patterns of inheritance

Question 1

genetic makeup of an organism

Answer 1

genotype

Question 2

visible characteristic of an organism

Answer 2

phenotype

Question 3

a version of a gene

Answer 3

allele

Question 4

not true-breeding; having different alleles at a particular gene locus on a pair of homologous chromosomes

Answer 4

heterozygous

Question 5

true-breeding; having identical alleles at a particular gene locus on a pair of homologous chromosomes

Answer 5

homozygous

Question 6

determined by a single gene

Answer 6

monogenic

Question 7

involving two gene loci

Answer 7

dihybrid

Question 8

where both alleles present in the genotype of a heterozygous individual contribute to the individual’s phenotype

Answer 8

codominance/ codominant

Question 9

characteristic for which there are three or more alleles in the population’s gene pool

Answer 9

multiple alleles

Question 10

gene present on (one of) the sex chromosome

Answer 10

sex-linked

Question 11

gene loci present on the same autosome (non-sex chromosome) that are often inherited together

Answer 11

autosomal linkage

Question 12

interaction of non-linked gene loci where one masks the expression of the other; from the greek, ephistanai, meaning ‘stoppage’

Answer 12

epistasis

Question 13

statistical test designed to find out if the difference between observed and expected data is significant or due to chance

Answer 13

chi-squared test

Question 14

variation that produces phenotypic variations where the quantitative traits vary by very small amounts between one group and the next

Answer 14

continuous variation

Question 15

genetic variation producing discrete phenotypes- two or more non-overlapping categories

Answer 15

discontinuous variation

Question 16

a type of natural selection that occurs when an environmental change favours a new phenotype and so results in a change in the population mean

Answer 16

directional selection

Question 17

when a small sample of an original population establishes in a new area; its gene pool is not as diverse as that of the parent population

Answer 17

founder effect

Question 18

a sharp reduction in size of a population due to environmental catastrophes such as earthquakes, floods, disease or human activities such as habitat destruction, overhunting or genocide, which reduces genetic diversity; as the population expands it is less genetically diverse than before

Answer 18

genetic bottleneck

Question 19

natural selection leading to constancy within a population; intermediate phenotypes are favoured and extreme phenotypes selected against; alleles for extreme phenotypes may be removed from the population; stabilising selection reduces genetic variation within the population

Answer 19

stabilising selection

Question 20

members of a species living in the same place at the same time that can interbreed

Answer 20

population

Question 21

formation of two different species from one original species, due to geographical isolation

Answer 21

allopatric speciation

Question 22

the splitting of a genetically similar population into two or more populations that undergo genetic differentiation and eventually reproductive isolation, leading to the evolution of two or more new species

Answer 22

speciation

Question 23

formation of two different species from one original species due to reproductive isolation while the populations inhabit the same geographical location

Answer 23

sympatric speciation

Question 24

selective breeding of organisms; involves humans choosing the desired phenotypes and interbreeding those phenotypes individually; therefore selecting the phenotypes that contribute to the gene pool of the next generation of these organisms

Answer 24

artificial selection