The disease that is caused by a deficiency of niacin is: MCQ with Answer and Explanation

Explanation:
Chloroplasts are the sites of photosynthesis in plant cells, converting solar energy into chemical energy (food). Hence they are called the kitchen of the cell. Mitochondria are the powerhouse, generating ATP; ribosomes are protein factories; Golgi apparatus is the packaging center.

Explanation:
Alveoli are tiny thin-walled air sacs surrounded by pulmonary capillaries. Oxygen diffuses into blood, and carbon dioxide diffuses out.

Explanation:
Amphibia (e.g., frogs, toads, salamanders) are characterized by their dual habitat (amphi = both, bios = life). They can live in water and on land. They have moist, glandular skin without scales, which aids in respiration. They typically have a larval stage (tadpole) that undergoes metamorphosis to become an adult.