In the human respiratory system, the 'Surfactant' is a lipoprotein complex secreted by which cells to reduce surface tension in the alveoli? MCQ with Answer and Explanation
In the human respiratory system, the 'Surfactant' is a lipoprotein complex secreted by which cells to reduce surface tension in the alveoli?
A. Type II alveolar cells
B. Alveolar macrophages
C. Goblet cells
D. Type I alveolar cells
Answer: Option A
Solution (By JKSSB Mock Tests)
Pulmonary surfactant is a complex mixture of lipids (primarily dipalmitoylphosphatidylcholine) and proteins secreted by Type II alveolar cells (septal cells) in the lungs. Its primary function is to reduce the surface tension of the fluid lining the alveoli. Without surfactant, the alveoli would collapse at the end of expiration (atelectasis) due to high surface tension, making it extremely difficult to re-inflate the lungs during inspiration.
Explanation:
Taq polymerase is a thermostable DNA polymerase enzyme isolated from the thermophilic bacterium Thermus aquaticus, found in hot springs. It is used in the Polymerase Chain Reaction (PCR) because it can withstand the high temperatures (around 94°C) required for the denaturation step of PCR without being destroyed, unlike normal DNA polymerases.
Explanation:
Riboflavin is vitamin B₂, a component of coenzymes FAD and FMN involved in redox reactions. Thiamine is B₁, niacin is B₃, pyridoxine is B₆. Riboflavin deficiency causes angular stomatitis.
Explanation:
Vitamin A (Retinol) is essential for the formation of rhodopsin (visual purple), a pigment in the rod cells of the retina necessary for vision in low light conditions. Deficiency of Vitamin A leads to night blindness (nyctalopia), where a person has difficulty seeing in dim light. Severe deficiency can also cause xerophthalmia and complete blindness.
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