Assertion (A): Plants wilt in salty soil. Reason (R): High salinity causes water to move out of root cells by osmosis. MCQ with Answer and Explanation

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.

Explanation:
Frederick Griffith in 1928 demonstrated the transformation of non-virulent pneumococci to virulent by heat-killed virulent strain, suggesting a transforming principle. Avery et al. later identified it as DNA. Hershey-Chase confirmed DNA is genetic material.

Explanation:
Fats yield about 9 kcal/g of energy, more than double the 4 kcal/g provided by carbohydrates and proteins. Roughage (dietary fiber) adds bulk to the stool and stimulates peristalsis, preventing constipation. Water is an essential nutrient, crucial for hydration, solvent functions, and temperature regulation, though it provides no calories. Thus, statements 1 and 2 are correct.