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Biology Exam Questions > Topic 5/6 > Flashcards

Topic 5/6 Flashcards

1
Q

Suggest why biofuels instead of burning petrol could reduce global warming (3)

A
  • burning fossil fuels releases CO2
  • CO2 is a green house gas
  • plants for biofuels take in CO2 for photosynthesis as they grow
  • No net CO2 change when biofuels burn
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2
Q

Describe the role of photolysis in non-cyclic phosphorylation

A
  • To split water
  • Electrons replace those lost in photosystems
  • Hydrogen ions used in production of NADPH
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3
Q

Explain the processes in the light-dependent stages of photosynthesis

A

Light energy used to excite electrons in chlorophyll

Photolysis used to produce oxygen, electrons and hydrogen ions

Electrons used to replace those lost in chlorophyll

ATP is produced by photophosphorylation

NADP is reduced to NADPH

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4
Q

Compare and contrast mitochondria and chloroplast (3)

A
  • Both have ribosomes
  • Bothe have double membrane
  • Chloroplasts have starch grains, mitochondria do not
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5
Q

Name one molecule produced in non-cyclic phosphorylation that is not produced in cyclic phosphorylation (1)

A

NADPH

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6
Q

Explain the role of PCR in DNA profiling (2)

A
  • Small samples of DNA can be obtained

- Number of copies need to be amplified so there is enough for analysis

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7
Q

Explain changes to sand dunes as distance from sea increases (6)

A
  • Soil depth increases with distance from the sea, as older dunes have more time to build up hummus
  • Organic material increases with distance from sea, older dunes allow for more organic matter to be decomposed and added
  • pH falls with distance from sea, as more hummus is added to sand
  • Percentage of bare rock decreases with distance from sea, as pioneer species break it down
  • types of species change as soils become more favourable
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8
Q

How can change in each of these factors affect estimated time of death (6)

  • Clothing
  • Position
  • Air movement
A
  • Estimate too short as clothing reduces heat loss, it traps heat
  • Estimate too short if body is curled up as heat loss is reduced, exposed surface area was smaller
  • Moving air speeds up heat loss, estimate too long
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9
Q

Explain how reduction in plant species affects animal species (3)

A
  • reduction of primary consumer
  • reduction of predators
  • change in distribution of plants changes distribution of herbivores
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10
Q

Explains effects of depth of water on NPP in a lake (4)

A
  • light reduced by deeper water
  • CO2 levels may be lower deeper down
  • temp may be lower deeper down
  • Photosynthesis reduces
  • less glucose converted into NPP
  • GPP reduces, respiration = same
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11
Q

Explain how a DNA profile can be made from a DNA sample (6)

A
  • multiple copies of DNA made using PCR
  • DNA primers, DNA polymerase and nucleotides are used to produce copies
  • Restriction enzymes cut different lengths of bases producing DNA fragments
  • fragments separated using gel electrophoresis
  • DNA placed on gel, electric current is applied
  • dye may be used before
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12
Q

Suggest how DNA fragments are made (3)

A
  • compare total number of bands
  • comparing position of bonds
  • comparing size of bonds
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13
Q

Explain how phagocytosis and lysosome action lead to antigen presentation of macrophages (4)

A
  • Pathogen taken in macrophage
  • fusion of phagosome with lysosome
  • pathogen digested by enzyme
  • part of pathogen has to be on surface of macrophage (antigens)
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14
Q

Suggest why NPP value would be useful to farmer who wants to use land for cattle (3)

A
  • cattle are primary consumers
  • therefor they gain energy available as NPP
  • farmer ensures enough NPP available for his cattle
  • may change to more NPP yielding crop
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15
Q

define each of the terms (3)
triplet code
non-overlapping
degenerate

A

each amino acid is coded by 3 bases

each code is discrete, each triplet gives a distinct code

more than one code used for same amino acid

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16
Q

Describe how translation of mRNA can synthesise part of a polypeptide molecule (5)

