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Unit 3 PPQ Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Some bacteria are described as facultative anaerobes and some as obligate anaerobes. State the difference between these two types of bacteria. [2]

A

Facultative anaerobes, grow better in presence of oxygen but can survive without it
Obligate anaerobes can’t survive in presence of O2

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2
Q

Complete the bullet points below to give four other methods which you would use to prevent contamination when plates were being inoculated. [4]

A

Flame mouth of tube
Flame inoculating loop
Lift Petri dish lid at an angle
Don’t put culture bottle cap onto bench

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3
Q

The plates are secured with adhesive tape and incubated at 25°C. Explain why the plates should not be:
I sealed completely from the air; [1]
II incubated at 37°C. [1]

A

I anaerobic conditions encourage pathogenic bacteria

II encourages human pathogenic bacteria

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4
Q

ATP is often described as the ‘universal energy currency’.

Explain why it is described in this way. [2]

A

Supplies energy for all reactions in all cells

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5
Q

Give three advantages of ATP for its function as a source of energy. [3]

A 
Soluble 
Easily transported across membranes
Easily hydrolysed
Energy released in useable amounts
Only one enzyme needed
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6
Q

Describe and explain how a parasite, such as the pork tapeworm, which lives in anaerobic conditions in the human gut can produce ATP. [4]

A

Glycolysis takes place whereby glucose is converted to pyruvate
Substrate level phosphorylation occurs which converts pyruvate into lactic acid, from NADH so NAD is regenerated
Regeneration allows glycolysis to continue

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7
Q

Atrazine is a commonly used weedkiller. It prevents non-cyclic photophosphorylation from taking place. Using your knowledge of the light independent stage of photosynthesis, explain why its use leads to the death of a plant. [5]

A 
Light dependent reactions don't take place
ATP and NADH no produced
Calvin cycle stops
GP not converted to TP
No hexose sugar made
No respiratory susbtrate
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8
Q

State three functions of a synapse. [3]

A

Transmit impulses between neurones
Filter out low level stimulations
Protect from over stimulations

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9
Q

State two differences between the structure or functioning of the neurones in a vertebrate and in the nerve net found in organisms such as jellyfish [2]

A

Nerve net: neurones shorter, branched, can transit in both directions, slower transmission, non-myelinated
* reverse for vertebrate

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10
Q

Suggest why myelinated fibres are never less than 1.0 μm in diameter. [1]

A

Conduct slower than non-myelinated

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11
Q

Suggest three ways in which organisms have been able to speed up the rate of conduction of the nerve impulse. [3]

A

Increase diameter
Myelination
Longer distance between nodes
Higher body temperature

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12
Q

In which region of the kidneys is the Bowman’s capsule found? [1]

A

Cortex

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13
Q

Explain why the urea concentration is higher towards the end of the PCT than the start [1]

A

Water has be absorbed

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14
Q

Explain how the kidney of Kangaroo rat which is found in desert regions are adapted to reduce the volume of urine produced. [2]

A

Loop of hence longer
Counter current multiplier
Creates region of very low water potential around loop
More water reabsorbed from collecting duct

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15
Q

Suggest how desert animals are able to obtain water from dry seeds. [2]

A

Metabolic water
Respiration
Fats

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16
Q

Apart from water and glucose, name two substances which will be present in the filtrate. [1]

A

Urea and small proteins

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17
Q

Explain the effect of a large loss of blood from the body on the filtration rate. [2]

A

Blood pressure decreased

Less filtrate forms

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18
Q

Describe the function of chlorophyll a. [1]

A

absorbs light energy of specific wavelength

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19
Q

Explain why it is an advantage for a leaf to contain more than one pigment. [2]

A

Any one chlorophyll absorbs in limited part of spectrum
Addition pigments increase range of wavelengths from which energy can be obtained
Increased rate of photosynthesis

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20
Q

Why do most leaves characteristically have a green colour? [1]

A

All wavelengths except green are absorbed

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21
Q

Describe the relationship between the absorption spectrum and the action spectrum and explain what this relationship tells us about light absorption and photosynthesis.
[2]

A

Peaks corresponds

suggests pigments responsible are responsible for light absorption which is then used in photosynthesis

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22
Q

State exactly where in the chloroplast you would expect to find photosystems. [1]

