3.4.4 Genetic diversity and adaptation ( 3.4 Genetic information , variation and relatoonships between organisms)

Question 1

what is genetic diversity

Answer 1

number of different alleles of genes in a population

Question 2

what are alleles and how do they arise

Answer 2

• variations of a particular gene ( same locus ) - different DNA base sequence
• arise by mutation

Question 3

what is a population

Answer 3

• a group of organisms of the same species in a particular space at a particular time
• That can interbreed to produce fertile offspring

Question 4

Explain the importance of genetic diversity

Answer 4

• enables natural selection to occur
• As in certain environments, a new allele of a gene might benefit its possessor
• By resulting in a change in the polypeptide chain coded for that positively changes its properties
• Giving selective advantage

Question 5

What is evolution

Answer 5

• change in allele frequency over many generations in a population
• occurring through the process of natural selection

Question 6

Explain the principles of natural selection in the evolution of populations

Answer 6

1) mutations = random gene mutations can result in new alleles of a gene
2) advantage = in certain environments , the new allele might benefit its possessor , has selective advantage
3) reproduction = possessors are more likely to to survive and have increased reproductive success
4) inheritance = advantageous allele is inherited by members of the next generation of offspring
5) allele frequency = over many generations , allele increases in frequency in the population

Question 7

describe 3 types of adaptations

Answer 7

natural selection results in species that are better adapted to their environment :
• anatomical - physical features that increases chance of survival
• physiological- processes / chemical reactions that increase chance of survival
• behavioural - ways in which an organism acts that increases their chance of survival

Question 8

explain two types of selection with examples

Answer 8

Directional selection :
- antibiotic resistance in bacteria
- organisms with an extreme variation of a trait
- often a change
- increased frequency of organisms with allele for extreme trait
- normal distribution curve shifts towards extreme trait
Stabilising selection :
- human birth weight
- organisms with an average variation of a trait
- usually stable
- increased frequency of an organism with / alleles for an average trait
- normal distribution curve similar , less variation around the mean