Category: Cell Biology Objective Questions

Cell Biology Questions and Answers for Aptitude teston “Nucleus – Transport of Molecules Through Nucleopores”.

1. Processing of mRNA includes __________
A. 5′ capping, 3′ polyadenylation and RNA splicing
B. 3′ capping, 5′ polyadenylation and RNA splicing
C. 5′ capping and 3′ polyadenylation
D. 5′ capping and RNA splicing
Answer: A
Clarification: After transcription, the pre-mRNA is modified to produce matured mRNA. The modification of mRNA includes the following- 5′ methul guanosine capping that protects the mRNA from RNases, 3′ polyadenylation and splicing of the introns of pre-mRNA.

2. The ability of importins and exportins to transport molecules in and out of the nucleoporins is regulated by ______________
A. ATPases
B. GTPases
C. AMPases
D. Both ATPases and GTPases
Answer: B
Clarification: Impotins and exportins are responsible for the transport of molecules inside the nucleus and outside to the cytoplasm respectively. This transport is regulated by GTPases, enzymes that hydrolyze guanosine triphosphate (GTP) to release energy. The major GTPase used in nuclear transport is ‘Ran’, which can bind either GTP or GDP.

3. Which of the following human cells are multinucleated?
A. Myocytes
B. Erythrocytes
C. Megakaryocytes
D. None of the mentioned
Answer: A
Clarification: Multinucleated cells have multiple nucleus. In humans, skeletal muscle cells which are also known as myocytes, become multinucleated during development. The results in the arrangement of nuclei near the periphery of the skeletal muscle cells and thus, allowing maximum intracellular space for myofibrils.

4. Why are red blood cells anucleated?
A. Presence of nucleus leads to heavier cells that cannot flow in blood stream
B. Absence of nucleus leads to increased space for haemoglobin that carries molecular oxygen
C. Presence of nucleus leads to increased proliferation of RBCs which harms the body
D. All of the mentioned
Answer: B
Clarification: Red blood cells (RBCs) present in human blood stream do not contain nucleus. Absence of nucleus leads to more space for stuffing of haemoglobin that carries molecular oxygen. This thus increases the oxygen-carrying capacity in blood. If the nucleus was present, haemoglobin content will be limited around the periphery. Furthermore, due to absence of nucleus, RBCs contain a disk-like depression that increases the surface are for haemoglobin content.

5. Which of the following first binds to the NLS protein sequence?
A. Importin-alpha
B. Importin-beta
C. CAS protein
D. NLS detecting protein
Answer: A
Clarification: The molecules that contain Nucleus Localization Signal (NLS) sequence, are immediately ushered into the nucleus through nucleopore. The first step of this transport involves binding of importin-alpha to the NLS sequence, which then acts as a bridge for the attachment of importin-beta.

6. Which of the following displaces Importin-alpha from the cargo transported inside the nucleus?
A. Impotin-beta
B. RanGTP
C. CAS
D. RanGTPase
Answer: C
Clarification: Once the complex composed of importin-alpha—importin-beta—molecule enters the nucleus, the importin-alpha and importin-beta has to be removed. RanGTP binds to Importin-beta and displaces it from the complex. Then the Cellular Apoptosis Susceptibility (CAS) protein which is an exportin and is bound to RanGTP, displaces Importin-alpha from the molecule with NLS sequence.

7. The import cycle of cargo or molecule inside the nucleus requires the hydrolysis of ___
A. 1 GTP
B. 1 ATP
C. 2 GTPs
D. 3 GTPs
Answer: C
Clarification: The import of cargo or molecule inside the nucleus is an active transport. This is because the whole of import cycle needs the energy from the hydrolysis of two Guanosine triphosphate (GTP) molecules.

