Category: Life Sciences Objective Questions

Life Sciences Multiple Choice Questions on “B-Cell”.

1. Which of the following is responsible for B-cell activation?
A. Infection
B. Antibody
C. Antigen
D. Allergy
Answer: C
Clarification: The activation of mature B-cell is done by antigen. When antigen come in contact with B-cells, it undergoes clonal proliferation and divided into memory cells and plasma cells.

2. What is the meaning of thymus independent B-cell activation?
A. Without the participation of T-cell
B. Do not mature in the thymus
C. Thymus would not take part in its activation
D. Affinity maturation takes place in the thymus
Answer: A
Clarification: In thymus independent B-cell pathway, antigen activates B-cell without the participation of TH cell. Response generated by thymus independent antigens only generate IgM and do not give rise to memory.

3. Which of the following acts as a coreceptor for B-cell activation?
A. CD28
B. IL-2
C. IgA
D. CD19
Answer: D
Clarification: CD19, CD81, and CD21 are present on the B-cell membrane and known as a B-cell coreceptor. These receptors are used to determine a cell’s identity and for transducing signals.

4. Out of these, which transcription factor does not take part in B-cell activation?
A. Abl
B. NF- kB
C. Jun
D. Fos
Answer: A
Clarification: Transcription factors like NF-AT, CREB, JUN, FOS, and AP-1 promote gene expression required for B-cell proliferation into a plasma cell and the memory cell.

5. Hybridoma technology is used to produce___________
A. Interferons
B. Monoclonal antibodies
C. Antibodies
D. Immune response
Answer: B
Clarification: It is a method which is used for the production of hybridoma of B-cells. This hybridoma B-cell later used for the production of monoclonal antibodies. Monoclonal antibodies are highly specific against a single epitope of the antigen.

6. Name the drug which is used to isolate hybridoma cells from the media?
A. Amphetamine
B. Opium
C. Aminopterin
D. Cocaine
Answer: C
Clarification: Aminopterin inhibits dHFR enzyme and block denovo pathway of nucleotide synthesis, which further allow the survival of only hybridoma cells and B-cells in HAT media.

7. Name the most commonly used monoclonal antibody for treatment of breast cancer?
A. Bradikinins
B. Prostaglandin
C. Erbutir
D. Herceptin
Answer: D
Clarification: Monoclonal antibodies are specific against the particular antigen and these are used to treat the cancer as they release their toxins in the growing cells which interfere with their cellular processes. Herceptin is particularly for breast cancer while erbutir is for colorectal cancer.

8. Mark the one which is NOT used in generating antibody diversity?
A. Combinatorial V(D)J joining
B. Juntional and insertional diversification
C. Somatic hypermutation
D. Binary fission
Answer: D
Clarification: Different classes of antibodies have variable amino acid sequences at the N-terminal end which interacts with different types of antigens. Four theories have been proposed for generating antibody diversity.

9. Tolerance of self-antigen by B-cells are known as B-cell tolerance.
A. True
B. False
Answer: A
Clarification: Self tolerance is the process by which the immune system does not attack self antigen. Immunological tolerance of B-cell is called B-cell tolerance, B-cell produced by this process does not recognize self-antigen but may recognize non-self antigens.

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Life Sciences Multiple Choice Questions on “DNA Repair”.

1. The correction of changes in DNA by a set of process known as___________
A. Replication
B. DNA repair
C. Translation
D. Transcription
Answer: B
Clarification: DNA repair is the correction process which is used to maintain genetic stability.

2. The genome can maintain its essential cellular function even without DNA repair.
A. True
B. False
Answer: B
Clarification: Genome cannot maintain its essential cellular function if the DNA is damaged. So, for the accurate functioning, a set of correction processes are used known as DNA repair.

3. Name the repair system for UV mediated damage of DNA?
A. Exchange of homologous segments
B. DNA glycosylase
C. Nucleotide excision repair
D. Photoreactivation
Answer: D
Clarification: Exposure to UV radiation can cause pyrimidine dimer which is repaired by a light dependent direct system called photoreactivation.

4. Which of the following enzyme is used in photoreactivation process?
A. DNA ligase
B. DNA photolyase
C. DNA polymerase
D. Primase
Answer: B
Clarification: DNA photolyase participates in the DNA repair system when the damage takes place by UV radiation.

