Genetic diversity and adaptations

Question 1

Substitution

Answer 1

When a base in a sequence of amino acid is changed.

Question 2

Deletion

Answer 2

When a base is removed from a sequence of amino acids this changes the sequence and results in the sequence being read differently.

Question 3

What happens during Meiosis

Answer 3

DNA replication - chromosomes and chromatids
Homologous chromosomes line up in pairs randomly (independent segregation)
Division 1- homologous pairs separate
Division 2- chromosomes and copies split
Gametes formed (haploid)

Question 4

Gene mutation

Answer 4

Any change to one or more nucleotide bases, or a change in the sequence of the bases in DNA

Question 5

What are the consequences of substitution

Answer 5

This can result in different amino acids however doesn’t often lead to a mutation as multiple codons code for the same amino acid and might occur in an intron which is non-coding and will be removed during splicing.

Question 6

What are the consequences of deletion

Answer 6

This will lead to a mutation as the exons will be changed as well as the introns changing the structure of the protein.
- polypeptide will be entirely different and might not function correctly

Question 7

What are the two types of chromosomal mutation

Answer 7

-changes in whole sets of chromosomes
-changes in the number of individual chromosomes

Question 8

changes in the number of individual chromosomes

Answer 8

sometimes individual homologous pairs of chromosomes fail to separate during meiosis, this is known as non-disjunction.

Question 9

non-disjunction

Answer 9

results in gametes having either one more or one fewer chromosomes

Question 10

How does meiosis produce genetic variation

Answer 10

-independent segregation
-crossing over

Question 11

Independent segregation

Answer 11

homologous pairs line up randomly

Question 12

Crossing over

Answer 12

-Chromatids of each pair become twisted around each other
-chromatids break off due to tension
-might re-join with the chromatid of its homologous pair

Question 13

genetic diversity

Answer 13

The number of different alleles of genes in a population

Question 14

Natural selection

Answer 14

The process that leads to evolution in population

Question 15

Describe the process of natural selection

Answer 15

1. New alleles for a gene are created by random mutations
2. If the new alleles increases the chances of survival in that environment then they are more likely to survive and reproduce
   3.This reproduction passes on the advantageous allele to the next generation.
3. As a result over many generations the new allele increases in frequency in the population

Question 16

Population

Answer 16

A group of individuals of the same species that live in the same place and can interbreed

Question 17

Gene pool

Answer 17

The total number of alleles in a particular population at a specific time

Question 18

Selection

Answer 18

The process in which organisms that are better adapted to their environment tend to survive and breed

Question 19

Directional selection

Answer 19

Occurs when the environmental conditions change and the phenotypes best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring.

Question 20

What is an example of directional selection

Answer 20

Bacteria being resistant to antibiotics.
-single bacteria has a mutation meaning it is not killed as it produces the enzyme penicillinase .
-As a result it can grow and populate and the frequency of alleles that enabled penicillinase production increased in population
-Therefore the population moved to have greater penicillin resistance

Question 21

Stabilising selection

Answer 21

The phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection doesn’t occur due to changes in the environment. If the environment stays the same then the individuals closest to the mean are favoured

Question 22

What is an example if stabilising selection

Answer 22

New born babies weights. Those that have birth weights of around 3kg are more likely to survive than those at the extremes