Category: Life Sciences Objective Questions

Life Sciences Multiple Choice Questions & Answers focuses on “Eukaryotic Chromatin and Chromosomes”.

1. Structure of DNA and protein found in the nucleus of eukaryotic cells___________
A. Nucleic acid
B. Nucleosome
C. Chromatin
D. Tetraplex
Answer: C
Clarification: Chromatin consists of single dsDNA in a coiled and condensed form which is an organized structure of DNA and proteins.

2. Centromere is located exactly at the center of the chromosomes.
A. True
B. False
Answer: B
Clarification: Centromere is the region in the eukaryotic chromosome where kinetochore is assembled and sister chromatids are held together. In some cases, centromere can also be located at the end of the chromosomes.

3. Which of the following is less condensed, less stained portion of chromatin?
A. Metaphase
B. Interphase
C. Heterochromatin
D. Euchromatin
Answer: D
Clarification: Less stained and less condensed portion of chromatin is euchromatin while a darkly stained and highly condensed region of chromatin is heterochromatin.

4. Name the part of a chromosome where t-loop is found.
A. Telomere
B. Centromere
C. Acromere
D. Tetraplex
Answer: A
Clarification: T-loop is found at the end of the chromosome or at the telomere region. It is responsible for the stability of the chromosomal ends.

5. Name the unit of replication?
A. DNA
B. Gene
C. Replicon
D. Chromosome
Answer: C
Clarification: Replicon is the unit of replication, which consists of its own origin of replication. Single chromatin has more than one replicon.

6. Which of the following phase is involved in the conversion of chromatin to chromosome?
A. S- phase
B. M- phase
C. G2- phase
D. G1- phase
Answer: B
Clarification: In G0 phase of non-dividing cells DNA exists as chromatin while in M-phase chromatin is converted to chromosome which is more condensed.

7. Name the basic structural unit of chromatin, which is described by R.Kornberg?
A. Scaffold protein
B. Solenoid
C. 30nm fiber
D. Nucleosome
Answer: D
Clarification: Nucleosome is the first level of DNA packing structure which is composed of beads-on-a-string structure. R.Kornberg in 1974 described the basic structure of chromatin.

8. What are protamines?
A. Large size DNA
B. Sequences that are unique
C. Histone like protein found in fish sperm
D. Highly repetitive DNA
Answer: C
Clarification: Protamine is a polypeptide basically composed of arginine and is present instead of histones in the sperm of fish and some other organisms.

9. Name the protein, which maintained the condensed structure of chromosomes.
A. HSP
B. SMC
C. Collagen
D. Elastin
Answer: B
Clarification: SMC stands for structural maintenance of chromosome protein, which maintained condensed structure of chromosomes.

10. Mark the process which does not involve in histone modification?
A. Acetylation
B. Methylation
C. Phosphorylation
D. Dehydration
Answer: D
Clarification: There are some chemical modification and structural changes take place in histones during replication and transcription called histone modification.

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Life Sciences Multiple Choice Questions on “Vitamins”.

1. Which of the following is not a fat-soluble vitamin?
A. Vitamin D
B. Vitamin K
C. Vitamin C
D. Vitamin A
Answer: C
Clarification: In general, there are only four fat-soluble vitamins (Vitamin A, D, E, K). Vitamin C is an ascorbic acid which is water soluble and precursors of all the coenzymes.

2. Deficiency of which vitamin causes Beri-Beri?
A. Vitamin B12
B. Vitamin B2
C. Vitamin B6
D. Vitamin B1
Answer: D
Clarification: Deficiency of thiamine (Vitamin B1) can lead to Beri-Beri. It is mostly found in the area where polished rice is a major component of the diet.

3. Name the disease caused by the deficiency of Niacin?
A. Pellagra
B. Rickets
C. Scurvy
D. Pernicious anemia
Answer: A
Clarification: Deficiency of niacin causes pellagra, it is a disease of the skin and central nervous system. Its symptoms included three Ds: Dementia, Dermatitis, and Diarrhea.

4. Which of the following is a component of the coenzyme A?
A. Retinol
B. Pantothenic acid
C. Pyridoxine
D. Retinoic acid
Answer: B
Clarification: Pantothenic acid is used in the synthesis of coenzyme A, which is also an acyl group carrier. It performs two main functions, activation of an acyl group for transfer and activation of hydrogen of the acyl group.

