Assertion (A): Human blood is a connective tissue. Reason (R): Blood cells are embedded in a liquid extracellular matrix called plasma. 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:
Cholera is caused by Vibrio cholerae, transmitted through contaminated water and food, causing severe watery diarrhea and dehydration. Influenza is a viral respiratory disease, ringworm is a fungal infection, dengue is a mosquito-borne viral disease. Cholera toxin disrupts ion transport in intestinal cells, leading to massive fluid loss. ORS (oral rehydration solution) is a simple life-saving treatment.

Explanation:
Edward Jenner developed the first successful vaccine against smallpox in 1796 using cowpox virus. Pasteur developed rabies vaccine, Koch TB bacterium, Salk polio.