Evolution ^

Question 1

What is the gene pool?

Answer 1

The complete range of alleles present in a population

Question 2

What is allele frequency?

Answer 2

How often alleles occur in a population

Question 3

How may evolution occur?

Answer 3

Natural selection

Question 4

What is selection in a stable environment called?

Answer 4

Stabilising selection. This is when alleles increase in the middle range and decreases the range of possible phenotypes

Question 5

What is it called when selection occurs in a changing environment?

Answer 5

Directional selection. This is when the most advantageous alleles change so other individuals are most likely to survive

Question 6

What is a population?

Answer 6

A group of individuals of species living together and being close enough to Interbreed.

Question 7

What is genetic drift?

Answer 7

Genetic drift is random fluctuations in allele frequency.
. Individuals show variation within their genotype
. By chance, the allele for one genotype is passed on to the offspring more often than others so the gene pool changes
. If by chance the allele is passed on more again and again, the allele will become more common in the population.

Question 8

When does genetic drift have more of an impact than natural selection for evolution?

Answer 8

In smaller populations

Question 9

What is a genetic bottleneck?

Answer 9

An event leading to a large decrease in population size and therefore gene pool. When the population increases, alleles may not recover.
Evolution by genetic drift has a larger effect if there is a genetic bottleneck

Question 10

What is the founder effect?

Answer 10

This is when a few organisms from a population start a new population and there is only a small number of different alleles. By chance they will mostly have one particular genotype. This is more influenced by genetic drift

Question 11

How does the founder effect occur?

Answer 11

The result of migration leading to geographical separation

Question 12

What is the hardy-weinberg principle?

Answer 12

A model which predicts that the frequency of alleles in a population wont change for one generation to the next. This is only true under certain conditions:
. Needs to be a large population that is closed
. Needs to be random mating

Question 13

What can the hardy weinberg equation be used for?

Answer 13

To estimate the frequency of alleles and genotypes

Question 14

How do you work out allele frequency?

Answer 14

The equation p+q=1
P is dominant
Q is recessive
They must add up to one

Question 15

What equation do you use to work out genotype frequency?

Answer 15

P²+2pq+q²=1

Question 16

What is artificial selection?

Answer 16

When humans select individuals in a population and breed together to get desirable characteristics

Question 17

How is artificial selection of milk cows done?

Answer 17

. Farmers select a very high milk yield female and a male whose mother had high yield and breed them
. They select the offspring with highest yield and breed together
. This is done over several generations

Question 18

What characteristics do milk cows want

Answer 18

. High quality milk
. Long lactation period
. Large udders
. Resistance to mastitis (inflammation of udders)
. Calm temperament

Question 19

What can artificial selection be done by now?

Answer 19

Artificial insemination
IVF
Animal cloning

Question 20

What is flour produced from?

Answer 20

Bread wheat (Triticum aestivum). It produces high yield of wheat

Question 21

Hat other characteristics are selected for in bread wheat?

Answer 21

. Higher tolerance of the cold
. Short stalks so they dont collapse under weight
. Uniform stalk heights to make harvesting easier.
Plant cloning may be easier to accomplish this

Question 22

What are the issues with artificial selection?

Answer 22

Reduced the gene pool:
Same alleles are bred together. This causes issues as it could lead to less resistance of specific diseases and mean potentially useful alleles are lost. It means genetic material may be lost
Problems for organisms:
It may exaggerate certain traits, leading to health issues. This is also linked to ethical issues

Question 23

What is Interbreeding?

Answer 23

Breeding with close relatives

Question 24

What is outbreeding?

Answer 24

Breeding of unrelated individuals

Question 25

What is the result of inbreeding?

Answer 25

Pedigree dogs

Question 26

What is a species?

Answer 26

A group of similar organisms that can reproduce to give fertile offspring.

Question 27

What is speciation?

Answer 27

The development of a new species

Question 28

What is allopatric speciation?

Answer 28

When populations become geographical isolated. This occurs when a physical barrier divides a population of species, causing some individuals to become separated. These 2 populations will experience different conditions, causing natural selection to occur differently

Question 29

How does reproductive isolation occur?

Answer 29

Because the changes in alleles and phenotypes of 2 populations prevent them from successfully breeding. E.g seasonal changes, mechanical changes and behavioural changes

Question 30

What is sympathise speciation?

Answer 30

Speciation without geographical isolation. Random mutations may occur resulting in changes and reproductive isolation, preventing breeding.

Question 31

What is polyploidy?

Answer 31

When the chromosome number in an organism increases. 3. Organisms with different number of chromosomes cannot breed so thag would make then reproductive isolated causing sympatric speciation