respiration exam Q/A Flashcards
An investigation was carried out into the production of ATP by mitochondria. ADP, phosphate, excess substrate and oxygen were added to a suspension of isolated mitochondria.
Suggest the substrate used for this investigation
- pyruvate
Explain why the concentration of oxygen and amount of ADP fell during the investigation.
ADP + Pi forms ATP
oxygen is the last electron acceptor and is used to form water
in which part of the mitochondria does the kerb cycle take place
matrix
Name two substances for which there would be net movement into the mitochondrion.
- pyruvate
- reduced NAD
The mitochondria in muscles contain many cristae. Explain the advantage of this.
provides a large surface area for contraction
Apart from respiration, give three uses of ATP in a liver cell.
- ATP
- phagocytosis
- cell division
Human skeletal muscle can respire both aerobically and anaerobically. Describe what happens to pyruvate in anaerobic conditions and explain why anaerobic respiration is advantageous to human skeletal musc
- forms lactate
- uses reduced NAD
- regenerates NAD which can be re-used to oxidise more respiratory substrate
- glycolysis continues
Can still release energy / form ATP
Pea plants respire aerobically, producing ATP which can be used for amino acid synthesis. Describe the role of oxygen in aerobic respiration.
final acceptor for hydrogen: to form water
The bacteria respire anaerobically. This produces hydrogen and ATP used in nitrogen fixation. The hydrogen comes from reduced NAD. Explain how the regeneration of NAD in this way allows ATP production to continue.
glycolysis can continue;
NAD can accept more hydrogen
The enzyme nitrogenase is specific to the reaction shown. Explain how one feature of the enzyme would contribute to this specificity.
tertiary structure;
produces particular shape of active site
Sodium ions act as a non-competitive inhibitor of the enzyme nitrogenase. Explain how the presence of a non-competitive inhibitor can alter the rate of the reaction catalysed by nitrogenase.
non-competitive inhibitor binds to enzyme
at a site other than active site;
resulting in change of shape of active site
When glucose is respired what happens to the energy which is not incorporated into ATP?
released as heat
When one mole of glucose is respired anaerobically, only 2 moles of ATP are produced. Explain why less energy is released in anaerobic respiration
glucose only partly broken down / only broken down to lactate
At the end of a sprint race, a runner continues to breathe rapidly for some time. Explain the advantage of this
- lactate has been produced
- oxygen is sued to break down lactate
- it is converted back to pyruvate
Other substances are produced in the Krebs cycle in addition to the carbon
compounds shown in the diagram. Name three of these other products.
- reduced NAD
- reduced FAD
- ATP
Seals are aquatic mammals. They use lungs as organs of gas exchange so they do not
breathe when they are under water during a dive.
The graph shows changes in oxygen and lactate concentration in the blood of a seal
before, during and after a dive.
The concentration of oxygen in the blood fell during the dive. Explain why.
Used in aerobic respiration to provide energy used by muscles
Explain what causes the concentration of blood lactate to fall after a dive.
- its converted back into pyruvate
Reducing the volume of blood pumped out by the heart reduces the rate of blood
flow to the diaphragm muscles.
(i) Give one other way in which blood flow into the diaphragm muscles may be
reduced
- contraction of muscles of
During a dive, blood flow to the diaphragm muscles of a seal is reduced.
Suggest the advantage to the seal of maintaining some blood supply to the
diaphragm muscles during a dive.
Supplies oxygen so cells can respire when not contracting
In an investigation, the effects of caffeine on performance during exercise were measured.
One group of athletes (A) was given a drink of decaffeinated coffee. Another group (B)
was given a drink of decaffeinated coffee with caffeine added. One hour later the athletes
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started riding an exercise bike and continued until too exhausted to carry on. Three days later the same athletes repeated the experiment, with the drinks exchanged.
(a) (i) The researchers added caffeine to decaffeinated coffee. Explain why they did
not just use normal coffee.
In case the coffee is different