A

thylakoid membranes

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23
Q

State the two products of the light dependent stage of photosynthesis that are required
in the Calvin cycle. [2]

A

NADPH

ATP

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24
Q

Describe the reactions that link glycolysis to the Krebs cycle. [3]

A

Pyruvate converted to acetate by reduction of NAD and decarboxylation
Acetate combines with coenzyme A to form Acetyl CoA

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25
Q

State the number of ATP molecules that are made directly per ‘turn’ of the Krebs cycle. [1]

A

1

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26
Q

Explain why the two hydrogen acceptors NAD and FAD lead to the production of different numbers of ATP molecules. [1]

A

Carrier system involving NAD has 3 pumps but FAD has 2 pumps

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27
Q

What is a reflex action? [2]

A

Rapid response to a stimulus

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28
Q

Describe how a resting potential is maintained in a neurone. [2]

A

Na+ ions actively removed faster than K+ moved in

K+ diffuse out more rapidly than Na+

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29
Q

Describe how the potential across the membrane is reversed when an action potential is produced. [2]

A

Sudden change in permeability of membrane to Na+

Na+ diffuse in

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30
Q

Explain why a myelinated axon uses less ATP to transmit a nerve impulse than a non-myelinated axon of the same diameter. [2]

A

ATP required for active transport
Na+ ions moved out only at nodes in myelinated
Na+ moved out along whole length of axon in non-myelinated

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31
Q

What are the functions of the myelin sheath?

[3]

A

Electrical insulation
Increase distance of local circuits
Speed up transmission
Protection of axon

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32
Q

Describe and explain the distribution of the bacteria in Engelmann’s experiment. [3]

A

Photosynthesis produces oxygen in light dependent stage
Aerobic bacteria needed
Most bacteria move to blue and red regions
Most photosynthesis occurs in these regions

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33
Q

A suitable control would be to repeat the experiment without the prism. Suggest how the bacteria would then be distributed. [1]

A

Evenly

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34
Q

Describe the process of ultrafiltration [6]

A

Afferent arteriole wider than efferent
Pores in endothelium and basement membrane
Urea and water pass through. Proteins doesn’t pass through
Filtration between podocytes

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35
Q

Use your knowledge of the structure of the bacterial cell wall to explain the differences in the appearance of gram positive and negative bacteria when stained with the Gram staining technique. [3]

A

+ve:
thick peptidoglycan cell wall retains crystal violet stain
-ve:
lipopolysaccharide layer doesn’t retain crystal violet stain but stains pink with safranin

36
Q

State four ways that the agar types could differ in composition. [2]

A

Different pH
Different C source
Different n source
Different growth factors

37
Q

Explain the advantage of legumes having root nodules [3]

A

Contain nitrogen fixing bacteria such as rhizobium which allows some ammonium ions to pass into the plant
This allows plant to grow in poor soil, using it for amino acid synthesis

38
Q

Nitrosomonas and Nitrobacter are two groups of bacteria which carry out nitrification. Explain this process and why it is so important to soil fertility. [3]

A

Nitrosomonas converts ammonia to nitrated
Nitrobacter converts nitrites to nitrates
Which the plant can absorb from soil and use for nucleic acid synthesis

39
Q

What units should be used on the axes of the AP graph? [2]

A

Membrane potential : mV

Time: ms

40
Q

Describe the mechanisms that are triggered in the mammalian body when water intake is reduced. [6]

A

Low water levels in blood detected by osmoreceptors in hypothalamus
More ADH secreted from posterior pituitary gland
travels in blood to DCT/CD Becomes more permeable as more aquaporins form
􏰀Water absorbed because of low Ψ in medulla

41
Q

Suggest a condition which might stimulate ADH secretion. [1]

A

Blood loss

42
Q

Describe the metabolism of pyruvate in the anaerobic respiration of glucose in yeast. [4]

A

Pyruvate converted to ethanal

With removal of CO2, ethanal reduced to ethanol using NADH

43
Q

What is the role of ribulose bisphosphate carboxylase (RuBisCo) in the Calvin cycle? [1]

A

Catalyses the reaction between RuBP and carbon dioxide

44
Q

Explain what is meant by cyclic photophosphorylation [2]

A

Light harvested by PSI

High energy electrons used to fuel H+ pump, creating EC gradient allowing ATP synthesis