5. Megaloblastic anemia is caused due to deficiency of ___________
A. Cobalamin
B. Pyridoxine
C. Niacin
D. Folic acid
Answer: D
Clarification: Deficiency of folic acid leads to megaloblastic anemia, where synthesis of purine and thymidine get diminished which makes cells unable to make DNA and divide.

6. Which of the following vitamin is also known as cobalamin?
A. Vitamin B11
B. Vitamin B12
C. Vitamin B6
D. Vitamin B2
Answer: B
Clarification: Vitamin B12 is also known as cobalamin, it is a part of vitamin B complex along with vitamin B11 (Folic acid), vitamin B6 (Pyridoxine), vitamin B2 (Riboflavin).

7. Mark the INCORRECT statement about Ascorbic acid.
A. It is a strong reducing agent
B. It can have synthesized in the body
C. Involves in hydroxylation of prolyl- and lysyl- residues of collagen
D. Shows antioxidant activity
Answer: B
Clarification: It can have synthesized in the body is incorrect as vertebrates such as birds, fishes, and humans are not able to synthesize vitamin C, due to lack of enzyme gulono-lactone oxidase.

8. All fat-soluble vitamin has a coenzyme function.
A. True
B. False
Answer: B
Clarification: Not all fat-soluble vitamin has coenzyme function, only vitamin K shows such activity. Fat-soluble vitamins released, absorbed and transported with the fat in the body.

9. Name the vitamin which functions as hormone as well as visual pigment?
A. Thiamine
B. Riboflavin
C. Retinol
D. Folic acid
Answer: C
Clarification: Vitamin A is also known as retinol, it is isoprenoid alcohol and essential for vision, growth, reproduction, and maintenance of epithelial tissues.

10. Which of the following vitamin serves as a hormone precursor?
A. Vitamin C
B. Vitamin A
C. Vitamin K
D. Vitamin D
Answer: D
Clarification: Vitamin D acts as a hormone precursor. UV component of sunlight falls on 7-dehydrocholesterol and gets converted to cholecalciferol (Vitamin D3) in the skin. Vitamin D3 absorbed into the blood and transported to liver and kidney where with the help of enzyme it formed calcitriol (a steroid hormone).

11. Name the vitamin which takes part in blood clotting?
A. Vitamin E
B. Vitamin K
C. Vitamin D
D. Folic acid
Answer: B
Clarification: Vitamin K plays role in post-translational modification of various blood clotting factors. It is a fat-soluble vitamin which requires complete synthesis of blood coagulation protein.

12. Name the structure analog of vitamin K, which is used as anticoagulant?
A. Warfarin
B. Tocopherol
C. Ergocalciferol
D. β-carotene
Answer: A
Clarification: Warfarin is a widely used rat poison which inhibits the vitamin K-dependent carboxylation of prothrombin and clinically used as an anticoagulant. Another anticoagulant is Dicoumarol, a derivative of coumarin.

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Life Sciences Multiple Choice Questions on “Endoplasmic Reticulum”.

1. Which of the following is the largest single membrane-bound intracellular compartment?
A. Ribosome
B. Golgi apparatus
C. Nucleus
D. Endoplasmic reticulum
Answer: D
Clarification: Endoplasmic reticulum is a network of closed and flattened single membrane-bound intracellular structure. ER lumen is the enclosed compartment between ER membranes which are physiologically active.

2. Protein undergoes modifications in ER before reaching their final destination.
A. True
B. False
Answer: A
Clarification: After the synthesis of protein, it undergoes various modifications before reaching their final destination i.e. Glycosylation, protein folding, the formation of disulfide bridges, and specific proteolytic cleavage.

3. What is microsome?
A. Compartment of Golgi
B. Smaller ribosomes
C. Small ER compartments
D. Small vesicles of fragmented ER
Answer: D
Clarification: Microsomes are small vesicles formed by the breakdown of ER membrane into fragments. Microsomes which are derived from RER are known as rough microsomes while microsomes lacking ribosomes are called smooth microsome.

