Question

Assertion :$F_1$ particles are present in the inner mitochondrial membrane. Reason: An electrochemial proton gradient formed on the inner mitochondrial membrane, forms ATP.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

• The inner surface of the cristae membranes, i.e, towards mitochondrial matrix side, is studded with a large number of knob or globular shaped particles with a conspicuous stalk like structure.
• Such globular particulate are called Racker particles which have been identified as F${}_1$ particles. They act as ATP synthetases and they are uniformly spaced at 10 nm apart.
• The number of F${}_1$ particles present in each mitochondria ranges from 100 to 1000. So, assertion is correct. The complete breakdown of glucose in the presence of oxygen is called cellular respiration. The last steps of this process occur in mitochondria.
• The reduced molecules NADH and FADH${}_2$ are generated by the Krebs cycle, glycolysis, and pyruvate processing. These molecules pass electrons to an electron transport chain, which uses the energy released to create a proton gradient across the inner mitochondrial membrane.
• ATP synthase then uses the energy stored in this gradient to make ATP. Thus, reason is correct. But, reason is not the correct explanation for assertion.