Evolution within Populations

Question 1

Hardy Weinberg Principle

Answer 1

The principle predicts that the proportion of dominant and recessive alleles of any gene in a population remains the same from one generation to next provided five conditions: No mutations, population is isolated, no natural selection (alleles are equally likely to be passed on), large population, mating is random

Question 2

all the different alleles of all the genes of all the individuals in a population at any one time

Answer 2

Gene Pool

Question 3

Allele frequency

Answer 3

the number of times an allele occurs within the gene pool in a population, relative to all others at same locus

Question 4

Distinct forms with no intermediate types.

Answer 4

Discontinuous variation

Question 5

No distinct categories – likely to obtain a bell-shaped curve known as a normal distribution curve.

Answer 5

Continuous variation

Question 6

Natural selection

Answer 6

Darwin’s theory to explain the mechanism of evolution. The process by which organisms better adapted to their environment survive and reproduce and pass on their advantageous alleles to the their offspring, whilst those less well adapted fail to do so.

Question 7

Directional selection

Answer 7

Favours one extreme of the range of characteristics and the other extreme is selected against – shift in population curve

Question 8

Favours the mean of the distribution because the extremes are at a selective disadvantage – frequency of mean phenotype increases

Answer 8

Stabilising selection

Question 9

Disruptive selection

Answer 9

Favours both extremes of a distribution, selection occurs against the mean – results in bimodal distribution.

Question 10

Causes random changes in allele frequencies in a population due solely to chance factors.

Answer 10

Genetic Drift

Question 11

Severe reduction in population size

Answer 11

Genetic bottleneck

Question 12

Isolation of a small group of individuals by migration or a physical barrier.

Answer 12

Founder effect

Question 13

Speciation

Answer 13

Evolution of new species from existing ones. Process by which reproductive isolation occurs between two populations so that they evolve along their own separate paths into 2 separate species with different allele frequencies.

Question 14

Species

Answer 14

A group of organisms that have a common ancestry and so share the same genes and are capable of breeding together to produce fertile offspring - are reproductively separated from other species.

Question 15

occurs when populations occupy different environments – they are geographically separated.

Answer 15

Allopatric speciation

Question 16

occurs when populations are reproductively isolated within the same environment.

Answer 16

Sympatric speciation

Question 17

reproductive success

Answer 17

advantages of advantageous allele

Question 18

Gene pool

Answer 18

All the alleles of all the genes within a population at one time