The structure that prevents the collapse of the trachea during breathing is:
A. Ciliated epithelium
B. C-shaped cartilaginous rings
C. Smooth muscle
D. Fibrous tissue
Answer: Option B
Solution (By JKSSB Mock Tests)
The tracheal wall contains C-shaped hyaline cartilage rings that keep the airway open, preventing collapse due to negative pressure during inspiration. Smooth muscle and fibrous tissue connect the rings, ciliated epithelium sweeps mucus upward.
Explanation:
The common cold is a viral infectious disease of the upper respiratory tract. While many viruses can cause it, Rhinoviruses are the most common causative agents, responsible for 30-50% of cases. Coronaviruses and adenoviruses can also cause colds. Influenza virus causes the flu, which is a more severe respiratory illness.
Explanation:
Estrogen promotes ductal growth in breasts and deposition of fat, contributing to breast development at puberty. Progesterone develops alveoli, prolactin synthesizes milk, oxytocin ejects milk.
Explanation:
A test cross is used to determine the genotype of an individual expressing a dominant phenotype by crossing it with a homozygous recessive individual. The resulting phenotypic ratios reveal whether the dominant individual is homozygous (all offspring dominant) or heterozygous (1:1 ratio). It is a valuable tool in genetic analysis.
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