Vocab

Question 1

Allele

Answer 1

An alternative form of a gene

Question 2

Centromere

Answer 2

The point where the 2 chromatids are joined together

Question 3

Chiasma

Answer 3

The point at which chromatids break and re-join in crossing over

Question 4

Chromosome

Answer 4

A structure in the nucleus made up of DNA which holds the genetic information of an organism

Question 5

Diploid

Answer 5

Full or complete number of chromosomes 2n/2 sets = 46 in humans

Question 6

Homologous pair

Answer 6

A pair of chromosomes with the same genes but may have different alleles

Question 7

Dominant

Answer 7

An allele that is always expressed if present - only one copy needed

Question 8

Gamete

Answer 8

Sex cell. Egg or sperm in humans

Question 9

Gene

Answer 9

A section of a DNA molecule that codes for a protein/characteristic

Question 10

Gene Pool

Answer 10

The total variety of genes and alleles present in a sexually reproducing population available to be passed on to the next generation

Question 11

Genome

Answer 11

All of an organism’s genes

Question 12

Haploid

Answer 12

Half the normal number of chromosomes n/1 set = 23 in eggs or sperm

Question 13

Heterozygous

Answer 13

Alleles are different eg. Tt

Question 14

Homozygous

Answer 14

Both alleles are the same eg TT, tt

Question 15

Linked

Answer 15

Genes that are located on the same chromosome

Question 16

Locus

Answer 16

Position of a gene on a chromosome

Question 17

Meiosis

Answer 17

Type of cell division producing four daughter cells each genetically different, with half the number of chromosomes of the parent cell = produces gametes

Question 18

Crossing over

Answer 18

Exchange of genetic material between homologous chromosomes aka the inner chromatids during meiosis

Question 19

Independent assortment

Answer 19

Each homologous pair of chromosomes are lined up randomly and are sorted independently of the other pairs during meiosis putting chromosomes/alleles into new combinations increasing genetic variation

Question 20

Segregation

Answer 20

In meiosis the 2 members of the pair of alleles of a gene becomes separated into different gametes so the allele can join with a different allele of that gene at fertilisation

Question 21

Mutation

Answer 21

A sudden change in the genetic base sequence of DNA in an organism

Question 22

Phenotype

Answer 22

How the gene is expressed/what the organism looks like

Question 23

Recessive

Answer 23

An allele that is only expressed when it is present in two copies - the dominant allele must be absent

Question 24

Somatic cells

Answer 24

Body cells other than sex cells

Question 25

Species

Answer 25

A group of organisms which can interbreed sexually and produce fertile offspring

Question 26

Testcross

Answer 26

Finding the genotype of an individual showing dominant phenotypes by crossing them with a homozygous recessive individual and looking at the phenotypes of the offspring

Question 27

Adaptation

Answer 27

A feature an organism has which helps it survive in its environment. It can be structural, behavioral or physiological

Question 28

Allele frequency

Answer 28

The proportion of a particular allele in a gene pool, relative to the other alleles of the same gene

Question 29

Evolution

Answer 29

Changes in the frequencies of alleles in a population over time

Question 30

Natural selection

Answer 30

The process where individuals with favorable combinations of alleles are more likely to reproduce successfully and pass on these traits

Question 31

Gene flow

Answer 31

The introduction of genes/alleles from one population to the gene pool of another - migration

Question 32

Genetic variation

Answer 32

All the genes, alleles, and their combinations present in a population

Question 33

Genetic drift

Answer 33

Random changes in allele frequencies in a population due to chance

Question 34

Inbreeding

Answer 34

Mating of closely related individuals of the same species

Question 35

Population

Answer 35

Members of the same species living in the same area at the same time

Question 36

Environmental factors

Answer 36

Factors which select for or against particular phenotypes in the process of natural selection

Question 37

Founders effect

Answer 37

Change in allele frequencies when a new population arises from only a few colonizing individuals. The new population will have reduced genetic diversity/smaller gene pool

Question 38

Bottleneck effect

Answer 38

Recovery of a population after a catastrophic event, the range of alleles will decrease and the frequencies of alleles will change. The recovered population will have reduced genetic diversity

Question 39

Sexual selection

Answer 39

Selection based on the choice of mating partners, usually female. This leads to evolutionary change if choices are based on differences in inherited characteristics e.g tail length in peacocks