Key Words

Question 0

Allele

Answer 0

Alternative form of a gene

Question 1

Mutation

Answer 1

Any change to the quantity or structure of an organism’s DNA

Question 2

Phenotypes

Answer 2

The visible characteristics of an organism, resulting from its alleles

Question 3

Phenotypic variation

Answer 3

The total variation in the characteristics of an organism, usually resulting from its genotype and the effects of its environment

Question 4

Population

Answer 4

All the freely interbreeding individuals of the same species occupying the same place at the same time

Question 5

Allele frequency

Answer 5

The number of times an allele occurs within the gene pool

Question 6

Parasites

Answer 6

An organism that lives on or in another organism that may cause harm

Question 7

Genetic factors

Answer 7

Presence of certain alleles

Question 8

Environmental factors:

Answer 8

Food availability/availability of mates

Question 9

Selective advantage

Answer 9

A variation that gives an organism an advantage over another, so it is more likely to survive and reproduce

Question 10

Intraspecific competition

Answer 10

Competition between organisms of the same species

Question 11

Natural selection

Answer 11

The process by which the best adapted organisms in a population survive, reproduce and pass on their alleles to their offspring

Question 12

Selection pressure

Answer 12

The environmental force altering the frequency of alleles in a population

Question 13

Speciation

Answer 13

The process by which new species develop

Question 14

Reproductive isolation

Answer 14

When groups within the population become isolated from another and cannot interbreed

Question 15

Gene pool

Answer 15

All the genetic information present within a population at a given time

Question 16

Allopatric speciation

Answer 16

Occurs when populations are prevented from interbreeding because they become geographically isolated

Question 17

Sympatric speciation

Answer 17

Occurs when populations living together are prevented from interbreeding, e.g. Reproductively isolated, but remain in the same place

Question 18

Prezygotic mechanisms

Answer 18

Reproductive isolating mechanism that takes place before fertilisation

Question 19

Post zygotic mechanisms

Answer 19

Reproductive isolating mechanism that takes place after fertilisation

Question 20

Geographical variation

Answer 20

Populations are isolated by physical barriers, e.g. Oceans

Question 21

Ecological variation

Answer 21

Populations inhabit different habitats within the same area and so individuals rarely meet

Question 22

Temporal variation

Answer 22

The breeding season of each population do not coincide and so they do not interbreed

Question 23

Behavioural variation

Answer 23

Changes in courtship, call, actions of particular mate prevents interbreeding

Question 24

Mechanical variation

Answer 24

Anatomical differences may prevent mating occurring

Question 25

Gametic variation

Answer 25

Gametes may be prevented from meeting due to genetic or biochemical incompatibility

Question 26

Hybrid sterility

Answer 26

Hybrids formed from a fusion of gametes from different species are often sterile because they cannot produce gametes

Question 27

Hybrid inviability

Answer 27

Despite fertilisation taking place, further development does not occur or fatal abnormalities arise in early growth - don’t reach maturity: no breeding

Question 28

Hybrid breakdown

Answer 28

The first generation of hybrids if fertile but the second generation fails to develop or, if it does, it is sterile