Category: Cell Biology Objective Questions

Cell Biology Multiple Choice Questions & Answers (MCQs)on “Cellular Membranes – Plasma Membrane”.

1. Transverse diffusion (flip-flop) is the movement of _____________
A. cholesterol molecule
B. amino acid
C. protein
D. phospholipid
Answer: D
Clarification: In case of a membrane phospholipid, two types of movements are possible: lateral shift i. e. movement from one place in the bilayer membrane to the other within the same leaflet; and transverse diffusion is movement of the phospholipid from one side of the membrane to the other, which is a relatively long process.

2. The mobility of integral proteins can be measured by physical state of the ______________
A. amino acids
B. external phospholipids
C. membrane phospholipids
D. membrane appendages
Answer: C
Clarification: Since integral proteins are embedded in the phospholipid bilayer of the membrane, the mobility of the integral proteins is determined largely by the physical state of membrane phospholipids.

3. Two cells can be operated in such a way that leads to a common continuous plasma membrane of both.
A. True
B. False
Answer: A
Clarification: In a technique called cell fusion, two cells from different species can be fused to have a common cytoplasm and a single continuous membrane.

4. Which of the following can not be used to mediate the fusion of plasma membranes of two different cells?
A. electric shock
B. inactivated viruses
C. Polyethylene glycol
D. emulsifier
Answer: D
Clarification: There are various techniques that can be used to fuse two different cells and all of these are basically used to either modify the surface of plasma membrane or attach to it (inactivated viruses). Emulsifiers however do neither and are hence not used in cell fusion.

5. FRAP can be used to analyze living cells.
A. True
B. False
Answer: A
Clarification: FRAP is a technique that can be used to monitor the movements of molecules across the plasma membranes of a living cell under a light microscope.

6. The erythrocyte has a _________________ shape.
A. spherical
B. convex
C. concave
D. bi-concave
Answer: D
Clarification: The peripheral proteins of the plasma membrane of an erythrocyte are located on the internal surface and make up a fibrillar membrane skeleton, which plays a major role in determining the bi-concave shape of an erythrocyte.

7. Which of the following genetic diseases is caused by mutations in a membrane protein?
A. Alzheimer’s disease
B. Parkinson’s disease
C. Anemia
D. Hemolytic anemia
Answer: D
Clarification: Hemolytic anemia is caused by the abnormal shapes of erythrocytes which have been traced to the mutations in ankyrin or spectrin which are plasma membrane proteins found in erythrocytes.

8. Glycophorin is involved in which of the following disease?
A. viral fever
B. common cold
C. asthma
D. malaria
Answer: D
Clarification: Glycophorin is the receptor utilized by the protozoan that causes malaria, providing a path for entry into the blood cells. Consequently, those who lack glycophorin A and B are immune against the disease.

Cell Biology Questions and Answers for Campus interviewson “Chloroplast Structure and Function – Photosynthetic Units and Reaction Centres”.

1. In which part of the plant, does photosynthesis takes place?
A. Peroxisomes
B. Glyoxisomes
C. Quantosomes
D. Lysosomes
Answer: C
Clarification: Quantosomes are sub cellular organelles present in the membrane of thylakoid in the chloroplast. Their function is to absorb light energy and start the photosynthesis mechanism.

2. Which pigment protects the photosystem from ultraviolet radiation?
A. Chlorophyll a
B. Chlorophyll b
C. Carotenoids
D. Anthocyanin
Answer: C
Clarification: Carotenoids are coloured pigments found in plants and some other prokaryotic algal cells. Carotenoids do not directly contribute to the photosynthesis, but they protect the plants from UV radiation.

3. What is the name of the book written by Jan Ingenhousz, which explains the basis of photosynthesis?
A. Experiments upon Fruits
B. Experiments upon Vegetables
C. Experiments upon Plants
D. Experiments upon Animals
Answer: B
Clarification: Jan Ingenhousz in the year 1779 carried out around 500 experiments to prove the mechanism of photosynthesis. He observed that plants absorb carbon di oxide and evolve oxygen with the help of light energy.

