topic 7

Question 1

what is a population

Answer 1

group of organisms of the same species living in a particular area at a particular time that can potenttially interbreed.

Question 2

what is a gene pool

Answer 2

range of alleles in a population

Question 3

what is allele frequency

Answer 3

how often allele occurs in a population

Question 4

what is the hardy-weinberg principle

Answer 4

predicts the frequency of alleles in a population that wont change from one generation to the next

Question 5

what do the conditions of hardy weinberg apply to

Answer 5

• large population
• no immigration
• no mutations
• no natural selection
  no emigration

Question 6

what does the p stand for in hardy weinberg

Answer 6

dominant allele

Question 7

what does the q stand forr in hardy weinberg

Answer 7

the recessive allele

Question 8

why might individulas within a population show a wide range of variation in a phenotype. (5 things)

Answer 8

-mutations
-random fertilisation
-independat segragation of homologus chromosomes
- crossing over
- environmental factors

Question 9

what is evolution

Answer 9

a change in allele frequency over time

Question 10

what way does evolution occur

Answer 10

natural selection

Question 11

describe the process of natural selection

Answer 11

Evolution: change in allele frequencies in a population over time
1. Variation within a population due to mutations
2. Selection pressure e.g. predation, disease, competition à struggle for survival
3. Some organisms have phenotypes providing selective advantages (due to favourable allele(s))
4. These organisms are more likely to survive and reproduce, producing more offspring and
passing on their favourable allele(s) to the next generation i.e. differential levels of survival and
reproductive success

Question 12

what do organisms need to fight for *******

Answer 12

-predation
- disease
- competiton

Question 13

what is stabilising selection

Answer 13

• selective pressure favours the mean phenotype
• individuals with the extreme phenotype are less likely to survive and reproduce.
• occurs in an unchanging environment

Question 14

what is directional selection

Answer 14

• selective pressure acts on the extreme phenotype.
• so they are more likely to survive and reproduce.
• due to a response to a change in the environment.

Question 15

what is disruptive selection

Answer 15

when both the extreme phenotypes are favoured .
this can result in two different species.
environment favours both the extreme phenotypes

Question 16

what are the two types of speciation

Answer 16

allopatric speciaiton
symptatric specition

Question 17

what is speciation

Answer 17

the development of a new species from an existing speces

Question 18

what happens to the population during speciation

Answer 18

they are reproductively isolated

Question 19

how do new species arise

Answer 19

when members of a population are unable to interbreed to produce fertile offsprings

Question 20

what type of isolation occurs in allopatric speciation

Answer 20

geographic isolation

Question 21

what are examples that may cause geographic isolation

Answer 21

flooding
earthquake

Question 22

what do physical barrieers prevent in allopatric speciation

Answer 22

inerbreeding between species

Question 23

describe allopatric speciation

Answer 23

• a population is geographically isolated and so are therfore reproductively isolated.
• mutations causes genetic variation in each population
• there are different selection pressures that acts on each population.
• natural selection on favourable alleles.
• alleleic frequency increases over time
  -memebers of the samee population cant inteerbreeed to produce fertile offsprings

Question 24

what is sympatric speciation

Answer 24

when the populations arent gentically isolated

Question 25

how does sympatric speciation occur

Answer 25

genetic variation due to mutations preventing membeers from of tthat population from breeding

Question 26

where can the mutations occur in sympatric speciation

Answer 26

in the chromosome number

Question 27

what are the different mechanisms that make individuals reproductively isolated

Answer 27

- seasonal - mechanical - behavioural

Question 28

temporal/ seasonal

Answer 28

different mating/ breeding seasons

Question 29

mechanical

Answer 29

changes in genitalia which prevents successful mating

Question 30

behavioural

Answer 30

different courtship behaviour preventing mating

Question 31

what is genetic drift

Answer 31

when allele frequency of a popoulation changes over generations due to chance

Question 32

what other factor affects natural selection

Answer 32

genetic drift

Question 33

what is the founder effect

Answer 33

when smaller colonies forms from a larger one.

Question 34

what is a community

Answer 34

a population of diffferent species

Question 35

what is an ecosystem

Answer 35

a community plus all the non living components

Question 36

what is a niche

Answer 36

the role of a species within its habitat like what it eats and where it feeds

Question 37

what are aibiotic conditions

Answer 37

non living components of an ecosystem

Question 38

what are biotic conditions

Answer 38

the living features of an ecosystem

Question 39

what is the carrying capacity

Answer 39

the maxiumum stable population an ecosysteem can support

Question 40

how can population size vary as a result of intercations between organisms

Answer 40

competition aibiotic factors predation

Question 41

what is interspecific competition

Answer 41

competition between organisms of dfferent species.

Question 42

what happens in interspecific competition

Answer 42

it reduces resources avaliable to both species when one species is better adapted it will out-compete the others

Question 43

what is intraspecific competition

Answer 43

competition between organisms of the same species

Question 44

what does a small population mean in terms of copetition

Answer 44

results in less competition

Question 45

what is predation

Answer 45

when an organism kills and eats another organism

Question 46

increased predator population size à more prey eaten à prey population falls à less food for predators à predator population size falls à prey population rises à predator population rises again…

Answer 46

increased predator population size à more prey eaten à prey population falls à less food for predators à predator population size falls à prey population rises à predator population rises again…

Question 47

what is succession

Answer 47

process by which an ecosystem changes overtime

Question 48

what is a pioneer species

Answer 48

the first species to colonise

Question 49

what do pioneer species do

Answer 49

they change the aibiotic consitions so that the environment is less hostile - which allows the environment to be more sutibale for other speciees with different species

Question 50

what happens to the biodiversity as succesion goes on

Answer 50

it increases

Question 51

what is the climax community

Answer 51

the final, complex, stable community

Question 52

why are pioneer species able to grow in aibiotic conditions

Answer 52

they are better adapted

Question 53

how do thee pioneer species change the aibiotic conditions

Answer 53

they die and microorganisms decompose dead matter to humus in order to form basic soil

Question 54

what is secondary succesion

Answer 54

when land has been cleared e.g a fire

Question 55

what is primary succession

Answer 55

land that has been newly formed or exposed

Question 56

what is plagioclimax

Answer 56

when succession is stoppedd artifically by human activity so stops a climax community from forming.

Question 57

how can you manage succession

Answer 57

conservation

Question 58

what is the purpose of conservation

Answer 58

in order to preserve the community in its current stage of succesion

Question 59

what is conservation

Answer 59

protection and management of species and habitats in a sustainable way