RESPIRATION IN PLANTS MCQs for NEET UG BIOLOGY — Medium, Page 3

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If a starving plant is provided with glucose, the rate of respiration would

View answer and explanation

Correct option: D

Increase

Option D (Increase) is correct because providing glucose to a starving plant provides readily available substrate for respiration, increasing its rate.

Solution approach

Correct Answer + Core Reason: Increase. Providing glucose to a starving plant provides a readily available substrate for respiration, thus increasing the rate.

Step-by-Step Solution:

Step 1: Understand the concept of respiration. Respiration is the process by which plants break down glucose to release energy.

Step 2: Consider the state of a starving plant. A starving plant has limited glucose reserves and a low rate of respiration.

Step 3: Analyze the effect of providing glucose. Providing glucose to a starving plant provides a readily available substrate for respiration, allowing the plant to increase its energy production.

Why other options are wrong:
- Option A: First rise then fall: While there might be a slight initial adjustment, the overall trend would be an increase in respiration rate.
- Option B: Become constant: The respiration rate would increase until other factors become limiting, but it wouldn't immediately become constant.
- Option C: Decrease: Providing glucose would increase, not decrease, the respiration rate.

Key Concepts:
- Respiration in plants
- Substrate availability
- Energy production

Memory Aids:
- More glucose = More respiration

Quick Tips:
- Consider the limiting factors in biological processes.

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Assertion : During the hydrolysis of typical
chemical bonds, about 3000 calories per mole
are liberated.

Reason : ATP also yields about 3000 calories
per mole after the release of any one of the two
terminal phosphates.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false

Option C (If Assertion is true but Reason is false) is correct because while the assertion about energy release during hydrolysis is approximately correct, the reason regarding ATP yielding 3000 calories per mole is false; ATP yields approximately 7300 calories per mole.

Solution approach

Correct Answer + Core Reason: If Assertion is true but Reason is false. The assertion is approximately true, but the reason is false regarding the energy yield of ATP.

Step-by-Step Solution:

Step 1: Evaluate the Assertion. The assertion states that during the hydrolysis of typical chemical bonds, about 3000 calories per mole are liberated. This is a reasonable approximation for some chemical bonds.

Step 2: Evaluate the Reason. The reason states that ATP also yields about 3000 calories per mole after the release of any one of the two terminal phosphates. This is incorrect. ATP yields approximately 7300 calories per mole (or 7.3 kcal/mol) upon hydrolysis of a phosphate bond.

Step 3: Determine the relationship between Assertion and Reason. The assertion is approximately true, but the reason is false. Therefore, the correct answer is that the assertion is true, but the reason is false.

Why other options are wrong:
- Option A (If both Assertion and Reason are true and Reason is the correct explanation of Assertion): This is incorrect because the reason is false.
- Option B (If both Assertion and Reason are true but Reason is not the correct explanation of Assertion): This is incorrect because the reason is false.
- Option D (If both Assertion and Reason are false): This is incorrect because the assertion is approximately true.

Key Concepts:
- Hydrolysis of chemical bonds
- ATP hydrolysis and energy yield

Memory Aids:
- ATP hydrolysis releases about 7.3 kcal/mol

Quick Tips:
- Remember the approximate energy yield of ATP hydrolysis.

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Seeds respire in?

View answer and explanation

Correct option: D

Both 1 and 3

Option D (Both 1 and 3) is correct because seeds can respire both in the presence and absence of oxygen, although the pathways differ.

Solution approach

Correct Answer + Core Reason: Both 1 and 3. Seeds can respire in both the presence and absence of oxygen.

Step-by-Step Solution:

Step 1: Understand aerobic respiration. Seeds respire aerobically when oxygen is available, using oxygen to break down glucose and release energy.

Step 2: Understand anaerobic respiration. Seeds can also respire anaerobically when oxygen is limited, using fermentation pathways to produce energy, although less efficiently.

Step 3: Consider the conditions within a seed. Seeds may experience limited oxygen availability, especially when imbibed with water.

Why other options are wrong:
- Option A: Presence of ${O_2}$ : Seeds do respire in the presence of oxygen, but this is not the only condition.
- Option B: Presence of $C{O_2}$ : Carbon dioxide is a product of respiration, not a requirement for it.
- Option C: Absence of ${O_2}$ : Seeds can respire in the absence of oxygen, but this is not the only condition.

Key Concepts:
- Aerobic respiration
- Anaerobic respiration
- Seed physiology

Memory Aids:
- Seeds respire with or without oxygen.

Quick Tips:
- Consider both aerobic and anaerobic pathways in seeds.

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Respiration in plants

View answer and explanation

Correct option: C

Is characteristic of all living cells

Option C (Is characteristic of all living cells) is correct because respiration is a fundamental process for energy production in all living cells, providing the energy needed for cellular functions.

Solution approach

Correct Answer + Core Reason: Is characteristic of all living cells. Respiration is essential for energy production in all living cells.

Step-by-Step Solution:

Step 1: Identify the question: What is true about respiration in plants?

Step 2: Recall the function of respiration: Respiration provides energy for all living cells.

Step 3: Conclusion: Respiration is characteristic of all living cells.

Why other options are wrong:
- Option A: Respiration occurs both during the day and night.
- Option B: Respiration does not result in the formation of vitamins.
- Option D: Respiration requires oxygen, not carbon dioxide (in aerobic respiration).

