Category: Life Sciences Objective Questions

Life Sciences Multiple Choice Questions on “Golgi Complex”.

1. Name the scientist who discovered Golgi apparatus?
A. Robert Remake
B. Rudolf Virchow
C. Camillo Golgi
D. Theodor Schwann
Answer: C
Clarification: Camillo Golgi was an Italian physician who first discovered Golgi complex, which is a single membrane-bound organelle. It consists of five to eight membrane-bound sacs called cisternae.

2. Golgi stack is the stack of Golgi cisternae.
A. True
B. False
Answer: A
Clarification: Golgi stack or dictyosome is the stack of flattened membrane bound sacs called cisternae. The cisternae in stack vary in number, shape, and organization and represented as cis, medial and transform.

3. Which of the following organelle takes part in the secretion?
A. Cytoplasm
B. Ribosomes
C. ER compartments
D. Golgi apparatus
Answer: D
Clarification: Golgi apparatus is prominent in cells that are specialized for secretion like goblet cell of intestinal epithelium secrete a large amount of mucus. Cell secretion takes place from trans-Golgi through exocytosis.

4. The chemical products of the cell are shipped and distributed by_______
A. ER lumen
B. Golgi apparatus
C. Lysosome
D. Endosome
Answer: B
Clarification: Golgi apparatus modifies and transport proteins and lipids that have been built in the endoplasmic reticulum to the outside of the cell or to other locations in the cell.

5. Which type of glycosylation takes place in the g=Golgi apparatus?
A. T-linked glycosylation
B. N-linked glycosylation
C. O-linked glycosylation
D. G-glycosylation
Answer: C
Clarification: O-linked glycosylation occurs by the linking of O-linked oligosaccharides to the hydroxyl group of amino acid via N-acetylglucosamine. Proteins undergo O-linked glycosylation in the cisternae of Golgi.

6. Which of the following is not the function of the Golgi apparatus?
A. Processing and shorting of glycoprotein
B. Lipid metabolism
C. Carbohydrate metabolism
D. Amino acid metabolism
Answer: D
Clarification: Golgi apparatus involves the metabolism of carbohydrates, and lipids, but not of amino acid, so, amino acid metabolism is incorrect. Synthesis of glycolipids and sorting of glycoprotein also takes place in Golgi apparatus.

7. Name the complex polysaccharide which does not synthesize in the Golgi apparatus?
A. Starch
B. Hemicellulose
C. Glycosaminoglycans
D. Pectins
Answer: A
Clarification: Complex polysaccharides are also synthesized in the Golgi apparatus such as hemicellulose and pectin in the cell wall of plant and glycosaminoglycans in the extracellular matrix of animals.

8. Which of the following hypothesis explain vesicle fusion?
A. Lipid raft hypothesis
B. SNARE hypothesis
C. Cell adhesion hypothesis
D. Cell kill hypothesis
Answer: B
Clarification: Snare hypothesis explains the vesicle fusion with target mediated by the interaction of specific proteins called SNAREs (Snape receptors). V-SNARE is present on vesicle while t-SNARE is present on the target.

9. Name the GTPase which control the recognition of interactions between v-SNARE and t-SNARE?
A. Rac protein
B. Ras protein
C. Rab protein
D. Rho protein
Answer: C
Clarification: Rab protein attached with the surface of the vesicle; when vesicle encounter with target membrane, the binding of v-SNARE and t-SNARE causes vesicle to bound the membrane and allow the Rab protein to hydrolyze its bound GTP.

10. Which of the following ATPase dissociate SNARE apart?
A. V-ATPase
B. F-ATPase
C. P-ATPase
D. NSF
Answer: D
Clarification: Once the vesicle fusion to target membrane is done, the complex dissociates with the help of NSF (NEM sensitive factor), which is a soluble ATPase that hydrolyses ATP and separate SNAREs.

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Life Sciences Multiple Choice Questions on “Immunoglobulins”.

1. Synthesis of antibodies takes place by which of the following cells?
A. Bone marrow cells
B. T-cells
C. B-cells
D. Lymph
Answer: C
Clarification: Antibodies are also called immunoglobulin, the antigen- binding glycoproteins, which are exclusively synthesized by B-cells and in billions of forms with different amino acid sequences and different antigen binding sites.

