Category: Cell Biology Objective Questions

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

1. What are molecular chaperones?
A. Enzymes
B. Cell mass
C. Tumor
D. Helper proteins
Answer: D
Clarification: Molecular chaperones are helper proteins that help unfolded or misfolded polypeptide chains to assume a certain folded state. The role of these proteins is to prevent the proteins from non-selectively interacting with other components in the cell.

2. Chaperones bind to which type of amino acids?
A. Charged
B. Uncharged
C. Hydrophobic
D. Hydrophilic
Answer: C
Clarification: The molecular chaperones also called the helper proteins attach to short stretches of hydrophobic amino acids which are exposed in nonnative proteins and are found deep within the core in a native protein.

3. Which of the following molecules bind to nascent polypeptides synthesized on the ribosomes?
A. Chaperonins
B. Hsp70
C. Hsp72
D. Hsp
Answer: C
Clarification: Hsp70 is a class of molecular chaperones that bind to nascent proteins being synthesized on ribosomes. Hsp70 chaperones prevent the newly synthesized proteins from binding to other proteins in the cytosol which could lead to misfolding or aggregation.

4. TriC is a _____________
A. hsp70
B. chaperonin
C. organelle
D. enzyme
Answer: B
Clarification: TriC is a chaperonin that helps stabilize long polypeptides. It contains chambers in which peptides can reside without any interference from the external environment.

5. Heat-shock response was first observed in which organism?
A. C. elegans
B. Drosophila
C. Arabidopsis
D. Bacteria
Answer: B
Clarification: Heat shock response on the form of production of heat shock proteins was first observed in Drosophila. In 1962, an Italian biologist was studying the development of Drosophila when it was observed that increasing the temperature, at which larvae grow new heat shock proteins appear on the chromosome.

6. Rubisco is a ________________
A. nucleic acid
B. protein
C. carbohydrate
D. fiber
Answer: B
Clarification: Rubisco is a protein found in chloroplasts of plant cells, it catalyzes the reaction in which carbon dioxide taken up from the atmosphere is covalently linked to organic molecules.

Cell Biology Multiple Choice Questions on “Nucleus – Structure and Function”.

1. Nucleoporins are __________
A. Nuclear pores
B. Ribosomes on nuclear membranes
C. rRNAs in the nucleolus
D. None of the mentioned
Answer: A
Clarification: The nuclear membrane is a double-layered membrane that is interrupted in places by the nuclear pores. The nuclear pores provide channels for the transport of molecules such as water, proteins, RNAs etc. The nuclear pores are collectively known as Nucleoporins.

2. The transport factors that help in the transport of molecules through the nuclear pores are known as ___________
A. Nucleopherins
B. Nucleoporins
C. Karyopherins
D. Karyoporins
Answer: C
Clarification: Proteins, ribosomal subunits, and some DNAs are transported through the pore complexes mediated by a family of transport factors known as karyopherins. Karyopherins are of two types- those that mediate movement of molecules into the nucleus are called importins and those that mediate movement out of the nucleus are called exportins.

3. Lamin proteins that bind to the intra-nuclear chromatin are _____________
A. Emerin
B. Nesprin
C. LEM-3
D. Cannot be said
Answer: C
Clarification: The nuclear lamina is mostly composed of lamin proteins. The cytosolic lamin proteins which face the cytoplasm, such as Emerin and Nesprin binds to the cytoskeleton to provide structural rigidity. Lamins such as LEM3 are found inside nucleus and form the nucleoplasmic veil and bind to the intra-nuclear chromatin.

4. Nuclear Organizer Regions (NOR) is found in ________
A. Nuclear matrix
B. Nucleolus
C. Nuclear lamina
D. Nucleoporins
Answer: B
Clarification: The nucleolus is a dense granular region present inside the nucleus. It is concerned with the production of rRNA and consists of tandems of rDNAs, DNA that codes for rRNA. These rDNA rich regions of nucleolus is called Nuclear Organizer Regions (NOR).

5. Cajal bodies mainly consist of the protein _________
A. Emerin
B. Actin
C. Coilin
D. Desprin
Answer: C
Clarification: Cajal bodies re sub-nuclear compact structures with diameter between 0.2-2.0 micrometers, depending on the species. Under electron microscope, the appear as small tangles threads with a dense dictricution of the Coilin protein. They are bound to the nucleolus by coilin proteins.

