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Unit 3 PPQ 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
State the number of ATP molecules that are made directly per ‘turn’ of the Krebs cycle. [1]
1
26
Explain why the two hydrogen acceptors NAD and FAD lead to the production of different numbers of ATP molecules. [1]
Carrier system involving NAD has 3 pumps but FAD has 2 pumps
27
What is a reflex action? [2]
Rapid response to a stimulus
28
Describe how a resting potential is maintained in a neurone. [2]
Na+ ions actively removed faster than K+ moved in | K+ diffuse out more rapidly than Na+
29
Describe how the potential across the membrane is reversed when an action potential is produced. [2]
Sudden change in permeability of membrane to Na+ | Na+ diffuse in
30
Explain why a myelinated axon uses less ATP to transmit a nerve impulse than a non-myelinated axon of the same diameter. [2]
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
31
What are the functions of the myelin sheath? | [3]
Electrical insulation Increase distance of local circuits Speed up transmission Protection of axon
32
Describe and explain the distribution of the bacteria in Engelmann's experiment. [3]
Photosynthesis produces oxygen in light dependent stage Aerobic bacteria needed Most bacteria move to blue and red regions Most photosynthesis occurs in these regions
33
A suitable control would be to repeat the experiment without the prism. Suggest how the bacteria would then be distributed. [1]
Evenly
34
Describe the process of ultrafiltration [6]
Afferent arteriole wider than efferent Pores in endothelium and basement membrane Urea and water pass through. Proteins doesn't pass through Filtration between podocytes
35
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]
+ve: thick peptidoglycan cell wall retains crystal violet stain -ve: lipopolysaccharide layer doesn't retain crystal violet stain but stains pink with safranin
36
State four ways that the agar types could differ in composition. [2]
Different pH Different C source Different n source Different growth factors
37
Explain the advantage of legumes having root nodules [3]
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
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]
Nitrosomonas converts ammonia to nitrated Nitrobacter converts nitrites to nitrates Which the plant can absorb from soil and use for nucleic acid synthesis
39
What units should be used on the axes of the AP graph? [2]
Membrane potential : mV | Time: ms
40
Describe the mechanisms that are triggered in the mammalian body when water intake is reduced. [6]
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
Suggest a condition which might stimulate ADH secretion. [1]
Blood loss
42
Describe the metabolism of pyruvate in the anaerobic respiration of glucose in yeast. [4]
Pyruvate converted to ethanal | With removal of CO2, ethanal reduced to ethanol using NADH
43
What is the role of ribulose bisphosphate carboxylase (RuBisCo) in the Calvin cycle? [1]
Catalyses the reaction between RuBP and carbon dioxide
44
Explain what is meant by cyclic photophosphorylation [2]
Light harvested by PSI | High energy electrons used to fuel H+ pump, creating EC gradient allowing ATP synthesis
45
Explain what is meant by non-cyclic photophosphorylation [4]
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
Explain how impulses are transmitted across a synapse. [3]
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
Explain the term carrying capacity. [2]
Maximum size of population that can be maintained
48
State two examples of density dependent factors that can affect the carrying capacity of an ecosystem. [2]
Disease Predation Accumulation of toxins
49
State one example of a density independent factor. [1]
Flood
50
Explain why the white matter is white and the grey matter is grey. [2]
White matter: made of myelin | Grey matter: made of cell bodies
51
What is the difference in function between an axon and a dendrite? [1]
Dendrite conducts impulse towards cell body | Axon conducts away from cell body
52
Explain how it is possible for Glycolysis, Calvin cycle and Krebs cycle to take place independently of each other in the same cell. [3]
Reactions take part in different parts within cell - Glycolysis - cytoplasm - Calvin cycle - chloroplast - Krebs cycle - mitochondrial matrix
53
Explain why photosynthesis is essential for the survival of animals on this planet. [2]
Produces Oxygen and organic materials
54
Why is magnesium required by plant cells? [1]
Chlorophyll
55
Suggest two ways by which excitatory drugs could change activity at the synapse [2]
