Topic 5B: Respiration Flashcards
Describe the process of glycolysis. [4]
- Phosphorylation of glucose using ATP;
- Oxidation of triose phosphate to pyruvate;
- Net gain of ATP;
- NAD reduced
Describe how acetylcoenzyme A is formed in the link reaction. [2]
- Oxidation of pyruvate and carbon dioxide released;
- Addition of coenzyme A
Describe how ATP is made in mitochondria. [6]
- ATP produced in Krebs cycle;
- Link reaction/Krebs cycle produces reduced NAD/reduced FAD;
- Electrons released from reduced NAD/reduced FAD;
- (Electrons) pass along electron transfer chain;
- Energy released;
- Protons pumped into intermembrane space;
- ADP + Pi;
- ATP synthase (makes ATP)
Explain why glucose cannot be used as the respiratory substrate for isolated mitochondria. [2]
- Glucose undergoes glycolysis in the cytoplasm;
- Glucose cannot be transported across the mitochondrial membranes
In which part of the mitochondrion does the Krebs cycle take place?
- Matrix
Name two substances for which there would be a net movement into the mitochondrion. [2]
- Pyruvate;
- ADP;
- Pi;
- reduced NAD;
- Oxygen
The mitochondria in muscles contain many cristae. Explain the advantage of this. [2]
- Larger surface area for electron transfer chain / oxidative phosphorylation;
- Provide enough ATP for contraction
Name two substances for which there would be net movement out of the mitochondrion. [2]
- ATP;
- Carbon dioxide;
- Water;
- NAD
Marlon ate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring cell. [2]
- Less/no reduced NAD;
- Oxygen is the final electron acceptor
In the methylene blue practical:
Why do you have to leave the tubes in a water bath for 5 mins before adding the methylene blue? [1]
- To equilibrate / so the tubes reach the required temperature
In the methylene blue practical:
How would you monitor the water bath temperature and keep it constant, without using a thermostatically-controlled water bath? [2]
- Use thermometer to measure throughout investigation;
- Add hot water
Cyanide inhibits the enzyme needed to allow oxygen to be reduced by electrons and protons at the end of the mitochondrial electron transfer chain.
Explain why, in the presence of cyanide, lactate production does occur, but not carbon dioxide production. [3]
- (Cyanide prevents oxidative phosphorylation so) reduced NAD is not oxidised in mitochondria/by electron transfer chain;
- Not enough NAD for the link reaction and Krebs cycle to continue so carbon dioxide release stops;
- Anaerobic respiration unaffected by cyanide so lactate still produced.
Plants produce ATP in their chloroplasts during photosynthesis. They also produce ATP during respiration. Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis. [5]
- In the dark no ATP production in photosynthesis;
- Some tissues unable to photosynthesise;
- ATP cannot be moved from cell to cell;
- Plant uses more ATP than produced in photosynthesis;
- ATP for active transport
Respiration produces more ATP per molecule of glucose in the presence of oxygen than it does when oxygen is absent. Explain why. [2]
- Oxygen is final electron acceptor;
- No link reaction/Krebs/oxidative phosphorylation without oxygen
Explain how converting pyruvate to ethanol and carbon dioxide allows glycolysis to continue. [2]
- Oxidised reduced NAD;
- NAD reduced in glycolysis
