1. Which statement comparing chloroplasts and mitochondria is true? Chloroplasts
ID: 95452 • Letter: 1
Question
1. Which statement comparing chloroplasts and mitochondria is true?
Chloroplasts and mitochondria each contain two membranes.
None of these statements are true.
Chloroplasts pump protons outside the organelle, while mitochondria pump protons inside the inner part of the organelle.
Chloroplasts and mitochondria use electrons from NADH to create a proton gradient.
Chloroplasts and mitochondria use energy from a proton gradient to make ATP.
2. Approximately how many more ATPs are made from one glucose molecule under aerobic conditions with oxidative phosphorylation than under anaerobic conditions?
104
0
2
30
3. As a cyclic pathway, why doens't the citrate cycle stop functioning when citrate cycle intermediates are siphoned off for use by other pathways?
Heme degradation produces succinyl-CoA, which is sufficient to restore the downstream citrate cycle intermediates that may be lacking.
Citrate cycle intermediates are constantly imported into the mitochondria from the cytosol, so these metabolites are never in low abundance.
Anaplerotic reactions catalyze the formation of citrate cycle intermediates, which can then enter the citrate cycle and maintain a functioning pathway.
Oxaloacetate is the only citrate cycle intermediate that leaves the pathway, and it is replenished by pyruvate carboxylase.
Chloroplasts and mitochondria each contain two membranes.
None of these statements are true.
Chloroplasts pump protons outside the organelle, while mitochondria pump protons inside the inner part of the organelle.
Chloroplasts and mitochondria use electrons from NADH to create a proton gradient.
Chloroplasts and mitochondria use energy from a proton gradient to make ATP.
Explanation / Answer
1. The last option is correct. Chloroplasts and mitochondria use energy from a proton gradient to make ATP. Although both chloroplast and mitochondria are surrounded by two membranes, chloroplast have an extra thylakoid membrane. Hence option first is not true. Chloroplast pumps protons inside the lumen of organelle and mitochondria pumps proton into intermembrane space from the matrix. Hence option 3rd is also not correct. Mitochondria use electrons from NADH while chloroplast use high energy electrons from chlorophyl (excited by sunlight and release electron). Hence 4th option is also not true.
2. The last option is correct. In aerobic condition 32 mollecule of ATP are generated while in anaerobic condition only 2 ATP are generated.
3. Option 3rd is correct. Anaplerotic reactions are chemical reactions that form intermediates of a metabolic pathway. Pyruvate is converted into oxaloacetate by pyruvate carboxylase which fills the requirement of TCA cycle intermediates and is therefore an anaplerotic reaction.
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