5. Name the repair system which involves the removal of the damaged segment of DNA?
A. Recombinational repair
B. Direct repair
C. Excision repair
D. Mismatched repair
Answer: C
Clarification: Excision of the damaged site comes under the excision repair system. It is of two types, base excision repair and nucleotide excision repair.

6. Name the enzyme which initiates base excision repair process?
A. RNA polymerase
B. DNA polymerase
C. DNA photolyase
D. DNA glycosylase
Answer: D
Clarification: DNA glycosylase cleaves N-glycosidic bonds which liberates altered base and generates apurinic or an apyrimidic site.

7. Which of the following enzyme works in the nucleotide excision repair?
A. DNA photolyase
B. ABC exinuclease
C. DNA glycosylase
D. RecA
Answer: B
Clarification: ABC excinuclease involves the removal of short, usually 12 nucleotide segment. This system is best studied in E.coli.

8. Mark the one, which is NOT a subunit of ABC exinuclease?
A. UvrA
B. UvrB
C. UvrC
D. UvrF
Answer: D
Clarification: ABC exinuclease binds at the site of lesion for the purpose of excision. It consists of three subunits i.e, UvrA, UvrB, and UvrC.

9. Which of the following is NOT the function of the enzyme systems involved in mismatch repair?
A. Recognize mismatched base pair
B. Gene conversion
C. Determine incorrect base from a mismatch
D. Excise incorrect base and carry out repair system
Answer: B
Clarification: Gene conversion is the phenomenon of changing allele forms during recombination and DNA repair.

10. Mark the one, which is CORRECT for SOS repair.
A. RecA protein participates
B. A free radical mechanism is involved
C. The repair enzyme functions only once
D. No bases or nucleotides are removed
Answer: A
Clarification: SOS repair involves RecA protein and is responsible for error prone replication. Final reaction is catalyzed by DNA ligase.

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Life Sciences Multiple Choice Questions on “Bioenergetics”.

1. Law of thermodynamics which states that energy can neither be created nor be destroyed is ___________
A. The second law of thermodynamics
B. Third law of thermodynamics
C. First law of thermodynamics
D. Zero-order kinetics
Answer: C
Clarification: First law of thermodynamics depicts that energy can neither be created nor be destroyed but it can transform from one form to another. This shows that the energy remains constant in the system and in surroundings.

2. Gibb’s free energy is the portion of the total energy which is available for useful work.
A. True
B. False
Answer: A
Clarification: Gibb’s free energy is also known as chemical potential and is denoted by ∆G. It is the portion of total energy in a system which is available for work.

3. Which of the following equation shows the relationship between free energy change (∆G) and the change in entropy (∆S), under constant temperature and pressure?
A. ∆G = T∆H – ∆S
B. ∆G = T∆H/∆S
C. ∆G = ∆H/T∆S
D. ∆G = ∆H – T∆S
Answer: D
Clarification: The relationship between free energy change and change in entropy of a reacting system under constant temperature and pressure is given by equation ∆G = ∆H – T∆S, where ∆H is the change in enthalpy and T is temperature.

4. What is the value of ∆G, when a system is in equilibrium?
A. ∆G = 0
B. ∆G = 1
C. ∆G = -1
D. ∆G = ∆G֯
Answer: A
Clarification: Under equilibrium, both forward and reverse reactions occur at equal rates which make a change in free energy zero.

5. Which of the following factor is not responsible for the actual change in free energy (∆G)?
A. Temperature
B. Pressure
C. The initial concentration of reactant and products
D. pH
Answer: D
Clarification: During a reaction, the actual change in free energy is influenced by temperature, pressure, and the concentration of reactant and product at an initial level while ph does not affect the rate of reaction.

6. Which of the following equation gives the relationship between ∆G֯ and Keq?
A. ∆G֯ = -RT ln K_eq
B. ∆G֯ = ln K_eq
C. ∆G = ∆G֯ (-RT K_eq)
D. ∆G = -RT ln K_eq
Answer: A
Clarification: Equation ∆G֯ = -RT ln Keqis correct as Keq is the equilibrium constant, R is the gas constant and T is the absolute temperature. This equation shows the simple prediction about the rate of reaction as if it proceeds forward, reverse or is at equilibrium.