8. Export of molecules from inside the nucleus to the cytoplasm needs hydrolysis ________
A. 1 GTP
B. 1 ATP
C. 2 GTPs
D. 3 GTPs
Answer: A
Clarification: The export of protein molecules from nucleus to cytoplasm is done due to the presence of Nuclear Export Sequence (NES). NES of the protein molecule can bind with an exportin and RanGTP to form a heterotrimeric complex. This complex is then transported outside nucleus by active transport as it requires the hydrolysis of one GTP molecule.

9. Export of proteins with exportin CRM1 can be inhibited by ___________
A. Leptomycin A
B. Leptomycin B
C. Leptomycin D
D. Leptomycin H
Answer: B
Clarification: CRM1 is an exportin which binds to the Nuclear Export Sequence (NES) of protein molecules destines to be transported out of the nucleus. The export process with exportin CRM1 can be stopped by Leptomycin B.

10. Which of the following cellular RNA is not dependent on RanGTP during transport outside nucleus?
A. tRNA
B. rRNA
C. mRNA
D. snRNA
Answer: C
Clarification: All and cellular RNAs such as tRNAs, rRNAs, snRNAs and miRNAs except mRNA are dependent on RanGTP for their transport outside the nucleus. Conserved mRNA export factors such as Mex67/Tap (large subunit) and Mtr2/p15 are required for mRNA transport. In higher eukaryotes, mRNA recruits the protein TREX for spliced mRNA sequences.

Cell Biology Multiple Choice Questions on “Cell Interactions – Cells with Other Cells”.

1. Which of the following is used by cells to interact with other cells?
A. Cell junctions
B. Cell adhesions
C. Cell detectors
D. Cell tubules
Answer: A
Clarification: Cell junctions are used by cells to interact with each other in certain tissues. These are stable interactions made for the development and function of the cell.

2. What is the name of the interaction made by the immune system?
A. Permanent
B. Transient
C. Active
D. Passive
Answer: B
Clarification: The transient or otherwise known as temporary interactions are the cell-cell interaction done by the immune system. These are done when there is an inflammatory reaction.

3. Cell junction is abundant in __________
A. Hepatic cells
B. Cardiac cells
C. Epithelial cells
D. Prokaryotic cells
Answer: C
Clarification: The cell junction is abundant in epithelial cells, which provide barrier and control over the transport in the cell. It is otherwise known as intercellular bridge, which is made up of multiprotein complexes.

4. What is the function of tight junctions in epithelial cells?
A. Separation of fluids
B. Biocatalyst to enzymes
C. Protection
D. Support and structure
Answer: A
Clarification: The tight junction is made up of multi-protein complexes, which helps in regulating the transport mechanism. In epithelial cells, the tight junction is useful in separating the extracellular fluids.

5. Tight junctions are made up of single junctions in our body.
A. True
B. False
Answer: B
Clarification: Tight junctions are made up of four different protein complexes namely occludin, claudin, junctional adhesional molecule and tricellulins. These molecules being heterophilic in nature, they help in regulating the transport.

6. Which of the following is the continuous channel formed by the cell membranes?
A. Desmosomes
B. Peroxisomes
C. Annulus
D. Integrins
Answer: C
Clarification: A continuous channel is formed by the cell membrane of the adjacent cell membranes in contact known as annulus. It is not present with gap junctions.

7. What is extravasation?
A. Movement of leukocytes to tissues
B. Movement of leukocytes to blood
C. Lysis of leukocytes
D. Formation of leukocytes
Answer: A
Clarification: The leukocytes move into the tissue when it is infected or affected by any pathogens, this is called extravasation. The proteins called selectins regulate these.

8. Which of the following is a signaling molecule for bacteria?
A. Heteroserine lactones
B. Polyserine lactones
C. Monoserine lactones
D. Homoserine lactones
Answer: D
Clarification: Homoserine lactones are the signaling molecules a bacteria uses in cell-cell interactions. These help in their growth and metabolism.

9. Bacteria uses glycoproteins and glycolipids to attach itself to the host cell.
A. True
B. False
Answer: A
Clarification: Bacterial cell wall contains glycoproteins and glycolipids to anchor itself to the cell wall. These bacteria release some toxins and disintegrates the cell wall.

