Category: Cell Biology Objective Questions

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.

Cell Biology Multiple Choice Questions on “Chemical Basis of Life – Lipids”.

1. Lipids cannot dissolve in _____________
A. organic solvents
B. chloroform
C. benzene
D. water
Answer: D
Clarification: Lipids are vital biomolecules that have a characteristic property of being able to dissolve in organic solvents such as benzene and chloroform and their inability to dissolve in water.

2. Which types of bonds are found in fats?
A. amide
B. glycosidic
C. ester
D. acidic
Answer: C
Clarification: Fatty acids consist of one glycerol moiety linked to three fatty acids via ester bonds; the composite molecule is called triacylglycerol or neutral fat.

3. How many carboxyl groups are present in fatty acids?
A. 1
B. 2
C. 3
D. 4
Answer: A
Clarification: Fatty acids are long chain hydrocarbons containing only one carboxyl group at the end of the molecule. Three fatty acid chains link up via ester bonds to a glycerol molecule to form triacylglycerol. The hydrocarbon chain of fatty acids is hydrophobic and the carboxyl group is hydrophilic.

4. Fatty acids that lack double bonds are call saturated.
A. True
B. False
Answer: A
Clarification: Fatty acids differ from each other by the length of hydrocarbon chain present and the nature of bonds between the atoms. Those with presence of double bonds are called unsaturated fatty acids and the other group is called saturate fatty acids.

5. Which type of bonds present in vegetable fats account for their liquid state?
A. Single bonds
B. Double bonds
C. Amide bonds
D. Glycosidic bonds
Answer: B
Clarification: Double bonds are profusely present in the vegetable fats which account for their liquid state at room temperature. Due to this reason they are also known as polyunsaturated. Fats that are liquid at room temperature are called oils.

6. Margarine is formed using unsaturated vegetable fats by _________________
A. oxidation
B. catalysis
C. hydrogenation
D. leaching
Answer: C
Clarification: Solid shortenings such as margarine are formed by chemically reducing the double bonds present in polyunsaturated vegetables with hydrogen atoms. This hydrogenation process also converts some of the cis-double bonds to trans-double bonds which are straight rather than kinked; called partially hydrogenated or trans-fats.

7. Fats contain more chemical energy than carbohydrates.
A. True
B. False
Answer: A
Clarification: Fats contain more energy content than carbohydrates. A gram of fat contains twice the energy than a gram of carbohydrates. Carbohydrates serve as short-term, readily available energy whereas fat reserves store energy on long-term basis.

8. In most animals, fats are stored in special cells called _____________
A. telomeres
B. granulocytes
C. lymphoid cells
D. adipocytes
Answer: D
Clarification: In many animals, fats are stored in adipocytes cytoplasm of which contains one or a few large droplets of lipids. Adipocytes have the ability to change their shape to accommodate varying quantities of fats.

9. Which of the following steroids is a precursor of hormones such as testosterone, progesterone and estrogen?
A. Collagen
B. Glycogen
C. Cholesterol
D. Glycerol
Answer: C
Clarification: Steroids are built on a four-ringed hydrocarbon skeleton. Cholesterol is a steroid and is found majorly in animal cell membranes, it is also a precursor in the synthesis of various steroid hormones such as testosterone, progesterone and estrogen.

10. What is the major difference between a fat (triacylglycerol) and a phospholipid (diacylglycerol)?
A. Glycerol conformation
B. Hydrogen bonding
C. Fatty acid chain
D. Solubility
Answer: C
Clarification: A phospholipid molecule resembles a fat molecule but differs in the sense that it contains only one less fatty acid chain (diacylglycerol) whereas fats contain three fatty acid chains (triacylglycerol).

Cell Biology Multiple Choice Questions on “Cellular Membranes – Membrane Potential and Nerve Impulses”.

1. Response to external stimulus is called _______________
A. reaction
B. immunity
C. response
D. irritability
Answer: D
Clarification: All organisms respond to external stimulus, a property known as irritability. Even the smallest amoeba and bacterial cell possess this feature. In response to external stimulus, a cell may activate from its whole range of metabolic pathways.