Mimic normal transmitter Inhibit breakdown of transmitter Blocks uptake back into presynaptic knob increases number of receptors on post synaptic membrane
56
Suggest two ways by which inhibitory drugs could change activity at synapse [2]
Prevent exocytosis Bind with receptors on post synaptic membrane and block it Prevent Ca2+ entry into presynaptic knob
57
State the general role of muscles and glands in simple reflexes. [1]
Effectors which bring about the response
58
Explain how carbon dioxide is used in the production of glycerate-3-phosphate [2]
CO2 fixed with RuBp Catalysed by rubisco enzyme Unstable 6C splits into 2 glycerine-3-phosphates
59
Describe how glycerate-3-phosphate is converted to triose phosphate. [3]
GP reduced using NADPH ATP also required to supply energy NADPH/ATP used from light dependent reactions
60
State why only some of the triose phosphate produced by the Calvin cycle can be used to produce hexose phosphate. [1]
Some needed to regenerate RuBP
61
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]
NADH supplies H+ and brings high energy electrons which supply energy for H+ pumping
62
Explain the biochemical reasons for carrying out anaerobic respiration, despite the fact that lactate is toxic in high concentrations. [3]
``` 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
Suggest an advantage to mammals of excreting urine with a high concentration of urea. [2]
Less water lost in urine | Reduces risk of dehydration
64
Suggest how the relationship between Rhizobium and a legume species is beneficial to both organisms [2]
Rhizobium synthesises N containing compounds which plant uses to grow in low fertility soil Plant syntheses organic acids which pass to Rhizobium
65
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]
Impulses can't jump from node to node AP doesn't reach destination Remyelinate axons
66
Explain the function of the Loop of Henle in osmoregulation. [4]
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
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]
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
Briefly describe how reduced FAD and reduced NAD are used to create an electrochemical gradient. [4]
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
Explain why farmers want to drain their land. [2]
Provide aerobic conditions which encourages nitrification to increase soil fertility
70
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]
``` 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
Give two examples of what might cause a rise in blood solute concentration [1]
High solute intake | Vomiting
72
Explain the toxic effects of the organophosphates. [5]
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
Suggest some different mechanisms by which psychoactive drugs could decrease the rate of synaptic transmission. [4]
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
Explain how the structure of Gram-negative bacteria allows them to be resistant to certain antibiotics. [2]
lipopolysaccharide present in gram -ve | Extra physical barrier
75
It is not possible to culture viruses on sterile agar plates. Explain why. [1]
Only reproduce inside living cells
76
Describe how bacterial culture plates are safely disposed of. [2]
Put culture plates in autoclave | Heat to 121*C for 15-30 mins
77
Distinguish between an absorption spectrum and an action spectrum. [2]
Absorption: quantity of light absorbed at each wavelength Action: rate of photosynthesis at each wavelength
78
How would you expect the pH of the thylakoid space of the chloroplast to differ from the stroma? Explain your answer. [2]
More acidic because of high [H+]
79
Explain what is meant by the description ‘intracellular aerobic’. [2]
Lives inside cells | Requires oxygen
80
Explain advantage of using Bacillus thuringiensis (Bt) [2]
specific | non toxic to people
81
Explain disadvantage of Bt [2]
only effective for short time | Doesn't eradicate pet totally
82
Explain why large proteins are not usually found in the glomerular filtrate. [2]
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
Glucose is filtered out of the blood, but is not found in urine. Explain why glucose is not present in urine. [2]
In PCT, glucose is actively transported into bloodstream
84
Explain why a person with diabetes produces a larger volume of urine than a person that does not have diabetes. [3]
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
Describe the role of oxygen in aerobic respiration. [2]
Final electron acceptor in electron transport qchain
86
Where in a cell does anaerobic respiration occur? [1]
cytoplasm
87
Describe the importance of ATP to muscle cells. [1]
Provides energy for muscle contraction

Biology (1 decks)

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