Consider statements about microorganisms: 1. Rhizobium fixes atmospheric nitrogen. 2. Yeast is used in baking. 3. All bacteria are pathogenic. Which are correct? MCQ with Answer and Explanation

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:
Phagocytosis ('cell eating') is the process by which cells like macrophages and neutrophils engulf solid particles, including pathogens, by extending pseudopodia to form a phagosome, which fuses with lysosomes for degradation. Pinocytosis is 'cell drinking', uptake of fluid. Exocytosis is secretion. Dialysis is artificial separation. Phagocytosis is a key innate immune defense.

Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by a network of pulmonary capillaries. Oxygen diffuses from alveolar air into blood, and CO₂ diffuses from blood into alveolar air. Bronchi and bronchioles are air passages, trachea is the windpipe. The large surface area of alveoli (about 70 m²) facilitates efficient gas exchange.