Key Area 6: Evolution of Species

Question 1

Mutation

Answer 1

is a random, spontaneous change in the structure of a gene , chromosome or number of chromosomes: only source of new alleles

Question 2

What Mutations are there?

Answer 2

They may be neutral, confer an advantage or a disadvantage to survival.

Question 3

Rate of mutation

Answer 3

Environmental factors such as radiation and some chemicals can increase the rate of mutation

Question 4

Adaption

Answer 4

feature of an organism that helps it to survive

Question 5

Variation

Answer 5

within a population makes it possible for a population to evolve over time in response to changing environmental conditions

Question 6

NATURAL SELECTION

Answer 6

Species produce more offspring than the environment can sustain

Natural selection or survival of the fittest occurs when there are selection pressures eg. competition or predation

The best adapted individuals survive to reproduce passing on favourable alleles (forms of a gene) that confer the selective advantage

These alleles increase the frequency within the population

Question 7

Isolation barrier

Answer 7

Barrier that prevents interbreeding and gene exchange between sub-populations of a species

Question 8

Speciation

Answer 8

Formation of two or more species from an original ancestral place

Question 9

Selection pressure

Answer 9

Factor such as predation or disease that affects a population, resulting in the death of some individuals and the survival of others

Question 10

Selective advantage

Answer 10

An increased chance of survival for an organism because of possession of favourable characteristics

Question 11

Name the molecule within a cell in which mutations would occur?

Answer 11

DNA