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biology: paper 2 > inheritance, variation and evolution > Flashcards

inheritance, variation and evolution Flashcards

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1
Q

DNA is a …..

A

Polymer

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2
Q

what is a genome?

A

the entire set of genetic material in an organism

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3
Q

why is understanding the human genome important?

A

-allows scientists to identify genes in genome that link to diff diseases
-knowing which genes are linked to inherited diseases, helps us develop treatments
-helps trace the migrations of people, as people migrated away from africa, they developed tiny differences in their genomes, scientists can work out when and where these populations split off

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4
Q

what is a gene

A

a small section of DNA found on a chromosome
that codes for a particular sequence of amino acids
that are put together to make a specific protein

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5
Q

what does each nucleotide consist of

A

a phosphate molecule
a sugar molecule
a base

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6
Q

complementary base pairings

A

A-T
C-G

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7
Q

what do non-coding genes do?

A

they switch on and off, so they control whether or not the gene is expressed (used to make a protein)

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8
Q

where are proteins made?

A

in cell cytoplasm on ribosomes

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9
Q

what is the role of mRNA?

A

-copies the DNA code, (the DNA is too big to leave nucleus) and acts as a messenger from DNA to ribosomes so the proteins can be made in the ribosomes from the code

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10
Q

different types of proteins?

A

-enzymes: biological catalysts
-hormones: send messages around body
-structural proteins: physically strong

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11
Q

what is a mutation? and what does it do

A

-a random change in DNA–> can be inherited
-most mutations have little affect on the protein, , function and appearance unaffected

-sometimes mutations will code for an altered protein with a change in its shape, affecting its ability to function
-if there is mutation in non-coding DNA, it can alter how genes are expressed

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12
Q

types of mutations:

A

-insertions
where new base inserted in DNA base sequence where it shouldn’t be
-deletion
when a random base is deleted from the base sequence
-substitution
when a random base in the sequence is changed to a different base

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13
Q

why the function of a protein may be affected by a gene mutation

A

-mutation alters the DNA base sequence
-can alter the amino acids that the bases code for
-can change the shape of the proteins amino acids make up, affecting its function

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14
Q

how many chromos in a gamete?

A

-23 half normal

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15
Q

what is natural selection?

A

-natural selection is the process through which populations of living organisms adapt and change and better survive in population

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16
Q

which organisms produce both ways?

-malaria
-fungi
-plants

A

malaria:
-parasite prod sexually in mosquito, asexually in host
fungus:
-sexual spores, genetically diff, variation, often prod as response to unfavourable changes in environment
asexual spores, gen identical
plants:
-can prod runners, stems growing away from plant across soil, with new strawberries growing identical
-bulbs from daffodils, each grow into a new one

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17
Q

what are xy chromos?

A

-they decide your sex
males: xy cromo, y causes male characteristics
female: xx allows female characteristics

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18
Q

what is an allele?

A

different versions of genes

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19
Q

what is a genotype?

A

combination of alleles you have

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20
Q

what is a phenotype?

A

characteristics you have

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21
Q

what did mendel discover?

A

-hereditary units and how characteristics followed from one generation to next
-inheritance of different characteristics

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22
Q

factors that contribute to species extinction:

A

-rapid habitat destruction/changes
-new predator kills them all
-new disease
-catastrophic event

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23
Q

what is speciation?

A

phenotypes of an organism changing to the extent that a new species is formed
development of a new species

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24
Q

what is selective breeding?

A

selective breeding is when humans breed plants and animals for particular genetic characteristics

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25
Q

examples of GM organisms:

A

-sheep
drugs in their milk, to be extracted and used to treat diseases
-bacteria
produce insulin, harvested for treating diabetes
-crops
size, quality of fruit
resistant to insects, diseases and herbicides

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26
Q

what is gene therapy?
drawbacks?
solution?

A

-transferring healthy version of gene to a person with faulty one
hard to fix this gene in every cell
-to transfer at early stage of development

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27
Q

how to transfer a gene from one organism to the other?

A

-find the gene we want, cut the section out (to isolate it) using enzymes
-insert it into a vector (a bacterial plasmid, or a virus)
-introduce it to other organism, whose cells will take up the vector and proteins that the gene codes for are made

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28
Q

what type of nucleus is used in adult cell cloning?

A

a diploid nucleus

29
Q

how are cuttings used to produce a clone of plant?

A

-take a small part of the plant you want to clone, (ideally growing shoot or a branch)
-place it in soil, along with nutrients and maybe hormones
-it will now grow into clone of original plant

30
Q

what is micropropagation?

A

using cell cultures to clone a plant

31
Q

micropropagation process:

A

cut small piece of plant tissue, explant, from tips of stems,
sterilise them to remove microorganisms.
place explants in petri dish that contains agar jelly, growth hormones, nutrients like glucose and mineral ions
once they grow a bit into calluses, transfer them to soil so they can grow into plantlets.
transfer them to their own pot
whole process done a reasonable temperature and that the plants get enough light and water

32
Q

suggest three ways fossils are created

A

-dead organisms, gradual replacement by minerals of slow decaying bones, teeth, shells

-casts and impressions

-no decay, amber and tar pits, no oxygen or moisture for decay
-really cold temperature, micro organisms that do decay cant survive
-peat bogs, too acidic

33
Q

what was wallace known for?