A
  • mRNA sequences attaches to ribosome
  • tRNA molecules attached to specific amino acid
  • anticodons on tRNA match to complimentary codons on mRNA
  • hydrogen bonds form between tRNA and mRNA
  • peptide bonds form between adjacent amino acids
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17
Q

two differences between genetic material of bacteria and viruses

A
  • bacteria have DNA, viruses can have DNA or RNA

- Bacteria have circular genetic material, viruses have linear

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18
Q

differences between cellulose and starch

A

cellulose - made of b-glucose, 1.4 glycosidic bonds, straight unbranched chain, alternating inverted glucoses

Starch - made of alpha glucose, 1.4 + 1.6 glycosidic bonds, branched due to amylopectin

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19
Q

describe role of lignin and xylem vessels (2)

A

for support

for waterproofing

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20
Q

explain artificial active immunity (3)

A
  • artificial is the idea of human intervention
  • active stimulation of primary immune response
  • immunity resulting in secondary immune response
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21
Q

How are bacterial cells killed by antibiotics (2)

A
  • weaken cell wall

- it bursts easily during division

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22
Q

explain why doctors are advised to limit prescription of antibiotics (2)

A
  • antibiotics are a selection
  • some bacteria are resistant to antibiotic
  • resistance bacteria survive and reproduce, antibiotic is ineffective
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23
Q

explain role of ATP and NADP in light-independent reaction (3)

A
  • both used in the conversion of GP to GALP
  • ATP provides energy for conversion
  • reduced NADP provides hydrogen
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24
Q

describe how membranes in chloroplast are involved in photosynthesis (3)

A
  • compartmentalisation from cytoplasm
  • thylakoid membrane site of light-dependent reaction
  • chlorophyll in thylakoid membrane
  • thylakoid membrane provides space for accumulation of H+ ions
  • stroma site of light-independent reaction
  • CO2 binds with RUBP
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25
Q

Importance of carbohydrate production in the thin lamina (2)

A
  • fast gas exchange
  • penetration of light
  • light used in photolysis
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26
Q

explain why theres a decrease in mass of leaves after decomposition (4)

A
  • bacteria release enzymes for decomposition
  • forms glucose that is soluble
  • some solute molecules taken up by organisms
  • water loss
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27
Q

suggest effect of increased temp in rate of decomposition of leaves (4)

A
  • increased temp increases rate of decomposition till optimum temp of enzymes
  • increased heat energy results in increased collisions between enzymes and substrate
  • increased temp increases rate bacteria reproduce
  • above certain temp decomposition stops
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28
Q

explain why phagocytosis only happens in response to some types of bacteria (3)

A
  • antigens/antibodies are proteins
  • antigens are specific to each bacteria
  • antibodies need to be complimentary to antigens so they can form bonds
  • some bacteria have different antigens
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29
Q

purpose of stop codon in translation (2)

A
  • used to stop further attachment of trna

- releases polypeptide from ribosome

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30
Q

what is meant by genetic diversity in a species (2)

A

variety of alleles in a gene pool

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31
Q

explain how energy from light is made available in ATP for synthesis of organic materials (6)

A
  • thylakoid membrane site of light dependent reaction, arranged in stacks called grana
  • light energy excites electrons
  • electrons released from chlorophyll using an electron carrier
  • NADP is reduced to NADPH, electron energy level falls
  • ATP synthase used in phosphorylation
  • electrons from photolysis loss those lost
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32
Q

describe how gel electrophoresis can be used to analyse DNA (3)

A
  • DNA extract extracted from blood
  • sample number amplified by PCR
  • potential current applied to separate stained fragments
  • bonds compared, similarity in bands indicates genetic similarity
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33
Q

explain what genetic mutation means (2)

A
  • change in base sequence of DNA

- leads to change of amino acid sequence in primary structure

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34
Q

suggest why effective treatment for HIV requires constant development of many new drugs (4)

