Respiration PPQs Flashcards
Describe how acetyle coA is formed in the link reaction (2)
- pyruvate is oxidised to acetate and carbon dioxide is released
- acetate combines with CoA
Explain how oxaloacetate binding to citrate synthase enables acetyl CoA to then bind to citrate synthase (2)
- changes tertiary structure and hence active site
- making it complimentary to the substrate
X has a similar shape to acetyl CoA. Suggest how production of x could control the rate of the reaction (2)
- x is a competitive inhibitor so it binds to the active site of the enzyme
- preventing and E-S complex forming
Why does converting pyruvate to lactate allow the continued production of ATP during anaerobic respiration (2)
- it regenerates NAD
- which is used in glycolysis
In muscles, some lactate is converted back to pyruvate when they are well supplied with oxygen. Why is this an advantage? (1)
build up of lactic acid is toxic
RQ value for aerobic respiration of glucose and why?
1
volume of CO2 produce = volume of O2 used up
RQ equation
vol. CO2 produced/ vol. O2 used up
Suggest why the rate of carbon dioxide release (spiracles opening) in insects increases as temperature increases. (3)
- higher temperatures means more enzyme activity
- respiration rate increases so CO2 production increases
- so needs to be released at a faster rate and spiracles must open more often
Why is a layer of oil used in an anaerobic respiration experiment? (1)
= prevents oxygen being taken up
Explain why the conversion of pyruvate to lactate allows for glycolysis to occur. (2)
- when pyruvate is converted to lactate it regenerates NAD
- which can be use din glycolysis (to form reduced NAD)
Aerobic respiration produces more ATP per glucose molecule than anaerobic respiration. Explain why. (2)
aerobic has Krebs cycle and oxidative phosphorylation
anaerobic only has glycolysis
People with mitochondrial disease have dysfunctioning mitochondria.
Why can people with mitochondrial disease only exercise for a short amount of time?
- the dysfunctioning mitochondria mean less aerobic respiration
- so less ATP produced for muscle contraction
ice cold
isotonic
reduce enzyme activity
prevent osmosis and cell from bursting/shrinking
Explain the constant (no gradient) line between P and Q
oxygen concentration is constant because
- no aerobic respiration
- because no substrate to respire
Explain the line between Q and R (steady negative gradient)
- aerobic respiration uses oxygen (so it is taken up)
- as terminal electron acceptor
When the mitochondria are isolated, what need sto be added to the solution for aerobic respiration to occur? (3)
- ADP
- Pi
- Respiratory substrates
Explain why, after cyanide is added to solution, oxygen concentration continues to decrease at a slower rate in plant mitochondria?
- oxygen conc. continues to fall in plant mitochondria because they continue to aerobically respire
- because oxidative phosphorylation continues in plant mitochondria
- because plant mitochondria cytochrome oxidase is more resistant to cyanide (than animal mitochondria which when cyanide is added immediately stop aerobically respiring because the cyanide screws up the ETC)
What number carbon compound enters the Krebs cycle and what does it join with?
2 carbon acetyl CoA combines with 4C oxaloacetate to form 6C citrate
Where does th elink reaction occur (what travels in) ?
pyruvate passes through mitochondrial membrane and then combines with CoA to form acetyl CoA (in the process reduced NAD and CO2 formed)
Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion. (3)
- ATP formed as electrons are passed along the ETC
- oxygen is the final acceptor of these electrons
- where they then combine with protons and oxygen to form water at the end of the chain
Describe the part played by the inner membrane of a mitochondrion in producing ATP. (3)
- electrons pass down ETC
- provides energy for active transport of protons into the intermembral space
- protons then flow back into matrix through ATP synthase
- this energy is used to combine ADP and Pi
Explain why the scientist did not use glucose as the respiratory substrate. (2)
- glucose broken down during glycolysis in the cytoplasm
- (this cannot happen bc mitochondria are isolated) - so glucose cannot cross the mitochondrial membrane
Explain how malonate inhibits the formation of fumarate from succinate. (2)
- competitive inhibitor
- prevents E-S complex forming
The scientist measured the uptake of oxygen by the mitochondria during the investigation. The uptake of oxygen decreased when malonate was added. Explain why. (2)
- Krebs inhibited as coenzymes not reduced
- H not passed to the ETC so oxygen not used as much as terminal electron acceptor
Apart from respiration, give three uses of ATP in a liver cell. (3)
- mitosis
- bile production
- DNA synthesis
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 muscle.(4)
- pyruvate converted to lactate
- NADH oxidised to NAD (regeneration of NAD) and also production of CO2
- allows glycolysis to continue
- so ATP production present even when no oxygen present
Humans synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP. (2)
- ATP cannot be stored
- ATP only releases a small amount of energy at a time