2. The basic structure of antibodies are______
A. Y-shaped
B. X-shaped
C. Linear
D. Hyperbolic
Answer: A
Clarification: The simple antibody structure has two identical antigen-binding sites forming a Y-shaped molecule. These antigen-binding sites are present on the tip of each arm of the Y.

3. Name the heavy chain of immunoglobulin G.
A. μ
B. ε
C. α
D. γ
Answer: D
Clarification: Immunoglobulin has five isotopes with different heavy chains, i.e. IgM has a μ heavy chain, IgE has ε, IgA has α, and IgG has a γ heavy chain.

4. What is the name of the hypervariable region of immunoglobin, which is responsible for its diversity?
A. CDR
B. Hinge region
C. Epitope
D. Agretope
Answer: A
Clarification: CDR is complementarity determining regions which impart the diversity in the variable region of both heavy and light chains. These are three small hypervariable regions and remaining part is called framework region.

5. Who discovered the structure of immunoglobulin by treating it with beta-mercaptoethanol?
A. Nisonoff
B. Edelman
C. Porter
D. Whittekar
Answer: B
Clarification: Edelman discovered that when immunoglobulin treated with beta-mercaptoethanol, it will fall apart into four chains, i.e. two identical light chain and two large heavy chains. This result was considered to propose a structure of immunoglobulin.

6. Which of the following amino acid is found in the hinge region?
A. Alanine
B. Aspargine
C. Proline and cysteine
D. Phenylalanine
Answer: C
Clarification: Hinge region is found in IgG, IgA, and IgD to provide flexibility in its structure. These regions are rich in proline and cysteine and basically found between two Fab arms of the Y-shaped antibody.

7. Which immunoglobulin can pass through placenta?
A. IgD
B. IgE
C. IgM
D. IgG
Answer: D
Clarification: IgG is the only antibody which can pass through the placenta, except IgG2 all other subtypes of IgG can cross the placenta and transfer immunity from mother to fetus.

8. Name the class of immunoglobulin which has a pentameric structure?
A. IgE
B. IgG
C. IgA
D. IgM
Answer: D
Clarification: IgM is the first antibody to produce during the primary response to antigen and it is also the first antibody which is made by the developing B-cells. It is composed of five units and formed pentameric structure with a J-chain.

9. Which of these immunoglobulins is present in external secretion?
A. IgG
B. IgM
C. IgA
D. IgE
Answer: C
Clarification: IgA is the predominant immunoglobulin which is present in the external secretion such as saliva, breast feed, tears, and mucus. It constitutes 10-15% of total immunoglobin in serum.

10. Name the class of immunoglobulin which takes part in hypersensitivity reaction?
A. IgG
B. IgE
C. IgA
D. IgM
Answer: B
Clarification: IgE mediates hypersensitivity reaction which is responsible for the symptoms of hay fever, asthma, and anaphylactic shock. It includes degranulation of basophils and mast cells.

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Life Sciences Multiple Choice Questions on “Recombination”.

1. Rearrangement of DNA that involves the breakage and reunion of DNA is called___________
A. Replication
B. Recombination
C. Translation
D. Transcription
Answer: B
Clarification: Recombination is the process of rearrangement of DNA of breakage and reunion and it can change the genomic configuration.

2. Recombination is responsible for crossing-over during meiosis of eukaryotic cells.
A. True
B. False
Answer: A
Clarification: Recombination was first recognized as the process which is responsible for crossing over in the meiosis. It is a large scale rearrangement of DNA molecules.

3. Which of the following is NOT true about homologous recombination?
A. Exchange of homologous segments
B. Exchange takes place between two homologous DNA molecules
C. It is also termed as general recombination
D. It involves a direct exchange of sequences of DNA
Answer: D
Clarification: Homologous recombination involves a reciprocal exchange of sequences of DNA.

4. Which of the following is site specific recombination?
A. Modification
B. Transposition
C. Holiday junction
D. Retrotransposons
Answer:b
Clarification: Transposition is the process of recombination, which allows one DNA sequence to inserted in another without taking care of sequence homology.