4. Endoplasmic reticulum membrane which is associated with ribosomes is called_______
A. ER lumen
B. Smooth endoplasmic reticulum
C. Rough endoplasmic reticulum
D. Endosome
Answer: C
Clarification: Endoplasmic reticulum membrane has been divided into rough or smooth based on the association of ribosome with their cytoplasmic surface. The region of ER that is bounded with ribosomes is called rough endoplasmic reticulum or RER.

5. Name the antibiotic which inhibits the synthesis of oligosaccharides?
A. Tunicamycin
B. Cephalosporins
C. Penicillins
D. Ofloxacin
Answer: A
Clarification: Tunicamycin is an antibiotic which inhibits the synthesis of oligosaccharides by blocking the first step in glycosylation of proteins.

6. Which of the following is not the function of Glycosylation?
A. Helps in proper folding of the protein
B. Confer stability in proteins
C. Helps in cell-cell adhesion
D. Synthesis of membrane lipid
Answer: D
Clarification: Glycosylation is the process of attachment of sugars molecule to the nitrogen atom in an amino acid residue of the protein. synthesis of membrane lipid is incorrect, SER produces membrane lipids.

7. Name the site where detoxification of xenobiotic compounds takes place?
A. Cytosol
B. RER
C. SER
D. Ribosome
Answer: C
Clarification: SER is smooth endoplasmic reticulum which is a part of endoplasmic reticulum membrane where ribosome is not attached. It is the major site for removal of xenobiotics, and the reaction is catalyzed by cytochrome P-450.

8. Name the sequence which allows the resident protein to retain in ER lumen?
A. KDEL
B. KKXX
C. KLDE
D. KXXK
Answer: A
Clarification: KDEL stands for lys-asp-glu-leu sequences, present at the C-terminus of resident proteins. These sequences act as a sorting signal which is necessary for retention of protein in the ER.

9. Which of the following coated vesicle transport protein from ER to Golgi?
A. Clathrin
B. COP II
C. COP I
D. COP III
Answer: B
Clarification: COP II vesicles form for an anterograde pathway from ER to the Golgi. These transport vesicles arise from specialized coated regions of the membrane.

10. Name the coated vesicle which is used to transfer protein from plasma membrane to endosome?
A. Clathrin
B. COP I
C. COP II
D. COP III
Answer: A
Clarification: Clathrin along with different adapter proteins (APs) forms coated vesicles which transport protein from plasma membrane to endosome.

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Life Sciences Multiple Choice Questions on “Major Histocompatibility Complex”.

1. Major Histocompatibility Complex is a tight cluster of linked___________
A. Carbohydrates
B. Proteins
C. Genes
D. Lipid molecules
Answer: C
Clarification: MHC is polygenic in nature, i.e. several genes control the expression of the MHC molecule. These are cell surface proteins which are present with peptide on antigen presenting cells.

2. What is the name of MHC in humans?
A. HLA
B. H2
C. Adjuvants
D. Haplotype
Answer: A
Clarification: Genes for MHC are located on the short arm of chromosome 6 in humans. In human, it is also known as human leukocyte antigens (HLA). MHC is glycoproteins which are expressed on all nucleated cells.

3. All the individual of the same species has the same allele of MHC genes.
A. True
B. False
Answer: B
Clarification: MHC is polymorphic in nature and shows genetic polymorphism by expressing different alleles of a gene. Different individuals have different types of MHC genes. MHC genes are expressed as codominantly.

4. Which of the following polypeptide is important for the expression of MHC I on the cell membrane?
A. Interferons
B. β₂-microglobin
C. Lymphokines
D. Interleukins
Answer: B
Clarification: β₂-microglobin is encoded by chromosome 15, it is always attached to α₃ subunit of MHC I molecules through non-covalent interactions. It does not have a tail.

5. Which of these are non-professional antigen presenting cells?
A. Macrophages
B. Dendritic cells
C. Fibroblast
D. B lymphocytes
Answer: C
Clarification: Antigen presenting cells (APC. is of two types i.e. professional and non-professional antigen presenting cells. Professional antigen presenting cells are B-lymphocytes, dendritic cells, and macrophages while non-professional APCs are fibroblast, epithelial cells, glial cells etc.

6. Name the cell which receives antigen presented by MHC molecule.
A. Nk cells
B. B-cells
C. T-cells
D. Macrophages
Answer: C
Clarification: MHC molecules present processed antigen to T-cells as T-cell receptor does not recognize free antigen, it will recognize only those antigens which are bound to MHC molecules.

