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BIOLOGY > 4B Diversity classification and variation > Flashcards

4B Diversity classification and variation Flashcards

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1
Q

what are gametes

A

sperm cells in males and the egg cells in females

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2
Q

when gametes join together in fertilisation what do they form

A

zygote, which divides and develops into a new organism

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3
Q

what diploid number to normal body cells have

A

2n

meaning each cell has two of each chromosome one from mum and one from dad

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4
Q

what is gametes haploid number

A

n

one copy of each chromosome

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5
Q

what happens at fertilisation

A

a haploid sperm fuses with a haploid egg making cell with normal diploid number
half chromosomes from mum (egg) and half from dad(sperm)

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6
Q

how is genetic diversity increased within species by fertilisation

A

fertilisation is random (any sperm with any egg(

so produces zygotes with different combinations of chromosomes to both parents (mixes genetic material)

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7
Q

where does meiosis take place

A

reproductive organs

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8
Q

how do cells start and finish via meiosis

A

start as diploid finish as haploids (have half the chromosomes)

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9
Q

6 steps of meiosis

A

1) before meiosis-DNA unravels & replicates so there are two copies of each chromosomes called chromatids
2) DNA condenses forming double armed chromosomes, made from two sister chromatids - sister chromatids joined by centromere
3) meiosis I- chromosomes orange into homologous pairs
4) homologous pairs separated halting chromosome number
5) meiosis II- pairs of sister chromosatids which make up each chromosome are separated (centromere divides)
6) four haploid cells(gametes) that are genetically different are formed

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10
Q

how many homologous pairs do human have

A

23

46 single chromosomes

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11
Q

during meiosis I what happens which causes the chromatids to have a different combination of alleles

A

homologous pairs of chromosomes pair up together
chromatids twist around each other and parts of the chromatids swap over
now chromatids still have same genes but different combination of alleles

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12
Q

how does the crossing over of chromatids during meiosis I produce cells which are genetically different

A

causes each of the four daughter cells formed have chromatids with different alleles
increases genetic variation

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13
Q

how does the independent segregation of chromosomes cause cells to be produced which are genetically different

A

when homologous pairs are separated (meiosis I) its random which chromosome from the pair ends up with which daughter cell
so 4 daughter cells have different combinations of those maternal and paternal chromosomes
this shuffling causes genetic variation in potential offspring

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14
Q

difference between meiosis and mitosis

A

1)mitosis produces cells w/same no. of chromosomes as parent cells
meiosis produces cells w/half chromosomes as parent cells

2)mitosis daughter cells are genetically identical to each other &parent cells
meiosis daughter cells are genetically different to each other and parent cell

3)mitosis produces two daughter cells
meiosis produces four daughter cells

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15
Q

how are chromosome mutations caused generally

A

errors in cell division

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16
Q

what is the chromosome mutation non-disjunction

A

failure of chromosomes to separate properly

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17
Q

what does non-disjunction of chromosome 21 cause

A

downs syndrome

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18
Q

detail how downs syndrome is caused

A

person having extra copy of chromosome 21

non disjunction means chromosome 21 fails to separate properly in meiosis so one cell gets an extra copy of chromosome 21 and the other cell gets none

so when the gamete with an extra chromosome fuses with another gamete at fertilisation the zygote will end up with 3 chromosomes 21

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19
Q

what is another mutation

A

changes to the base sequence of DNA

deletion or substitution

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20
Q

what is deletion mutation

A

one base is deleted (in DNA)

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21
Q

what is substitution mutation

A

one base is substituted with another (in dna)

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22
Q

how can a change in dna bases cause a mutation

A

as order of dna bases determines order of amino acids and therefore the protein which is made,
if the bases change the sequence of amino acids change and therefore a different protein is coded for

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23
Q

why do not all mutations affect the order of amino acids

substitution

A

as the genetic code is degenerate and more than one dna triplet can code for an amino acid
this mean substitution does not always result in change in amino acid sequence

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24
Q

why does deletion always cause change in amino acid sequence

A

as when a base is deleted it changes the number of base present - this causes a shift in all the base triplets after it

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25
Q

what are mutagenic agents

A

things that increase rate of mutations

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26
Q

examples of mutagenic agents

A

ultraviolet radiation
ionising radiation
some chemicals and viruses

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27
Q

how can gentic diversity within a population be increased

A
  • mutations in DNA

- different alleles introduced into population

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28
Q

what is gene flow

A

when individuals from another population migrate into them and reproduce -causing genetic diversity increases

