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Biology > topic 7 > Flashcards

topic 7 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is genotype?

A

the genetic makeup of an organism contains all the alleles an orgnaism has.

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2
Q

what is phenotype?

A

observable characteristcs of an organism. It is a result of an expression of the genotype and the environment

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3
Q

what is a gene?

A

a length of DNA that is a sequence of nucleotide base that code for a polypeptide

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4
Q

what is homozygous dominant/recessive

A

when the allele of each chromosome in the homogous pair are both dominant/recessive

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5
Q

what is heterozygous?

A

when the alleles in the homologous pair are different

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6
Q

what is codominance?

A

when both the alleles are shown in the phenotype

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7
Q

what is monohybrid inheritance?

A

the inheritance of a single gene

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8
Q

describe a ratio

A

a ratio is measure of the relative of 2 groups expressed as a proportion

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9
Q

what are autosomes?

A

All the chromosmes apart from the sex chromosomes.

We have 22 pairs of autosome chromosomes

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10
Q

what is autosomal linkage ?

A

When the genes are linked on the chromosome.

this means they are inherited together

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11
Q

what is a linkage group?

A

All the genes on a chromosome form a linkage group

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12
Q

what is dihybrid crosses

A

A genetic cross where the inheritance of 2 genes is considered at the same time

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13
Q

what is the ratio for dihybrid 2 heterozygous crosses? what are the exceptions to this?#

A

9:3:3:1
this is unless their is autosomal linkage or crossing over
crossing over in meiosis creates new creates new combination of alleles in gametes

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14
Q

what is the ratio for autosomal linkage

A

3:1

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15
Q

what is an allele?

A

a form of a gene

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16
Q

how are genes written down in codominance?

A

You cannot use a capital and lower case letter as both are dominant
instead you use a lettter for the characteristic and then the actual characteristic e.gcow fur colour
C^r= red colour
C^w = white colour

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17
Q

what is the difference in chromosomes between male and female?

A

22 chromosomes are the same

however the sex chromosome men have XY while females have XX

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18
Q

what is sex linkage? and what does this mean in terms

A

any gene that is carried is carried on the x or y chromosome
however the x chromosome is much longer than the y chromosome
this means for a large region of the x chromosome there is no homologous portion on the y alleles
any recessive alleles that appear in this reigon is more likely to be expressed in a man as in a female a recessive allele has to be expressed 2 times to be expressed

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19
Q

who do males inherit sex linkage diseases from?

A

men inherit Y chromosome from father (mother has no Y)
and then X chromosome from mother
this means X linked diseases are inherited from mother

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20
Q

what type of gametes do autosomal linkage autosomes produce?

A

the gametes are AB and ab

normally with 2 genes the gametes would for a single autosome would be AB Ab aB ab

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21
Q

what is epistasis?

A

when the allele of one gene masks or affects the expression of another in the phenotype

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22
Q

what is the ratio in epistasis?

A

9:4:3

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23
Q

what does the chi squared test test for?

A

null hypothesis (if the deviation of the results away from the expected is due to chance)

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24
Q

what is the gene pool?

A

all the alleles in a population

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25
Q

what is allelic frequency?

A

the amount of a specific allele in a genepool

26
Q

what is the harvey windberg principle? and equations?

A

the proportion of dominant and recessive allelse remains the same in a population if:
their is a large population
mating is random
no new alleles are introduced (isolated population)
there are no mutations
their is no selection all alleles are favoured

p + q = 1.0
p^2 + 2pq + q^2 = 1.0

27
Q

what are three things that cause genetic variation?

A

meiosis - random fertilisation
crossing over
mutations

28
Q

what is a selection pressure?

A

environmental factors that limit the population of a species

they also affect the frequency of alleles in a genepool

29
Q

what does evolution by natural selection?

A

organisms creating more offspring that can be supported by the light,water ect to promote competition
genetic variation within the population of all species
a variety of phenotypes

30
Q

what does over production of offspring cause in natural selection?

A

over production allows populations to survive to breed and reproduce
they compensates high death rates from predation,competition and natural disasters
when there is too many offspring their in intraspecific competition for limited resources. Higher competition means more offspring will die.the offsprings that survive are the ones with more advantageous alleles for the environment.
this processs however does require individuals of the environment to be genetically different

31
Q

what is the role of varitation in natural selecttion?

A

Once an organism has survived to reproduce it would make sense for its offspring to be identical to also survive as variation may cause the offspring to be less like likely to.
however as the environment is always changing having a wide range of genes (and therefore phenotype) will it give it the opportunity to survive in more new circumstances/environments
populations with little variance are often more vulnerable to new diseases

32
Q

what are the three types of selection?

A

stabilising - preserves the average phenotype by selecting away from extremes and towards the average
directional - changes the phenotype of a population by favouring phenotypes that vary in one direction from the mean phenotype
disruptive - favours individuals with extreme phenotypes rather than the average phenotype

33
Q

what is speciation ?

A

the evolution of new species from existing ones

34
Q

how does speciation occur?

A

population becomes seperated
mutations occur and they experience different selection pressures due to them being in different environments
natural selections will lead to changes in allele frequency
the different phenotypes produced by different alleles will lead to adaptations (adaptive radiation)
2 populations now unable to interbreed as they are 2 different species

35
Q

what is genetic drift

A

occurs in small populations as their is less variation of alleles across populations
advantageous alleles that are passed on quickly affect the population as their frequency is high
this causes the population as a whole to change quicker
in larger the populations the effect of mutations/advantageous allels is less as their is less frequency as their is a larger gene pool

36
Q

what is the difference betweeen allopatric speciation and sympatric speciation?

