topic 7

Question 1

ecosystem

Answer 1

Group of interrelated organisms and their physical environment. Living and non living components interact

Question 2

environment

Answer 2

Set of conditions surrounding an organism. Abiotic factors within an ecosystem.

Question 3

abiotic

Answer 3

Non-living, physical conditions of an ecosystem (temperature, pH, light, soil conditions (EDAPHIC))

Question 4

biotic

Answer 4

Effects of the activities of living organisms on other organisms

Question 5

population

Answer 5

Group of organisms of the same species living in a habitat at the same time

Question 6

community

Answer 6

All individuals of different species living in the same place at the same time

Question 7

habitat

Answer 7

Part of an ecosystem in which particular organisms live

Question 8

microhabitat

Answer 8

Immediate surroundings (especially for small organisms)

Question 9

niche

Answer 9

An organisms habitat and role within an ecosystem (what it eats, predators, conditions it lives in)

Question 10

genotype

Answer 10

the complete set of genetic material of an organism

Question 11

phenotype

Answer 11

the observable traits or characteristics of an organism. Determined by genotype and environmental factors

Question 12

dominant

Answer 12

only a single allele is required for the characteristic to be expressed in the phenotype

Question 13

recessive

Answer 13

the characteristic is only expressed if there is no dominant allele present. must be homozygous recessive for the phenotype to be expressed

Question 14

codominant

Answer 14

both alleles are expressed in the phenotype

Question 15

allele

Answer 15

another form of a gene

Question 16

locus

Answer 16

the position of a gene on the chromosome

Question 17

homozygous

Answer 17

a pair of homologous chromosomes carrying the same alleles for a single gene

Question 18

heterozygous

Answer 18

a pair of homologous chromosomes carrying two different allels for a single gene

Question 19

multiple alleles

Answer 19

more than 2 alleles for a single gene

Question 20

sex linkage

Answer 20

a gene whose locus is on a sex chromosme

Question 21

autosomal linkage

Answer 21

genes that are located on the same chromosome, not sex chromosome

Question 22

epistasis

Answer 22

when one gene modifies or masks the expression of a different gene

Question 23

monohybrid

Answer 23

genetic inheritance cross of a characteristic determined by one gene

Question 24

dihybrid

Answer 24

genetic inheritance cross of a chracteristic determined by two genes

Question 25

assumptions for the Hardy-Weinberg equation

Answer 25

- no mutations occur to create new alleles. - there is no movement of alleles into or out of the population by migration. - the population is large. - there is no selection, so every allele has an equal chance of being passed to the next generation. - mating is random.

Question 26

what is the hardy weinberg equation used for

Answer 26

to estimate the frequency of alleles in a population and to see whether a change in allele frequency is occurring in a population over time

Question 27

what does each letter represent in the hardy weinberg equation

Answer 27

p= frequency of dominant allele q= frequency of recessive allele p^2= frequency of homozygous dominant 2pq= frequency of heterozygous q^2= frequency of homozygous recessive

Question 27

what does each letter represent in the hardy weinberg equation

Answer 27

p= frequency of dominant allele q= frequency of recessive allele p^2= frequency of homozygous dominant 2pq= frequency of heterozygous q^2= frequency of homozygous recessive

Question 28

gene pool

Answer 28

all of alleles of all the genes within a population at one time

Question 29

population

Answer 29

all of the individuals of one species in one area at one time

Question 30

allele frequency

Answer 30

the proportion of an allele within a gene pool

Question 31

what is disruptive selection

Answer 31

-when individuals which contain the alleles coding for either extreme trait are more likely to survive and pass on their alleles -allele frequency changes so more individuals possess the allele for the extreme trait while the middling trait becomes less frequent -this can lead to speciation

Question 32

what is speciation

Answer 32

the creation of new species

Question 33

what is allopatric speciation

Answer 33

-populations become geographically separated e.g. mountain ranges, bodies of water, so they are now unable to reproduce -within each population, random mutations lead to genetic variation -both separate populations will have different beneficial mutations over time to help them survive in their environments -eventually they become so genetically different that they are unable to interbreed to produce fertile offspring

Question 34

what is sympatric speciation

Answer 34

-populations can become reproductively isolated due to differences in their behaviour -may be due to a random mutation within the population that impacts reproductive behaviour (e.g. being fertile at different times of the year) -these individuals will not reproduce with eachother and there will be no gene flow between the two groups within the population -eventually, these reproductively isolated populations will accumulate different mutations until they can't interbreed to produce fertile offspring

Question 35

what is genetic drift

Answer 35

-change in the allele frequency within a population between generations -continual, substantial genetic drift results in evolution -affects smaller populations more so evolution occurs more rapidly in smaller populations

Question 36

how do abiotic factors affect population size

Answer 36

include: -temp -O2 and CO2 conc -light intensity -pH -soil conditions plants and animals are adapted to the abiotic conditions in their ecosystem which develop through natural selection less harsh conditions e.g. lots of light and water mean larger range of species and larger population sizes

Question 37

how do biotic factors affect population size

Answer 37

interspecific competition- when members of different species compete for the same resource that is in limited supply intraspecific competition- when members of the same species compete for resources and a mate

Question 38

describe mark-release-recapture

Answer 38

-initial sample of population is captured and the number is recorded -they are then marked and released into the wild -they are left for a period of time to allow them to randomly disperse throughout the habitat -a second sample is captured -the total number captured and the total number recaptured with the marking is recorded -size of population is estimated proportionally

Question 39

equation to estimate total population

Answer 39

no. organisms initially caught x no. organisms in second sample / no. marked organisms recaptured

Question 40

ethical considerations of mark-release-recapture

Answer 40

mark should be non toxic, must not increase chances of predation or reproduction

Question 41

assumptions of mark-release-recapture

Answer 41

population size remains constant animals redistribute evenly

Question 42

what is succession

Answer 42

the change in an ecological community over time

Question 43

describe primary succession

Answer 43

-starts with a pioneer species colonising rock or sand e.g. lichen which are adapated to live in harsh abiotic factors -they make the environment less harsh by changing the abiotic factors and form a thin layer of soil ,humus -mosses and small plants can now survive and further increase the depth and nutrient content of the soil -this pattern repeats as abiotic conditions become less harsh -each new species outcompetes the previous species -the final stage is the climax community and is dominated by trees

Question 44

what is secondary succession

Answer 44

the succession is disrupted and plants are destroyed e.g. due to fire succession starts again but soil is already created so it doesn't start from the bare rock stage

Question 45

evidence that the condition is caused by a recessive allele

Answer 45

2 parents who don't have the condition have a child who does both parents must be carriers

Question 46

evidence that the condition is caused by a dominant allele

Answer 46

2 parents who do have the condition have a child who does not therfore both parents must be carriers of the recessive allele but have the dominant allele

Question 47

evidence that an allele is sex linked

Answer 47

only seen in males not females