5. Energy Transfers EQs Flashcards
Give the function of a mitochondrian (1 mark)
Produce ATP for respiration
The mitochondria in muscles contain many cristae. Explain the advantage of this (2 marks)
- large surface area
- more enzymes for ATP production
Explain why converting pyruvate to ethanol is important in allowing the continued production of ATP in anaerobic respiration (2 marks)
- Allows NAD to be re-formed
- so more glucose can be converted into pyruvate
Give two ways in which anaerobic respiration of glucose in yeast is similar to anaerobic respiration of glucose in a muscle cell (2 marks)
- ATP formed
- Pyruvate formed
Give two ways in which anaerobic respiration of glucose in yeast is different to anaerobic respiration of glucose in a muscle cell (2 marks)
- Yeast = ethanol
Muscle = lactic acid - CO2 released by yeast, not muscle
In anaerobic respiration, what is the net yield of ATP molecules per molecule of glucose? (1 mark)
2
Describe how NAD is regenerated in anaerobic resp in yeast cells (1 mark)
reduced NAD is reduced
Explain why most of the energy is provided by anaerobic respiration rather than aerobic? (2 marks)
- high respiration rate
- so unable to supply enough oxygen to muscles
The athlete continues to breathe deeply for several minutes after the race ends. Explain why this is necessary (2 marks)
- oxidise lactate into pyruvate
- by aerobic respiration
Explain why some muscles become fatigued when insufficient oxygen is available (2 marks)
- increased conc of lactate
- lowers pH
Without oxygen, less ATP is produced by respiration. Explain why (2 marks)
- only glycolysis can take place
- only produces 2 ATP
When glucose is respired what happens to the energy which is not incorporated into ATP? (1 mark)
released as heat
Describe how acetylcoenzyme A is formed in the link reaction (2 marks)
1.Oxidation of pyruvate and carbon dioxide released;
2.Addition of coenzyme A.
In link reaction pryruvate is converted to a substance with 2 carbon atoms. Describe what happens in this process (2 marks)
- decarboxylation
- acetyl coenzyme A produced
Apart from respiration, give three uses of ATP in a liver cell (3 marks)
- Cell division
- Active transport
- Phagocytosis
Aerobic respiration produces more ATP per molecule of glucose than anaerobic
respiration. Explain why. (2 marks)
- Oxygen is final electron acceptor
- In aerobic respiration oxidative phosphorylation
- In anaerobic respiration only glycolysis occurs which only produces 2 ATP
Explain the purpose of the strip of filter paper in the potassium hydroxide solution in a respirometer (1 mark)
to increase surface area for carbon dioxide absorption
The level of liquid in the right-hand side of the manometer went down during
the experiment. Explain why. (2 marks)
- oxygen is used and carbon dioxide emitted is absorbed;
- so decrease in volume
What measurements are needed to calculate the rate of oxygen uptake by the
snails in mm3 g –1 h –1 ? (3 marks)
- change of level of (manometer) liquid over time;
- mass of snails;
- time interval;
Why would coloured liquid move in respirometer? (3 marks)
- Oxygen used (by woodlouse);
2.Carbon dioxide is absorbed by potassium hydroxide; - Decrease in pressure;
Describe the role of oxygen in aerobic respiration (2 marks)
- final acceptor for hydrogen:
- to form water;
Describe how ATP is made in mitochondria? (6 marks)
- ATP and reduced NAD produced in Krebs cycle
- Electrons produced from reduced NAD
- Electrons pass along electron transport chain
- Releasing energy for ADP + Pi
- Protons move into intermembrane space
- By ATP synthase
Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion (3 marks)
- ATP formed as electrons pass along transport chain
- Oxygen is terminal electron acceptor to form water
- However if no oxygen then electrons cannot be accepted
Describe the part played by the inner membrane of a mitochondrion in producing ATP (3 marks)
- Electrons transferred down electron transport chain
- Provide energy to take protons into space between membranes;
- Protons pass back, through membrane into matrix through ATP synthase;
- Energy used to combine ADP and phosphate to produce ATP;
In photosynthesis, which chemicals are needed for the light-dependent
reaction? (1 mark)
NADP, ADP, Pi and water;
Describe what happens during photoionisation in the light-dependent
reaction. (2 marks)
- Chlorophyll absorbs light which excites electrons
- Loses electrons to the electron transport chain
Heat stress decreases the light-dependent reaction of photosynthesis.
