All Free Biology MCQs with Answers

1081. What is called movement of cell against concentration gradient ?

• A. Passive Transport
• B. Osmosis
• C. Active Transport
• D. Diffusion

Explanation: Active transport moves substances against their concentration gradient and requires energy, usually from ATP, through membrane transport proteins. Osmosis and diffusion are passive processes down a gradient, so students may choose diffusion when they focus on movement across a membrane without considering its direction.

1082. Membrane that separates 'cytoplasm' and 'nucleus' is called ___________ ?

• A. Cell wall
• B. Cell membrane
• C. Boundary
• D. Nuclear envelop

Explanation: The nuclear envelope is a double membrane surrounding the nucleus and separating its contents from the cytoplasm. Students may choose the cell membrane, but it surrounds the entire cell rather than only the nucleus.

1083. Crysanthemum is propagated by___________?

• A. Suckers
• B. corms
• C. corals
• D. None

Explanation: Chrysanthemum can be propagated vegetatively by suckers, which are shoots arising from the base of the plant and capable of forming independent plants. Students may choose corms because corms are also vegetative structures, but chrysanthemum is not normally propagated through corms.

1084. Biebs that are broke off from cell are called __________?

• A. Apoptotic bodies
• B. Necrosis bodies
• C. Tuberculosis bodies
• D. Cytokinetic bodies

Explanation: During apoptosis, the cell breaks into membrane-bound fragments called apoptotic bodies, which are then removed by phagocytic cells. Students may choose necrosis bodies, but necrosis is uncontrolled cell death and does not characteristically produce these neatly packaged fragments.

1085. Number of cells that are destroyed in adults by apoptosis are ________ ?

• A. 20 to 35 billion cells
• B. 50 to 70 billion cells
• C. 10 to 20 billion cells
• D. 15 to 25 billion cells

Explanation: Apoptosis continuously removes approximately 50 to 70 billion cells per day in an adult, balancing the production of new cells and maintaining tissue size. Students may choose 20 to 35 billion by underestimating the large amount of normal cell turnover in the body.

1086. Special enzymes are released during necrosis from __________ ?

• A. lysosomes
• B. Vacuoles
• C. Cytoplasm
• D. Golgi bodies

Explanation: During necrosis, damaged cells lose membrane integrity and lysosomal enzymes are released, digesting cellular components and surrounding tissue. Students may choose the cytoplasm because it contains many cell substances, but the characteristic digestive enzymes are stored in lysosomes.

1087. Guard cells of stoma are ________ ?

• A. Irregular in shape
• B. Convex in shape
• C. Long and cylindrical in shape
• D. Kidney-shaped

Explanation: In most dicot plants, guard cells are kidney-shaped and change their turgor to open or close the stomatal pore. Students may choose long and cylindrical because grass guard cells have a dumbbell-like form, but that is not the usual shape in most plants.

1088. Stamens are not usually pendulous in plants pollinated by __________ ?

• A. Wind
• B. Insects
• C. Water
• D. Rain

Explanation: Wind-pollinated flowers commonly have long, flexible filaments with pendulous anthers so pollen can be shaken into the air. Insect-pollinated stamens are usually positioned to brush against visiting insects, so students may incorrectly choose wind if they overlook the word 'not'.

1089. Sessile flowers have _________ ?

• A. No scent
• B. Irregular shape
• C. No pedicles
• D. No petals

Explanation: A sessile flower is attached directly to the stem or inflorescence and therefore has no pedicel, the stalk of an individual flower. Students may choose no petals because some sessile flowers are inconspicuous, but lack of a pedicel is the defining feature.

1090. Examples of Epigeal germination include _________ ?

• A. Maize
• B. Sword bean seed
• C. Broad bean seed
• D. Corn

Explanation: In epigeal germination, the hypocotyl elongates and lifts the cotyledons above the soil; sword bean is an example. Students may choose broad bean, but broad bean and maize generally show hypogeal germination, in which the cotyledons remain below the soil.