changes in the genetic makeup of a population

Question 1

define gene

Answer 1

a segment of DNA coding for a particular characteristic or trait

Question 2

define allele

Answer 2

alternative form of a gene

Question 3

genotype

Answer 3

the alleles possessed by an organism

Question 4

phenotype

Answer 4

the observable characteristics of an organism as a result of the interaction of its genotype with its environment

Question 5

monogenic trait

Answer 5

a trait controlled by one gene

Question 6

discontinuous variation

Answer 6

when there is a limited number of variations determined by a gene

Question 7

locus

Answer 7

a specific position on a chromosome where a particular gene is located

Question 8

polygenic trait

Answer 8

a trait controlled by multiple interacting genes

Question 9

continuous variation

Answer 9

when a gene/s codes for a range of non-distinct variations

Question 10

gene pool

Answer 10

the total sum of alleles found in a population

Question 11

aneuploidy

Answer 11

the presence of an abnormal number of a particular chromosome, either trisomy or monosomy

Question 12

polyploidy

Answer 12

a condition where an organisms has more than 2 complete sets of chromosomes

Question 13

polymorphism

Answer 13

the presence of variations of a gene

Question 14

define natural selection

Answer 14

the influence of environmental pressures on particular phenotypes, impacting allele frequencies within a population

Question 15

define selection pressures

Answer 15

conditions that give organisms with certain traits a reproductive advantage over those with different traits, influencing allele frequency in a population as a result.

Question 16

genetic drift

Answer 16

describes changes in allele frequencies in a populations as a result of random, unselective events - decreases genetic variation

Question 17

what is the bottleneck effect

Answer 17

when a random event, such as a natural disaster, acts on a population, reducing population size and genetic variation. Offspring of surviving individuals can only inherit the remaining alleles, resulting in reduced variation .

Question 18

are larger or smaller populations more effected by genetic drift

Answer 18

smaller

Question 19

what is founder effect

Answer 19

the loss of genetic variation that occurs when a new population is established by a small ‘founder’ group from a larger one.

Question 20

gene flow

Answer 20

is the movement of alleles between populations as a result of migration and interbreeding

Question 21

what genetic isolation results in allopatric speciation

Answer 21

geographical isolation

Question 22

steps in allopatric speciation

Answer 22

1. geographical isolation, preventing gene flow between the populations
2. differing selection pressures act on the populations, resulting in differing allele frequencies within the populations
3. when the populations are brought back together they will be unable to produce viable offspring.

Question 23

alelle frequency

Answer 23

the proportion of a particular allele within a population

Question 24

equation for allele frequency

Answer 24

2(number of homozygotes) + (number of heterozygotes)
_____________________________________________
2 (total number of individuals)

Question 25

what defines different species

Answer 25

when they are unable to produce viable and fertile offspring

Question 26

what is a mutation

Answer 26

a change DNA that can affect a single gene, multiple genes, or entire chromosomes

Question 27

what type of mutation can be passed on

Answer 27

a germ-line mutation

Question 28

name of a factor that induces mutation

Answer 28

a mutagen

Question 29

2 types of point mutation

Answer 29

substitution and frameshift

Question 30

types of substitution mutations

Answer 30

silent, missense (when substitution results in an amino acid replacement) and nonsense (when substitution results in a stop codon)

Question 31

which has more of an effect, substitution or frameshift

Answer 31

frameshift as it alters every following codon.

Question 32

types of block mutations

Answer 32

duplications (part of a chromosome is replicated), deletion mutation (part of a chromosome is removed), inversion mutations (section of DNA breaks off, rotates 180 degrees and reattaches), insertion mutations (when a section of one chromosome breaks off and reattaches to another), translocations (when segments of chromosomes are exchanged with each other)

Question 33

define evolution

Answer 33

the change in genetic composition of populations over time

Question 34

speciation

Answer 34

the process by which populations evolve to become distinct species

Question 35

prezygotic isolating mechanisms

Answer 35

geographical, temporal, ecological (niche partitioning), behavioural, morphological

Question 36

postzygotic isolating mechanisms

Answer 36

hybrid inviability (zygote dies), reduced hybrid viability (zygote survives but wont reach adulthood), hybrid sterility (cant produce offspring), and hybrid breakdown (sometimes produces offspring but they will be infertile)

Question 37

what is geographical isolation

Answer 37

populations occupy and mate in different geographical areas (separated by a geographical barrier)

Question 38

what is temporal isolation

Answer 38

populations mate at different times during the year

Question 39

what is ecological isolation (niche partitioning)

Answer 39

populations occupy and mate in different ecological niches

Question 40

what is behavioural isolations

Answer 40

populations have different courtship rituals

Question 41

what is morphological isolation

Answer 41

when the morphological structure of organisms prevent interbreeding

Question 42

what type of isolation in allopatric speciation

Answer 42

geographical

Question 43

selective breeding

Answer 43

the process by which humans decide which individuals may breed based on 'favourable' traits

Question 44

process of selective breeding:

Answer 44

a desirable trait is determined, parents who show trait are interbred, offspring that display trait are selected and interbed, process is continued until the population reliably reproduces the trait

Question 45

detrimental effects of selective breeding

Answer 45

reduces resistance to environmental changes (reduced genetic variation) reduces biodiversity can increase abnormalities due to gene linkage