A

studying warning colouration in animals eg golden birdwing butterfly
his theory of speciation

34
Q

explain how two different species of rabbit could have developed from a common ancestor:

A

> Two populations became separated/isolation (by a geographical barrier like a river or mountain)
->These populations had different gene pools / developed different mutations
->Each population was exposed to different environmental conditions (e.g. weather, water levels etc)
->Natural selection occurs in the two populations…
which favours the alleles that best suit each environment
->So the two populations become genetically different
->Eventually they cannot interbreed to produce fertile offspring

35
Q

linnean system:

A

-domain
-kingdom
-phylum
-class
-order
-family
-genus
-species

36
Q

circumstances where fungi develop sexually and asexually:

A

-asexual to develop spores
-sexual to increase variation

37
Q

disadvantages of sexual reprod:

A

-two parents needed; difficult to do in endangered species
-more time and energy needed; fewer offspring produced

38
Q

describe fertilization and outcome:

A

-gametes fuse to restore normal chromosome number
-new cell starts to divide through mitosis (cells start to differentiate)

39
Q

what need to occur prior to mitosis:

A

-interphase; copies of genetic info made

40
Q

Explain how ethene is used in the transport of food:
-ripen

A

-ethene stimulates fruit ripening
-fruit picked when still hard
-so doesn’t get damaged in transport
-then softened b4 getting to consumers

41
Q

uses of ethene:

A

-stimulating the ripening of fruit
by stimulating an enzyme that causes this

42
Q

uses of gibberellins:

A

-induce germination
-inducing flowering
-growing larger fruit

43
Q

what is auxin?
eg?
-plants die

A

-a growth hormone
eg. can be used to grow tissue culture, cuttings (rooting powder)

-can kill weeds
if enough of it added to plant, disrupts growth pattern and it dies

44
Q

diff ways malaria parasites reproduce

A

-sexually in mosquito
-asexually in human (in liver and blood cells)

45
Q

diff ways fungi can reprod

A

–spores released asexually
-spores released sexually when conditions change to + variation and avoid extinction

46
Q

diff ways some plants reprod

A

-sexually, pollen
-strawberry/ prod asexually, runners, new identical plant

47
Q

what is evolution

A

change in the inherited characteristics of a population overtime by natural selection, can lead to new species

48
Q

process of speciation

A

-two populations of same species become geographically isolated
-show genetic variation
-natural selec happens diff in both pops. bcs of diff environments and selection pressures
-leads to genetic divergence
pop. cant interbreed anymore

49
Q

why cant decomposers work in glaciers, peat bogs

A

-extreme low temp
//
-extreme acidity

50
Q

what is stabilising selection

A

type of natural selection that favours the average phenotype

51
Q

what is directional selection

A

type of natural selection that favours an extreme phenotype

52
Q

what is rooting powder

A

(in cuttings) contains plant hormones, encourages plant to develop roots

53
Q

how does plant tissue culture work
-what is it used for

A

-few plant cells put into growth medium w/ hormones
-grow into new plants (clones)
-can be made very quickly, in very little space, all year
-used to prevent rare species dying

54
Q

process of animal cloning using embryo

A

-take egg and sperm from animal with wanted characteristics
-let fertilise
-develops into embryo (w/o specialising)
-use glass rod to split embryo into 2
-transplant embryos into two mothers, now will grow n develop

55
Q

disadvantage of embryo cloning

A

because it starts with gametes, not certain offspring will have wanted characteristics

56
Q

process of adult cell cloning

A

-remove a body cell from animal u want to clone
-remove nucleus
-take an unfertilised egg cell from same species
-dispose of nucleus is egg
-put nucleus of body cell into egg cell
-give cell an electric shock, forms embryo
-insert embryo into womb of adult female

57
Q

advantage of adult cell cloning

A

-from adult, so certain of what characteristics clone will have

58
Q

Who developed the ‘three-domain system’ of classification?

A

-carl woese

59
Q

why does tissue culture need:
several groups of cells

A

so many plants can grow

60
Q

why does tissue culture need:
nutrients in agar jelly

A

for respiration

61
Q

why does tissue culture need:
hormones

A

so differentiation occurs

62
Q

why does tissue culture need:
sterile conditions

A

to prevent growth of microorgs

63
Q

why does tissue culture need:
temp 20C

A

so optimum growth

64
Q

two things that increase risk of mutations

A

-carcinogens
harmful chemicals, i.e. smoke

-certain types of radiation

65
Q

mutations can cause proteins it codes for to have…

A

a different shape or function

66
Q

most mutations occur in

A

non - coding dna

67
Q

Describe how a change of one of the bases in the gene for an enzyme could affect the functioning of that enzyme

A

Change in a base changes the triplet/codon

This changes the amino acid it codes for

So there will be a different sequence of amino acids

This means the polypeptide will fold into a differently shaped protein/enzyme

The protein/enzyme may have a differently shaped active site

So it may no longer be complementary to the substrate

Which would mean it couldn’t form an enzyme-substrate complex

So it couldn’t catalyse the reaction as well / the rate would be lower

68
Q

how many amino acids in human body

A

20

69
Q

why do camels have a fat store

A

so it can me metabolised / respired to water

biology: paper 2 (3 decks)

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