7. Name the class of MHC which is recognized by CD4 TH cell.
A. MHC cannot recognize T cells
B. MHC III
C. MHC I
D. MHC II
Answer: D
Clarification: CD4 is a monomeric single chain which recognizes MHC II molecule and is present on T helper cell. It consists of a core extracellular domain and has three critical serine residues on a cytoplasmic tail.

8. Which MHC molecule recognizes CD8 TC cells?
A. MHC I
B. MHC II
C. MHC III
D. HLA-C
Answer: A
Clarification: CD8 is a co-receptor of T-cell and is present on the T cytosolic cell. It is a hetrodimer of α and β chains and recognizes MHC I molecule.

9. Name the part of processed antigen that binds to the MHC molecule and recognized by T-cells?
A. Immunoglobulin
B. Agretope
C. Epitope
D. Chaperone
Answer: B
Clarification: Agretope is the part of processed antigen that is attached to MHC molecule and exposed to T-cell.

10. Which of the following statement is INCORRECT about superantigens?
A. Viral or bacterial proteins
B. Endogenous by nature
C. Unique binding ability
D. Activate a large number of T-cells
Answer: B
Clarification: Superantigens are viral or bacterial proteins which have the unique binding ability of T-cell receptor and MHC II molecules, i.e. it binds simultaneously to both and activate large numbers of T-cells. It can be both either endogenous or exogenous in nature.

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Life Sciences Multiple Choice Questions on “DNA Replication”.

1. Double-helix structure of DNA is discovered by___________
A. Gobind Khurana
B. Nirenberg
C. Watson and Crick
D. Darwin
Answer: C
Clarification: In 1953, Watson and Crick worked out on the double – helix structure of DNA and find out the complementary nature of two strands.

2. Base sequence of each parental strand considered to synthesis new complementary strand.
A. True
B. False
Answer: A
Clarification: The two strands of DNA are separated without breakage of a covalent bond and its base sequence act as the template strand to synthesize a new complementary strand.

3. What is a mode of replication in E.coli?
A. Intermediate
B. Dispersive
C. Conservative
D. Semiconservative
Answer: D
Clarification: Meselson and Stahl in 1958 conducted an experiment and demonstrated the semiconservative replication of DNA in E.coli.

4. What is the origin of replication?
A. Particular site at which DNA replication starts
B. Site which prevents initiation
C. Random location on the DNA
D. Site at which replication terminated
Answer: A
Clarification: Origin of replication is particular sites on DNA as replication does not start at random sites. Replication starts from a particular site and proceeds bidirectionally or unidirectionally till the terminus site.

5. How many numbers of replicon is found in E.coli?
A. Five replicon
B. Two replicon
C. Single replicon
D. Multiple replicon
Answer: C
Clarification: E.coli is monorepliconic and have single replicon while eukaryotic cells contain many replication origins on a single chromosome and called multirepliconic.

6. Which of the following protein does not involve in the initiation of replication?
A. DnaA
B. SSB (Single strand binding protein)
C. DnaB
D. DnaF
Answer: D
Clarification: In eukaryotic replication, more than 20 proteins take part out of that the initiation of replication takes place in the presence of helicase, primase, SSB, DnaC, DnaA.

7. Which of the following protein is required for connecting Okazaki fragments?
A. Scaffold protein
B. Helicase
C. Primase
D. DNA gyrase
Answer: D
Clarification: After initiation, the chain elongation and joining of Okazaki fragments take place by DNA gyrase, DNA ligase, DNA polymerase.

8. Name the protein, which is used for termination of replication?
A. DnaC
B. SSB
C. Tus protein
D. DNA polymerase
Answer: C
Clarification: Tus protein is terminus binding protein which is used for termination of replication.

9. Which of the following would relax negatively supercoiled DNA?
A. DNA gyrase
B. Type I topoisomerase
C. Collagen
D. Elastin
Answer: B
Clarification: Negatively supercoiled DNA can be relaxed by topoisomerase I. It creates the nick in one strand of DNA and rotates freely to resolve supercoiling.

10. Name the protein, which is responsible for the formation of RNA primer?
A. Topoisomerase
B. Gyrase
C. Helicase
D. Primase
Answer: D
Clarification: RNA primers are generated by using protein, primase which is also known as RNA polymerase. Primers are short RNA sequences.