A
  • HIV has many strains in infected person
  • some strains are resistant to specific drugs
  • these would survive if only one drug used
  • more drugs means more strains can be destroyed
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35
Q

Factors that could affect rate at which body cools after death (3)

A

body mass
ambient temperature
clothing

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36
Q

suggest why not all light hitting plant is used by chloroplast (2)

A

reflection

incorrect wavelength

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37
Q

discuss why production of biofuels may not be carbon neutral (5)

A
  • carbon neutral means CO2 produced equals CO2 used
  • forests are carbon sinks
  • deforestation increases net CO2
  • less plants means less CO2 used for photosynthesis
  • burning trees produced CO2
  • burning of biofuels produces CO2
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38
Q

explain the relationship between GPP and NPP (3)

A

NPP = GPP - R

  • GPP is energy lost
  • energy lost by heat
  • NPP is stored energy available for next trophic level
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39
Q

suggest how GALP can be used to synthesise cellulose in plant cell walls (4)

A
  • GALP is converted to glucose
  • b glucose
  • 1.4 glycosidic bonds form between b glucose molecules
  • cellulose is a polysaccharide
40
Q

Explain how combustion products from burning fossil fuels leads to global warming (4)

A
  • produces greenhouse gas CO2
  • these gases form layer in upper atmosphere
  • they absorb heat energy, reflect it to earth trapping it
  • more gases means more warming
41
Q

Explaining meaning of phagocytosis (2)

A
  • binding of pathogen to phagocyte wall

- pathogen engulfed into phagocyte using endocytosis

42
Q

Explaining mean of term non-specific response (2)

A
  • body defends itself against pathogen

- response is not dependent on specific pathogen

43
Q

explain meaning of term infection (2)

A

pathogens invading cells

44
Q

explain why ambient temp and core body temp are used to determine time of death of a person (3)

A
  • temp of body changes with time after death
  • core body temp depends on ambient temp
  • decomposition also depends on body temp
45
Q

describe and explain how global warming affects plant species (4)

A

D- extinction, change in number of plants

E- changes in rainfall potential, temp may be too hot for some species

46
Q

describe roles of template DNA strand and mRNA in determining primary structure of protein (4)

A
  • DNA contains base sequence coding for amino acids
  • DNA used in transcription to make mRNA
  • mRNA is a copy of DNA which moves out of nucleus
  • amino acids arranged in sequence
47
Q

describe role of bacteria in transferring carbon from forests to the atmosphere (3)

A
  • decomposition of organic matter
  • bacteria produce enzymes for digestion
  • respiration produces CO2
48
Q

Name type of reaction that takes place during decomposition (1)

A

hydrolysis

49
Q

suggest why more carbon enters the atmosphere than leaves (3)

A
  • rate of CO2 production exceeds rate of CO2 removal
  • using fossil fuels releases CO2
  • this carbon in fossil fuels was locked up for years
  • deforestation reduces photosynthesis
50
Q

mitochondria synthesises ATP, name other organelle than synthesises ATP (1)

A

Chloroplast

51
Q

how can hospitals reduce % of strains of bacteria resistant to antibiotics (2)

A
  • codes of conduct

- appropriate antibiotic given to patient

52
Q

Structures found: (3)
only in chloroplast
only in mitochondria
BOTH

A

grana
cristae
double membrane

53
Q

describe structure of triglyceride (3)

A
  • 1 glycerol and 3 fatty acids
  • ester bond between fatty acid and glycerol
  • triglyceride may be saturated or un-saturated
54
Q

explain how products of both light dependent and light independent reactions can be used to synthesise triglycerides (4)

A
  • reduced NADP is used
  • ATP from light dependent reaction used
  • light independent reaction produces GALP used in triglyceride
  • GALP converted to amino acids used to produce enzymes
55
Q

Suggest how vaccine against virus works (6)

A
  • vaccine needs to be injected into person
  • to stimulate primary response
  • macrophages present antigens in the vaccine to T helper cells
  • T helper cells release cytokines to stimulate T killer cells/B cells
  • memory T and B cells produced, remain in blood
  • immune response is faster due to memory cells
56
Q

explain why vaccines contain 3 strains of inactive version of a virus (4)

