Consider statements about plant stems: 1. Nodes are the regions where leaves arise. 2. Internodes are the regions between nodes. 3. All stems grow underground. Which are correct? MCQ with Answer and Explanation

Explanation:
The Krebs cycle, also known as the citric acid cycle or TCA cycle, is the central metabolic pathway for the oxidation of acetyl-CoA to produce energy (ATP, NADH, FADH2). It was discovered by the British-German biochemist Sir Hans Adolf Krebs in 1937. He was awarded the Nobel Prize in Physiology or Medicine in 1953 for this discovery. Melvin Calvin elucidated the carbon pathway in photosynthesis.

Explanation:
Adenosine triphosphate (ATP) stores energy in its high-energy phosphate bonds and releases it for cellular work. Glucose and NADH are fuel molecules, not direct energy carriers.

Explanation:
Human Immunodeficiency Virus (HIV) specifically targets and destroys CD4+ T-helper cells, severely compromising the immune system and leading to AIDS. Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis, which primarily affects the lungs (pulmonary TB). Malaria is not caused by a virus; it is caused by a protozoan parasite of the genus Plasmodium, transmitted by the Anopheles mosquito. Thus, statements 1 and 3 are correct.