4. Photosystem II happens before photosystem I.
A. True
B. False
Answer: A
Clarification: Photosystem II happens before photosystem I but the name I and II denotes the order of their discovery. The electrons usually flow from photosystem II to photosystem I.

5. Which of the following amino acid is helpful in the synthesis of plastoquinone?
A. Valine
B. Isoleucine
C. Leucine
D. Tyrosine
Answer: D
Clarification: Plastoquinone is a branched chain unsaturated quinone, which helps in the electron transport chain of photosynthesis. P-hydroxyphenylpyruvate is synthesized from tyrosine which then converts finally to plastoquinone.

6. What is the other name of Plastoquinol – plastocyanin reductase?
A. Cytochrome b₄f complex
B. Cytochrome b₅f complex
C. Cytochrome b₆f complex
D. Cytochrome b₅g complex
Answer: C
Clarification: Plastoquinol – plastocyanin reductase is also known as the Cytochrome b₆f complex. It is an enzyme that helps to transfer electrons from Photosystem II to Photosystem I.

7. What is the maximum wavelength of light photosystem II can absorb?
A. 680nm
B. 450nm
C. 700nm
D. 230nm
Answer: A
Clarification: Photosystem II primary donor or P680 is a complex of many pigments which has the potentiality to absorb maximum light at 680nm. It is also known to be the strongest biological oxidizing agent.

8. Which of the following Vitamins act as an electron acceptor in light dependent photosynthesis?
A. Vitamin A
B. Vitamin D
C. Vitamin E
D. Vitamin K
Answer: D
Clarification: Vitamin K also known as phylloquinone acts as an electron acceptor during photosynthesis. It donates a hydrogen molecule and helps in the electron transport chain.

9. During photosynthesis, how many chlorophyll molecules are required to produce one oxygen molecule?
A. 1000
B. 2000
C. 2500
D. 3000
Answer: C
Clarification: Scientists Emerson and Arnold found that in a photosynthetic reaction 2500 molecules of chloroplast is required to produce one molecule of oxygen. They also require eight photons in the process of producing one molecule of oxygen.

To practice all areas of Cell Biology for Campus Interviews,

Cell Biology Multiple Choice Questions on “Cytoplasmic Membrane Systems – Vesicle Transport”.

1. A protein coat of diameter ________ is present on the transport vesicles.
A. 0.5-1 mm
B. 0.5-1 nm
C. 0.5-1 pm
D. 0.5-1 μm
Answer: D
Clarification: The Golgi complex was discovered by Camillo Golgi for which he was awarded Nobel Prize in 1908. It consists of flattened, disk-like membranous cisternae of diameter 0.5 to 1 μm.

2. Which molecule activates the formation of a transport vesicle?
A. G-protein
B. Lactose
C. DNA helicase
D. Inducer
Answer: A
Clarification: A protein coat made of soluble proteins is assembled on the cytosolic surface of the donor membrane at the site where budding takes place; this assembly is triggered by the activation of G-protein.

3. COPII-coated vesicles move the materials from ____________ to ____________
A. ERGIC, Golgi complex
B. Golgi complex, ERGIC
C. ER, Golgi complex
D. Golgi complex, ER
Answer: C
Clarification: COPII-coated vesicles (COP is an acronym for coated proteins) transport the materials from endoplasmic reticulum (ER) to ERGIC and Golgi complex.

4. COPI-coated vesicles move the materials in __________________ direction.
A. retrograde
B. anterograde
C. radial
D. lateral
Answer: A
Clarification: The COPI-coated vesicles transport the materials in retrograde direction; from endoplasmic reticulum (ER) to Golgi stack and from trans Golgi cisternae backward to cis Golgi cisternae.

