Variation and Natural Selection

Question 1

Genetic diversity

Answer 1

The variety of alleles in a population resulting in a variety of phenotypes. Important to help the survival of species in a changing environment.

Question 2

Genetic drift

Answer 2

A change in allele frequency due to random/ chance such as fire, earthquakes, migrations.

Question 3

Founder effect

Answer 3

when a small number of pioneers begin a new population, which is likely to have allele frequencies unrepresentative of the original population

Question 4

Natural selection

Answer 4

When there is inherited variation in a population, some variants are more favourable than others

Question 5

Population bottleneck

Answer 5

occurs when there is a severe reduction in the size of the population due to a catastrophe therefore very little genetic diversity .

Question 6

Gene flow

Answer 6

interbreeding between 2 different populations, resulting in the posibility of introducing different alleles into the existing population

Question 7

Allopatric speciation

Answer 7

Formation of a new species due to geographical isolation preventing gene flow, followed by exposure to different environmental pressures and/or genetic drift.

Question 8

Fossil

Answer 8

are evidence of past ‘lifeforms’ usually preserved in sedimentary rock.

Question 9

Homologous structures

Answer 9

Structures are similar in anatomy but different in function due to different selection pressures.
DIVERGENT

Question 10

Analogous structures

Answer 10

structures are different in anatomy, but similar in function due to similar selection pressures
CONVERGENT

Question 11

relative age

Answer 11

based on stratigraphy (layers of rock)

Question 12

Approximate age

Answer 12

index fossils (past life forms)

Question 13

Absolute age

Answer 13

a) radiometric methods

b) non-isotopic methods