6. Which of the following is not a function of Cajal bodies?
A. snRNP biogenesis
B. histone mRNA processing
C. telomere assembly
D. tRNA processing
Answer: D
Clarification: Cajal bodies re sub-nuclear compact structures with diameter between 0.2-2.0 micrometers, depending on the species. They are mainly related to RNA synthesis and helps in RNA-related metabolic processes such as snRNPs biogenesis, maturation and recycling, histone mRNA processing and telomere maintenance.

7. Which of the following is also known as Kremer bodies?
A. Cajal bodies
B. PML bodies
C. Nuclear speckles
D. Nucleolus
Answer: B
Clarification: Promyelocytic leukaemia bodies (PML bodies) are spherical bodies that are found scattered throughout the nucleoplasm and are around 0.1–1.0 µm. They are also known by a number of different names such as nuclear domain 10 (ND10), Kremer bodies, PML oncogenic domains and also nuclear dots.

8. Which of the following plays a role in oncogenic function?
A. Kremer bodies
B. Cajal bodies
C. Splicing speckles
D. None of the mentioned
Answer: A
Clarification: Kremer bodies, also known as Promyelocytic leukaemia bodies (PML bodies) are spherical matrix-associated nuclear bodies. Their specific role in not yet known though their role in ongenesis and viral infection is unavoidable. They may be a site for RNA transcription, storage of rRNAs of other transcriptional activity.

9. Nuclear speckles ______________
A. perform splicing of snRNPs
B. perform splicing of rRNAs
C. act as a transcription site for rRNAs
D. act as a storage site for snRNPs
Answer: A
Clarification: Nuclear speckles, also called as splicing speckles are subnuclear structures that are enriched in pre-messenger RNA splicing factors and are located in the interchromatin regions of the nucleoplasm. The splicing factors help in the splicing of snRNPs and other splicing proteins that are necessary for pre-mRNA processing.

10. Which of the following is not true?
A. Paraspeckles are irregular shaped sub-nuclear compartments
B. Paraspeckles disappear in absence of RNA polemerase II transcription
C. They are transcription dependent
D. They are present during interphase and absent during mitosis.
Answer: D
Clarification: Paraspeckles are irregular shaped sub-nuclear compartments which are transcription dependent. Paraspeckles disappear in absence of RNA polemerase II transcription and all of its associated protein components form a crescent shaped perinucleolar cap in the nucleolus. However, paraspeckles are present during the interphase and all the stages of mitosis except the telophase.

Cell Biology Objective Questions & Answerson “Self-assembling Macromolecules”.

1. Tobacco Mosaic Virus consists of one long molecule of ______________
A. DNA
B. Carbohydrates
C. Glycerol
D. RNA
Answer: D
Clarification: In 1955 at the University of California, it was demonstrated that TMV particles consist of one long molecule of RNA which is 6600nucleotides long wound in a helical capsule made of 2130 identical protein subunits.

2. TMV particles are not capable of self-assembly.
A. True
B. False
Answer: B
Clarification: In the first experiments conducted in 1955, the RNA and protein components of a TMV were separated and then mixed together. After a brief incubation period, the recovered mixture contained infective particles. This confirmed the self-assembly property in TMV.

3. Ribosomes consist of RNA and _____________
A. carbohydrates
B. nucleic acids
C. proteins
D. nucleotides
Answer: C
Clarification: Ribosomes consist of different types of RNAs and proteins. Regardless of the source, all ribosomes contain two subunits of different sizes.

4. The large (50S) ribosomal subunit of bacteria contains _______ molecules of RNA.
A. 1
B. 2
C. 3
D. 4
Answer: B
Clarification: The large (50S) ribosomal subunit of bacteria contains 2 molecules of RNA and approximately 32 different proteins. The smaller 30S subunit contains one RNA molecule and 21 different proteins.

5. Which protein of the smaller subunit of bacterial ribosome was found to have a function in ribososme assembly?
A. S12
B. S14
C. S16
D. S18
Answer: C
Clarification: The S16 protein of the smaller ribosomal subunit 30S was found to have a function solely in ribosome assembly. The deletion of this protein slowed down the in vitro assembly process.

6. Eukaryotic subunits are not capable of self-assembly.
A. True
B. False
Answer: A
Clarification: Ribosomal subunits of bacteria are capable of self-assembly whereas those of eukaryotes are not. Transient association of proteins is required in the in vitro synthesis of eukaryotic ribosomes that don’t even end up in the final product.

To practice all objective questions on Cell Biology,

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.