2. Information is coded in the form of fast moving impulse in which types of cells?
A. epithelial
B. endothelial
C. neurons
D. hepatocytes
Answer: C
Clarification: Nerve cells are called neurons; they conduct, transmit and collect information in form of electrical impulses. The structure of neurons is unique and different from other cells in the body.

3. Which part of a neuron receives information from other neurons?
A. cell body
B. axon
C. dendrites
D. myelin sheath
Answer: C
Clarification: The fine extensions from cell body of the neurons are called dendrites which receive information from external sources, usually other neighboring neurons.

4. The information is forwarded from the neuron through which part?
A. axon
B. soma
C. dendrites
D. nucleus
Answer: A
Clarification: Axon is a single prominent extension that emerges from the cell body and is responsible for conducting outgoing impulses away from the cell and towards other cells.

5. Myelin sheath is composed mainly of _____________
A. proteins
B. lipids
C. nucleic acids
D. cholesterol
Answer: B
Clarification: Myelin sheath surrounds the axon which extends from the soma of a neuron. Myelin sheath is composed mainly of lipids and their function is to prevent loss of impulses.

6. Membrane potential is present only in nerve cells.
A. True
B. False
Answer: B
Clarification: A membrane potential of -70 mV is present in neurons. However this phenomena is not specific to neurons, membrane potential exists in other types of cells as well from anywhere between -15 to -100 mV.

7. Which of the following exists in nerve and muscle cells?
A. resting potential
B. membrane potential
C. potassium equilibrium potential
D. sodium equilibrium potential
Answer: A
Clarification: Nerve and muscle cells are the only excitable cells in the body; the potential difference that exists between extracellular and intracellular environments is termed as resting potential. However in other cells this voltage is termed as membrane potential.

8. Which of the following has the highest permeability in a resting nerve cell?
A. Na⁺
B. Cl^–
C. I^–
D. K⁺
Answer: D
Clarification: K⁺ has the highest permeability in resting nerve cells. Most of the ion channels open in the membrane of a resting nerve cell are selective for potassium, referred to as potassium leak channels.

9. On which of the following organisms, the research on nerve cells was first carried out?
A. Drosophila melanogaster
B. Grasshopper
C. Giant squid
D. Octopus
Answer: C
Clarification: The first research on action potential and nerve impulses was carried on the axons of giant squid in the late 1940s and early 1950s by Alan Hodgkin, Andrew Huxley, and Bernard Katz.

10. Depolarization is when ___________ ions flow inside the neuron’s membrane.
A. Potassium
B. Sodium
C. Chloride
D. Magnesium
Answer: B
Clarification: Depolarization is the flow of sodium ions into the membrane. These are positively charged and reduce the polarity of a cell with respect to external environment and are therefore cause depolarization.

11. A neuron fires when _____________________
A. action potential is achieved
B. apoptosis is induced
C. re-stimulation occurs
D. stimulation ceases
Answer: A
Clarification: When the external stimulation is strong enough to reach the threshold value which is around -50 mV, the action potential is generated, and firing of the neurons occurs. This is actually the response to stimulus.

12. Saltatory conduction occurs due to _______________
A. axon hillock
B. soma
C. myelin sheath
D. nodes of ranvier
Answer: C
Clarification: Saltatory conduction occurs due to the presence of lipid-rich myelin sheath on the length of the axon. Due to this the action potential jumps from one node to the other, resulting in faster action potential transmission.

13. The parts in the figure are A.__________, B._____________, C.___________, D.____________.

A. dendrites, soma, myelin sheath, nodes of ranvier
B. dendrites, soma, cell body, axon hillock, myelin sheath
C. soma, axon hillock, myelin sheath, dendrites
D. soma, axon hillock, axon, dendrites
Answer: A
Clarification: Dendrites are the fine extensions from cell body, responsible for receiving information from other neurons. The information is processed in soma and then travels down the length of the axon where myelin sheath is discontinuously present. The gaps between the sheath are called nodes of Ranvier.