45
Q

Explain what is meant by non-cyclic photophosphorylation [4]

A

Light harvested by both PSII
High energy electrons passed to carriers and replaced in PSII by photolysis of water
Electrons replaced in PSI from PSII

46
Q

Explain how impulses are transmitted across a synapse. [3]

A

Transmitter substances synthesised in synaptic knob
Impulse causes secretory vesicle to migrate to presynaptic membrane
Ca ions to rush in
Vesicle fuses with membrane discharges transmitter by exocytosis
Diffusion of transmitter substance across cleft Transmitter binds to post-synaptic membrane
Stimulates depolarisation

47
Q

Explain the term carrying capacity. [2]

A

Maximum size of population that can be maintained

48
Q

State two examples of density dependent factors that can affect the carrying capacity of an ecosystem. [2]

A

Disease
Predation
Accumulation of toxins

49
Q

State one example of a density independent factor. [1]

A

Flood

50
Q

Explain why the white matter is white and the grey matter is grey. [2]

A

White matter: made of myelin

Grey matter: made of cell bodies

51
Q

What is the difference in function between an axon and a dendrite? [1]

A

Dendrite conducts impulse towards cell body

Axon conducts away from cell body

52
Q

Explain how it is possible for Glycolysis, Calvin cycle and Krebs cycle to take place independently of each other in the same cell. [3]

A

Reactions take part in different parts within cell

  • Glycolysis - cytoplasm
  • Calvin cycle - chloroplast
  • Krebs cycle - mitochondrial matrix
53
Q

Explain why photosynthesis is essential for the survival of animals on this planet. [2]

A

Produces Oxygen and organic materials

54
Q

Why is magnesium required by plant cells? [1]

A

Chlorophyll

55
Q

Suggest two ways by which excitatory drugs could change activity at the synapse [2]

A

Mimic normal transmitter
Inhibit breakdown of transmitter
Blocks uptake back into presynaptic knob
increases number of receptors on post synaptic membrane

56
Q

Suggest two ways by which inhibitory drugs could change activity at synapse [2]

A

Prevent exocytosis
Bind with receptors on post synaptic membrane and block it
Prevent Ca2+ entry into presynaptic knob

57
Q

State the general role of muscles and glands in simple reflexes. [1]

A

Effectors which bring about the response

58
Q

Explain how carbon dioxide is used in the production of glycerate-3-phosphate [2]

A

CO2 fixed with RuBp
Catalysed by rubisco enzyme
Unstable 6C splits into 2 glycerine-3-phosphates

59
Q

Describe how glycerate-3-phosphate is converted to triose phosphate. [3]

A

GP reduced using NADPH
ATP also required to supply energy
NADPH/ATP used from light dependent reactions

60
Q

State why only some of the triose phosphate produced by the Calvin cycle can be used to produce hexose phosphate. [1]

A

Some needed to regenerate RuBP

61
Q

The proton gradient can be maintained as long as reduced NAD is available in the mitochondrion. Explain the reasons for reduced NAD being required to maintain a proton gradient. [2]

A

NADH supplies H+ and brings high energy electrons which supply energy for H+ pumping

62
Q

Explain the biochemical reasons for carrying out anaerobic respiration, despite the fact that lactate is toxic in high concentrations. [3]

A 
Allows NADH to be converted back to NAD+
Allows ATP production 
Allows glycolysis to continue
No O2 to act as final electron acceptor
NADH uses pyruvate
63
Q

Suggest an advantage to mammals of excreting urine with a high concentration of urea. [2]

A

Less water lost in urine

Reduces risk of dehydration

64
Q

Suggest how the relationship between Rhizobium and a legume species is beneficial to both organisms [2]

A

Rhizobium synthesises N containing compounds which plant uses to grow in low fertility soil
Plant syntheses organic acids which pass to Rhizobium

65
Q

Multiple sclerosis is a progressive, degenerative disease of the nervous system in which the myelin is destroyed. Symptoms include increasing muscle weakness and loss of vision. Suggest an explanation for these symptoms and a medical treatment for it. [2]

A

Impulses can’t jump from node to node
AP doesn’t reach destination
Remyelinate axons

66
Q

Explain the function of the Loop of Henle in osmoregulation. [4]

