[3.4.4] Genetic diversity and adaptation (+RP 6)

Question 1

Define Genetic Diversity

Answer 1

The number of different alleles of genes in a population

→alleles = variations of a gene

Question 2

Define Natural Selection

Answer 2

1. Random mutation can result in new alleles of a gene.
2. In certain environments, the new allele is advantageous and increases the probability of survival and reproduction
3. Advantageous allele is inherited by offspring
4. Over many generations, the new allele increases in frequency in the population

(e.g giraffes: short necks → long necks)

Question 3

Types of adaptations

Answer 3

• anatomical
• physiological
• behavioural

Question 4

Types of natural selection

Answer 4

• directional
• stabilising
• disruptive

Question 5

Define directional selection

Answer 5

when selection favours one extreme phenotype

this shifts the normal distribution curve towards the favoured phenotype as it appears more often in the population

Question 6

[Potential Exam Q.] Explain, by using natural selection, how bacteria might develop antibiotic resistance

Answer 6

1. Random mutation creates a resistance allele in the bacterial population.
2. When exposed to the antibiotic, only those with the resistance allele will survive and reproduce
3. resistance allele frequency increases over generations

Question 7

Define stabilising selection

Answer 7

when the “average phenotype” has the selective advantage

variation of traits decrease over generations

Question 8

Define Disruptive Selection

Answer 8

when the extreme phenotype have the selective advantage over the “average phenotype”

(results in more variance as the population becomes more diverse)

Question 9

Define a “Single Gene Trait” and a “Polygenetic Trait”

Answer 9

Single Gene Trait = a trait that is controlled by only one gene
Polygenetic Trait = traits controlled by more than one gene (range of phenotypes)