14. Local anesthetics act by _____________ the ion channels.
A. inactivating
B. opening
C. closing
D. mutating
Answer: C
Clarification: Local anesthetics act by closing the ions channels present in the membranes of sensory cells and neurons. As a result no action potential is generated and information can not be sent to the brain about events occurring at the skin or teeth.

15. Action potential can only flow in the forward direction.
A. True
B. False
Answer: A
Clarification: Action potential can only move in the forward direction generating nerve impulses. This is because the area of the membrane that has just experienced action potential, remains in a refractory period and can not be stimulated again.

Cell Biology Multiple Choice Questions on “Chloroplast Function – Photophosphorylation”.

1. What is photophosphorylation?
A. Addition of phosphate without light
B. Removal of phosphate without light
C. Addition of phosphate with light
D. Addition of phosphate with light
Answer: C
Clarification: Photophosphorylation is the process of addition of phosphate group with the presence of light, which happens as a part of the photosynthesis reactions. In this reaction the ADP molecule is phosphorylated to ATP molecule.

2. Who discovered photophosphorylation?
A. D David
B. D Benjamin
C. D Arnon
D. D Robert
Answer: C
Clarification: D Arnon and his coworkers found photophosphorylation in the bacterial cells. He also found the cyclic and non-cyclic photophosphorylation reactions.

3. Cyclic photophosphorylation has both photosystem I and II.
A. True
B. False
Answer: B
Clarification: Photophosphorylation contains only photosystem I. Because there is only a transfer of electrons, but there’s no reduction of NADP+.

4. The site of photophosphorylation is __________
A. Chloroplast
B. Mitochondria
C. Endoplasmic reticulum
D. Nucleus
Answer: A
Clarification: The photophosphorylation occurs in the thylakoids of chloroplast. Because photophosphorylation requires sunlight to occur and chloroplast is the site for absorption of light.

5. Which enzyme helps in the flow of protons from the thylakoid to the stroma?
A. ADP synthase
B. ATP synthase
C. ADP hydrolase
D. ADP hydrolase
Answer: B
Clarification: ATP synthase helps in the flow of protons from thylakoids to the stroma. It also helps in the production of ATP. It yields 1 molecule of ATP for every 2 photons.

6. How many micromoles of CO₂ is fixed per milligram of chloroplast in an hour?
A. 2.5
B. 3
C. 3.5
D. 4
Answer: C
Clarification: For one milligram of chloroplast 3.5 micromoles of CO₂ is fixed in an hour. This reaction is also known as the “dark reaction”.

7. Which of the following organisms contain chromosome?
A. Green Sulphur bacteria
B. Blue green bacteria
C. Purple bacteria
D. Plant cells
Answer: A
Clarification: A photosynthetic antenna complex found in Green Sulphur bacteria is known as chromosome. They are smaller than the usual antennas in bacteria and lack some protein complexes that aids support for the pigments required for photosynthesis.

8. Which of the following organisms lack photophosphorylation?
A. Algae
B. Cyanobacteria
C. Plants
D. Yeast
Answer: D
Clarification: Yeast is a heterotroph which cannot synthesize its own food by the use of sunlight. It is devoid of the photosynthetic pigments and photophosphorylation requires these pigments.

9. In the conversion of ADP to ATP by the enzyme ATP synthase, which reaction helps in the movement of H⁺ across the membranes?
A. Redox reaction
B. Oxidation reaction
C. Chemiosmosis
D. Redox reaction
Answer: C
Clarification: The chemiosmosis is the process by which H⁺ ions move from thylakoids to stroma. It is simultaneous process of osmosis with chemical reactions.

10. Which of the following protein is disrupted due to the disorder in photophosphorylation reaction?
A. C1
B. D1
C. H1
D. K1
Answer: B
Clarification: The disorder in photophosphorylation due to high intensity light causes an accumulation of reactive oxygen species. This causes them to bind with D1 protein and inactivates them.