A
  • virus needs to be inactive so it does not cause disease
  • there are 3 different antigens
  • 3 different antibodies are produced
  • all 3 types of memory cells are produced in primary response
  • vaccine will result in long term immunity against all 3 strains
57
Q

explain importance of mitosis in the proliferation of activated T killer cells (2)

A
  • to increase the number of T killer cells
  • so T killer cells are antigen specific
  • so infected host cell can be destroyed faster
58
Q

explain how virus infected cells are destroyed by T killer cells (2)

A
  • release of chemicals from T killer cells

- enzymes cause lysis of host infected cells

59
Q

describe role of macrophage in activation of T killer cells (2)

A
  • Macrophage present antigens to T helper cells

- T helper cells release cytokines to activate T killer cells

60
Q

describe role of macrophage in destruction of viruses (3)

A
  • phagocytosis of virus
  • destruction of virus by enzymes
  • enzymes breakdown protein coat
61
Q

describe how virus gives active immunity (3)

A
  • using harmless form of microorganism
  • vaccine contains antigens
  • T/B memory cells are produced
  • Body able to produce antibodies faster upon second infection
62
Q

state how useful body temp and state of decomposition are in determining time of death (2)

A

Temp only useful for 24 hours after death, it drops after death

Body has a sequence of decomposers, not useful if body is fully decomposed

63
Q

environmental factors that effect rigor mortis (2)

A

Physical damage

external temp

64
Q

distinguish between bacteriostatic and bactericidal antibodies (2)

A
  • bacteriostatic antibodies prevent bacteria from dividing

- Bactericidal antibodies kill the bacteria

65
Q

why are antibiotics not used to treat viral infections (1)

A

Viruses are non-living

66
Q

explain why pollen in peat bogs is preserved for years (4)

A
  • lack of decomposition
  • due to lack of bacteria involved in decomposition
  • fewer enzymes, also few due to increased pH reducing enzyme activity
  • Bacteria cant break cell wall of pollen
67
Q

describe structure of cellulose in cell wall (4)

A
  • cellulose is a polymer of b glucose
  • has 1.4 glycosidic bonds
  • cellulose may be arranged in microfibrils joined by hydrogen bonds
68
Q

describe investigation to study effect of temp on time taken for maggot to become pupa (5)

A
  • use range of temperatures
  • control temp using water baths
  • time starts when first egg hatches into instar maggot
  • end time when maggot begins to pupate
  • use at least 3 maggots for each temp
69
Q

suggest why treatment with antibodies may be ineffective against dormant bacteria and tubercles (2)

A
  • bacteria needs to be accessible to antibodies

- bacteria inside macrophages

70
Q

explain how person can develop artificial active immunity following vaccination (3)

A
  • dead pathogen put in person
  • Macrophages act as APC and T helper cells are activated
  • B cell activated, act as APC
  • T killer cells activated by cytokines released by B cells
71
Q

suggest why common cold viruses cant infect cells if they land on unbroken skin (2)

A

Skin is a barrier

skin lacks receptors virus can bind to

72
Q

what is meant by the term reproductively isolated populations (3)

A
  • no interbreeding between organisms
  • due to geographical barrier
  • each population has a discrete gene pool, different alleles
73
Q

explain why DNA is described as doubled stranded polynucleotide (3)

A
  • made by two strands joined together by hydrogen bonds between bases
  • polynucleotide of many nucleotides
  • nucleotides linked by phosphodiester bonds
74
Q

suggest how anti-virus drugs work in treatment of patients with HIV (5)

A
  • drug prevents viral replication
  • T helper cells will not be destroyed by virus particles
  • reverse transcriptase is inhibited
  • viral DNA can not be made from Viral RNA
  • Integrase is inhibited
75
Q

explain why using biofuels instead of petrol reduces global warming (3)

