Module 5- Respiration Flashcards
2 marks
Describe how acetylcoenzyme A is formed in the link reaction
- Oxidation of pyruvate and CO2 released
- Addition of coenzyme A
Give ways in which the properties of ATP make it a suitbale source of energy in biological processes
- Immediate source of energy
- Soluble
- Involves in a simple reaction
- Energy released in small amounts
2 marks
Explain why it is necessary for humans to synthesise a large amount of ATP
- Immediate source of energy
- ATP only releases a small amount of energy at a time
3 marks
Describe the part played by the inner membrane of a mitochondrion in producing ATP
- Electrons transferred down electron transport chain
- Electrons transfer energy to proteins which actively trasnport protons from matrix to intermemembrane space
- Protons diffuse down proton gradient and back into matrix via ATP synthase
- Energy used to combine ADP + Pi to produce ATP
6 marks
Describe how ATP is made in mitochondria
- Substrate level phosphorylation
- Krebs cycle produces reduced coenzyme- reduced NAD and reduced FAD
- Electrons released from reduced coenzymes
- Electrons pass along electron transport chain
- Energy released
- ADP+Pi –> ATP
- Protons move to intermembrane space via ATP synthase
5 marks
Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis
- In the dark no ATP production in photosynthesis
- Some tissues unable to photosynthesise —> produce ATP
- ATP cannot be stored
- Plants uses more ATP than produced in photosynthesis
- ATP for active transport
4 marks
Describe process of glycolysis
- Glucose is phosphorylated using Pi from ATP
- NAD is reduced
- As TP is oxidised to form pyruvate
- Net gain of 2 ATP molecules- 4 ATP molecules are produced
2 marks
Malonate inhibits the Krebs cycles
Explain why malonate would decrease the uptake of oxygen in a respiring cell
- Less reduced NAD and reduced FAD made
- Less oxidative phosphorylation
- Less oxygen is used as a final electron acceptor
2 marks
At the end of a sprint race, a runner continues to breathe rapidly for some time. Explain the advantage of this.
- Lactate has built up
- Oxygen used to break down lactate to pyruvate
2 marks
Mitochondria in muscle cells have more cristae than mitochondria in skin cells. Explain the advantage of mitochondria in muscle cells having more cristae.
- More cristae = larger surface area for electron transport chain –> more enzymes for ATP production / oxidative phosphorylation
- Muscle cells use more ATP than skin cells
Explain glycolysis
- Glucose is phosphorylated using Pi from ATP
- NAD is reduced
- As TP is oxidised to form pyruvate
- Net product of 2 ATP & 4 ATP produced
Anaerobic respiration in plants/yeasts and animals
Plants/ yeast: pyruvate–> ethanol +CO2—> ethanol
Animals: pyruvate–> lactic acid
Reduced NAD is oxidised
Anaerobic respiration ATP production
- Only ATP produced comes from glycolysis
- The oxidised NAD can be used in glycolysis again
Explain link reaction
- Pyruvate enters mitochondrial matrix by active transport
- Pyruvate oxidised to acetate
- Acetate + coenzyme A–> acetlycoenzyme A
Explain Krebs cycle
- Acetlycoenzyme A + 4C–> 6C + coenzyme A
- Series of redox reactions= coenzymes (to be used in oxidtive phosphorylation)
- Carbon dioxide is released
- ATP generated by substrate level phosphorylation
- Other respiratory substrates- aa+ lipid breakdown products can fuel krebs cycle
- Products from one glucose: 2 ATP, 6 reduced NAD, 6 reduced FAD, 6 CO2
Explain oxidative phosphorylation
- Electrons donated from coenzymes
- e- transferred down ETC- releasing energy- series of redox reactions
- Protons (H+) pumped across inner mitochondrial membrane
- Conc gradient of H+ established- H+ diffuse through ATP synthase
- ADP + Pi–> ATP (chemisosmotic theory)
- Oxygen is the final electon acceptor–> H2O is formed
6 marks
Oxidative phosphorylation
- Reduced NAD and reduced FAD are oxidised, and they donate elctrons to membrane protein
- This forms protons, NAD and FAD
- Electrons move along along membrane proteins through a series of redox reaction along ETC
- Electrons transfer energy to the proteins, which is used to actively transport protons from the matrix to intermembrane space
- Protons in intermebrane space diffuse down proton gradient and back into matrix via ATP synthase
- ADP+Pi–> ATP, catalysed by ATP synthase/ ATPase
- Oxygen is final electron acceptor
- Over 30 ATP molecules can be made
6 marks
Describe how ATP is made in the mitchondria
- Substrate level phosphorylation in the Krebs cycle
- Krebs cycle produces reduced coenzymes e.g. reduced FAD and reduced NAD
- Electrons released from FADH and NADH
- Electrons pass along ETC, through a series of redox reactions
- Energy is released
- ADP+Pi—> ATP
- Protons move into intermembrane space
- ATP synthase
5 marks
The concentration of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur.
- High concentration of carbon dioxide at night as no photosynthesis is occurring as light required for light-dependent reaction.
- In the dark plants still respire.
- In the light uptake of carbon dioxide is greater than carbon dioxide produced.
- Decrease in carbon dioxide concentration with light
- Increase in carbon dioxide concentration closer to ground as at ground level less photosynthesising due to less light.
2 marks
Describe the role of oxygen in aerobic respiration
- Final acceptor for hydrogen
- To form water
2 marks
Explain why the scientist did not use glucose as the respiratory substrate for these isolated mitochondria.
- Glucose is broken down during glycolysis in the cytoplasm
- Glucose cannot cross mitochondrial membranes
1 mark
A student investigated the rate of anaerobic respiration in yeast. She put 5 g of yeast into a glucose solution and placed this mixture in the apparatus shown in the figure below. She then recorded the total volume of gas collected every 10 minutes for 1 hour. Explain why a layer of oil is required in this investigation
Prevents O2 being taken up
2 marks
Respiration produces more ATP per molecule of glucose in the presence of oxygen than it
does when oxygen is absent. Explain why.
- Oxygen is final electron acceptor
- Oxidative phosphorylation provides most ATP, only glycolysis without O2
2 marks
What measurements would the scientists have made in order to calculate the rate of carbon dioxide production?
- Volume of carbon dioxide given off
- From known area / per m2 / m-2
- In a set time