7. What is the standard free energy change of ATP?
A. Small and negative
B. Large and positive
C. Large and negative
D. Small and positive
Answer: C
Clarification: The phosphoryl transfer potential determines the negative free energy values. ATP has a higher tendency to transfer its terminal phosphoryl group to water during hydrolysis and generate large and negative free energy change.

8. Which of the following act as a storage form of high energy phosphate?
A. Glucose-6-phosphate
B. Phosphoenolpyruvate
C. Phosphagens
D. Glycerol phosphate
Answer: C
Clarification: High energy phosphate stored as the phosphagens. It is of two types, creatine phosphate in vertebrates and arginine phosphate in invertebrates. Phosphagens maintains the concentration of ATP when it is utilized as a source of energy.

9. What is the name of the molecule which donates its electrons?
A. Reducing agent
B. Oxidative agent
C. Standard reduction potential
D. Oxidant
Answer: A
Clarification: An electron-donating molecule in an oxidation-reduction reaction is called the reducing agent while an electron accepting molecule is called an oxidizing agent or oxidant.

10. What is reduction potential?
A. The molecule loses an electron
B. An atom/molecule gains an electron
C. Reducing the power of an electron
D. Oxidation power of an electron
Answer: B
Clarification: Reduction potential is the readiness with which a molecule gains an electron. It is calculated in volts (V). Electrons move more rapidly from less positive reduction potential to molecules having more reduction potential.

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Life Sciences Multiple Choice Questions on “Nucleus”.

1. Name the control center of the eukaryotic cell?
A. Nucleus
B. Ribosome
C. Cytoplasm
D. Golgi complex
Answer: A
Clarification: Nucleus contains most of the genetic material of the cell and is called the control center of the eukaryotic cell. Eukaryotic cell may have a single nucleus (uninucleate) or have many nuclei (multinucleate).

2. Red blood cells are multinucleate in nature.
A. True
B. False
Answer: B
Clarification: Mature red blood cells do not have a nucleus, so, these cells are neither multinucleate nor uninucleate.

3. Which of the following microorganism have two nuclei?
A. Slime molds
B. Cyanobacteria
C. Amoeba
D. Paramecium
Answer: D
Clarification: Paramecium is unicellular ciliate protozoa which have two nuclei, one is macronucleus and other is micronucleus. Genes for everyday function of the cell is stored in macronucleus and sexual reproduction is controlled by micronucleus.

4. Which of the following is not a component of the nucleus?
A. Chromosome
B. Nucleolus
C. Cytoplasm
D. Nuclear envelope
Answer: C
Clarification: Cytoplasm is not the component of the nucleus but the nucleus is found in the cytoplasm. The four components of the nucleus are nucleoplasm, nuclear envelope, nucleolus, and chromosomes.

5. Mark the INCORRECT statement about nuclear lamina.
A. Filaments present in the inner membrane of the nucleus
B. Made up of lamin proteins
C. Provide mechanical support to the nucleus
D. It has bounded with the ribosomes
Answer: D
Clarification: Bounded with the ribosomes is incorrect for nuclear lamina as ribosomes present on the outer membrane of nucleus while nuclear lamina is a network of an intermediate filament which is present on the nuclear side of the inner membrane of the nucleus.

6. Name the structure which is used to transfer macromolecules between the cytoplasm and nucleus.
A. Microtubules
B. Nuclear pores
C. Cilia
D. Centrioles
Answer: C
Clarification: Nuclear pores are present on the nuclear envelope which helps in transport of macromolecules among nucleus and cytoplasm. Nuclear pores are the part of a nuclear pore complex which includes inner and outer membranes of the nucleus.

7. Name the signal which helps protein to move in or out of the nucleus?
A. Notch signal
B. Paracrine signal
C. Nuclear localization signal
D. Chemical signals
Answer: C
Clarification: Nuclear localization signals are also known as a nuclear-export signal which helps protein to import and export in the nucleus through nuclear pores. These signals are specific amino acid sequences present on the proteins.

