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 846 of 993
- A. Plastoquinone, Cytochrome complex, Ferredoxin
- B. Plastocyanin, Cytochrome complex, Plastoquinone
- C. Ferredoxin, Plastocyanin, Plastoquinone
- D. Cytochrome complex, Plastocyanin, Ferredoxin
Explanation: The cytochrome b6f complex is a protein complex that facilitates the transfer of electrons between plastoquinone and plastocyanin…
Correct answer: Cytochrome complex, Plastocyanin, Ferredoxin- A. 6
- B. 4
- C. 5
- D. 8
Explanation: Out of 6 molecules of G3P only one leaves the calvin cycle.
Correct answer: 6- A. Glycolysis
- B. Pyruvic acidoxidation
- C. Krebs cycle
- D. Respiratory chain
Explanation: The respiratory chain, also known as the electron transport chain (ETC), is a critical component of cellular respiration in eukaryotic…
Correct answer: Respiratory chain- A. Acetyl-coenzyme A.
- B. Citrate
- C. Coenzyme A
- D. Ethanol
Explanation: Acetyl-Coenzyme A (acetyl-CoA) is a crucial molecule in cellular metabolism, serving as a key intermediate in various biochemical…
Correct answer: Acetyl-coenzyme A.16905. How many moles of carbon dioxide are produced by the complete oxidation of 1 mole of pyruvate?
- A. 1
- B. 2
- C. 3
- D. 4
Explanation: 1 mole of carbon dioxide are produced by the complete oxidation of 1 mole of pyruvate.
Correct answer: 3- A. Acetyl coenzyme A
- B. ATP
- C. Pyruvate
- D. Reduced NAD
Explanation: In biology, ATP is a molecule that carries energy within cells. It is often referred to as the "energy currency" of the cell because it…
Correct answer: ATP- A. Red light
- B. Green light
- C. Blue light
- D. Violet
Explanation: As green light wavelength is least effective in photosynthesis.
Correct answer: Green light- A. ADP
- B. ATP
- C. GTP
- D. ATP and NADPH2
Explanation: This option is incorrect, as during cyclic photophosphorylation, energy molecules are obtained in the form of ATP.
Correct answer: ATP- A. Photosynthetic enzyme
- B. Carbohydrates present in leaf
- C. Water
- D. Carbon dioxide
Explanation: "The explanation for this question will be added soon!".
Correct answer: Water- A. In the stroma of chloroplast
- B. Present in the outer membrane of chloroplast
- C. Present in mitochondria
- D. Bound to the thylakoid
Explanation: "The explanation for this question will be added soon!".
Correct answer: Bound to the thylakoid16911. Respiration in plants:
- A. Often requires carbon dioxide
- B. Is characteristic of all living cells
- C. Occurs only during day
- D. Results in the formation of amino acid
Explanation: Respiration in plants occurs in all living cells and is, therefore, characteristic of all living cells so option A) is correct.
Correct answer: Is characteristic of all living cells- A. 34 molecules of ADP into 34 molecules of ATP
- B. 30 molecules of ADP into 30 molecules of ATP
- C. 38 molecules of ADP into 38 molecules of ATP
- D. 32 molecules of ADP into 32 molecules of ATP
Explanation: Option A: 34 ADP into 34 ATP. This is incorrect because the actual yield of ATP from the oxidation of one glucose molecule is less than…
Correct answer: 38 molecules of ADP into 38 molecules of ATP- A. Starch and O2
- B. H2O and energy
- C. CO2, H2O and energy
- D. Sugar and O2
Explanation: "The explanation for this question will be added soon!"
Correct answer: CO2, H2O and energy- A. Ethanol and water
- B. Water and carbon dioxide
- C. Methanol and CO2
- D. Ethanol and carbon dioxide
Explanation: "The explanation for this question will be added soon!"
Correct answer: Ethanol and carbon dioxide- A. It produces a net gain of NADH
- B. It produces a net gain of ATP
- C. It is an aerobic process
- D. It produces more energy per glucose molecule than aerobic respiration
Explanation: "The explanation for this question will be added soon!"
Correct answer: It produces a net gain of NADH- A. All 36 ATP molecules inside the mitochondria
- B. 2 ATP molecules during glycolysis and 34 ATP during the Krebs cycle
- C. 2 ATP molecules during glycolysis and 34 ATP during respiratory chain
- D. 2 ATP molecules outside the mitochondria and 34 ATP molecules inside the mitochondria
Explanation: "The explanation for this question will be added soon!"
Correct answer: 2 ATP molecules outside the mitochondria and 34 ATP molecules inside the mitochondria- A. NADPH2
- B. NADH2
- C. FADH2
- D. FAD
Explanation: "The explanation for this question will be added soon!"
Correct answer: NADH2- A. Symbiosis
- B. Chemiosmosis
- C. Both A and B
- D. None of these
Explanation: "The explanation for this question will be added soon!"Chemiosmosis is a process in which ions move across a semi-permeable membrane and…
Correct answer: Chemiosmosis- A. ATP
- B. Carbon dioxide
- C. Water
- D. Both A and C
Explanation: "The explanation for this question will be added soon!"This is the correct answer as both ATP and water are the end products of the ETC in…
Correct answer: Both A and C- A. Coenzyme c
- B. Coenzyme d
- C. Coenzyme b
- D. Coenzyme a
Explanation: "The explanation for this question will be added soon!"
Correct answer: Coenzyme b