5. Glycosyltransferases are selected by CopII-coat proteins.
A. True
B. False
Answer: A
Clarification: The COPII-coat selects and concentrates various proteins for transport sing vesicles. Proteins selected by COPII-coated vesicles include glycosyltransferases which function at later stages in a biosynthetic pathway.

6. Sar1 is a _______
A. carbohydrate
B. glycolipid
C. G-protein
D. alkali
Answer: C
Clarification: Among COPII proteins, Sar1 is a G-protein which initiates vesicle formation and regulates the assembly of the vesicle coat. G-proteins function as molecular switches inside the cells.

7. The protein coated vesicle must release its components into the Cytosol before fusing with the target site.
A. True
B. False
Answer: A
Clarification: Before fusing with the target site the protein coat is disassembled and contents released in the cytosol. This is triggered by the hydrolysis of GTP bound to Sar1.

8. ARF1 is a _______ binding protein.
A. carbohydrate
B. GTP
C. GDP
D. ATP
Answer: B
Clarification: Similar to Sar1 protein found in COPII-coat proteins, ARF1 is a GTP-binding protein found in COPI-coat proteins. The GTP is hydrolyzed prior to disassembly of the coat.

9. Retrieval signals, present on the C-terminus of ER resident proteins are captured by the receptors present on __________________
A. Clathrin-coated vesicles
B. Golgi complex
C. COPI-coated vesicles
D. COPII-coated vesicles
Answer: C
Clarification: The COPI-coated transport vesicles operate in the retrograde direction and are responsible for retention of proteins that reside in the ER membrane or lumen and are accidentally carried away by the Golgi complex. Such proteins possess retrieval signals at their C-terminus which is captured by receptors on the COPI-coated vesicles, which transport them back to the endoplasmic reticulum.

10. Clathrin present on the clathrin-coated vesicles is a ______________
A. carbohydrate
B. protein
C. oligosaccharide
D. enzyme
Answer: B
Clarification: Clathrin is a protein present on the outer surface of clathrin-coated vesicles forming a honeycomb-like lattice. The main function of these vesicles is to transport lysosomal enzymes.

11. GTP-bound ‘Rabs’ (G-proteins) associated with membranes by a __________ anchor.
A. lipid
B. protein
C. carbohydrate
D. ribonucleic acid
Answer: A
Clarification: Rabs are G-proteins that recruit specific cytosolic tethering proteins to specific membrane surfaces. These are associated with membranes by a lipid anchor.

12. Which state of the ‘Rabs’ is the active state?
A. GDP-bound
B. GTP-bound
C. Membrane-bound
D. Lipid-bound
Answer: B
Clarification: The ‘Rabs’ are encoded by over 60 diverse genes in humans and they cycle between two states; GTP-bound active state and GDP-bound inactive state.

13. t-SNAREs are present on the _____________________
A. budding vesicle
B. transportation material
C. target compartment
D. tethering proteins
Answer: C
Clarification: SNAREs are proteins that function in docking vesicles to the target compartment. There are two types of these proteins; v-SNAREs and t-SNAREs. The latter are present on the target compartments.

14. Synaptobrevin is a ______________
A. membrane vesicle
B. lipid anchor
C. t-SNARE
D. v-SNARE
Answer: D
Clarification: During the regulated release of neurotransmitters, synaptic vesicles are docked to the presynaptic membrane of the nerve cell. Synaptobrevin is a v-SNARE present on the membrane of a synaptic vesicle.

15. Which of the following are the targets of bacterial toxins botulism and tetanus?
A. Sar1
B. SNAREs
C. Rabs
D. ARF1
Answer: B
Clarification: SNAREs present on the membranes of synaptic vesicles and presynaptic membranes are the only targets of potent bacterial toxins; botulism and tetanus. Cleavage of SNAREs by these toxins blocks the release of neurotransmitters and lead to paralysis.