The muscular tube that connects the pharynx to the stomach is the:
A. Bronchus
B. Trachea
C. Larynx
D. Esophagus
Answer: Option D
Solution (By JKSSB Mock Tests)
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:
Viruses do not reproduce by binary fission; they replicate by hijacking host cell machinery. Binary fission is a method of asexual reproduction in bacteria. All other statements are correct.
Explanation:
Active transport uses energy (usually ATP) to pump molecules or ions across a membrane against their electrochemical gradient, e.g., Na⁺/K⁺ pump. Diffusion, osmosis, and facilitated diffusion are passive processes that move substances down their gradient without energy expenditure.
Explanation:
A mature embryo sac (female gametophyte) in angiosperms is 7-celled but 8-nucleate: 3 antipodal cells (3 nuclei), 2 synergids (2 nuclei), 1 egg cell (1 nucleus), and 1 central cell with 2 polar nuclei. Thus total 8 haploid nuclei. The central cell is homodiploid (2 polar nuclei). Double fertilization involves these nuclei. This is typical of Polygonum type of development.
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