Diphtheria is a bacterial disease caused by: MCQ with Answer and Explanation

Explanation:
Thyroxine is an animal hormone secreted by the thyroid gland, regulating metabolism. Auxin, gibberellin, cytokinin, abscisic acid, and ethylene are plant hormones (phytohormones). Plant hormones control growth, development, and responses to environment. Thyroxine contains iodine and affects basal metabolic rate. Thus, thyroxine is unrelated to plant physiology.

Explanation:
Arthropoda is the largest phylum, with over a million described species, including insects, arachnids, crustaceans, and myriapods. They are characterized by jointed appendages, chitinous exoskeleton, and segmented bodies. Insects alone represent the majority of animal species. Chordata is comparatively smaller.

Explanation:
Pinocytosis (cell drinking) is a type of endocytosis where the cell membrane forms small vesicles to engulf extracellular fluid and dissolved substances. Phagocytosis is for large particles, exocytosis is export, endocytosis is general term.