8. Non-membrane bound body of the nucleus which disappears in the late prophase and reappears in telophase_______
A. Nucleolus
B. Chromosome
C. Nucleoplasm
D. Nuclear pore
Answer: A
Clarification: Nucleolus is the component of the nucleus which is a non-membrane bound body produced by Nucleolar-organizing region of a chromosome. It disappears in the late prophase and then appears again in the telophase stage of cell division.

9. Which of the following is not true for chromatin?
A. Organized structure of DNA and protein
B. These are highly condensed DNA
C. It is found in the nucleus
D. It contains a single dsDNA
Answer: A
Clarification: Organized structure of DNA and protein is incorrect as chromatin is less condensed and extended DNA while highly condensed DNA is of chromosomes.

10. Which region of chromatin is transcriptionally silent?
A. Nucleoid
B. Centromere
C. Euchromatin
D. Heterochromatin
Answer: D
Clarification: Heterochromatin is darkly stained and highly condensed region of chromatin which is generally believed to be transcriptionally silent.

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Life Sciences Multiple Choice Questions on “T-Cells”.

1. Which of the tracing is NOT the role of T-cell receptor complex?
A. α and β chain
B. CD3
C. CD19
D. CD40L
Answer: C
Clarification: CD19 is a co-receptor of B-cell receptor complex while T-cell receptor complex consists of antigen recognizing α and β chains, expressed on the surface of T-cell in noncovalent association with CD3 molecule. CD40L and CD28 are co-stimulatory molecules.

2. Coreceptor CD3 is used to bind antigen.
A. True
B. False
Answer: B
Clarification: CD3 is present with antigen recognizing α and β chain of TCR; these molecules do not bind with antigen instead of transduce signals after the activation.

3. Name the syndrome occurs in children due to deficiency of the thymus.
A. Acromegaly
B. Gigantism
C. Cushing syndrome
D. DiGeorge syndrome
Answer: D
Clarification: Thymus is required for the development of T-cells. Children which are born without thymus undergo adverse effects of not having matured T-cells; this syndrome is known as DiGeorge syndrome.

4. Which of the following steps is NOT involved in the activation of T-cell?
A. Double positive cell converts to single positive T-cell
B. Foreign peptide bound to MHC provide signals
C. CD28 of TCR interacts with B7 of APC
D. CD23 has ITAM, which transducer signals
Answer: A
Clarification: The conversion of double positive cells to a single positive cell is thymic selection process in which T-cell mature with the interaction of MHC and develops the tolerance to self-antigen.

5. Name the cytokines which act as a T-cell growth factor?
A. IL-3
B. IL-2
C. IL-4
D. IL-5
Answer: B
Clarification: Cytokines released by T-helper cells and have several functions like IL-2 act as T-cell growth factor while IL-4 and IL-5 help in B-cell activation, IL-3 involved in hematopoiesis and secreted by both TH1 and TH2 subset of T-helper cell.

6. Cytokinin which acts as a growth factor of B-cell is________
A. IFNγ
B. IL-10
C. IL-13
D. TNFβ
Answer: C
Clarification: IL-13 is secreted by TH2 and act as B-cell growth factor while IL-10 inhibits macrophages, while IFNγ and TNFβ secreted by TH1 and used to activate macrophages and inflammatory responses.

7. Mark the correct role of cytosolic T-cells.
A. Help in B-cell activation
B. Produce cytotoxin
C. Proliferate T-cell
D. Kill the target cell
Answer: D
Clarification: Cytotoxic T-cell (CTL) once activated it initiate killing of target cells by attaching to it. After interaction with a target cell, it undergoes conjugate formation with the help of calcium. The killing action is performed by cytotoxic substances contained in granules of T-cells.

8. Name the major constituents of cytotoxic T-lymphocyte?
A. Lysozyme
B. Lymph
C. Protein
D. Perforin and granzyme
Answer: D
Clarification: Perforin and granzyme are the cytotoxic substances present in granules of CTL. Perforin involves in the formation of pores on the target cell while granzyme performs apoptosis by direct activation of apoptosis.

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Life Sciences Multiple Choice Questions on “Transcription”.

