Topic 9 - Genetic Diversity and Adaptation

Question 1

What can cause genetic diversity?

Answer 1

• Change in quantity or structure of the DNA (mutation).
• Recombining DNA of 2 individuals after meiosis / binary fission.

Question 2

What are the different forms of gene mutations?

Answer 2

• Substitution (swap 1 nucleotide, might not have an effect).
• Addition.
• Deletion.

A and D cause a frame shift.

Question 3

What’s the consequence of a mutation on a protein?

Answer 3

Change sequence of amino acids in primary structure which affects 3D shape in tertiary structure. Breaks hydrogen bonds, protein will be non-functioning as no enzyme-substrate complexes can be formed.

Question 4

What’s a degenerate code?

Answer 4

Will code for same amino acid in an intron (non-coding DNA).

Question 5

What’s a chromosome mutation?

Answer 5

Changes in the structure or number of whole chromosomes.

Question 6

How does crossing over during prophase 1 lead to genetic variation?

Answer 6

Homologous chromosomes pair up along equator (random).
Maternal and paternal chromosomes are reshuffled before being separated, one chromosome of each homologous pair goes to each daughter cell.
During second meiotic division, each sister chromatid separated randomly, combination going into each daughter cell also random.

These increase genetic variation.

Question 7

What is independent segregation?

Answer 7

When chromosomes line up, it is completely random. Completely independent.

Question 8

How does reproductive success affect allele frequency?

Answer 8

1) Organisms produce more offspring than can be supported.
2) Most populations remain relative constant in size.
3) Due to Intraspecific competition.
4) Random mutation of alleles within gene pool mean some will have combinations of alleles that make them more likely to survive.
5) These will have a better chance at breeding and passing on these alleles.
6) New offspring also have these advantageous alleles, pass them on by breeding.
7) Disadvantageous alleles decrease overtime.

Question 9

What is directional selection?

Answer 9

Change in a population from one phenotype to another (will increase an allele).

Question 10

What is stabilising selection?

Answer 10

A reduction of variation about an optimal modal value.

Question 11

Why are antibiotics ineffective against viruses?

Answer 11

Viruses don’t have cell walls.
Viruses don’t have own metabolic processes.