10. Which of the following is the result of platelet interaction?
A. Tearing of cells
B. Coagulation
C. Antigen response
D. Inflammation
Answer: B
Clarification: Coagulation happens when the blood platelets interact with the damaged tissue. It releases a chemical signal for the other platelets to do the process of coagulation.

Cell Biology Multiple Choice Questions on “Biological Molecules Structures and Functions – Bonds Types”.

1. The electron clouds around the nucleus are of ___________
A. Spherical shape
B. Spherical and Dumbbell shape
C. Spherical and Hexagonal shape
D. Cannot be determined
Answer: B
Clarification: Electrons swarm around the nucleus of an atom in a mostly unpredictable fashion. Erratic electron behaviour is best described by the electron cloud model. The electron cloud is an area around the nucleus of an atom where electrons are most likely to be found. The clouds are roughly defined by their boundaries which is either spherical or dumbbell shape.

2. Atoms or molecules having orbitals containing a single unpaired electron is known as ___________
A. Captions
B. Anions
C. Free radicals
D. Carbocation
Answer: C
Clarification: Atoms or molecules that have orbitals containing a single unpaired electron are highly unstable. They are called free radicals. Free radicals may be formed when a covalent bond is broken such that each portion keeps one-half of the shared electrons. They may also be formed when an atom or molecule accepts a single electron transferred during an oxidation-reduction reaction.

3. Which of the following is true based on the strength of the bond?
A. Ionic > Covalent > Vanderwaal > Hydrogen
B. Covalent > Ionic > Vanderwaal > Hydrogen
C. Covalent > Ionic > Hydrogen > Vanderwaal
D. Covalent > Ionic > Hydrogen = Vanderwaal
Answer: B
Clarification: Intramolecular bonds are called covalent bonds and are far stronger that intermolecular forces (or bonds). The latter are usually ranked as follows: ionic > Vanderwaal > hydrogen. Hydrogen bonding includes inter molecular interactions with permanent dipoles (and partial charges) between hydrogen atoms and a few other elements. Vander Waals interactions are based on random and instantaneous dipoles which last for fractions of a second in long, polarizable bonds.

4. Which of the following is a non-polar molecule?
A. Water
B. Ammonia
C. Ethylene
D. Ethanol
Answer: C
Clarification: Polar molecules occur when two atoms do not share electrons equally in a covalent bond. A dipole is formed, with part of the molecule carrying a slight positive charge and the other part carrying a slight negative charge. This happens when there is a difference between the electronegativity of each atom. An extreme difference forms an ionic bond, while a lesser difference forms a polar covalent bond. When molecules share electrons equally in a covalent bond there is no net electrical charge across the molecule. In a nonpolar covalent bond, the electrons are evenly distributed.

5. The detailed tertiary structure of a protein is determined by the ___________ technique.
A. HPLC
B. Spectrometry
C. X-ray
D. X-ray crystallography
Answer: D
Clarification: In X-ray crystallography technique, a crystal of the protein is bombarded by a thin beam of X-ray and the radiation that is scattered by the electrons of the protein’s atoms is allowed to strike a radiation sensitive plate or detector, forming an image of spots. When these diffraction patterns are subjected to complex mathematical analysis, an investigator can work backward to derive the structure responsible for producing the pattern.

6. Which of the following is not true?
A. Steroids are built around a four-ringed hydrocarbon skeleton
B. Cholesterol, testosterone, progesterone are examples of steroids
C. Steroids are found in the cell membranes of both plant and animal
D. Cannot be determined
Answer: C
Clarification: Cholesterol is a steroid which is found in the cell membranes of animals. Cholesterol is largely absent from plant cells, which is why vegetable oils are considered “cholesterol-free”.