A

Water leaves descending limb
Na+ retained in descending limb
At apex, Na+ is very concentrated
Na+ actively transported out of ascending limb, lowering water potential of medulla
Ascending limb doesn’t allow escape of water

67
Q

Give three examples of minerals taken up from the soil and state what molecules are produced when each example combines with the products of the light independent stage. [3]

A

Synthesis of amino acids using a nitrogen source
Synthesis of phospholipids with phosphate
Synthesis of chlorophyll with magnesium
Synthesis of nucleotides with n source

68
Q

Briefly describe how reduced FAD and reduced NAD are used to create an electrochemical gradient. [4]

A

NADH and FADH2 pass electrons to ETC
High energy electrons provide energy to power proton pumps on cristae with pump H+ into inter-membrane space
NADH powers all 3 pumps, FADH2 passes to 2nd pump

69
Q

Explain why farmers want to drain their land. [2]

A

Provide aerobic conditions which encourages nitrification to increase soil fertility

70
Q

Patients with severe kidney disease may be told to follow a protein controlled diet with low sodium chloride (salt) intake. Using your knowledge of the role of the kidney, suggest why this diet is recommended. [3]

A 
Protein controlled:
High proteins means more urea which can't be removed
Low NaCl:
Excess salt doesn't need to be removed
High salt causes high blood pressure
71
Q

Give two examples of what might cause a rise in blood solute concentration [1]

A

High solute intake

Vomiting

72
Q

Explain the toxic effects of the organophosphates. [5]

A

Acetylcholine normally hydrolysed by acetylcholinesterase
Organophosphates prevent breakdown of acetylcholine
So acetylcholine remains bound to receptors on post-synaptic membrane
So synaptic transmission continues to be generated
Uncontrolled contractions of intercostal muscles

73
Q

Suggest some different mechanisms by which psychoactive drugs could decrease the rate of synaptic transmission. [4]

A

Some drugs prevent synthesis of neurotransmitter
Blocking of Ca2+ uptake
Inhibition of exocytosis of neurotransmitters
Blocking receptors in post synaptic membrane preventing neurotransmitters binding to them
Sodium ion channels change shape

74
Q

Explain how the structure of Gram-negative bacteria allows them to be resistant to certain antibiotics. [2]

A

lipopolysaccharide present in gram -ve

Extra physical barrier

75
Q

It is not possible to culture viruses on sterile agar plates. Explain why. [1]

A

Only reproduce inside living cells

76
Q

Describe how bacterial culture plates are safely disposed of. [2]

A

Put culture plates in autoclave

Heat to 121*C for 15-30 mins

77
Q

Distinguish between an absorption spectrum and an action spectrum. [2]

A

Absorption: quantity of light absorbed at each wavelength
Action: rate of photosynthesis at each wavelength

78
Q

How would you expect the pH of the thylakoid space of the chloroplast to differ from the stroma? Explain your answer. [2]

A

More acidic because of high [H+]

79
Q

Explain what is meant by the description ‘intracellular aerobic’. [2]

A

Lives inside cells

Requires oxygen

80
Q

Explain advantage of using Bacillus thuringiensis (Bt) [2]

A

specific

non toxic to people

81
Q

Explain disadvantage of Bt [2]

A

only effective for short time

Doesn’t eradicate pet totally

82
Q

Explain why large proteins are not usually found in the glomerular filtrate. [2]

A

Gaps in capillary wall are too small to allow large proteins to pass through
Basement membrane has pores which are too small to allow proteins to pass through

83
Q

Glucose is filtered out of the blood, but is not found in urine. Explain why glucose is not present in urine. [2]

A

In PCT, glucose is actively transported into bloodstream

84
Q

Explain why a person with diabetes produces a larger volume of urine than a person that does not have diabetes. [3]

A

High glucose levels lower water potential of tissue fluid in collecting duct
Less of a water potential gradient
Less water moves from CD into medulla by osmosis

85
Q

Describe the role of oxygen in aerobic respiration. [2]

A

Final electron acceptor in electron transport qchain

86
Q

Where in a cell does anaerobic respiration occur? [1]

A

cytoplasm

87
Q

Describe the importance of ATP to muscle cells. [1]

A

Provides energy for muscle contraction

Biology (1 decks)

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