Definitions

Question 1

Genotype

Answer 1

The genetic composition of an organism

Question 2

Geographical Isolation

Answer 2

When a physical barrier prevents two populations from breeding with one another

Question 3

Speciation

Answer 3

The evolution of new species from existing species

Question 4

Directional Selection

Answer 4

Selection that favours individuals at one extreme

Question 5

Stabilising Selection

Answer 5

Selection that favours average individuals

Question 6

Allelic Frequency

Answer 6

The number of times the allele occurs within a gene pool

Question 7

Gene Pool

Answer 7

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

Question 8

Multiple Alleles

Answer 8

More than 2 possible alleles for a particular gene

Question 9

Co-dominance

Answer 9

Both alleles are equally dominant and are both expressed in a phenotype

Question 10

Phenotype

Answer 10

The characteristics of an organism (often visible), resulting from its genotype and the environment

Question 11

Sex Linkage

Answer 11

Any gene that is carried on the X or Y chromosome

Question 12

Homozygous

Answer 12

When the alleles are the same for a particular gene

Question 13

Heterozygous

Answer 13

When the alleles are different for a particular gene

Question 14

Recessive

Answer 14

An allele that is only expressed in the phenotype when there is another identical allele

Question 15

Dominant

Answer 15

An allele that is always expressed in the phenotype

Question 16

Homologous Chromosomes

Answer 16

A pair of chromosomes that have the same gene loci and determine the same features

Question 17

Allele

Answer 17

One form of a gene

Question 18

Gene

Answer 18

A length of DNA that codes for a polypeptide

Question 19

Community

Answer 19

The organisms of all species that live in the same area

Question 20

Ecosystem

Answer 20

Self-contained unit made up of the biotic and abiotic factors in an area

Question 21

population

Answer 21

A group of individuals of the same species in a habitat

Question 22

Habitat

Answer 22

The place where an organism normally lives

Question 23

niche

Answer 23

All the conditions and resources required for an organism to survive and reproduce (its ‘role’)

Question 24

microhabitat

Answer 24

a smaller unit with its own climate

Question 25

Abundance

Answer 25

count number individuals
of a species
in a given space