7. Which of the following bond is not present in DNA?
A. Phosphate bond
B. Hydrogen bond
C. VanderWaal’s force
D. Disulphide bond
Answer: D
Clarification: Disulphide bond is not present in a DNA molecule. Phosphate bond is present between two deoxy-nucleotides (dNTPs) of DNA. The nitrogen bases on the two strands of DNA have hydrogen bonds between them. Adenine is connected Thymine by 2 hydrogen bonds, Guanine is bound to Cytosine by 3 hydrogen bonds. The base stacking in DNA is due to Vanderwaal’s force.

8. Which of the following amino acids may or may not be protonated at neutral pH?
A. Glutamate
B. Lysine
C. Histidine
D. Arginine
Answer: C
Clarification: The amino acids may be negatively charged, positively charged or neutral at a neutral pH. Here, Arginine and Lysine are positively charged or protonated at neutral pH, while Glutamate is negatively charged at neutral pH. However, Histidine may or may not be protonated at normal pH. The side chain of Histidine has a pKa of 6.5, which means only 10% of Histidine is protonated.

9. Heparin is an example of ___________
A. Tertiary protein
B. Oligosaccharides
C. Glycoproteins
D. Glycosaminoglycan
Answer: D
Clarification: A more complex structures of polysaccharides is glycosaminoglycan (GAGs). Unlike other polysaccharides, they have an A-B-A-B where A and B represent two different sugars. An example of GAG is heparin, which is secreted by cells in lungs against tissue damage. Heparin prevents blood coagulation, enabling free flow of blood to heart or lungs.

Cell Biology Multiple Choice Questions on “Aerobic Respiration – Oxidative Metabolism”.

1. Which of the following molecules is present in the mitochondrion?
A. Acetyl CoA
B. Acetyl CoB
C. Acetylanase
D. Acetylcholine
Answer: A
Clarification: Acetyl CoA is present in the mitochondrion which binds with the pyruvate and undergoes the TCA cycle. 2 ATP molecules are generated for one molecule of oxygen; as a result of mitochondrial metabolism.

2. The enzymes of glycolysis are located in the ______________
A. mitochondria
B. golgi complex
C. cytosol
D. cytoplasm
Answer: C
Clarification: Cytosol is the fluid part of the cytoplasm. Starting with the glucose, the initial steps of oxidation process are carried out by the enzymes of glycolysis.

3. How many reactions are constituted in a glycolytic pathway?
A. 2
B. 5
C. 10
D. 15
Answer: C
Clarification: A total of 10 reactions are present in a glycolytic pathway. The first step is phosphorylation of glucose at the expense of one adenosine triphosphate molecule.

4. At the expense of two ATP molecules, how many phosphate groups are present on the fructose in the third step of glycolysis?
A. 2
B. 3
C. 4
D. 5
Answer: A
Clarification: Glucose is first phosphorylated at the expense of one ATP molecule, rearranging to form fructose phosphate and then phosphorylation takes place again leading to a total of two phosphate groups attached to the fructose chain.

5. How many molecules of ATP are formed per molecule of glucose oxidized?
A. 1
B. 2
C. 3
D. 4
Answer: B
Clarification: Two ATP molecules are formed per molecule of glucose oxidized. Along with ATP, in the net reaction two pyruvate molecules and two molecules of water are also formed.

6. Most of the free energy present in the glucose is stored as ATP after glycolysis.
A. True
B. False
Answer: B
Clarification: Only a small fraction of free energy available in glucose is available to cell for the net synthesis of two ATP molecules during glycolysis. Most of the energy is stored in pyruvate.

7. In presence of oxygen, how many additional molecules of ATP can be formed by metabolizing pyruvate and NADH in the mitochondria?
A. more than 20
B. more than 30
C. more than 50
D. more than 100
Answer: B
Clarification: The end products of glycolysis, pyruvate and NADH can be metabolized in the mitochondria in presence of oxygen. This process can generate more than 30 additional molecules of ATP.

8. Decarboxylation of pyruvate group takes place in the ________________
A. outer mitochondrial membrane
B. inner mitochondrial membrane
C. mitochondrial matrix
D. cytosol
Answer: D
Clarification: In the process of extracting energy from the pyruvate, the molecule is transported to the inner mitochondrial membrane and then to the matrix where it is decarboxylated to form a two-carbon acetyl group.

