametes

Question 7

How does meiosis differ from mitosis?

Answer 7

• Meiosis produces four genetically different cells with half no. of chromosomes as parent cells
• Mitosis produces two genetically identical cells with same no. of chromosomes as parent cells

Question 8

What happens during meiosis I?

Answer 8

1. Homologous chromosomes pair to form bivalents
2. Crossing over (exchange of sections of genetic material) occurs at chiasmata
3. Cell division into 2. Homologous chromosomes separate randomly. Each cell contains either maternal or paternal copy

Question 9

What happens during meiosis II?

Answer 9

1. Independent segregation of sister chromatids
2. Each cell divides again, producing 4 haploid cells

Question 10

Give 2 ways meiosis produces genetic variation

Answer 10

1. Crossing over during meiosis I
2. Independent assortment (random segregation) of homologous chromosomes & sister chromatids

Result in new combinations of alleles