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Life Sciences Multiple Choice Questions on “Enzymes – 1”.

1. A __________is a biocatalyst that increases the rate of the reaction without being changed.
A. Aluminum oxide
B. Silicon dioxide
C. Enzyme
D. Hydrogen peroxide
Answer: C
Clarification: Among these options, an enzyme is an only option which is a biocatalyst that catalyzes the chemical reaction without being changed while all other options are of the catalyst which increases or decrease the rate of reaction based on their concentration.

2. Enzyme increases the rate of reaction by lowering the activation energy.
A. True
B. False
Answer: A
Clarification: Activation energy is the difference in free energy between the reactants and transition state. To complete a reaction, enzyme lowers the activation energy and crosses the transition state.

3. What is the nature of an enzyme?
A. Vitamin
B. Lipid
C. Carbohydrate
D. Protein
Answer: D
Clarification: All enzymes are protein except Catalytic RNA molecule. The native protein conformation of an enzyme defines its catalytic activity. Once the enzyme is denatured, its catalytic activity is also lost.

4. What is an apoenzyme?
A. It is a protein portion of an enzyme
B. It is a non-protein group
C. It is a complete, biologically active conjugated enzyme
D. It is a prosthetic group
Answer: A
Clarification: Removal of cofactor from a conjugated enzymes forms apoenzyme which is a protein component. A cofactor is a non-protein group while a complete conjugated enzyme is known as a holoenzyme.

5. Name the coenzyme of riboflavin (B2)?
A. NAD or NADP
B. FAD and FMN
C. Coenzyme A
D. Thiamine pyrophosphate
Answer: B
Clarification: Riboflavin is a part of vitamin B complex, its coenzyme form is a FAD (Flavin adenine dinucleotide) which involves a redox reaction. NAD is a coenzyme form of nicotinic acid, and thiamine pyrophosphate is a coenzyme of thiamine.

6. Which of this vitamin is associated with the coenzyme Biocytin?
A. Nicotinic acid
B. Thiamine
C. Biotin
D. Pyridoxine
Answer: C
Clarification: Biocytin is a coenzyme of biotin which involves in carboxylation reaction while thiamine takes part in decarboxylation reaction.

7. Name the enzyme secreted by pancreas?
A. Pepsin
B. Chymotrypsin
C. Trypsin
D. Alcohol dehydrogenase
Answer: C
Clarification: Trypsin is a proteolytic enzyme, secreted by the pancreas. It is one of the three digestive proteinases along with pepsin and chymotrypsin which breaks down dietary protein molecules into simpler forms.

8. Name the enzyme which catalyzes the oxidation-reduction reaction?
A. Transaminase
B. Glutamine synthetase
C. Phosphofructokinase
D. Oxidoreductase
Answer: D
Clarification: Oxidoreductase is a class of enzyme which catalyze the oxidation-reduction reaction. Some of the oxidoreductase enzymes are oxidases, dehydrogenases, peroxidases etc.

9. What is the function of phosphorylase?
A. Transfer inorganic phosphate
B. Transfer a carboxylate group
C. Use H₂O₂ as the electron acceptor
D. Transfer amino group
Answer: A
Clarification: Phosphorylase is a transferase enzyme which involves a transfer of inorganic phosphate to a substrate while transcarboxylase transfer a carboxylate group and transaminase transfer amino group from amino acid to the keto acid.

10. Mark the CORRECT function of enzyme, Peptidase?
A. Cleave phosphodiester bond
B. Cleave amino bonds
C. Remove phosphate from a substrate
D. Removal of H₂O
Answer: B
Clarification: Hydrolases are the enzymes which cleave the bond by adding water. Peptidases belong to hydrolase class and it is used to cleave amide bonds of proteins.

11. Which of the following reaction is catalyzed by Lyase?
A. Breaking of bonds
B. Formation of bonds
C. Intramolecular rearrangement of bonds
D. Transfer of group from one molecule to another
Answer: A
Clarification: Lyase is the class of enzymes which does not involve hydrolysis or oxidation to break the bond. It catalyzes the breaking of C-C, C-O, C-N, C-S bonds by the process of elimination and results in the formation of a double bond.

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