Assertion(A): | NAD+ is the most versatile electron acceptor in cellular respiration and functions in several of redox steps during the breakdown of glucose. |
Reason(R): | As an electron acceptor, NAD+ functions as an oxidizing agent during respiration. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A) |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Oxidation of organic compounds by molecular oxygen results in the production of carbon dioxide and water and releases free energy. This is because:
1. | High energy covalent bonds in organic molecules are broken to produce weaker covalent bonds in water and carbon dioxide. |
2. | Electrons are being moved from atoms that have a lower affinity for electrons to atoms with a higher affinity for electrons. |
3. | The electrons in water and carbon dioxide have higher potential energy than the electrons in organic compounds. |
4. | The covalent bonds in organic molecules are unstable and stable in water and oxygen. |
The mitochondrial proton gradient would be highest leading to ATP synthesis when the following condition is present:
1. | pyruvate (present)-oxygen (present)-ATP levels (high) |
2. | pyruvate (present)-oxygen (present)-ATP levels (low) |
3. | pyruvate (present)-oxygen (absent)-ATP levels (high) |
4. | pyruvate (absent)-oxygen (present)-ATP levels (low) |