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29
Q

what is a genetic bottleneck

A

an event which causes a big reduction in a population

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30
Q

how do genetic bottlenecks cause reduction in genetic diversity

A

the reduction in population causes number of different alleles to reduce in the gene pool so reduces genetic diversity

31
Q

what is the founder effect

A

type of genetic bottleneck
when a few organisms start new colony with only small number of alleles in gene pool
a gene which is rare in initial population may be very common in new colony
my lead to higher chance of genetic disease

32
Q

how does founder effect normally occur

A

result of migration leading to geographical seperation

colony operates from original population for religion

33
Q

example of founder effect

A

the amish

34
Q

what is behavioural adaptations

A

ways an organism acts that increases chance of survival and reproduction

35
Q

what is physiological adaptations

A

processes inside an organisms body which increase chance of survival

36
Q

what are anatomical adaptations

A

structural features of an organisms body which increase chance of survival

37
Q

what is directional selection

A

where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce

38
Q

example of directional selection

A

bacteria evolving antibiotic resistance

39
Q

what is stabilising selection

A

where individuals with alleles for the characteristics towards the middle of the range are more likely to survive and reproduce

40
Q

what’s an example of stabilising slection

A

human birth weight -larger and smaller baby less likely to survive birth

41
Q

what is phylogeny and what can it tell us

A

study of evolutionary history of groups of organisms

tells us who’s related to whom and how closely they are related

42
Q

what is taxonomy

A

science of classification and names organisms organising them into groups

43
Q

what does heriachy mean

A

groups organised into largest groups at top and smallest at Bottom
no overlapping groups

44
Q

what are the three domains

A

eukarya
bacteria
archaea

45
Q

what are the eight taxons

A 
domain
kingdom
phylum
class 
order
family 
genus
species
46
Q

what is a species

A

group of similar organisms able to reproduce and give fertile offspring

47
Q

what is the binomial system

A

nomenclature for classification

given one internationally accepted name in latin with two parts

48
Q

what are the fist and second parts of names in classification called

A

genus is first

species is second

49
Q

what is courtship behaviour

A

carried out by organisms to attract mate of right species

50
Q

why is courtship behaviour species specific

A

prevents interbreeding

making reproduction more successful

51
Q

explain genome sequencing

A

DNA base sequence of an organism can be compared to see how closely related they are
more closely related species will have a higher percentage of similarity in there base sequence

52
Q

explain comparing amino acid sequence

A

related organisms have similar amino acid sequences in there proteins

53
Q

what is cytochrome c

A

short protein found in many organisms

54
Q

explain immunological comparisons

A

similar proteins bind to same antibodies

55
Q

what is genetic diversity

A

the number of different alleles in a population

56
Q

what can variation be caused by

A

genetic factors
environment
combination of genes and environment

57
Q

why are samples used to study variation

A

as its too time consuming and impossible to be able to study a whole population

58
Q

why do samples need to be random

A

make sure it accurately represents the population and makes sure it isn’t biased
could use random number generator

59
Q

what is biodiversity

A

the variety of living organisms in an area

60
Q

what is habitat

A

the place where an organism lives

61
Q

what is community

A

all the populations of different species in a habitat

62
Q

what local biodiversity

A

variety of species living in small habitats that’s local to you

63
Q

what’s global biodiversity

A

variety of species on earth

greatest at the equator

64
Q

what’s species richness

A

measure of number of different species in a community

65
Q

how cam species richness/ biodiversity be worked out

A

take random samples of a community and count number of different species

66
Q

what also effects the biodiversity number

A

the population size

big and small populations should not be treated the same way

67
Q

what’s index of diversity

A

another way of measuring biodiversity
calculated with formula
higher number + more biodiversity

68
Q

what can reduce biodiversity

A

agricultural practices

69
Q

how can woodland clearance decrease biodiversity

A

decreases number of trees and tree species
destroys habitats and food resources
species may be forced to migrate or die

70
Q

how can hedgerow removal decrease biodiversity

A

same reasons as woodland clearance

71
Q

how can pesticides decrease biodiversity

A

chemicals kill pests that feed on crops

also reduces food resource

72
Q

how can herbicides reduce biodiversity

A

chemicals kill unwanted plants

73
Q

how can monoculture reduce diversity

A

farmers have fields which only contain one type of plant

74
Q

what are some examples of conservation schemes which protect biodiversity

A

SSSI/ AONHb

environmental stewardship scheme

BIOLOGY (20 decks)

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