In the recombinant plasmid pBR322, the 'rop' gene codes for a protein that: MCQ with Answer and Explanation

Explanation:
Veins carry blood back to the heart under low pressure and have one-way valves that prevent backflow. Skeletal muscle contractions also assist venous return.

Explanation:
A balanced diet provides all the essential nutrients (carbohydrates, proteins, fats, vitamins, minerals, and water) in the correct proportions required for optimal health and growth. Malnutrition refers to deficiencies, excesses, or imbalances in a person's intake of energy and/or nutrients; therefore, overeating (leading to obesity) is a form of malnutrition. Water is an essential nutrient, crucial for hydration, transport, and chemical reactions, though it provides no calories. Thus, statements 1 and 2 are correct.

Explanation:
Birds and mammals are endothermic (warm-blooded), maintaining a constant internal body temperature regardless of the environment. Crow is a bird, hence warm-blooded. Fish, frog (amphibian), and snake (reptile) are ectothermic (cold-blooded), their body temperature varies with the environment. Endothermy requires high metabolic rate and insulation (feathers, fur).