Explain why this leads to a decrease in the light-independent reaction. (2 marks)
- Less ATP;
- Less reduced NADP;
A decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis.
Explain why. (2 marks)
- (Less/no) carbon dioxide (reacts) with RuBP;
- (Less/no) GP;
Where precisely is rubisco found in a cell? (1 mark)
stroma
Describe the process of glycolysis. (4 marks)
- Phosphorylation of glucose using ATP
- Oxidation of triose phosphate to pyruvate
- Net gain of ATP
- NAD reduced
Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring
cell. (2 marks)
- Less/no reduced NAD
- Oxygen is the final/terminal (electron) acceptor;
In chromatography, explain why the student marked the origin using a pencil rather than using ink. (1 mark)
Ink and pigments would mix
Describe the method the student used to separate the pigments after the solution of
pigments had been applied to the origin. (2 marks)
- Level of solvent below origin
- Remove before (solvent) reaches top
The pigments in leaves are different colours. Suggest and explain the advantage of having
different coloured pigments in leaves. (1 mark)
Absorb different/more wavelengths of light for photosynthesis;
A teacher studying these data with her students told her class that no definite conclusions
could be drawn when comparing the mean values in the graph.
Suggest why the teacher said this. (2 marks)
- No SD;
- To show if overlap occurs so difference (in means) is not significant / due to chance
Atrazine binds to proteins in the electron transfer chain in chloroplasts of weeds, reducing
the transfer of electrons down the chain.
Explain how this reduces the rate of photosynthesis in weeds (4 marks)
- Reduced transfer of protons across thylakoid membrane
- So less ATP produced;
- So less reduced NADP produced
- So light-independent reaction slows
When treated with herbicide, weeds have been shown to give off small amounts of heat.
Suggest an explanation for this observation (1 mark)
energy is released from high energy
Explain the relationship between stomatal opening and photosynthesis. (2 marks)
- Stomata allow uptake of carbon dioxide;
- Carbon dioxide used in photosynthesis;
Explain why a log scale is used to record the number of cells (1 mark)
large increase in numbers
Many yeast cells die in the death phase, Suggest why (1 mark)
No glucose
Suggest and explain why (a chosen temp) was 20 degrees for this experiment (2 marks)
- optimum temp
- for enzymes involved in respiration
Explain why less energy is released in anaerobic respiration (1 mark)
glucose only partly broken down to lactate
Why would concentration of oxygen fall underwater? (1 mark)
oxygen used in aerobic respiration to provide energy and oxygen not replaced by breathing
Explain why concentration of lactate would fall (2 marks)
- converted back to pyruvate
- oxidised
Give one way blood flow into the diaphragm muscles may be reduced (1 mark)
constriction of muscles in arteries
Suggest one explanation for higher glycerol and fatty acid concentrations (2 marks)
- breakdown of fats
- at increased rate
Describe the roles of coenzymes and carrier proteins in the synthesis of ATP (3 marks)
- NAD / FAD reduced / hydrogen attached to NAD / FAD;
- electrons transferred from
carrier to carrier in a series of redox reactions; - energy made available as electrons passed on;
energy used to synthesise ATP from ADP and phosphate - H+ / protons passed into intermembrane space;
- H+ / protons flow back through enzyme;
Explain the advantage of the student using the IC50 in this investigation. (1 mark)
provides a standard/reference point
Explain how chemicals which inhibit the decolourisation of DCPIP could slow the
growth of weeds. (2 marks)
- Less/no ATP produced;
- Less/no reduced NADP produced;
- Less/no GP reduced/converted to TP;
Suggest one way in which an increase in the uptake of phosphate could increase
plant growth. (1 mark)
Used to produce ATP
Explain why an increase in shoot biomass can be taken as a measurement of
net primary productivity. (2 marks)
- Represents dry mass / mass of carbon;
- Represents gross production minus respiratory
losses;
Suggest and explain how digesting insects helps the sundew to grow in soil with very
low concentrations of some nutrients. (2 marks)
- Digestion/breakdown of proteins;
- Provides amino acids
Farming cattle for humans to eat is less efficient than farming crops because of
energy transfer.
