4.4-Variation And Evolution

Question 1

What is variation ?

Answer 1

The differences between organisms of the same species

Question 2

What causes variation ?

Answer 2

Different genotypes
Different epigenetic modifications
Different environments

Question 3

By what sexual reproduction mechanisms is variation inherited by ?

Answer 3

Crossing over during prophase 1 of meiosis
Random distribution of chromosomes during metaphase 1 of meiosis
Random distribution of chromatids at metaphase 2 of meiosis
Mixing of 2 different paternal genotypes at fertilisation

Question 4

What are the 2 types of variation ?

Answer 4

Continuous and discontinuous

Question 5

What is continuous variation controlled by ?

Answer 5

Many gene- polygenic
Highly determined by the environment

Question 6

What are examples of continuous variation?

Answer 6

Height
Body mass
Foot length

Question 7

What is discontinuous variation controlled by ?

Answer 7

A single gene- myogenic

Question 8

How is discontinuous variation represented ?

Answer 8

By bar charts

Question 9

What are examples of discontinuous variation ?

Answer 9

Eye colour
Blood group
Shoe size

Question 10

What is competition ?

Answer 10

Determines survival and passing on of genes leading to successful breeding

Question 11

What are the 2 types of competition ?

Answer 11

Inter specific
Intra specific

Question 12

What is an example of intra specific competition ?

Answer 12

Occurs between individuals of the same species; deer competing for mates

Question 13

What is an example of inter specific competition ?

Answer 13

Between individuals of different species competing for the same resources ; cheetah and lion competing for prey

Question 14

What are gene pools ?

Answer 14

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

Question 15

What are selective agencies ?

Answer 15

Environmental factors that can alter the frequency of alleles in a population when they are limiting

Question 16

What are examples of selective agencies ?

Answer 16

Supply of food
Breeding sites
Climate
Human impact

Question 17

What are selective pressures ?

Answer 17

The effort of selective agencies acting on the population through natural selection, survival of the fittest affect

Question 18

What is meant by the value of an allele ?

Answer 18

Different phenotypes having an advantage due to the environment, this means the beneficial allele is passed onto the next generation. For example a white rabbit in a cold habitat

Question 19

What is genetic drift ?

Answer 19

Change in frequency of an existing gene variant in the population due to random chance, this is more significant in smaller populations

Question 20

What is the founder effect ?

Answer 20

A new population founded from a small sample of the original gene pool resulting in a smaller population of alleles

Question 21

What is speciation ?

Answer 21

Occurs as a result of the founder effect, genetic variation and natural selection.

Question 22

What are the 2 types of speciation ?

Answer 22

Allopatric and sympatric

Question 23

What is allopatric speciation ?

Answer 23

Speciation caused by any mechanism of geographically separating demes resulting in evolution of a new species.

Question 24

What is sympatric speciation ?

Answer 24

When a new species develops in the same area. Can further be divided into morphological isolation, behavioural isolation, seasonal isolation and hybrid sterility.

Question 25

What is a deme?

Answer 25

A sub group within the population that may breed more often with each other than the rest of the population causing reduced gene flow and allopathic and sympatric speciation.

Question 26

What is temporal isolation ?

Answer 26

Organisms breed at different times of year therefore demes with different breeding seasons cannot interbreed and become isolated.

Question 27

What is ecological isolation ?

Answer 27

Organisms living in different habitats in the same area

Question 28

What is behavioural isolation ?

Answer 28

Different mating rituals attract different species so demes with different rituals are not attracted so no interbreeding occurs and they become isolated

Question 29

What is mechanical isolation ?

Answer 29

Incompatible genetic is means they cannot interbreed

Question 30

What is hybrid sterility ?

Answer 30

When 2 different but similar species interbreed producing an infertile offspring so no further species can be produced. Often due to an uneven chromosome number

Question 31

What is an example of hybrid sterility ?

Answer 31

Donkey (n=62) +Horse (n=64) = Mule (n=63)

Question 32

What is hybrid fertility ?

Answer 32

When infertility is overcome

Question 33

What did Darwin believe ?

Answer 33

That natural selection caused gradual changes from 1 generation to the next overtime, driven by competition

Question 34

What 5 factors play a role in natural selection ?

Answer 34

Variation Overproduction Survival of the fittest Inheritance Speciation/ change

Question 35

What are the 3 types of selection ?

Answer 35

Stabilising Directional Disruptive

Question 36

What is stabilising selection ?

Answer 36

When there is an optimum phenotype for the environment with conditions that are not severe

Question 37

What is directional selection ?

Answer 37

A response to gradual environmental changes causing an extreme

Question 38

What is disruptive selection ?

Answer 38

When 2 of more phenotypes exit in a population causing the rise of a new species

Question 39

What is Hardy Weinbergs principle ?

Answer 39

That in ideal conditions allele and genotype frequencies in a population are constant between generations

Question 40

What are the ideal conditions for organisms according to Hardy Weinbergs principle ?

Answer 40

Diploid Reproduce sexually Random mating Non overlapping generations Equal allele frequencies in both sexes

Question 41

What are the ideal conditions for the population according to Hardy Weinbergs principle ?

Answer 41

Large No migration No mutation No selection

Question 42

What is allele frequency ?

Answer 42

Proportion of an allele within a gene pool

Question 43

What does p stand for in Hardy Weinbergs principle ?

Answer 43

Frequency of dominant allele

Question 44

What does q stand for in Hardy Weinbergs principle ?

Answer 44

Frequency of recessive allele

Question 45

What does p2 stand for in Hardy Weinbergs principle ?

Answer 45

Frequency of homozygous dominant genotype

Question 46

What does q2 stand for in Hardy Weinbergs principle ?

Answer 46

Frequency of homozygous recessive genotype

Question 47

What does 2pq stand for in Hardy Weinbergs principle ?

Answer 47

Frequency of heterozygous genotype

Question 48

What does p+q = in hardy Weinbergs principle

Answer 48

1

Question 49

What does p2+2pq+q2= in Hardy Weinbergs principle ?

Answer 49

1