11. The inactivation of photosynthesis is known as photo inhibition.
A. True
B. False
Answer: A
Clarification: When there is a high intensity of light, the photosynthesis inhibition happens due to the block in the electron transport chain. This is known as photo inhibition. This photosynthetic capacity is reduced, which in turn reduces the normal metabolism of all plants.

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

1. The main function of lysosomes is ____________
A. excretion
B. synthesis
C. mobility
D. digestion
Answer: D
Clarification: Lysosomes are digestive organelles of a cell and contains over 50 diverse types of hydrolases. These enzymes work at an acidic pH and can hydrolyze mostly all types of biomolecules.

2. Where is the proton pump located in a lysosome?
A. cytosol
B. membrane
C. attached with enzymes
D. extracellularly connected
Answer: B
Clarification: The high internal concentration of the lysosomes is maintained by the H+-ATPase proton pump present in the organelle’s boundary membrane.

3. Kupffer cells are located in the _________
A. kidney
B. lungs
C. liver
D. intestine
Answer: C
Clarification: Kupffer cells are phagocytic cells situated in the liver which are responsible for engulfing the aging red blood cells. The lysosomes of these cells have irregular shape and variable electron density.

4. Which of the following are phagocytic cells?
A. neutrophils, macrophages
B. neutrophils, mast cells
C. mast cells, macrophages
D. mast cells, antibodies
Answer: A
Clarification: Neutrophils and macrophages are the phagocytic cells that ingest potentially dangerous microbes; the microbes are then inactivated by the low pH of lysosomes present in these cells followed by their enzymatic digestion.

5. Destruction and replacement of cell’s own organelles is called ____________
A. transition
B. turnover
C. endocytosis
D. exocytosis
Answer: B
Clarification: Organelle turnover, also called autophagy is the process of regulated destruction and replacement of the cell’s own organelles. This function is performed by the lysosomes.

6. In autophagy, the organelle’s to be ingested are covered by a ______________
A. protein coat
B. oligosaccharides
C. double membrane
D. single membrane
Answer: C
Clarification: In autophagy, the organelles of the cell are fused and subsequently ingested by the lysosomes. Prior to fusion a double membrane wraps up the organelle to be degraded, forming an autophagosome.

7. When a cell is in nutrient deprived state, autophagy increases.
A. True
B. False
Answer: A
Clarification: Worn-out organelles are digested by fusion with the lysosomes and the contents are made available to the cell. In a state of nutrient deprivation the occurrence of autophagy in a cell increases.

8. After the digestive process in an autophagolysosome is over, it is termed as _______________
A. autophagosome
B. residual body
C. endosome
D. peroxisome
Answer: B
Clarification: Autophagolysosome is the structure that forms by the fusion of lysosome with double-membrane wrapped organelle. After the digestive process is over this structure is called residual body which is then ready for exocytosis.

9. Lipofuscin granules decrease in number as individual grows older.
A. True
B. False
Answer: B
Clarification: The residual bodies formed after the digestion of organelles by lysosomes are either discharged from the cell by exocytosis or retained inside the cell, known as ‘lipofuschin granules’. These granules increase in numbers as an individual grows older.

10. In the ‘I-cell disease’, lysosomes are ___________
A. absent
B. bloated
C. short-lived
D. immobile
Answer: B
Clarification: In the cells of individuals affected by the ‘I-cell disease’, lysosomes are bloated due to undegraded materials. This is because the hydrolytic enzymes are not in proper conformation.

11. The enzyme N-acetylglucosamine phosphotransferase is responsible for ____________
A. mannose phosphorylation
B. sucrose phosphorylation
C. tethering Golgi stack
D. modification of integral proteins
Answer: A
Clarification: Mannose 6-phosphate residues are present on the lysosomal enzymes that direct these proteins to the lysosomes after their synthesis from Golgi complex. N-acetylglucosamine phosphotransferase adds the mannose residues on lysosomal enzymes.