A
  • Using biofuels releases CO2
  • CO2 is a green house gas
  • CO2 is taken up in photosynthesis in production process
  • no net change in CO2
76
Q

explain how glycoproteins enable HIV to infect human cells (3)

A
  • used for attachment to cell membrane

- on T helper cells

77
Q

describe structure of an enzyme (3)

A
  • globular proteins
  • has an active site
  • charged R groups project on the outside of enzyme
78
Q

describe how to carry out study of distribution of plant species from a glacier (4)

A
  • Use a transact
  • Use quadrate along transact to collect samples
  • systematic samples taken ever n meters
  • estimate number of plants for entire area
79
Q

problems doctors face in prescribing antibiotics for wounds (2)

A
  • doctors dont know what bacteria caused it
  • dont know which antibiotic will be effective
  • wrong prescription can increase antibiotic resistance
80
Q

define global warming (2)

A

increase in average temperature of the earths atmosphere

81
Q

explain why rainfall can effect tree ring width (3)

A
  • water used in photolysis
  • glucose made contributes to growth
  • increase in xylem size results in increased tree ring width
82
Q

advantage of skin flora in wound (2)

A
  • they reduce number of foreign bacteria in the wound

- by competing with them for space

83
Q

explain appearance of wound during inflammatory phase (2)

A

swollen due to increased flood flow to area

84
Q

explain role of mitosis in healing a wound (2)

A
  • results in skin cells to repair wound

- produces identical cells so skin carries same function

85
Q

describe structure of fibrous protein (2)

A
  • long polypeptide chain

- no tertiary structure

86
Q

suggest why scientists many not agree reduction of burning fossil fuels will prevent further global warming (6)

A
  • CO2 produced by burning fossil fuels
  • no direct evidence that increased CO2 leads to global warming
  • CO2 is also released by respiration
  • removal of carbon sinks increase CO
  • other greenhouse gases are being released from other sources eg methane from melting ice
  • scientists may be biased
87
Q

suggest why plant community changes over time (5)

A
  • lichens and moss are a pioneer community
  • able to grow with no soil
  • they break up rock layer forming shallow soils
  • able to grow in shallow soil
  • changes in soil structure allow trees to grow
88
Q

why is a climax community stable (4)

A
  • has high biodiversity
  • balance equilibrium of species
  • there is a dominant plant or species
  • Stable if there are no changes to environment
89
Q

suggest how same gene gives rise to different proteins (6)

A
  • mRNA is spliced, some bases added or removed
  • length of mRNA will be different
  • longer mRNA has more codons
  • more amino acids during translation
90
Q

what fibrous protein does the skin contain (1)

A

keratine

91
Q

describe structure and properties of fibrous proteins (4)

A
  • mainly secondary structure
  • made of long polypeptides
  • Has cross-linked polypeptide chains
  • insoluble, strong
92
Q

explain how CO2 is removed from air into oceans (2)`

A
  • carbon dissolves in water for light independent reaction
93
Q

explain difference between GPP and NPP (2)

A
  • GPP is organic matter produced due to photosynthesis

- NPP is biomass remaining after respiration

94
Q

explain how plant material is changed during decomposition (6)

A
  • release of enzymes from bacteria
  • bonds are hydrolised
  • cellulose is digested
  • products absorbed by decomposers may be used for respiration
  • CO2 released by decomposers
95
Q

Define gross primary productivity (2)

A

rate at which energy is incorperated into organic matter by plants

96
Q

explain how conditions in compost affect decomposition of a body

A
  • decomposes faster
  • enzymes work faster
  • only occurs if temp was above ambient temp and below opt temp of enzyme
  • core temp will drop slower
  • putrefaction would be faster
  • maggots hatch faster
97
Q

how microscope slide positioned to observe mitosis of B cells (3)

A
  • sample of b cells from lymph nodes
  • stained with toluidine blue
  • heat cells, add HCL and observe under microscope

Biology Exam Questions (4 decks)

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