Which disease is caused by the bacterium Salmonella typhi? MCQ with Answer and Explanation

Explanation:
The esophagus is a muscular tube (about 25 cm) that propels swallowed food from the pharynx to the stomach via peristalsis. The trachea is the windpipe (air), larynx is the voice box, bronchus is a lung airway. The esophageal sphincters prevent reflux.

Explanation:
Testosterone, produced by Leydig cells in the testes, promotes development of male characteristics like facial hair, deepening of voice, and muscle growth. It also regulates spermatogenesis.

Explanation:
The plasma membrane is selectively permeable, regulating the entry and exit of specific molecules into and out of the cell. Lysosomes are membrane-bound organelles containing powerful hydrolytic (digestive) enzymes for intracellular digestion. The nucleolus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, not protein synthesis, which occurs at ribosomes. Thus, statements 1 and 3 are correct.