Free Cell Structure and Function MCQs with Answers

• A. pores in the nuclear envelope
• B. the enzymes that digest the cell wall
• C. protein channels in the plasma membrane of animal cells
• D. cytoplasmic strands passing through the walls and connecting adjacent plant cells

Explanation: These fine channels of cytoplasm run through pits in the cell walls and join neighbouring plant cells into one continuous system, so…

• A. it magnifies the specimen many more times
• B. the wavelength of an electron beam is far shorter, giving much greater resolving power
• C. it can be used on living specimens
• D. it uses ultraviolet light instead of visible light

Explanation: Resolution is limited by wavelength, and the very short wavelength of an electron beam allows two points less than a nanometre apart to be…

• A. cellulose
• B. peptidoglycan
• C. chitin
• D. lignin

Explanation: Fungal walls are built from chitin, the same nitrogen containing polysaccharide found in the exoskeleton of insects, which is one reason…

• A. peptidoglycan
• B. cellulose
• C. chitin
• D. phospholipid

Explanation: Peptidoglycan, also called murein, is a mesh of sugar chains cross linked by short peptides, and it is unique to bacteria, which is why…

• A. is made of the protein flagellin
• B. rotates like a propeller at its base
• C. is shorter and never used for movement
• D. has a 9 plus 2 arrangement of microtubules enclosed by the plasma membrane

Explanation: A eukaryotic flagellum, as in a sperm, is an extension of the cell containing nine outer pairs of microtubules around a central pair, and…

• A. does not require a carrier protein
• B. requires ATP and can move a substance against its concentration gradient
• C. occurs only in plant cells
• D. moves only water molecules

Explanation: Both use carrier proteins, but facilitated diffusion is passive and can only run down a gradient, whereas active transport spends ATP and…

• A. from a region of low water potential to one of high water potential
• B. against a concentration gradient using ATP
• C. from a region of higher water potential to one of lower water potential through a partially permeable membrane
• D. along with dissolved solutes through a partially permeable membrane

Explanation: Water always moves down its own water potential gradient, that is from the more dilute solution to the more concentrated one, and the…

• A. the rigid cellulose wall resists further expansion once the cell is turgid
• B. water cannot enter the cell at all
• C. the vacuole absorbs the excess water permanently
• D. the plasma membrane is impermeable to water

Explanation: Water enters by osmosis until the wall pushes back with a pressure equal to the inward osmotic pull, and the cell stops taking in more…

• A. shrink and become crenated
• B. remain unchanged
• C. become turgid but survive
• D. swell and burst

Explanation: Water enters the cell by osmosis because the cytoplasm has the lower water potential, and with no cell wall to resist the pressure the…

• A. a plant cell takes in water and becomes turgid
• B. the protoplast of a plant cell shrinks away from the cell wall in a concentrated solution
• C. the cell wall dissolves completely
• D. the nucleus divides into two

Explanation: In a solution of lower water potential than the cell sap, water leaves the vacuole, the protoplast contracts and pulls away from the wall…

• A. the complete set of genes in a gamete
• B. the sequence of bases in one chromosome
• C. a display of all the chromosomes of a cell arranged in pairs by size and shape
• D. the number of chromatids in a chromosome

Explanation: Chromosomes are photographed at metaphase, when they are most condensed, then cut out and arranged in numbered pairs, which makes an…

• A. 22
• B. 23
• C. 21
• D. 44

Explanation: Twenty two pairs are autosomes, which carry the genes for body characters and are identical in appearance in both sexes, and the remaining…

• A. digests worn out organelles
• B. synthesises hydrogen peroxide for defence
• C. adds sugar groups to newly made proteins
• D. breaks down toxic hydrogen peroxide into water and oxygen

Explanation: Hydrogen peroxide is a damaging by product of several oxidation reactions, and catalase destroys it almost as fast as it forms, making it…

• A. cellulose
• B. chitin
• C. peptidoglycan
• D. lignin

Explanation: Cellulose microfibrils, polymers of beta glucose, give the plant wall its strength, while chitin builds fungal walls and peptidoglycan…

• A. cellulose
• B. pectin
• C. lignin
• D. suberin

Explanation: The middle lamella is a shared pectin-rich layer formed first during cell division, gluing adjacent walls together.

• A. increases steadily
• B. remains constant
• C. decreases
• D. first falls and then rises again

Explanation: Volume grows with the cube of the radius while surface area grows only with the square, so a larger cell has proportionally less membrane…

• A. pinocytosis
• B. osmosis
• C. facilitated diffusion
• D. phagocytosis

Explanation: Phagocytosis, literally cell eating, wraps the membrane around a particle to form a vacuole, as white blood cells do to bacteria.

• A. engulfs large solid particles
• B. occurs without any membrane
• C. takes in dissolved substances in tiny droplets of fluid
• D. occurs only in plant cells

Explanation: Pinocytosis brings in small vesicles of extracellular fluid with dissolved solutes, while phagocytosis handles solid particles.

• A. releases materials in vesicles that fuse with the plasma membrane
• B. takes in fluid droplets from its surroundings
• C. pumps ions against their concentration gradient
• D. divides its cytoplasm during cell division

Explanation: Secretory vesicles from the Golgi move to the surface and merge with the membrane, discharging their contents outside, which is how…

• A. isotonic
• B. hypotonic
• C. pure water
• D. hypertonic

Explanation: In a hypertonic solution the external solute concentration is higher, so water leaves the cell by osmosis and it crenates.