Amoeba moves and captures food using temporary extensions of its cell body called: MCQ with Answer and Explanation

Explanation:
Primary lymphoid organs are where lymphocytes are produced and mature. Bone marrow (where B cells mature) and thymus (where T cells mature) are primary. Secondary lymphoid organs, like spleen, lymph nodes, and tonsils, are where mature lymphocytes encounter antigens and initiate immune responses. The bone marrow also is the site of hematopoiesis.

Explanation:
Iodine is a key constituent of the thyroid hormones thyroxine (T₄) and triiodothyronine (T₃). Deficiency leads to goiter and hypothyroidism. Iron is for hemoglobin, calcium for bones, zinc for enzyme function. Iodized salt is a public health measure to ensure adequate iodine intake.

Explanation:
Daniel Koshland proposed the induced fit model (1958), where enzyme active site changes shape upon substrate binding. Fischer had proposed lock-and-key.