D4 Continuity and Change : Ecosystems

Question 1

gene pool

Answer 1

The combination of all the genes that are present in a reproducing population.

Question 2

allele frequency

Answer 2

The incidence of an allele relative to other alleles of the same gene in a population.

Question 3

bottleneck effect

Answer 3

The dramatic reduction in the population size due to natural disasters such as famines, hurricanes or floods resulting in loss of genetic variation.

Question 4

genetic drift

Answer 4

Change in frequency of an existing gene variant in the population due to random chance events.

Question 5

founder effect

Answer 5

The resultant loss in genetic variation when a few members of the original population establish a new population.

Question 6

gene flow

Answer 6

The transfer of genetic material from one population to another.

Question 7

stabilising selection

Answer 7

Selection that favours individuals with average or median traits.

Question 8

directional selection

Answer 8

Selection that favours individuals with one extreme form of the trait over all the other forms of the trait.

Question 9

disruptive selection

Answer 9

Selection that favours individuals with both the extreme forms of the trait over the intermediate forms of the trait.

Question 10

hardy Weinberg equation

Answer 10

p2 + 2pq + q2 = 1

Question 11

bioaccumulation

Answer 11

The process by which certain substances, such as toxins or pollutants, accumulate and increase in concentration within the tissues of organisms over time.

Question 12

biomagnification

Answer 12

The increase in the concentration of certain substances, such as toxins or pollutants, at higher levels of the food chain. As organisms consume other organisms, the accumulated substances become more concentrated in the tissues of higher-level predators.

Question 13

primary succession

Answer 13

The process of ecological succession that occurs in a newly formed or exposed area with no pre-existing soil.

Question 14

climax community

Answer 14

The final stage of ecological succession in which a stable and self-perpetuating community of plants and animals is established.

Question 15

phenology

Answer 15

Phenology is a scientific field that investigates the timing of biological events and their relationship with seasonal and environmental factors. These events include flowering, budburst, bird migration and nesting.