All Free Biology MCQs with Answers
Every Biology question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
19,844 questions · page 842 of 993
- A. It occurs in darkness.
- B. It does not require light energy.
- C. It cannot occur during the daytime.
- D. It occurs more rapidly at night.
Explanation: The dark reactions of photosynthesis are also known as the Calvin cycle, and they are called "dark reactions" not because they occur in…
Correct answer: It does not require light energy.- A. Oxidation
- B. Reduction
- C. Redox
- D. None of the above
Explanation: In biological systems oxidation-reduction is a chemical reaction that usually involves the removal of the hydrogen atom from one molecule…
Correct answer: Redox- A. Chloroplast
- B. Grana
- C. Thylakoid
- D. Stroma
- E. A,B and C
Explanation: The light reactions of photosynthesis indeed take place in the thylakoid membranes within the chloroplasts of plant cells.
Correct answer: A,B and C- A. ATP sysnthesis
- B. Reduction of NADP
- C. Cyclic photophosphorylation
- D. Oxidation of the reaction center of photosystem
Explanation: The cooperation of two photosystems of the chloroplast is required for the reduction of NADP+ to NADPH, which is an important step in the…
Correct answer: Reduction of NADP- A. Pq
- B. Pc
- C. Pt
- D. Po
Explanation: Plastoquinone is an electron carrier abbreviated as Pq in plants respiratory system.
Correct answer: Pq- A. Carbon dioxide
- B. Oxygen
- C. Carotenoid
- D. Wavelength
Explanation: Absorption spectrum or photosynthesis spectrum deals with wavelengths of light absorbed by each pigment whereas the action spectrum…
Correct answer: Wavelength- A. Oxidation
- B. Reduction
- C. Redox
- D. None of the above options is correct
Explanation: Cellular respiration is a redox reaction, i.e., both oxidation & reduction occurs.
Correct answer: Redox- A. ATP is hydrolyzed and NADP is reduced
- B. ATP is hydrolyzed and NADPH is oxidized
- C. ATP is synthesized and NADP is reduced
- D. ATP is synthesized and NADPH is oxidized
Explanation: "The explanation for this question will be added soon!".
Correct answer: ATP is synthesized and NADP is reduced- A. Grana
- B. Stroma
- C. Thylakoid
- D. Intergrana
Explanation: Option A: Grana: Stacks of thylakoids within the chloroplast responsible for the light-dependent reactions of photosynthesis.
Correct answer: Stroma- A. Light dependent reaction
- B. Light independent reaction
- C. Both of these options are correct
- D. None of the above options are correct
Explanation: The Calvin cycle takes place in the stroma and uses the ATP and NADPH from the light-dependent reactions to fix carbon dioxide, producing…
Correct answer: Light independent reaction- A. Hydrogen sulphide
- B. Carbon dioide
- C. Water
- D. Hydrogen peroxide
Explanation: In photosynthesis, photosystem II loses its electrons when excited by photons.
Correct answer: Water- A. Glycolysis
- B. Ribulose Bisphosphate
- C. Glyceraldehyde 6-phosphate
- D. NADH
Explanation: In the oxidative phase, each molecule of glyceraldehyde 3-phosphate (produced earlier in the preparatory phase) undergoes dehydrogenation.
Correct answer: Glyceraldehyde 6-phosphate- A. Cytochrome A
- B. Oxygen
- C. Cytochrome a3
- D. Cytochrome C
Explanation: The final acceptor of electrons in the respiratory chain is oxygen (O2).
Correct answer: Oxygen- A. Chlorophyll a and b have same absorption spectra.
- B. Chlorophyll a and b have different absorption spectra.
- C. Chlorophyll a and carotenoids have same absorption spectra.
- D. Carotenoids and chlorophyll b have same absorption spectra.
Explanation: Yes, chlorophyll-a and chlorophyll-b, the two main types of chlorophyll found in photosynthetic organisms, have slightly different…
Correct answer: Chlorophyll a and b have different absorption spectra.- A. Calvin Cycle
- B. Bundle Sheath cells
- C. Pepco
- D. CO2 Fixation in Mesophyll
Explanation: CO2 fixation does occur in the mesophyll cells of C4 plants, but it follows a different pathway compared to C3 plants.
Correct answer: CO2 Fixation in Mesophyll- A. I only
- B. II only
- C. I and II only
- D. II and III only
- E. I, II and III only
Explanation: ATP is produced during photosynthesis as well as aerobic and anaerobic respiration.
Correct answer: I, II and III only- A. Photosystem I
- B. Non cyclic photophosphorylation
- C. Photosystem II
- D. Cyclic photophosphorylation
Explanation: "The explanation for this question will be added soon!".
Correct answer: Non cyclic photophosphorylation16838. Cu is present in
- A. Plasmalemma
- B. Plastoquinone
- C. Ferredoxin
- D. Plastocyanin
Explanation: "The explanation for this question will be added soon!"
Correct answer: Plastocyanin16839. When a molecule of pyruvic acid is subjected to anaerobic oxidation and forms lactic acid, there is
- A. Gain of 2 ATP molecules
- B. Loss of 3 ATP molecules
- C. Loss of 6 ATP molecules
- D. Gain of 3 ATP molecules
Explanation: "The explanation for this question will be added soon!"
Correct answer: Loss of 6 ATP molecules16840. Fermentation is
- A. Incomplete oxidation of proteins
- B. Complete oxidation of carbohydrates
- C. Aerobic respiration
- D. Incomplete oxidation of carbohydrates
Explanation: ]Fermentation is incomplete oxidation of carbohydrates.
Correct answer: Incomplete oxidation of carbohydrates