Free Cell Structure and Function MCQs with Answers

• A. Both chloroplasts and mitochondria contain DNA.
• B. The mitochondria are generally smaller than chloroplasts.
• C. Both chloroplasts and mitochondria contain an inner and an outer membrane
• D. Both chloroplasts and mitochondria have an internal compartment - the thylakoid space bounded by the thylakoid membrane

Explanation: This statement is incorrect. Only chloroplasts have an internal compartment known as the thylakoid space.

• A. Movement of chromosomes towards poles
• B. Cytoplasmic cleavage
• C. Crossing over
• D. Transcription

Explanation: The centromere is crucial during cell division as it is the region where spindle fibers attach to chromosomes, facilitating their movement…

• A. Membrane potential
• B. Accumulation of Na ions
• C. Accumulation of K ions
• D. Proton gradient

Explanation: The chemiosmotic theory, proposed by Peter Mitchell, suggests that a proton gradient across the membrane is used to generate ATP.

• A. Thylakoids - flattened membranous sacs forming the grana of chloroplasts
• B. Centrioles - sites for active RNA synthesis
• C. Ribosomes - those on chloroplasts are larger (80S) while those in the cytoplasm are smaller (70S)
• D. Lysosomes - optimally active at a pH of about 8.5

Explanation: Thylakoids are flattened membranous sacs forming the grana of chloroplasts.

• A. Outer membrane
• B. Inner membrane
• C. Thylakoids
• D. Stroma

Explanation: Thylakoids are the flattened sac-like membranous structures within chloroplasts.

• A. Oxidative enzymes
• B. Hydrolytic enzymes
• C. Reductive enzymes
• D. Anabolic enzymes

Explanation: Hydrolytic enzymes are responsible for breaking down various biomolecules and are the primary components of lysosomes, facilitating…

• A. Ribosomes which occur on the nuclear membrane and ER
• B. Ribosomes of only cytosol
• C. Ribosomes of only nucleolus and cytosol
• D. Ribosomes of only mitochondria and cytosol

Explanation: Ribosomes attached to the nuclear membrane and endoplasmic reticulum (ER) are involved in synthesizing proteins destined for secretion or…

• A. Ribosome
• B. Peroxisome
• C. Golgi apparatus
• D. Mitochondria

Explanation: The Golgi apparatus is essential for modifying, sorting, and packaging proteins and lipids.

• A. Centrosomes
• B. Golgi bodies
• C. Ribosomes
• D. Mitochondria

Explanation: Ribosomes are the site of protein synthesis in the cell, where amino acids are assembled into proteins, earning them the nickname "protein…

• A. Chemiosmotic theory
• B. Munch's hypothesis (mass flow model)
• C. Relay pump theory of Godlewski
• D. Cholodny­-Went model

Explanation: The chemiosmotic theory, proposed by Peter Mitchell, is the most widely accepted explanation for ATP synthesis in mitochondria and…

• A. Only in the cytoplasm
• B. In the cytoplasm as well as in the mitochondria
• C. In the nucleolus as well as in the cytoplasm
• D. Only on ribose attached to nucleus

Explanation: In the cytoplasm, ribosomes are present and mitochondria also have its own DNA and ribosomes.

• A. Protein synthesis
• B. Phosphorylation of flavoprotein.
• C. Breakdown of macromolecules.
• D. Oxidation-reduction reaction.

Explanation: The cristae of mitochondria house the electron transport chain, where oxidation-reduction reactions occur as part of cellular respiration…

• A. Thylakoids
• B. Lamellae
• C. Cristae
• D. Grana

Explanation: Cristae are the infoldings of the inner membrane in mitochondria, increasing surface area for cellular respiration and ATP production.

• A. Lysosomes
• B. Plastids
• C. Grana of chloroplasts
• D. Protein synthesis

Explanation: Golgi body is the series of flattened stacks which has two faces: cis and trans.

• A. Photorespiration
• B. Phototropism
• C. Photoperiodism
• D. Photosynthesis

Explanation: Peroxisomes are involved in the photorespiration process, primarily in C3 plants.

• A. Complete permeability
• B. Semipermeability
• C. Differential permeability
• D. Impermeability

Explanation: The cell wall is completely permeable, allowing most substances to pass freely in and out of the cell.

• A. While proteins can flip­-flop, lipids cannot
• B. Neither lipids, nor proteins can flip­-flop
• C. Both lipids and proteins can flip-­flop
• D. While lipids can rarely flip-­flop, proteins cannot

Explanation: Lipids can flip-flop, they do so slowly with the help of protein called Flippases. But protein do not flip-flop.

• A. Cellular level
• B. Organismic level
• C. Atomic level
• D. Submicroscopic molecular level

Explanation: The cellular level is where biological organization begins because cells are the basic units of life.

• A. The outer membrane resembles a sieve.
• B. The outer membrane is permeable to all kinds of molecules.
• C. The enzymes of the electron transfer chain are embedded in the outer membrane.
• D. The inner membrane is highly convoluted forming a series of infoldings.

Explanation: The enzymes of the electron transfer chain are not embedded in the outer membrane. They are present in inner membrane.

• A. Cilia contain an outer ring of nine doublet microtubules surrounding two singlet microtubules
• B. The organized beating of cilia is controlled by fluxes of Ca2+ across the membrane
• C. Cilia are hair-like cellular appendages
• D. Microtubules of cilia are composed of tubulin

Explanation: Option B is incorrect because the organized beating of cilia is not controlled by fluxes of Ca but by the sliding of microtubule doublets.