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Biology AQA A Level > Topic 5 Exam Questions: Energy Transfers In/Between Organisms > Flashcards

Topic 5 Exam Questions: Energy Transfers In/Between Organisms Flashcards

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1
Q

5.1 Photosynthesis

In photosynthesis, which chemicals are needed for the light-dependent reaction? (1)

A

NADP, ADP, Pi and water

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2
Q

5.1 Photosynthesis

Describe what happens during photoionisation in the light-dependent reaction. (2)

A
  1. Chlorophyll absorbs light OR Light excites/moves electrons in chlorophyll
  2. Electron/s are lost OR (chlorophyll) becomes positively charged
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3
Q

5.1 Photosynthesis

Describe the method (chromatography) used to separate the pigments after the solution of pigments had been applied to the origin. (2)

A
  1. Level of solvent below origin/line
  2. Remove/stop before (solvent) reaches top/end
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4
Q

5.1 Photosynthesis

The pigments in leaves are different colours. Suggest and explain the advantage of having different coloured pigments in leaves. (1)

A

(Absorb) different wavelengths (of light) for photosynthesis

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5
Q

5.1 Photosynthesis

Exposing plants to high temperatures for prolonged periods of time decreases the LDR, explain why this leads to a decrease in the LIR (2)

A
  1. (Less/no) ATP
  2. (Less/no) reduced NADP
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6
Q

5.1 Photosynthesis

A decrease in activity of enzyme rubisco due to heat stress limits the rate of photosynthesis. Explain why. (2)

A
  1. (Less/no) carbon dioxide (reacts) with RuBP
  2. (Less/no) GP
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7
Q

5.1 Photosynthesis

Where is rubisco found in a cell? (1)

A

Stroma (of/in chloroplast)

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8
Q

5.1 Photosynthesis

The solution the students used to produce the chloroplast suspension has the same water potential as the chloroplasts. Explain why this is important. (2)

A
  1. Osmosis doesn’t occur
  2. Chloroplast / organelle doesn’t burst / lyse/ shrivel / shrink
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9
Q

5.1 Photosynthesis

Explain how chemicals which inhibit the decolorisation of DCPIP could slow the growth of weeds. (2)

A
  1. Less/no ATP produced
  2. Less/no reduced NADP produced
  3. Less/no GP reduced/converted to TP
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10
Q

5.1 Photosynthesis

In natural ecosystems, most of the light falling on producers is not used in photosynthesis. Explain why. (2)

A
  1. (Light is) reflected
  2. (Light is) wrong wavelength
  3. (Light) missed chlorophyll/ chloroplasts/ photosynthesis tissue
  4. CO2 conc or temperature is a limiting factor
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11
Q

5.1 Photosynthesis

Name the two products of the light-dependent reaction required for the light-independent reaction. (2)

A
  1. ATP
  2. NADPH / reduced NADP
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12
Q

5.1 Photosynthesis

Atrazine binds to proteins in electron transfer chain in chloroplasts of weeds, reducing the transfer of electrons down the chain. Explain how this reduced the rate of photosynthesis in weeds. (4)

A
  1. Reduced transfer of protons across thylakoid membrane OR reduced chemiosomotic gradient / proton gradient across thylakoid membrane
  2. (So) less ATP produced
  3. (So) less reduced NADP produced
  4. (So) light-independent reaction slows / stops OR less reduction of GP to triose phosphate
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13
Q

5.2 Respiration

Describe the process of glycolysis. (4)

A
  1. Phosphorylation of glucose using ATP
  2. Oxidation of triose phosphate to pyruvate
  3. Net gain of ATP
  4. NAD reduced
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14
Q

5.2 Respiration

Malonate inhibits a reaction in the Krebs cycle. Explain why malonate decreases the uptake of oxygen in a respiring cell. (2)

A
  1. Less/no reduced NAD/coenzymes OR fewer/no hydrogens/electrons removed (and passed to electron transfer chain)
  2. Oxygen is the final/terminal (electron) acceptor
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15
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. (2)

A
  1. Regenerates/produces NAD OR oxidises reduced NAD
  2. (So) glycolysis continues
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16
Q

5.2 Respiration

Describe the advantage of the Bohr effect during intense exercise. (2)

A
  1. Increases dissociation of oxygen
  2. For AEROBIC respiration at the tissues/muscles/cells
    OR anaerobic respiration delayed at the tissues/muscles/cells
    OR less lactate at the tissues/muscles/cells
17
Q

