All Free Biology MCQs with Answers

• A. Cyt. b
• B. Cyt. c
• C. Cyt. a3
• D. Cyt. a1

Explanation: The terminal carrier of the cytochrome complex is specifically cytochrome a3 (Cyt A3).

• A. Glycolysis
• B. The oxidation of pyruvates
• C. Krebs cycle
• D. All of these

Explanation: FADH2 is indeed produced during the Krebs cycle, which is also known as the citric acid cycle or TCA (tricarboxylic acid cycle).

• A. Fructose-I, 4-phosphate
• B. Fructose-1,6-bisphosphate
• C. Bisphosphate
• D. Fructose

Explanation: Phosphofructokinase (PFK) is an enzyme that catalyzes an important regulatory step in glycolysis.

• A. CO2 and H2O
• B. CO2, H2O and ATP
• C. C6HI2O6 and H2O
• D. None

Explanation: The respiratory activity that occurs in green cells in the presence of light resulting in the release of carbon dioxide is termed…

• A. Light-dependent reaction
• B. Light-independent reaction
• C. Both of these
• D. None of the above

Explanation: The dark reactions take place in the stroma of chloroplast. These reactions do not require light directly and can occur in the presence or…

• A. Calvin cycle
• B. Photosystem I
• C. Photosystem II
• D. The light reaction

Explanation: The cyclic series of reactions, catalyzed by respective enzymes, by which the carbon is fixed and reduced resulting in the synthesis of…

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: "The explanation for this question will be added soon!".

• A. 85%
• B. 95%
• C. 97%
• D. 73%

Explanation: The commonly quoted water content of the human brain is about 73%, reflecting the high water requirement of nervous tissue for metabolism…

• A. 1-2%
• B. 3-4%
• C. 5-7%
• D. 90%

Explanation: Cuticular transpiration is a small fraction of total transpiration, commonly given in this syllabus as about 5% to 7%, so 5% to 7% is the…

• A. Galactose
• B. Gluconic acid
• C. B­-methyl galactoside
• D. Sucrose

Explanation: All those sugars which have free aldehyde or ketone group are called reducing sugars.

• A. Nerve cells
• B. Bone cells
• C. Brain cells
• D. None of the above

Explanation: Water varies from os to 89 percent in different organisms, Human tissues contain about 20% water in bone cells and 85 percent in brain…

• A. Butyric acid
• B. Stearic acid
• C. Oleic acid
• D. Palmitic acid

Explanation: Butyric acid, palmitic acid and stearic acids examples of saturated fatty acids.

• A. 1st carbon & 2nd carbon
• B. Only 1st carbon
• C. 1st carbon and 5th carbon
• D. 1st carbon and 6th carbon

Explanation: 1st and 2nd Carbon: This option suggests that the 1st and 2nd carbon atoms are present outside the ring of fructose.

• A. Primary structure
• B. Secondary structure
• C. Quaternary structure
• D. Tertiary structure

Explanation: The tertiary structure of an enzyme refers to the three-dimensional arrangement of its polypeptide chain, including the interactions…

• A. Coordinated catabolic activities
• B. Coordinated anabolic activities
• C. Both A and B
• D. None of these

Explanation: Interconversion involves both breaking down and building up molecules, requiring both catabolic and anabolic activities to work in…

• A. Metabolic reactions
• B. Catabolic reactions
• C. Anabolic reactions
• D. Both B and C

Explanation: Reactions in which simple substances are combined to form complex substances are called anabolic reactions.

• A. Specific Heat of Vaporization
• B. Caloric heat
• C. Specific heat capacity
• D. Both a and b

Explanation: It is defined as the amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

• A. Primary structure
• B. Secondary structure
• C. Tertiary structure
• D. Quaternary structure

Explanation: Tertiary structure refers to the overall 3D shape of a single polypeptide chain, including the arrangement of secondary structures and…

• A. Egg
• B. Grains
• C. Pulses
• D. Both B and C

Explanation: Vegetative sources of protein come from plants. Grains (like wheat, rice, maize) and pulses (like beans, lentils, peas) are rich sources…

• A. Structural and Regulatory
• B. Structural only
• C. Regulatory only
• D. Transport proteins

Explanation: Conjugated histone proteins play both structural and regulatory roles in the cell.