All Free Biology MCQs with Answers

3561. In Calvin Cycle, the conversion of 5 molecules of Glyceraldehyde 3-phosphate into 3 molecules of Ribulose 1-5, bisphosphate by utilization of ATP is termed as

• A. CO2 Fixation
• B. Phosphorylation
• C. Reduction
• D. Regeneration

Explanation: The process of recreating a molecule that is used in a cyclic pathway, like the regeneration of ribulose-1,5-bisphosphate (RuBP) in the Calvin cycle, which allows CO₂ fixation to continue in subsequent cycles.

3562. The production of energy is:

• A. Faster in anaerobic respiration
• B. Faster in aerobic respiration
• C. The same in both types of respiration
• D. Not associated with respiration

Explanation: Anaerobic respiration is generally faster than aerobic respiration because it does not require oxygen, allowing cells to produce energy more quickly in the absence of oxygen. This process yields ATP (adenosine triphosphate) through fermentation or other pathways, often resulting in byproducts like lactic acid or ethanol. However, anaerobic respiration produces less ATP per glucose molecule compared to aerobic respiration.

3563. The pathway to the breakdown of glucose, carried out by microorganism, is called:

• A. Lactic acid fermentation
• B. Alcoholic fermentation
• C. Cellular respiration
• D. None of the above

Explanation: Alcoholic fermentation is an anaerobic process used by yeast and some bacteria to produce energy.

3564. The process of ATP synthesis through a combination of chemical and osmotic events is known as:

• A. Fermentation
• B. Glycolysis
• C. Oxidative phosphorylation
• D. Oxidation of pyruvate to acetyl CoA

Explanation: Oxidative phosphorylation is the final stage of cellular respiration, where most of the cell's ATP is produced. This process occurs in the inner mitochondrial membrane and relies on an electron transport chain (ETC) and chemiosmosis.

3565. Photosynthesis is

• A. Reduction process
• B. Oxidation process
• C. Redox process
• D. None of the given options

Explanation: Photosynthesis consists of oxidation (water losing electrons) and reduction (carbon dioxide gaining electrons).

3566. Following are the products of photosynthesis:

• A. Glucose and water
• B. Oxygen and glucose
• C. Oxygen, glucose, and water
• D. None of the given options

Explanation: Photosynthesis produces glucose and oxygen through a chemical processwhere palnts use sunlight,water,carbon dioxide. Sunlight energy is converted into chemical energy, stored in glucose and oxygen as a byproduct.

3567. Which statement is correct about the glycolysis process?

• A. 2 ATP are produced and 2 ATP are consumed
• B. 1 ATP is produced and 2 ATP are consumed
• C. 2 ATP are produced and 1 ATP is consumed
• D. 4 ATP are produced and 2 ATP are consumed

Explanation: 4 ATP are produced and 2 ATP are consumed - Correct. Glycolysis generates 4 ATP molecules but consumes 2, leading to a net gain of 2 ATP.

3568. During the light-dependent phase of photosynthesis, the water molecule is broken down into:

• A. 2H, 2e and 1/2 O₂
• B. 4H, 4e and 2 O₂
• C. 2H, 2e and 2 O₂
• D. 4H, 2e and 4 O₂

Explanation: 2H, 2e and 1/2 O₂ - Correct. Photolysis of water during photosynthesis produces 2 protons (H⁺), 2 electrons (e⁻), and ½ molecule of oxygen (O₂) per water molecule.

3569. ATP is best defined as:

• A. The molecule that has no role in muscle contraction
• B. The molecule that releases energy when a phosphate molecule is added
• C. The molecule that is only present inside the nucleus
• D. The molecule that releases energy when the phosphate molecule is removed

Explanation: The molecule that releases energy when the phosphate molecule is removed - Correct. ATP releases energy when hydrolyzed to ADP by removing a phosphate group.

3570. In the electron transport chain, the ultimate electron acceptor is:

• A. NADH
• B. None of these
• C. Oxygen
• D. Cytochrome complex

Explanation: Oxygen - Correct. Oxygen acts as the final electron acceptor in the electron transport chain, forming water.