9. Coenzyme A is derived from _________________
A. thiamin
B. riboflavin
C. pantothenic acid
D. biotin
Answer: C
Clarification: Coenzyme A is an organic compound derived from pantothenic acid. Pantothenic acid is a B-group vitamin and is water soluble. The acetyl group from the decarboxylation of pyruvate is transferred to coenzyme A, making it acetyl CoA.

Cell Biology written test Questions & Answerson “Extracellular Matrix and Cell Interactions – Immunoglobulin Superfamily and Cadherins”.

1. Which of the following immunoglobulin is naturally given to the fetus?
A. IgG
B. IgM
C. IgD
D. IgE
Answer: A
Clarification: IgG is the most commonly found immunoglobulin in the serum of humans. It is passed to the fetus from mother through the placenta. It has two antigen binding sites.

2. What is the range of amino acids present in an immunoglobulin molecule?
A. 50-110
B. 70-110
C. 60-10
D. 80-110
Answer: B
Clarification: The immunoglobulin molecules have 70-100 amino acids, which varies according to the functions they are involved in our body. The number of amino acids also depends upon their size.

3. In an immunoglobulin, the heavy chains and the light chains are held together by ____________
A. Diphosphate bond
B. Dichloride bond
C. Disulphide bond
D. Dihydroxide bond
Answer: C
Clarification: The immunoglobulin has two chains, the light chain and the heavy chain. Two light chains and two heavy chains are held together by disulphide bond.

4. What ions is required for the function of cadherins?
A. Ca²⁺
B. Na⁺
C. K⁺
D. H⁺
Answer: A
Clarification: The cadherins is also known as calcium-dependent adhesion molecule. They require calcium ions for its transmembrane function.

5. Cadherins are 720-750 amino acids long.
A. True
B. False
Answer: A
Clarification: Cadherins contain around 720 to 750 amino acid molecules. These amino acids are synthesized by the posttranslational modifications made to the polypeptide chain.

6. Which of the following has abundant protocadherins?
A. Circulatory system
B. Reproductive system
C. Nervous system
D. Coordination system
Answer: C
Clarification: Protocadherins are abundant in the nervous system. They are present in neurons of our nervous system. A certain gene is present here to express the protocadherin protein.

7. What is epithelial mesenchymal transistion?
A. Loss of adhesion and gain of migration
B. Loss of migration and gain of adhesion
C. Lysis of cell
D. Formation of mesenchymal cells
Answer: A
Clarification: Epithelial mesenchymal transition is the property of cells losing adhesion and gaining migration. It is highly useful in the pluripotency of stem cells in organ development.

8. Where are CDH3 gene found?
A. Bone marrow
B. Lymph nodes
C. Neurons
D. Placenta
Answer: D
Clarification: CDH3 type of cadherin expression gene is present in the placenta. This gene is also responsible for some forms of breast cancer.

9. Which of the following is caused by cadherin disorder?
A. Zellweger syndrome
B. Usher syndrome
C. Bubble boy syndrome
D. Down’s syndrome
Answer: B
Clarification: Usher syndrome is an autosomal recessive genetic disorder caused by mutation. In this disorder the cadherin 23 is responsible for the deafness.

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Cell Biology Multiple Choice Questions on “Types of Biological Molecules”.

1. Proteome is a ____________
A. A precursor of protein
B. Storehouse of proteins
C. An inventory of the total amount of proteins
D. None of the mentioned
Answer: C
Clarification: The entire inventory of proteins that is produced by an organism is known as that organism’s proteome. It may be also applied to the inventory of proteins in a particular tissue or cell. Proteomics is the field of protein biochemistry.

