All Free Biology MCQs with Answers

• A. Their physical properties like size and weight
• B. Physical properties of the medium like its density
• C. Their electrical properties like their charges
• D. Both Options A and B are correct

Explanation: In cell fractionation, various components of a cell including its organelle can be isolated in different layers depending upon their…

• A. Osmoregulation
• B. Secretion
• C. Protein synthesis
• D. Formation of spindles

Explanation: Centrosomes are made up of 2 centrioles that form mitotic spindles. Osmoregulation is a function of the plasma membrane, secretion is a…

• A. Mitochondria and Ribosomes
• B. Mitochondria and Chloroplast
• C. Mitochondria and Vacuole
• D. Mitochondria and lysosomes

Explanation: Both mitochondria and chloroplasts are self replicating as they contain their own DNA and enzymes.

• A. Mitochondria
• B. Sarcoplasmic reticulum
• C. RER
• D. SER

Explanation: Fact: Smooth endoplasmic reticulum(SER) is involved in lipid metabolism.

• A. Tay-Sach's disease
• B. Phenylketonuria
• C. Klinefelter's syndrome
• D. Down's syndrome

Explanation: Tay-Sachs disease is the one in which a lipid digesting enzyme is missing or inactive and the brain becomes impaired by an accumulation of…

• A. It contains F1 particles
• B. It is double membranous
• C. is a self-replicating organelle
• D. Number of mitochondria is constant

Explanation: The number of mitochondria varies according to the activity of cells.

• A. Grana
• B. Cnstae
• C. Thylakoid membrane
• D. Intergrana

Explanation: "The explanation for this question will be added soon!".

• A. Both chloroplasts and mitochondria contain DNA.
• B. The mitochondria are generally smaller than chloroplast
• 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: The statement D is incorrect. While chloroplasts have an internal compartment called the thylakoid space, mitochondria do not have a…

• A. RBC
• B. Muscle cell
• C. Mesophyll cell
• D. E.coli

Explanation: Mitochondria are most abundant in muscle cells because of the strenuous metabolic activities.

• A. as energy transferring organelles
• B. in post translational modification of proteins and glycosylation of lipids
• C. in trapping the light and transforming it nto chemical energy
• D. in digesting proteins and carbohydrates.

Explanation: Post translational modification (PTM) is a step in protein biosynthesis.

• A. Mitochondria - ­Produce cellular energy in the form of ATP
• B. Golgi body ­- Provides packaging material
• C. Lysosomes - Secrete hydrolytic enzymes
• D. Endoplasmic reticulum­- Synthesis of lipids

Explanation: Mitochondria are miniature biochemical factories where food stuffs or respiratory substrates are completely oxidised to carbon dioxide and…

• A. Na+ and K+ ions move across cell membrane by passive transport.
• B. Proteins make up 60 to 70% of the cell membrane.
• C. Lipids are arranged in a bilayer with polar heads towards the inner part.
• D. Fluid mosaic model of cell membrane was proposed by Singer and Nicolson.

Explanation: According to the fluid mosaic model of cell membrane structure proposed by Singer and Nicolson (1972), the plasma membrane contains about…

• A. Ribosome
• B. Peroxisome
• C. ER
• D. Mesosome

Explanation: Ribosomes are the location of protein synthesis in a cell is a structure, composed of both RNA and protein.

• A. lacks membrane and contains air
• B. lacks membrane and contains water and excretory substances
• C. is membrane-­bound and contains storage proteins and lipids
• D. is membrane-­bound and contains water and excretory substances.

Explanation: A vacuole in a plant cell is a membrane-bound organelle that functions as a storage compartment.

• A. While proteins can flip­-flop, lipids can not
• 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. Ribosomes which occur on 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 present in nuclear membrane and endoplasmic reticulum take part in protein synthesis.

• A. Ribosome
• B. Peroxisome
• C. Endoplasmic reticulum
• D. Mitochondria

Explanation: Glycolysation of protein means linking of sugars to proteins which starts in the rough endoplasmic reticulum and is completed in the golgi…

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

Explanation: Chemiosmotic coupling hypothesis is the most widely accepted explanation for oxidative phosphorylation in mitochondria and…

• A. Golgi
• B. Porter
• C. De Robertis
• D. Palade

Explanation: Factual Recall. Ribosomes are minute, cellular and non­-membranous particles having an average diameter of 23 mm (230 A°).

• A. Endoplasmic reticulum
• B. Centrosome
• C. Lysosomes
• D. Chloroplast

Explanation: The centrosome is a non-membranous organelle found in animal cells. It is involved in the organization of the microtubules, which are the…