The silkworm disease caused by the protozoan Nosema bombycis is called: MCQ with Answer and Explanation

Explanation:
After ovulation, the ruptured Graafian follicle transforms into a temporary endocrine structure called the corpus luteum. Its primary function is to secrete large amounts of progesterone (and some estrogen). Progesterone is crucial for maintaining the thickened, highly vascularized uterine endometrium (secretory phase), making it receptive for the implantation of a blastocyst. If fertilization does not occur, the corpus luteum degenerates, progesterone levels drop, and menstruation begins.

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).

Explanation:
B lymphocytes differentiate into plasma cells that produce antibodies (immunoglobulins) against specific antigens, providing humoral immunity. T cells mediate cellular immunity, macrophages and neutrophils are phagocytes.