The sperm cell is the smallest cell in the human body, about 5 µm in length (head). The ovum is the largest (about 100 µm diameter). RBCs are about 7-8 µm, neurons can be up to a meter long. Sperm cells are highly specialized for motility and genetic material delivery.
Consider the following statements about the endocrine system:
1. The pituitary gland is the master gland.
2. Thyroxine regulates basal metabolic rate.
3. Adrenaline decreases heart rate during stress.
Which of the above is/are correct?
Explanation:
The pituitary controls many glands (master gland). Thyroxine from the thyroid increases BMR. Adrenaline increases heart rate during stress, not decreases. So 1 and 2 are correct.
Explanation:
Metabolism is the sum of all chemical reactions occurring in a living body. It is the only feature present in all living organisms without exception. While growth and reproduction are common, they are not universal (e.g., sterile mules). Non-living things can also exhibit growth by accumulation or movement, making metabolism the true defining property.
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