2. Which of the following is not a protein denaturant?
A. SDS
B. Phenol
C. DTT
D. Acetic acid
Answer: D
Clarification: Sodium dodecyl sulfate or SDS is a strong denaturant of protein and is used in SDS-PAGE technique. DTT is oftentimes used along with SDS to further denature proteins by reducing their disulfide bonds to allow for better separation of proteins during electrophoresis. Phenol is used as a protein denaturant during isolation of RNA from plants.

3. Which of the following is untrue?
A. Protein folding occurs in Golgi bodies
B. Protein folding is assisted by a protein molecule called Chaperone
C. Transmembrane or organelle proteins contain a signal peptide
D. Proteins are present in cytoplasm and cell organelles of all cells
Answer: A
Clarification: The folding of proteins occurs in the lumen of the Endoplasmic Reticulum (ER). A newly synthesized protein undergoes a series of modifications in the ER with the help of a number of molecular chaperones and folding enzymes that all together assist its proper folding and subsequent release from ER. The majority of ER proteins are dedicated to the folding of proteins. Golgi bodies help in the proper packaging and transport of proteins.

4. RNA does not have the nitrogen base of _______
A. Uracil
B. Cytosine
C. Thymine
D. Adenine
Answer: C
Clarification: RNA does not have the pyrimidine Thymine and has Uracil instead while DNA has Thymine. In RNA, Adenine binds to Uracil with two hydrogen bonds while in DNA, Adenine binds to Thymine by two hydrogen bonds.

5. Which of the following is functionally the odd one out?
A. siRNA
B. miRNA
C. shRNA
D. snRNA
Answer: D
Clarification: micro RNA (miRNA. is a small non-coding RNA that helps in gene silencing. Small interfering RNA (siRNA. helps in gene silencing through the RNA interference pathway. Short hairpin RNA (shRNA. silences target gene via RNA interference. However, small nuclear RNA or snRNA helps in RNA splicing and processing.

6. Which of the following RNA is artificially made?
A. snRNA
B. scRNA
C. miRNA
D. siRNA
Answer: B
Clarification: siRNA, snRNA and miRNA are all produced naturally in the cell. Small cytoplasmic RNA (scRNA. is an engineered (artificial) RNA molecule that helps in in-vitro and in-vivo signal transduction.

7. In RNA transcription, which of the following is a part of TBP-associated factor (TAF)?
A. TFIID
B. TFIIB
C. TFIIF
D. TFIIH
Answer: A
Clarification: TFIID includes the TBP subunit which binds to the TATA box along with some other proteins, together known as the TBP-associated factors. TFIIB provides a binding site for RNA Polymerase. TFIIF contains a special subunit which is bound to the entering RNA Polymerase. TFIIH contains 10 subunits, 3 of which possess enzymatic activity.

8. Those part of the DNA or gene that contribute to the mRNA product is called _________
A. Introns
B. Intervening sequences
C. Exons
D. Split genes
Answer: C
Clarification: Intervening sequences, also called introns are the portions of DNA excluded during transcription and thus are not there in the mRNA product. Exons are the part of DNA transcribed to form mRNA. The genes with intervening sequences are called split genes.

9. Which of the following disaccharides have beta (1->4) bond?
A. Maltose and Sucrose
B. Maltose and Isomaltose
C. Lactose and Cellobiose
D. Sucrose and Cellobiose
Answer: C
Clarification: Among the disaccharides, sucrose, maltose and isomaltose have alpha(1->4) glycosidic bond. However, lactose, lactulose and sucrose have beta(1->4) glycosidic linkage.

10. An example of polar but uncharged amino acid is ___________
A. Lysine
B. Aspartate
C. Serine
D. Arginine
Answer: C
Clarification: Lysine and Arginine are polar and positively charged amino acids. While Aspartate is a polar and negatively charged amino acid. Serine is a polar and uncharged amino acid.

11. Example of a polar amino acid is ____________
A. Glutamine
B. Alanine
C. Methionine
D. Valine
Answer: A
Clarification: Glutamine is a polar but non-charged amino acid. Alanine, Valine and Methionine, on the other hand, are non-polar amino acids.

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