All Free Biology MCQs with Answers

3611. Phosphatases belong to which group of the following:

• A. Lyases
• B. Ligases
• C. Hydrolases
• D. None

Explanation: Phosphatases belong to the group of enzymes known as hydrolases. Specifically, they are a type of hydrolase called phosphohydrolases. Phosphatases catalyze the removal of phosphate groups from molecules through hydrolysis reactions. The removal of phosphate groups is a crucial regulatory step in various cellular processes, as it can activate or deactivate proteins and other molecules.

3612. Van Neil hypothesis about the production of oxygen during photosynthesis was based on the study and investigations on:

• A. Bacteria
• B. Algae
• C. Protonema
• D. Cyanobacteria

Explanation: Using evidence from bacteria that utilize hydrogen sulfide (H2S) for photosynthesis, van Niel hypothesized that all photosynthetic organisms need a hydrogen source and that plants split water as their hydrogen source, releasing oxygen. Scientists confinned this hypothesis by using a heavy isotope of oxygen (O18).

3613. Location of photosynthetic pigments in purple sulphur bacteria:

• A. Thylakoids
• B. Grana
• C. Stroma
• D. Cytoplasm

Explanation: Some bacteria are photosynthetic but they lack chloroplast. Their photosynthetic pigments are present in cytoplasm of cell. In purple sulfur bacteria the photosynthetic pigments such as, bacteriochlorophylls and caretinoids are located in the cytoplasm rather than within specialised membrane structure such as chloroplast. These pigments are dispersed through out the cytoplasmic region of bacteria and are responsible for capturing light energy during photosynthesis.

3614. Given plants carry on respiration:

• A. Only during the day
• B. Only at day
• C. During both day and night
• D. Only when photosynthesis is going on
• E. Only when photosynthesis is not going on

Explanation: Respiration occurs all through the day, but the photosynthesis process occurs in the daytime, in the presence of sunlight only. Consequently, respiration becomes evident at night time in plants.

3615. Energy can be made available to the body in the following ways :(I) Conversion of surplus amino acids and glycerol to blood glucose and mobilization of fat deposits which pass to the tissue for oxidation .(II) Breakdown of liver and muscle glycogen to form glucose .(III) Tissue protein to release aminoacids which are then converted into glucose in which order does the body draw on potential energy when it is being starved of food?

• A. I -> II -> III
• B. I -> III -> II
• C. II -> I -> III
• D. II -> III -> I
• E. III -> I -> II

Explanation: This energy comes from the food we eat. Our bodies digest the food we eat by mixing it with fluids (acids and enzymes) in the stomach. When the stomach digests food, the carbohydrate (sugars and starches) in the food breaks down into another type of sugar, called glucose.

3616. The first stable product of Calvin cycle is:

• A. 3-phosphoglycerate
• B. 1. 3 biphosphoglycerate
• C. Glyceraldehyde - 3 phosphate
• D. Ribulose - 5 - phosphate

Explanation: 3-phosphoglycerate (3-PG) is an important intermediate compound in the Calvin cycle, which is a series of biochemical reactions that occur during the light-independent reactions of photosynthesis. The Calvin cycle takes place in the stroma of chloroplasts and is responsible for the conversion of carbon dioxide into carbohydrates.

3617. Which substance enter and leave a mitochondrion during aerobic respiration?

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Pyruvate enters and ATP leaves a mitochondrion during aerobic respiration.

3618. The final acceptor of electron during noncyclic electron pathway is

• A. PS I
• B. PS II
• C. ATP
• D. NADP+

Explanation: "The explanation for this question will be added soon!".plants, the final electron acceptor in noncyclic electron flow is (a) NADP+. When this electron carrier molecule accepts electrons from the electron transport chain in the thylakoid membrane of chloroplasts, it will be reduced into NADPH.

3619. Fatty acid release considerable amount of energy in oxidation during:

• A. Citric acid cycle
• B. Krebs cycle
• C. Dark reaction
• D. Light reaction

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

3620. In which stage of photosynthesis. ATP and NADPH are converted to ADP-Pi and NADP+?

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

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