Upsc science and technology Mcqs

The correct answer is C. Golgi apparatus (often called the Golgi body or Golgi complex). The Cellular Post Office • Function: The Golgi apparatus functions exactly like a cell's post office or packaging plant. It receives newly synthesized proteins from the Endoplasmic Reticulum (ER), modifies them (by adding sugar chains to make glycoproteins), sorts them based on their final destination, and packages them into membrane-bound vesicles for shipping. Why the Other Options are Incorrect • A. Chloroplast: This is exclusive to plant cells and is responsible for photosynthesis (converting light energy into chemical energy/sugar), not protein logistics. • B. Centrosome: As discussed earlier, this is primarily found in animal cells and is responsible for organizing microtubules during cell division. • D. Large central vacuole: This is a plant-specific feature primarily responsible for maintaining turgor pressure and storing water/waste.

The correct answer is A. Turgor pressure. Why the Central Vacuole Matters Turgor Pressure: The large central vacuole absorbs water and pushes outward against the rigid cell wall. This internal fluid pressure is called turgor pressure. It keeps the plant crisp, upright, and structurally stable. Without enough water to fill the vacuole, turgor pressure drops, and the plant wilts. Why the Other Options are Incorrect Options B, C, and D are physiological processes and components found exclusively in animals with circulatory systems: Blood clotting (B): This is managed by blood platelets and plasma proteins to prevent bleeding. Haemoglobin Concentration (C): Haemoglobin is an iron-rich protein found in red blood cells that transports oxygen. Antibody Production (D): This is a function of specialized white blood cells (B lymphocytes) within an animal's immune system.

The correct answer is B. Bryophyta. Quick Facts about Sphagnum Common Names: It is universally known as "Peat moss" or "Bog moss". Classification: It belongs to the class Bryopsida (Mosses) under the division Bryophyta. Key Characteristic: Sphagnum is highly valued for its incredible water-retention capacity (holding up to 18–26 times its dry weight in water), making it a staple for soil conditioning, shipping live plants, and historic surgical dressings. What do the other divisions mean? Plant Division Core Characteristic Common Example(s) Thallophyta Simple, undifferentiated body; lacks true roots/stems; includes algae. Spirogyra, Volvox Pteridophyta First terrestrial plants with vascular tissue (xylem/phloem) but produce spores instead of seeds. Ferns, Selaginella Gymnospermae Vascular seed-producing plants, but their seeds are "naked" (not enclosed in fruit). Pines, Cedars, Cycads