Genetic Variation

Question 1

Heredity

Answer 1

Passing on characteristics from one organism to another

Question 2

Gene

Answer 2

Section on a chromosome that codes for a particular protein controlling a particular characteristic

Question 3

Allele

Answer 3

Variety of a gene

Question 4

Genotype

Answer 4

The alleles an individual has for a particular gene

Question 5

Phenotype

Answer 5

The expression of the genotype and how it is affected by the environment

Question 6

Genetic(bio)diversity

Answer 6

Variations in genotypes within a gene pool

Question 7

Allele frequency

Answer 7

The number of times an allele occurs in a gene pool compared to all other alleles

Question 8

Natural selection

Answer 8

Individuals with helpful alleles have a survival and reproductive advantage and therefore their alleles get passed on in a gene pool

Question 9

Adaptations

Answer 9

Features controlled by alleles that individuals have that enable survival

Question 10

Mutation

Answer 10

A random and permanent change in the base sequence of a gene giving rise to new alleles

Question 11

Gametic mutation

Answer 11

Mutation occurring on a sex cell that can be inherited and can enter a gene pool if it is fertilised

Question 12

Somatic mutation

Answer 12

Mutation occurring in a body cell which cannot be inherited or enter a gene pool

Question 13

Meiosis

Answer 13

Cell division occurring in sex organs producing sex cells by halving chromosome number

Question 14

Homologous chromosomes

Answer 14

Chromosomes in a pair that have the same gene at the same locus

Question 15

Independent assortment

Answer 15

Process in meiosis That creates variation by homologous chromosomes lining up in pairs At random on the spindle, which creates new combinations of maternal and paternal chromosomes in the gametes in the final stages of meiosis

Question 16

Crossing over

Answer 16

Process that occurs after assortment in which homologous chromatids swap sections of DNA, thereby creating recombinant chromatids with new combinations of alleles, not seen in the parents

Question 17

Independent segregation

Answer 17

Process That occurs after crossing over where chromosomes separate independently from each other and as such So do their alleles Which creates new combinations of alleles and gametes, not seen in parent cells 

Question 18

Genetic drift

Answer 18

Random changes in allele frequency of a population

Question 19

Fertilisation

Answer 19

Process whereby a sperm fertilises an egg to form a zygote with a full set of chromosomes

Question 20

Gene pool

Answer 20

All the alleles in a population

Question 21

Complete dominance

Answer 21

One allele is completely expressed over a recessive if it is present in the genotype

Question 22

Incomplete dominance

Answer 22

Both alleles are equally dominant and as such they are both expressed to form an intermediate phenotype

Question 23

Codominance

Answer 23

Both alleles are independently and equally expressed and as such 2 phenotypes are produced

Question 24

Lethal allele

Answer 24

And allele that causes death of an individual if it is present in the genotype

Question 25

Multiple allele

Answer 25

One gene has more than 2 alleles controlling one phenotype

Question 26

Test cross

Answer 26

cross with a homozygous recessive which is performed to find out an unknown individual is homozygous dominant or heterozygous

Question 27

Homozygous

Answer 27

2 of the same alleles in a genotype

Question 28

Heterozygous

Answer 28

2 different alleles in a genotype

Question 29

Pure breeding

Answer 29

Homozygous individuals that can only produce one type of gamete

Question 30

Linked genes

Answer 30

Genes that are found in the same chromosome and as such do not segregate independently of each other in meiosis

Question 31

Genetic change

Answer 31

Change in allele frequencies of a gene pool overtime

Question 32

Bottleneck effect

Answer 32

A catastrophic event that reduces the gene pool of a population to a few surviving individuals

Question 33

Fitness

Answer 33

Individuals who have advantageous alleles have an increased survival and reproductive chance are said to be ‘fitter’

Question 34

Selection pressure

Answer 34

A factor in the environment that can cause differential survival of individuals in a population

Question 35

Migration (gene flow)

Answer 35

Individuals leaving or entering a population and contributing their alleles to the gene pool if they successfully breed in the new population

Question 36

Founder effect

Answer 36

Event whereby a small group of individuals from a large population colonise a new habitat