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biology > topic 4 > Flashcards

topic 4 Flashcards

1
Q

species richness

A

the number of species in a habitat

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2
Q

biodiversity

A

variety of species in a habitat
variety of alleles in a population

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3
Q

diversity index

A

higher index, greater biodiversity
record number of species and the number of individuals of each species

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4
Q

describe how the scientific community critically evaluates new theories

A

communicating theory to specific community
peer review
checking of evidence to ensure its validity

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5
Q

explain the relationship between the structure and functions of a granum in photosynthesis

A
  • granum is formed from many layers of thylakoid membranes to increase surface area
  • thylakoid membranes contain chlorophyll to absorb light
  • electron carrier molecules in thylakoid membrane involved in ATP production
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6
Q

how are nitrate ions transported from the root to the leaves

A

through the xylem in water

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7
Q

monomer that makes cellulose

A

beta - glucose
Every other molecule is inverted
6 carbons

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8
Q

how are monomers in cellulose held together

A

by 1,4 glycosidic bonds in an unbranched chain
Alternative monomers are inverted

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9
Q

why do seeds need magnesium ions

A

magnesium is needed to make chlorophyll
because chlorophyll is required for photosynthesis
because shoots need chlorophyll to carry out photosynthesis to grow
(produce glucose during photosynthesis whcih is needed to produce cellulose for cell walls)

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10
Q

plant tissue that has lignin in its cell walls and the position

A

xylem on inside of vascular bundle. sclerenchyma on outer side of vascular bundle

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11
Q

role of middle lamella when plant cell completes mitosis

A

produced between adjacent new cells
because the middle lamella holds cell walsl together
Contains calcium pectate

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12
Q

effect of magensium defficiency on plants

A

limits production of chloroplasts
lack of glucose due to less photosynthesis
plant leaves may be yellow and plants may be small

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13
Q

why does sieve tube element not require RER and ribosomes

A

no transcription/mRNA so ribosomes not required for translation
no proteins will be synthesised to be processed in ER

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14
Q

polygenic meaning

A

a characteristic showing variation
caused by multiple genes at different loci

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15
Q

explain how epigenetic chanegs affect development of tissues in embryo

A

dna is wrapped around histones
histone modification affects binding of rna polymerase
methylation of dna affects transcription of genes
therefore gene expression is altered

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16
Q

difference between organ and tissue

A

tissue made up of one type of cell
organ made of different tissues

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17
Q

decisions society had to make about embryonic stem cells

A

they are totipotent
source of them has to be considered
moral issues as embryos destroyed
research establishments to be regulated

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18
Q

totipotent

A

a cell that has the ability to differentiate into all cell typesd

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19
Q

how do cells become specialised

A

chemicals cause some genes to be activated
only atcivated are transcribed producing specific mrna
mrna translated to produce specific proteins. this determines cell structure
causing cell modification/different types of cells being produced

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20
Q

amylopectin

A

alpha glucose

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21
Q

bonds between cellulose molcules in microfibril

A

hydrogen

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22
Q

role of middle lamella

A

produced between adjacent new cells becasue they hold cell walls togethr

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23
Q

starch

A

Polysaccharide made from alpha glucose
Monomers in the chains joined by 1.4 glycosidic links
Contains amylopectin which is branched, so it is rapidly hydrolysed
Insoluble so has no osmotic effect
Branches are joined to chains by 1,6 glycosidic links
Contains amylose which is coiled making starch making

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24
Q

sieve tube

A

provide a channel

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25
Q

positions in stems of schlerenchyma fibres and xylem vessels

A

schlerenchyma fibres on the outsid eof vascular bundels
xylem vessels on the inside of vascular bundeles

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26
Q

what contains nucelus

A

companion cell

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27
Q

the wall of the sieve tube contains

A

microfibrils, pectin, cellulose

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28
Q

if cells arent totipotent

A

some genes have already been aciutvated/deactivated
so cant specialsie

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29
Q

as we grow older

A

fewer mesenchymal stem cells
to replace cells in tissues

30
Q

stem cells

A

undifferentiated cell that can give rise to sepcialsiec cells that can divide to produce more cells

31
Q

Why use stem cells from patient than donor

A

Genetically identical cells to patient
No risk of rejection
Less risk of infection
No need to take immunosuppressant drugs

32
Q

Difference between pluripotent and totipotent

A

Totipotebt can give rise to any cell
Pluripotent can not give rise to extra embryonic tissues
Only totipotent cells can give rise to other totipotent cells
Totipotent cells can give rise to an entire human being while pluripotent cells can’t

33
Q

Explain why a second sperm cell cannot fertilise the egg cell.

A

cortical reaction
thickening/hardening of zona pellucida
so sperm cells cannot reach egg cell membrane

34
Q

Explain why DNA is replicated before mitosis begins

A

to ensure daughter cells are genetically identical
to ensure diploid number of chromosomes in eac daughter cell

35
Q

Describe how each gamete receives only one allele of each gene.

A

homologous chromosomes are separated from one another
sister chromatids are also separated from one another
spindle fibres pull the chromatids to opposite poles of the cell

36
Q

Describe how the acrosome is involved in the digestion of the zona pellucida

A

membrane of acrosome fuses with plasma membrane of sperm
releasing enzymes by exocytosis

36
Q

Explain how large numbers of cells with the same phenotype can be produced in a
tissue.

