The protein responsible for muscle contraction are: MCQ with Answer and Explanation

Explanation:
Each kidney contains about one million nephrons, each consisting of a renal corpuscle (glomerulus + Bowman's capsule) and tubules (PCT, loop of Henle, DCT).

Explanation:
The plasma membrane is selectively permeable, regulating the entry and exit of specific molecules into and out of the cell. Lysosomes are membrane-bound organelles containing powerful hydrolytic (digestive) enzymes for intracellular digestion. The nucleolus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, not protein synthesis, which occurs at ribosomes. Thus, statements 1 and 3 are correct.

Explanation:
Phagocytosis is receptor-mediated or non-specific engulfment of large particles, forming a phagosome that fuses with lysosomes. Key in immune defense.