12. Lysosomal storage disorders are caused due to ______________
A. absence of lysosomes
B. absence of a single lysosome
C. absence of integral membrane proteins
D. accumulation of lipofuschin granules
Answer: B
Clarification: Lysosomal storage disorders are caused due to the absence of a single lysosomal enzyme. For example, the ‘Pompe disease’ is caused by the absence of alpha-glucosidase.

13. Gaucher disease is caused due to deficiency of ______________
A. hexosaminidase A
B. lysosomes
C. glucocerebrosidase
D. mannose phophate
Answer: C
Clarification: Gaucher’s disease is caused by the deficiency of the lysosomal enzyme glucocerebrosidase. Due to this deficiency, large quantities of glucocerebroside accumulate in the lysosomes of macrophages.

Cell Biology Multiple Choice Questions on “Chemical Basis of Life – Proteins”.

1. In an amino acid, the carboxyl group and amino group are separated from each other by a single ____________ atom.
A. nitrogen
B. sulphur
C. hydrogen
D. carbon
Answer: D
Clarification: Proteins are polymers containing amino acids as monomers. There are twenty different types of amino acids, with varying functional groups. Every amino acid has a carboxyl group and an amino group separated by a single carbon atom between them.

2. Amino acids used in the synthesis of proteins on a ribosome are ________________
A. D-amino acids
B. Mutated amino acids
C. L-amino acids
D. Fluorescing amino acids
Answer: C
Clarification: The Cloud User or the cloud consumer or the self-service user decides which computing resources such as CPU, memory, storage etc. to use for their instances.

3. Instances in cloud computing are also known as ___________
A. Images
B. Resources
C. Virtual Machines
D. Services
Answer: C
Clarification: D-amino acids have methyl and amide groups located on the right side of the molecule and L-amino acids have methyl and amide groups located on the left side of the molecule. The amino acids used for synthesis of proteins on a ribosome are L-amino acids.

4. Microorganisms use D-amino acids.
A. True
B. False
Answer: A
Clarification: Unlike animals, microorganism use D-amino acids in the synthesis of certain small peptides, including those present in cell walls and several antibiotics.

5. Which bonds are present in two neighboring amino acids?
A. Glycosidic bonds
B. Polypeptide bonds
C. Amide bonds
D. Hydrogen bonds
Answer: B
Clarification: Peptide bonds are present between two consecutive amino acids. Carboxyl group of one amino acid is bonded to the amino group of neighboring amino acid, by the elimination of water.

6. The longest known polypeptide is of the muscle protein called __________
A. chitin
B. myoglobin
C. titin
D. papain
Answer: C
Clarification: An average polypeptide chain consists of about 450 amino acids. The longest known polypeptide chain is found in the muscle protein called titin, consisting of over 30,000 amino acids.

7. Which of the following amino acids does not belong to polar charged group?
A. Serine
B. Aspartic acid
C. Lysine
D. Arginine
Answer: A
Clarification: Serine belongs to the category of polar uncharged amino acids whereas aspartic acid, lysine, glutamic acid and arginine belong to polar charged amino acids. These are fully charged at physiological pH and their side chains contain strong organic acids and bases.

8. Histidine is a polar uncharged amino acid.
A. True
B. False
Answer: B
Clarification: Histidine is considered a polar charged amino acid although it is not fully charged at physiological pH. The ability of Histidine to gain or lose a proton in physiological pH ranges, it is an important residue in active sites of many proteins.

9. Which residues are present in histone proteins?
A. Lysine
B. Glutamic acid
C. Arginine
D. Histidine
Answer: C
Clarification: Histone proteins are highly alkaline proteins around which DNA winds and packaged structures of wound DNA on histones are called nucleosomes. The positively charged arginine residues of histone proteins are linked by ionic bonds to negatively charged phosphate groups of DNA.

10. Which of the following groups of amino acids does not interact with water?
A. Polar
B. Non-polar
C. Polar charged
D. Polar uncharged
Answer: B
Clarification: The side chains of non-polar amino acids are hydrophobic in nature and therefore do not form electrostatic bonds. The amino acids included in this category are alanine, valine, leucine, isoleucine, tryptophan, phenylalanine and methionine.