All Free Biochemistry MCQs with Answers

• A. Parahydroxy phenyl pyruvate Hydroxylase
• B. Homogentisate oxidase
• C. Tyrosine transaminase
• D. Tyrosine oxidase

Explanation: Alkaptonuria results from deficiency of homogentisate oxidase in tyrosine degradation.

• A. It is required for the process of transmination
• B. It is co-factor in oxidative reduction
• C. It is co-enzyme for transketolase in pentose phosphate pathway
• D. It is co-enzyme for pyruvate dehydrogenase

Explanation: Thiamine pyrophosphate is a coenzyme for pyruvate dehydrogenase, allowing pyruvate to enter acetyl-CoA formation and the TCA cycle for…

• A. Pyruvate to acetyl CoA
• B. Citrate to alpha ketoglutarate
• C. Succinyl CoA to fumarate
• D. None of the above

Explanation: Thiamine pyrophosphate, the active form of vitamin B1, is required by pyruvate dehydrogenase for conversion of pyruvate to acetyl-CoA.

• A. DNA polymerase
• B. Reverse transcriptase
• C. RNA polymerase
• D. Phospho kinase

Explanation: Reverse transcriptase synthesises DNA using an RNA template, producing a complementary DNA strand and ultimately a double-stranded DNA…

• A. Protein storage
• B. m RNA synthesis
• C. Modification of proteins
• D. t RNA synthesis

Explanation: The Golgi apparatus modifies, sorts, and packages proteins received from the endoplasmic reticulum, including glycosylation and…

• A. Mitochondria
• B. Golgi bodies
• C. Nucleus
• D. Poly ribosomes

Explanation: Protein synthesis occurs on ribosomes, and multiple ribosomes translating the same mRNA form a polyribosome or polysome.

• A. Mitochondria
• B. Endoplasmic reticulum
• C. Nucleolus
• D. Plasma membrane

Explanation: Most cytoplasmic ribosomes are attached to the rough endoplasmic reticulum, where they synthesise proteins destined for secretion…

• A. Protein lipid synthesis
• B. Protein synthesis
• C. Sorting of glycoproteins
• D. None of the above

Explanation: The Golgi apparatus modifies, sorts, and packages glycoproteins for delivery to their correct destinations.

• A. Centriole
• B. Golgi body
• C. Endoplasmic reticulum
• D. Mitochondrion

Explanation: Mitochondria contain their own circular DNA and replicate semi-autonomously.

• A. Lysomes
• B. Rough endoplasmic reticulum
• C. Golgi apparatus
• D. Mitochondria

Explanation: Lysosomes function as the cell’s digestive compartments because their acid hydrolases degrade proteins, lipids, nucleic acids, and…

• A. c AMP
• B. c GMP
• C. Phosphatidyl glycerol
• D. Phosphatidyl inosital

Explanation: Phosphatidylglycerol is a membrane phospholipid and is not a standard second messenger.

• A. Ribsomes
• B. Nucleolus
• C. Golgi apparatus
• D. Nucleus

Explanation: The nucleus contains the cell's nuclear DNA and is therefore the expected answer among these options.

• A. G Proteins act as inhibitory and excitatory because of difference in alpha subunit
• B. All the three subunits alpha, beta and gamma should bind each other for G protein to act
• C. G proteins bind to hormones on the cell surface
• D. G protein is bound to GTP in resting stateOrder DNA Kits

Explanation: G-protein effects can be stimulatory or inhibitory largely because different alpha subunits activate or inhibit target enzymes such as…

• A. Integrin a6-B4
• B. The catenins desmoplakin
• C. cadherins desmoglein
• D. a and B catenin

Explanation: Hemidesmosomes use integrin α6β4 to attach epithelial cells to laminin in the basal lamina.

• A. Watson and Crick
• B. Edwarg Angle
• C. Singer and Nicolson
• D. G.V Black

Explanation: Singer and Nicolson proposed the fluid mosaic model in 1972, describing proteins floating within a dynamic phospholipid bilayer.

• A. Immunofluoresence
• B. Widal test
• C. Electrophoresis
• D. Real time PCR

Explanation: Real-time PCR quantitatively amplifies and detects viral nucleic acid, allowing estimation of viral load.

• A. Cyclic AMP
• B. Cyclic GMP
• C. Adenosine cyclate
• D. Calcium release

Explanation: FSH, LH and TSH bind G-protein-coupled receptors that activate adenylate cyclase, increasing cyclic AMP as the second messenger.

• A. Post transcriptional modification
• B. Post translation modification
• C. DNA replication
• D. Splicing

Explanation: RNA directly participates in post-transcriptional processing, splicing, and DNA replication through RNA primers.

• A. Mitochondria
• B. Centrosome
• C. Nucleus
• D. Ribosome

Explanation: Translation is the ribosome-mediated reading of mRNA to assemble an amino-acid chain.

• A. m-RNA
• B. DNA
• C. t-RNA
• D. Ribosomal RNA

Explanation: Codons are three-base sequences on mRNA that specify amino acids or stop signals during translation.