5. Who proposed holiday model for homologous recombination?
A. Gobind Khurana
B. Louis Pasteur
C. Robin Holiday
D. Niels Bohr
Answer: C
Clarification: Robin Holiday in 1964, proposed an appealing scheme for recombination called holiday model or hetroduplex model.

6. Which of the following is NOT a recombination system?
A. RecBCD
B. RecE
C. RecF
D. DnaF
Answer: D
Clarification: Homologous recombination was first described in bacterial systems. The three different recombination systems are RecF, RecE, and RecBCD.

7. Name the phenomenon of allele replacement during recombination and DNA repair?
A. Replication
B. Mutation
C. Transversion
D. Gene conversion
Answer: D
Clarification: Gene conversion is the phenomenon of changing allele forms during recombination and DNA repair.

8. Name the protein, which is involved in homologous recombination in E.coli?
A. Topoisomerase
B. Gyrase
C. Helicase
D. RecBCD enzyme
Answer: D
Clarification: The three different recombination systems are RecF, RecE, and RecBCD. RecBCD is known as Exonuclease V and it has both helicase and nuclease activity.

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Life Sciences Interview Questions and Answers focuses on “Enzymes – 2”.

1. Which of the following function is catalyzed by Racemases?
A. Removal of water
B. Intramolecular transfer of a functional group
C. Interconversion of L and D stereoisomers
D. Inversion of asymmetric carbon atom
Answer: C
Clarification: Racemases are the class of Isomerases which catalyzes the intramolecular rearrangement and interconvert L and D stereoisomers. Like racemases another isomerase which catalyzes the intramolecular transfer of functional group is mutases.

2. The zymogen is an inactive precursor of an active enzyme.
A. True
B. False
Answer: A
Clarification: Inactive precursor is first cleaved to form active enzyme and this inactive precursor is known as a zymogen. Many proteolytic enzymes are first synthesized as an inactive precursor which further cleaved to form the active enzyme.

3. Which of the following is an example of ligases enzyme?
A. Mutases
B. Epimerases
C. Racemases
D. Carboxylases
Answer: D
Clarification: Carboxylases are the example of ligases enzyme. Ligases are the class of enzyme which deals with the formation of C-C, C-S, C-O and C-N bonds.

4. What is the binding energy?
A. Free energy released in the formation of enzyme-substrate interaction
B. The energy required to form a bond
C. The energy required to bind substrate
D. It is the activation energy
Answer: A
Clarification: Binding energy is the free energy released when the enzyme-substrate complex is formed. This energy is used to lessen the activation energy. Binding energy can be maximum when the only correct substrate binds to the enzyme.

5. Which of the following is INCORRECT for the lock-and-key model?
A. It is used to describe the binding process
B. The active site of the enzyme is complementary to the substrate
C. It demonstrates enzyme-substrate complex
D. The binding of the substrate produces a conformational change in enzyme
Answer: D
Clarification: Lock-and-key model is used to describe the enzyme-substrate complex. It is the binding process where the active site of an enzyme is complementary to the shape of the substrate. The binding of the substrate produces a conformational change in the enzyme is incorrect as the confirmation of enzyme changes only in the induced fit model.

6. Which of the following is not a catalytic strategy for an enzyme to perform specific reaction?
A. Covalent catalysis
B. Metal ion catalysis
C. Michaelis constant
D. Acid-base catalysis
Answer: C
Clarification: Enzymes involves more than one strategies to catalyze specific reactions. Acid-base catalysis, metal ion catalysis, and covalent catalysis are best-characterized mechanisms employed by an enzyme.

7. What is the SI unit of enzyme activity?
A. Km
B. Kat
C. K_cat
D. V_max
Answer: B
Clarification: Kat stands for katal, SI unit of enzyme activity. One katal is equals to the amount of enzyme that catalyzes the transformation of 1 mole of substrate per second. 1 katal = 1 mol sec^-1.

8. Which of the following is not an example of irreversible enzyme inhibitor?
A. Cyanide
B. Sarin
C. Diisopropyl phosphoflouridate (DIPF)
D. Statin drugs
Answer: D
Clarification: Irreversible inhibitor binds to the active site of the enzyme and destroys the functional group. These inhibitors are mostly toxic in nature. Statin drugs are the example of competitive inhibitors which is used to control cholesterol.

