Science Group
Explore subjects and practice MCQs
10
Chapters
1,000
Total MCQs
Unit-3 The cell
Answer: The cell wall is non-living and rigid, unlike the living plasma membrane.
Answer: The plasma membrane is built on a double layer (bilayer) of phospholipid molecules with embedded proteins.
Answer: Singer and Nicolson proposed the fluid mosaic model in 1972, describing proteins floating in a fluid lipid bilayer.
Answer: A selectively permeable membrane permits some molecules to pass while preventing others.
Answer: In the fluid mosaic model, proteins float in or on the fluid phospholipid bilayer like mosaic pieces.
Answer: Osmosis is the net movement of water from a region of higher water concentration to lower concentration across a semipermeable membrane.
Answer: Small nonpolar molecules diffuse easily through the lipid bilayer down their concentration gradient.
Answer: In a hypotonic solution water enters the cell, making it swollen and turgid.
Answer: In a hypertonic solution the cell loses water and the cytoplasm shrinks away from the wall, causing plasmolysis.
Answer: The plasma membrane consists mainly of a phospholipid bilayer with proteins and some carbohydrates.
Answer: The plasma membrane is also called the cell membrane or plasmalemma.
Answer: Cytoplasm is the semi-fluid material filling the cell between the plasma membrane and the nucleus.
Answer: The cytosol is the fluid part of the cytoplasm in which organelles are suspended.
Answer: Cytosol is the water-based fluid containing dissolved salts, sugars, and other small molecules.
Answer: The cytoplasm is the site of most metabolic activities of the cell.
Answer: The nucleus directs and controls the activities of the cell and holds genetic material.
Answer: The nuclear envelope (nuclear membrane) separates the nucleus from the cytoplasm.
Answer: The nucleus is enclosed by two membranes forming the nuclear envelope with pores in between.
Answer: The nucleolus produces RNA and is involved in ribosome formation.
Answer: Chromatin consists of DNA coiled around proteins and condenses into chromosomes during cell division.