A

phenotype is determined by genotype and effect of environment
mitosis produces cells with the same genotype

37
Q

Describe one advantage and disadvantage of using ropes made from plant fibres rather than ropes from oil-based plastics

A

Advantage - being sustainable
Disadvantage - less strong

38
Q

Describe two aseptic techniques that should be used when working safely with bacteria

A

Boiling culture medium before use
‘Flaming’ of the instruments
Keeping lids off for the minimum time
Disinfecting the bench

39
Q

Explain why some bacteria can grow rapidly in skin wounds

A

The temperature is warm, increasing the rate of reactions in bacteria
Availability of energy source from blood
Availability of water for bacterial cell functions
Oxygen availability is good, allowing aerobic respiration

40
Q

Explain how breeding programmes in zoos maintain genetic diversity of captive populations

A

Animals are selected to prevent breeding between closely related individuals
A stud book is used to select individuals for mating
Exchange of animals between zoos

41
Q

Explain why healthy volunteers were give different doses of the drug or placebo

A

Check for side effects
Different doses to determine safe dose
Placebo to make sure that any side effects described were due to the drug

42
Q

Compare modern clinical trials with William Withering when he tested digitalis soup

A

Both trials used different doses
William withering didn’t use healthy volunteers and this drug trial did
William withering did not use a placebo while his trial did

43
Q

Describe how clinical trials of a vaccine would be conducted.

A

healthy volunteers are given the vaccine to test for side effects
they are tested for presence of antibodies to the virus
a group of people at risk of contracting the disease is given the vaccine
the number of people who develop the viral disease are monitored

44
Q

justify the use of vaccine, if clinical trials have not been done

A

large numbers of people died
health workers are in close contact with people suffering from the disease
side effects of the vaccine will not be worse than contracting the disease
vaccinating immediate family will help to reduce the spread of disease
if health workers were vaccinated they could care for more people

45
Q

suitable conditions for keeping seeds in a seed bank.

A

cold and dry

46
Q

Describe how aseptic techniques are used when handling bacterial cultures.

A

working near a bunsen burner to provide a convection current
sterilising work surfaces
sterilising equipment with heat
limiting time containers are open

47
Q

Explain the role that a placebo has in producing valid conclusions

A

provides a control group for comparison
ensuring that the active ingredient is causing the effect

48
Q

Explain the role that a double blind trial has in producing valid conclusions

A

neither doctors nor patietns know who has been given the actual drug
bias has been removed

49
Q

Explain why the agar plate was incubated at 25 °C.

A

allow bacteria to multiply
without encouraging pathogenic organisms

50
Q

Describe roles that zoos play in animal conservation

A

Protection - from hunting, poachers, vet care
Repopulation - increase numbers, breeding programmes, release back into wild
Education - conservation
Role in research - improving health

51
Q

Explain advantages of drying seeds before storage

A

Extends storage time of seeds
Because drying prevents germination of seeds
Prevents damage to seeds

52
Q

Benefits of conserving seeds

A

Prevent species from becoming extinct
Conserves genetic diversity
Protected from effects of climate change
Ensures future food security
Conserving species with medical properties
Safeguarding genes that may prove useful in the future
Allow reintroduction of species

53
Q

Explain why bacteria are able to multiply in bloodstream when they enter body

A

Warm conditions/water/glucose/ideal pH available
Suitable temperature/pH for bacterial enzymes
Glucose used for respiration
Amino acids used for growth

54
Q

Advantage of washing seeds

A

Washing with disinfectant will kill any microorganisms

55
Q

Why use of fibres from plants is sustainable

A

More plants can be grown
Plants are renewable source
Available to future generations

56
Q

Inbreeding effect on genetic diversity

A

Increases genetic diversity
Introduction of new alleles

57
Q

Explain how two species may have risen from a common ancestor

A

Mutation leads to variation within the population
Species with better adaption survive to reproduce
Giving rise to population with differing allele frequency
Populations become reproductively isolated

58
Q

Explain how molecular phylogeny shows populations are reproductively isolated

A

Comparing differences in DNA
comparison of amino acid sequences
Greater differences number, more likely they are reproductively isolated

59
Q

Heterozygosity index

A

Measure of genetic diversity within a species

60
Q

Species

A

Group of organisms that can interbreed to produce fertile offspring

61
Q

Explain how Hardy Weinberg equation shows natural selection occurring in the population

A

The equation shows allele frequency in a population
If natural selection is occurring there would be a change in allele frequency over timr

62
Q

Effect of calcium ion deficiency

A

Without calcium for the middle lamella new leaves cannot grow fully

63
Q

Lignin

A

Strength and waterproofing

64
Q

Why starch must be broken down before it can be used by cells

A

Produce glucose
Which is transported easily/soluble/used in respiration

65
Q

Companion cells

A

Contain nucleus

66
Q

Why are plant fibres strong

A

Cell wall made of strong cellulose microfibrils in a net like arrangement
Secondary thickening, cell wall which is thicker and has more lignin

67
Q

Why is plastic material only partially sustainable

A

Starch comes from plants that can be regrown
Not 100% starch so some oil-based products needed

68
Q

what happens during telophase

A

spindle fibres break aparrt
chromosomes decondense
nuclear envelope forms
two separate sets of chromosomes

69
Q

the importance of nitrate ions for plants

A

used to mkae amino acids
makes DNA
if lacking,growth is reduced

70
Q

how does dna methylation affect thr activation of a gene

A

methyl groups attahced to dna
prevents transcription
transcription factors cannot bind to dna
deactivating a gene

71
Q

compare and contrast the sturcture of unfertilised egg cell with zygote

A

both contain mitochodnria/rer in the cytoplasm
both possess cell cytoplasm/cell membrane
unfertilised egg has a haploid nucleus whereas zygote has a diploid nucleus
unfertilised egg cells contains cortical granules

biology (10 decks)

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