9. Lineweaver-Burk plot is also known as______
A. Double reciprocal plot
B. Hanes-Woolf plot
C. Eadie-Hofstee plot
D. Steady-state equation
Answer: A
Clarification: Lineweaver-Burk plot is a double reciprocal plot as it is the reciprocal of Michaelis-Menten equation represented in the graphical form.
1/V = Km/V_max [S] + 1/V_max.

10. Name the enzyme which is found in tears, sweat, and an egg white?
A. Ribozyme
B. Lysozyme
C. Zymogen
D. Isozymes
Answer: B
Clarification: Lysozyme is an enzyme which is present in secretions such as tears, sweat and found in egg white. Lysozyme cleaves the glycosidic bond that connects NAG and NAM of peptidoglycan cell wall.

11. What is an Isozyme?
A. Same structure, different function
B. Different structure, the same function
C. Same structure, the same function
D. Different structure, different function
Answer: B
Clarification: Isozymes are multiple forms of enzymes that have the same functions but differ in structure. For example, lactate dehydrogenase which catalyzes the conversion of pyruvate to lactate, it has five isoenzymes.

To practice all areas of Life Sciences for Interviews, .

This set of Life Sciences Multiple Choice Questions on “Lysosome”.

1. Which of the following organelle control intracellular digestion of macromolecules with the help of hydrolytic enzymes?
A. Plastid
B. Peroxisome
C. Lysosome
D. Actin
Answer: C
Clarification: Lysosomes are membrane-bound compartment filled with hydrolytic enzymes which control intracellular digestion in the macromolecules. It contains about 40 types of different hydrolytic enzymes.

2. pH of the lysosome is acidic in nature.
A. True
B. False
Answer: A
Clarification: The acidic nature of lysosome is maintained by a hydrogen pump in the lysosomal membrane which pumps hydrogen ion into lysosome and maintains pH of about 5.0 in its interior.

3. Which of these are not the hydrolytic enzymes of lysosome?
A. Lipases
B. Sulfatases
C. Phosphatases
D. Aldolase
Answer: D
Clarification: Lysosomes contain 40 types of hydrolytic enzymes which include lipases, sulphatases, phosphatases, glycosidases etc. These enzymes work optimally in the acidic environment and the lysosome provides an acidic environment for these enzymes.

4. Digestion of cell’s own component is known as__________
A. Autophagy
B. Heterophagy
C. Phagocytosis
D. Pinocytosis
Answer: A
Clarification: Autophagy is the process of self-digestion, autophagic vacuoles contain cells own components, known as autophagosome which further fuse to the lysosome where digestion of components takes place.

5. What is amphisome?
A. Early endosome
B. Fusion of endosome and autophagosome
C. Vacuole
D. The bigger size of lysosome
Answer: B
Clarification: Amphisome is formed when autophagosome fused with the endosomes. This amphisome further fused with lysosome for digestion. It will result in the release of macromolecules into the cytosol.

6. The release of melanosomes from melanocytes is mediated by which of the following process?
A. Autophagy
B. Endocytosis
C. Exocytosis
D. Pinocytosis
Answer: C
Clarification: In the condition of stress, cell releases undigested content by exocytosis of lysosomes. It is a minor pathway. Melanocyte in skin stores its pigment in lysosomes which releases it into the extracellular space of the epidermis.

7. Name the single membrane which surrounded the vacuoles?
A. Contractile vacuole
B. Meninges
C. Tonoplast
D. Sarcolemma
Answer: C
Clarification: Vacuoles are large, fluid-filled vesicles, present in most of the plants and fungal cells. These are surrounded by a single-membrane called tonoplast.

8. Which of the following organelle works as a lysosome in the plants?
A. Contractile vacuole
B. Peroxisome
C. Plastid
D. Vacuole
Answer: D
Clarification: Like a lysosome in animal cells, vacuoles are present in plants and fungi contain a variety of hydrolytic enzymes. The pH of vacuole is also acidic and is maintained by transport protein in the vacuolar membrane.

9. Which of the following pumps excess water out of the cell?
A. Contractile vacuole
B. Lysosome
C. Peroxisome
D. Vacuoles
Answer: A
Clarification: Contractile vacuole is different from vacuoles as it helps in osmoregulation. It is mainly found in protists and is used to pump excess water out of the cell.

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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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