Chapter 11

Question 1

What is a mutation?

Answer 1

a change in the nucleotide sequence of DNA

Question 2

What is base deletion?

Answer 2

• nucleotide lost from DNA base sequence

- leads to codons not being read properly

Question 3

What is a base substitution?

Answer 3

where one nucleotide base is changed for another

Question 4

What is a mutagenic agent and what are some examples?

Answer 4

• something that increases the frequency of mutations above the rate of naturally occurring mutations
• radiation, some chemicals, etc

Question 5

What is non-disjunction?

Answer 5

chromosomes don’t pull apart properly during meiosis

too many/few chromosomes

Question 6

What is the process of meiosis?

Answer 6

23 homologous pairs
MEIOSIS 1
- pairs replicate sister chromatids (X)
- crossing over 
- pairs split halving chromosome number (23 chromatids) (independent segregation)
MEIOSIS 2
-sister chromatids separate (independent segregation)
- haploid cells produced

Question 7

What are 2 ways in which variation occurs during meiosis?

Answer 7

CROSSING OVER:
2 chromosomes twist and swap genetic material
INDEPENDENT SEGREGATION OF CHROMOSOMES
chomosomes line up randomly and random combination when pulled apart

Question 8

What is genetic diversity?

Answer 8

number of different alleles in a population

Question 9

What is natural selection?

Answer 9

when an organism adapts over time to become better suited to its environment

Question 10

What is stabilising selection?

Answer 10

• selection that trends towards the average
• alleles towards middle range likely to survive
• occurs when environment is stable

Question 11

What is directional selection?

Answer 11

• natural selection that favours an extreme
• alleles to one side of mean likely to survive
• response to environmental change