Explain why. (2 marks)
- Energy lost between/at trophic/feeding levels;
- Energy lost via respiration/excretion/faeces;
Apart from time, give two measurements the student would have to make to
determine the rate of aerobic respiration of these seeds in cm3 hour –1 (2 marks)
- Distance (drop/liquid moves);
- Diameter/radius/bore of tubing/lumen;
The student used the same apparatus to determine the volume of carbon dioxide the
seeds produced during 48 hours.
Give the change the student would need to make to the contents of the apparatus
and describe how he could calculate the volume of carbon dioxide produced.
[3 marks]
- Remove potassium hydroxide
- Record distance liquid moves (without potassium hydroxide);
- Use difference in distance liquid moves (with
potassium hydroxide and without potassium
hydroxide)
Explain why the scientists measured the rate of production of oxygen when finding rate of photosynthesis (2 marks)
- Oxygen produced in light-dependent reaction;
- The faster oxygen is produced, the faster the light-dependent reaction.
The stomata close when the light is turned off.
Explain the advantage of this to the plant. (2 marks)
- (Because) water is lost through stomata;
- (Closure) prevents / reduces water loss;
- Maintain water content of cells.
Explain why a layer of oil is required in an investigation on anaerobic respiration. (1 mark)
Prevents oxygen being taken up
Yeast can also respire aerobically. The student repeated the investigation with
a fresh sample of yeast in glucose solution, but without the oil. All other conditions remained the same.
Explain what would happen to the volume of gas in the syringe if the yeast were only respiring aerobically. (2 marks)
- (Stays the) same
- Same volume of oxygen uptake and carbon dioxide
release;
Explain why oxygen concentration would fall (2 marks)
- Aerobic respiration (uses oxygen);
- Oxygen is terminal / electron acceptor;
GW1516 is a performance-enhancing drug. GW1516 activates acetyl-coenzyme A and develops slow muscle fibres at rest. Use diagram above to justify why professional athletes are not allowed to take GW1516. (4 marks)
- More acetylcoenzyme A would enter the Krebs cycle;
- (So) the Krebs cycle generates (more) reduced coenzymes
- (So more) ATP would be produced;
- Athletes could build (slow) muscle (fibres) without exercising;
- (Having more) slow muscle (fibres) would increase endurance;
Explain why the scientists sterilised the surfaces of the seeds and grew them in soil
that had been heated to 85 °C for 2 days. (2 marks)
- To kill any fungus / bacteria on surface of seeds or in soil;
- So only the (thing you’re measuring) has any effect.
Explain why determination of dry mass was an appropriate method to use in this
investigation. (2 marks)
- Dry mass measures increase in biological material;
- Water content varies.
Describe the role of microorganisms in producing nitrates from the remains of
dead organisms. (3 marks)
- Saprobiotic break down dead
material into ammonia - Ammonia into nitrite and then into nitrate
- (By) Nitrifying bacteria / nitrification;
Upwelling happens in coastal waters and is a process where water moves from deeper parts of the sea to the surface. This
water contains a lot of nutrients from the remains of dead organisms. Explain why some of the most productive fishing areas are found in coastal waters. (2 marks)
- nutrients used by plant for growth
- More food so more fish / fish reproduce more