A

allopatric speciation - animals are geography sepereated via a barrier
sympatric speciation - same country/area speciation occurs

37
Q

list all the isolating mechanisms?

A

geographical- barriers r.g oceans
ecological - differet habitat same area
temporal - breeding seasons do not match
behavioral - courtship behaviours is not replicated
mechanical - anatomy differences
gametic - genetic biochemical incompatibility
hybrid sterility - fusion of gamets from different species are sterile (cant produce
gametes)

38
Q

what is the difference between biotic and abiotic factors?

A

biotic is livning

abiotic is non living

39
Q

what is an ecosystem?

A

dynamic systems made up of a community and all its non living factors of its environment

40
Q

what is a population?and carrying capacity?

A

A population is a group of species that live in the same area/habitat and are able to succesfully interbreed
carrying capacity is the maximum population in an ecosystem it is usually linked to abiotic factors,interactions between organisms(predation)

41
Q

what is a community?

A

all the populations of different species living in a particular space

42
Q

what is a niche?

A

a niche describes how an organism fits into its enviroment

no 2 species have the same niche

43
Q

what is a habitat?

A

a habiat is where organisms live

within an ecosystem there are many different habitats

44
Q

why can populations not grow forever?

A

each population reaches a limiting factor

45
Q

what are the 2 types of competition?

A

intraspecific- withing a species inddividuals compete for resource e.g food,water light, the more resources there is the less competition their is hence a larger population.less resources will mean more competition and hence the population to decrease
interspecific- against different species this leads to one species growing and the other eventually dying out. (competitive exclusion principle). The species that can better utilise the resource will survive. No 2 species that can occupy the same niche

46
Q

why does an increase in a factor not always result in an increase in populatino size?

A

The factor may not cause the population size to increase it may just result in bigger organism

47
Q

what is predation?

A

when one organism consumes another

48
Q

what is the effect on predator - prey relationship on population size?

A

predator eats prey reducing its population size
fewer prey left so their is competition within predator for prey
predator population reduce as some are unable to obtain enough prey for their survival/reproduction
this causes prey population increases as fewer are eaten and more survive to reproduce

49
Q

what is abundance?

A

the number of individuals of a species at an area/habitat

50
Q

how are quadrats used in investigations (random sampling)?

A

2 types-grid/point
three factors considered :size of quadrat,number of sample quadrats to record in study area, position of each quadrat within study area
1)2 tape measures at right angles to measure area and form coordinates
2)random number generator to obtain coordinates
3) place quadrat at each coordinate

51
Q

how are transects used in systematic sampling?

A

belt transect made by stretching a string across the ground in a straight line. Laying a quadrat across this line . it measures abundance of a species
for species that dont move abundance can be measured by
frequency e.g in15/30 quadrants its frequency is 50%
percentage cover- rough estimate of how much of the quadrat is covered.best used when there is too much of a species to count

52
Q

what is the mark - capture release techniques

A

quadrants and transects are best for slow moving or non motile organisms
the mark capture release technique is when a known amount of animals are caught marked and released. later on a given amount of the same animal is collected randomly and the amount marked is noted.
population= 1st sample x 2nd sample/amount marked recaptured

53
Q

assumptions for mark recapture technique

A

proportion marked to unmarked in second sample is same as proportion marked to unmarked in whole population
the marked release animals from the 1st samples have enough time to evenly distribute
population has defined boundary (no immigration in and out)
few deaths / births
marking does not make individual more susceptible to prey
mark / label is not lost

54
Q

what is succession?

A

the changes over time of the species in that area

55
Q

what happens at every stage of succession

A

at every stage a new species colonise the area and make changes to it by making it: less suitable for the originial species this leads to the new species out competing it
more suitable for more new species leading to the new species being outcompeted

56
Q

what is the first stage of succession?

A

colonisation of an inhospitable environment by pioneer species
they are best suited as they have features such as
asexual reproduction
wind dispersed seeds reaching isolated areas
rapid germination of seeds (no period of dormacy)
ability to photosynthesis with light (no food is avaliable)
fix nitrogen
tolerance to extreme conditions

57
Q

what is the 2nd stage of succession?

A

as the pioneer species die and decompose they release nutrients for the organisms that follow.
mosses are usually the next stage which increase depth and nutrients in soil as they die reducing abiotic conditions
this process continues and now larger plants can survive and further change the species
these make the environment less hostile and increase biodiversity
the final step is the climax community which remains stable over a long period of time
the animals go through a similar succession as the as they depend on the plants for food/habitat

58
Q

what are the common features which emerge in succession

A

non living abiotic environment becomes less hostile (soils form /more nutrients)
more habitats and niches which increases biodiveristy

59
Q

describe secondary successsion?

A

when sustained land is suddenly altered
there land quickly returns to climax community this time as their is already soil and animals living there.
their is an influx of migration from the surrounding area

60
Q

what is convservation?

A

management of Earths natural resources by humans so that maximum usage can be made in the future.this involves active interventions by humans to maintain biodiversity in ecosystems

61
Q

what are the main reasons for conservation?

A

personal: to maintain our planet
ethical
economic
cultural and aesthetic

62
Q

what is one way of conservation ?

A

managing succession as in the climax community many of the original species had been outcompeted or lost their habitat

Biology (9 decks)

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