5.2 Respiration
Increase in intensity of exercise causes increase in CO2 produced. Suggest ONE physiological change that would cause this result. Explain how the physiological change would allow for the removal of the increase in the volume of carbon dioxide produced. (2)

A

Physiological change : Increase in breathing (rate)
Explanation: similar/same pCO2 per breath, but more breaths

OR 1. Increase in tidal volume
2. Similar/same pCO2 per breath, but increased volume per breath

18
Q

5.2 Respiration

At more than 80% of maximum muscle effort, ATP can only be made for a limited time. Suggest ONE reason why. (1)

A

Muscle fibres have a limited amount of phosphocreatine

19
Q

5.2 Respiration

Suggest an explanation for the effect of temperature on the rate of carbon dioxide release in an insect. (3)

A
  1. Enzymes/metabolism faster
  2. Higher rate of respiration and carbon dioxide production/release
  3. Spiracles open more often/remain open to excrete/ get rid of carbon dioxide/get more oxygen
20
Q

5.3 Energy and Ecosystems

Freshwater marshes have one of the highest rates of GPP and NPP. Carbon use efficiency (CUE) is the ratio of NPP:GPP. Fresh water marshes have a high CUE. Explain why freshwater marshes have a high CUE and the advantage of this. (2)

A
  1. Low respiration - explanation
  2. More growth/biomass/colonisation - advantage
21
Q

5.3 Energy and Ecosystems

Fresh water mash soils and usually waterlogged with anaerobic conditions suggest why these soils contain relatively high conc of ammonium compounds and low conc of nitrate ions and nitrite ions. (2)

A
  1. Less nitrification OR fewer/less nitrifying bacteria OR notification/nitrifying Bacteria require oxygen/aerobic conditions
  2. (Less) oxidation/conversion of ammonium (ions) to nitrite (ions) add and nitrate (ions)
  3. More denitrification OR more active denitrifying bacteria OR Denitrifying bacteria don’t require oxygen/ require anaerobic conditions
  4. (So more) nitrate (ions) reduced/converted to nitrogen (gas)
22
Q

5.3 Energy and Ecosystems

A scientist determined the dry s of soo poach plants. First he heated each sample to 80°C for 2 hours. Suggest how he could ensure that all water from sample has been removed (2)

A
  1. Weigh and heat
  2. (Until) mass is constant
23
Q

5.3 Energy and Ecosystems

Suggest one way in which an increase in the up pale of phosphate cooks increase plant growth. (1)

A

Used to produce named phosphate compound in cells
E.g ATP/DNA/RNA/ADP/TP/GP/ phospholipids etc.

24
Q

5.3 Energy and Ecosystems

Explain why an increase in shot biomass can be taken as a measurement of net primary productivity. (2)

A
  1. Represents dry MASS/MASS of carbon
  2. Represents gross production minus respiratory losses
25
Q

5.3 Energy and Ecosystems

Ecologists dried the samples in an oven at 103°C. Describe hope they could have determined whether or not this drying removed all the water from a sample of wood. (2)

A
  1. Record mass and reheat
  2. Until constant mass recorded
26
Q

5.4 Nutrient Cycles

Describe the role of saprobionts in the nitrogen cycle. (2)

A
  1. (They use enzymes to) decompose proteins/DNA/RNA/ urea
  2. Producing/releasing ammonia/ammonium compounds/ammonium ions.
27
Q

5.4 Nutrient cycles

Eutrophication can cause cloudy water. Describe how you would obtain a quantitive measurement of the water sample’s cloudiness. (3)

A
  1. Use of colorimeter
  2. Measure the absorbency/transmission (of light)
  3. Examples of how methods can be standardised eg same volume of water, zeroing colorimeter, Same wavelength of light, shaking sample
28
Q

5.4 nutrient cycles

Suggest one method of sterilising bottles containing bacteria and explain why it is necessary to sterilise them. (2)

A
  1. Suitable method eg. In boiling water/ steam/ autoclave/ wash in disinfectant/ wash in alcohol
  2. (Reason) to remove/kill other bacteria/organisms that might break down ammonia
29
Q

5.4 Nutrient Cycles

Give two examples of nitrogen containing biological molecules that would be removed when a crop is harvested. (2)

A

Two examples: DNA/RNA/amino acid/protein/polypeptide/peptide/nucleic acid/nucleotide/base/chlorophyll/cyclic AMP (cAMP)

Biology AQA A Level (4 decks)

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