population and evolution

Question 1

define a population

Answer 1

a group of organisms of the same species that occupies a particular space at a particular time

Question 2

can a species exist as more than one population

Answer 2

yes

Question 3

define a gene pool

Answer 3

all the alleles of all the genes of all the individuals within a population

Question 4

define allele frequency

Answer 4

the number of times an allele appears within a gene pool

Question 5

what are conditions for the Hardy-Weinberg principle

Answer 5

-no mutations
- the population is isolated
- there is no selection ( all alleles are equally likely to be passed to the next generation
- the population is large
- mating within the population is random

Question 6

which is the dominant allele in the Hardy-Weinberg equation

Answer 6

p

Question 7

which is the recessive allele in the Hardy-Weinberg principle

Answer 7

q

Question 8

what are equations that can be used in Hardy-Weinberg

Answer 8

p+q=1

p^2 +2pq+q^2=1

Question 9

which genetic factors can variation arise from

Answer 9

mutations - changes in genes and r chromosomes may or may not be passed to the next generation

meiosis - a new combination of alleles are produced before they enter the gametes

random fertilisation -

Question 10

what are selection pressures

Answer 10

the environmental factors that limit the population of a species

Question 11

what does evolution by natural selection depend upon

Answer 11

• organisms produce more offspring than can be supported by the available food supply
• there is genetic variety within the population of all the species
• a variety of phenotypes that selection operates against

Question 12

when will intraspecific competition occur

Answer 12

where there are too many offspring for the available resources, so there is competition between individuals

Question 13

how does intraspecific competition lead to variation

Answer 13

the greater the numbers, the greater the competition and the more individuals that will die. but those that are suited to the environment will survive, those with resistance to disease, catch prey or find a mate better will be able to pass their allele frequencies to the next generation

tis more favourable for them

this selection process does depend upon individuals of a population being genetically different from obe another

Question 14

which types of populations are more vulnerable to genetic disease

Answer 14

populations with little genetic variation between individuals

Question 15

why is a large pop good

Answer 15

because there is a higher chance that the most favourable allele combination will be present within the pop

Question 16

define stabilising selection

Answer 16

preserves the average phenotype of a population

Question 17

define directional selection

Answer 17

changes the phenotypes of the pop by deviating either side of the mean

Question 18

what is disruptive selection

Answer 18

favours individuals with extreme phenotypes rather from thsoe surrounding the mean

Question 19

what is polymorphism

Answer 19

forms that are genetically distinct but exist within the same interbreeding population

Question 20

define a species

Answer 20

a group of individuals witht the same genes but different alleles that can reproduce to produce fertile offspring

Question 21

where does genetic drift occur

Answer 21

small population

Question 22

what is genetic drift

Answer 22

in smaller populations there is a smaller variety of alleles within the population - therefore genetic diversity is small.so when offspring with new allele frequencies have the ability to affect the whole population

Question 23

what is difference between allopatric speciation and sympatric speciation

Answer 23

allopatric speciation involves a geographical isolator but sympatric does not

Question 24

describe sympatric speciation

Answer 24

there must be two populations within a group where no gene flow can occur, populations become separated because they live in different environments within the same area. or could there could be behavioural separation, differences in feeding, communication or courtship behaviour.