1. The process of formation of RNA is known as___________
A. Replication
B. DNA repair
C. Translation
D. Transcription
Answer: D
Clarification: Transcription is a process of formation of the transcript or RNA with the help of RNA polymerase.

2. Like replication, transcription also occurs bidirectionally.
A. True
B. False
Answer: B
Clarification: Transcription occurs unidirectionally and synthesized RNA chain from 5’ to 3’ direction.

3. Mark the statement which is INCORRECT about the transcription unit?
A. It is a transcribed segment of DNA
B. Eukaryotes have monocistronic transcription unit
C. Prokaryotes also have a monocistronic transcription unit
D. Immediate product of transcription is primary transcript
Answer: C
Clarification: Transcription unit is the transcribed segment of DNA. If the transcription unit carries information of one gene, it is called monocistronic while a set of adjacent genes when transcribed as a unit called polycistronic.

4. Name the site where upstream sequences located?
A. Prior to start point
B. After the startpoint
C. Right border of DNA
D. In the middle of DNA
Answer: A
Clarification: Start point is the first base pair from which transcription starts. Upstream sequences are located prior to the start point while sequences after the start point are called downstream of it.

5. Which of the following is TRUE for the RNA polymerase activity?
A. DNA dependent DNA synthesis
B. Direct repair
C. DNA dependent RNA synthesis
D. RNA dependent RNA synthesis
Answer: C
Clarification: RNA polymerase is also known as DNA dependent RNA polymerase enzyme and it involves a synthesis of RNA from DNA.

6. Who discovered RNA polymerase?
A. Samuel B. Weiss
B. Nirenberg
C. Watson and Crick
D. Darwin
Answer: A
Clarification: Samuel B. Weiss and Jerard Hurwitz in 1960 discovered RNA polymerase. RNA polymerase is also known as DNA dependent.

7. Which of the following ensure stable binding of RNA polymerase at the promoter site?
A. DNA photolyase
B. Sigma factor
C. DNA glycosylase
D. RecA
Answer: B
Clarification: Sigma factor decreases the binding of the core enzyme to non-specific DNA sequences and increases binding to the promoter.

8. What is the work of the sigma factor in transcription?
A. Helicase action
B. Transcription initiation
C. Transcription elongation
D. Transcription termination
Answer: B
Clarification: Sigma factor is only involved in transcription initiation not in elongation. The sigma factor is released from the core enzyme when the transcript reaches more than 8-9 nucleotide.

9. Name the sigma factor which is used for promoter recognition?
A. Sigma 32
B. Sigma 70
C. Sigma 60
D. Sigma 40
Answer: B
Clarification: There are 7 different types of sigma factors have been reported in E. coli but the most common is sigma 70.

10. Which of the following is used to describe the time taken by RNA polymerase to leave the promoter?
A. Promoter clearance time
B. Abortive initiation
C. Elongation factor
D. Mean time
Answer: A
Clarification: Promoter clearance time is the time taken by RNA polymerase core enzyme to leave the promoter. More the efficient promoter sequences, lesser would be the promoter clearance time.

11. How many base pairs of DNA is transcribed by RNA polymerase in one go?
A. 5-6
B. 3
C. 4
D. 7-8
Answer: D
Clarification: The RNA polymerase core enzyme moves along the template strand at uneven base i.e, moves over 7-8 base pairs in one go.

12. Which of the following transcription termination technique has RNA dependent ATPase activity?
A. Intercalating agents
B. Rho dependent
C. Rho independent
D. Rifampcin
Answer: B
Clarification: The rho factor functions as a Hexamer and has an RNA binding site and is responsible for the termination of transcription. It has RNA dependent ATPase activity.

13. Name the one intrinsic terminator of transcription.
A. Intercalating agents
B. Rho independent
C. Rho dependent
D. Acridine orange
Answer: B
Clarification: Rho independent transcription termination is also known as intrinsic terminators and about 50% of E. coli genes have these types of terminators.

14. Mark the one, which is NOT the transcription inhibitor in eukaryotes.
A. Rifampicin
B. Acridine dye
C. Actinomycin D
D. Rho factor
Answer: D
Clarification: Rifampicin inhibits beta subunit of RNA polymerase II while acridine orange and actinomycin D is used to block elongation.

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