Key Concepts:
- Respiration
- Energy production
- Living cells

Memory Aids:
- Respiration = Energy = All living cells

Quick Tips:
- Remember that respiration is a continuous process in living cells.

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Respiratory substrates are the organic substances which are ____ during respiration to liberate energy?

View answer and explanation

Correct option: A

Oxidised

Option A (Oxidised) is correct because respiratory substrates are organic substances that are oxidized during respiration to release energy.

Solution approach

Correct Answer + Core Reason: Oxidised. Respiratory substrates are oxidized during respiration.

Step-by-Step Solution:

Step 1: Define respiratory substrates.

Step 2: Respiratory substrates (e.g., glucose) are oxidized to release energy during respiration.

Why other options are wrong:
- Option B: Respiratory substrates are not reduced during respiration; they are oxidized.
- Option C: Respiratory substrates are not synthesized during respiration; they are broken down.
- Option D: Only oxidation occurs.

Key Concepts:
- Respiratory Substrates
- Oxidation

Memory Aids:
- Oxidation = Loss of electrons

Quick Tips:
- Respiration involves the oxidation of organic molecules.

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Respiratory enzymes are present in the following organelle

View answer and explanation

Correct option: C

Mitochondria

Option C (Mitochondria) is correct because mitochondria are the primary site of cellular respiration, where respiratory enzymes are located.

Solution approach

Correct Answer + Core Reason: Mitochondria. Respiratory enzymes are located in the mitochondria.

Step-by-Step Solution:

Step 1: Identify the question: Where are respiratory enzymes located?

Step 2: Recall the function of mitochondria: Mitochondria are the powerhouses of the cell and the site of aerobic respiration.

Step 3: Consider other options: Peroxisomes, chloroplasts, and lysosomes have other functions.

Step 4: Conclusion: Respiratory enzymes are present in the mitochondria.

Why other options are wrong:
- Option A: Peroxisomes are involved in detoxification and lipid metabolism.
- Option B: Chloroplasts are involved in photosynthesis.
- Option D: Lysosomes are involved in waste disposal and cellular digestion.

Key Concepts:
- Cellular respiration
- Mitochondria
- Respiratory enzymes

Memory Aids:
- Mitochondria = Powerhouse = Respiration

Quick Tips:
- Remember that mitochondria are the site of the Krebs cycle and electron transport chain.

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Aldolase enzyme is present in

View answer and explanation

Correct option: C

Cytoplasm

Option C is correct because aldolase, an enzyme involved in glycolysis, is located in the cytoplasm.

Solution approach

Correct Answer + Core Reason: Cytoplasm. Aldolase is an enzyme in glycolysis, which occurs in the cytoplasm.

Step-by-Step Solution:
Step 1: Recall the location of glycolysis: Glycolysis occurs in the cytoplasm.
Step 2: Understand the role of aldolase: Aldolase is an enzyme involved in glycolysis.
Step 3: Conclude the location of aldolase: Aldolase is present in the cytoplasm.

Why other options are wrong:
- Option A: Mitochondria are the site of the Krebs cycle and electron transport chain, not glycolysis.
- Option B: Chloroplasts are the site of photosynthesis, not glycolysis.
- Option D: Endoplasmic reticulum is involved in protein synthesis and lipid metabolism, not glycolysis.

Key Concepts:
- Glycolysis
- Cytoplasm
- Aldolase
- Cellular organelles

Memory Aids:
- Glycolysis = cytoplasm.

Quick Tips:
- Know the location of major metabolic pathways.

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How many ATP molecules could maximally be generated from one molecule of glucose, if the complete oxidation of one mole of glucose to

C{{O}_{2}}

and

{{H}_{2}}O

yields 686 kcal and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is 12 kcal?

View answer and explanation

Correct option: B

Fifty seven

Option B (Fifty seven) is correct because the total energy from glucose oxidation (686 kcal) divided by the energy per ATP (12 kcal) gives the maximum possible ATP molecules.

Solution approach

Correct Answer + Core Reason: Fifty seven. Divide the total energy released by glucose oxidation by the energy stored in one ATP molecule.

Step-by-Step Solution:

Step 1: Identify the total energy released during complete glucose oxidation: 686 kcal.

Step 2: Identify the energy stored in the high energy phosphate bond of one mole of ATP: 12 kcal.

Step 3: Calculate the maximum number of ATP molecules that can be generated.

Step 4: Calculation: 686 kcal / 12 kcal/ATP = 57.17 ATP.

Step 5: Round down to the nearest whole number since we are looking for the number of whole ATP molecules.

Step 6: Final Answer: 57 ATP molecules

Why other options are wrong:
- Option A (Thirty): This is incorrect. It is a significant underestimation of the ATP yield.
- Option C (One): This is incorrect. It represents a misunderstanding of the energy conversion process.
- Option D (Two): This is incorrect. It represents a misunderstanding of the energy conversion process.

Key Concepts:
- Cellular Respiration
- ATP Production
- Energy Conversion

Memory Aids:
- Remember the approximate energy released during glucose oxidation and the energy stored in ATP.

Quick Tips:
- Always consider the energy conversion efficiency when calculating ATP yield.

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In alcohol fermentation,

View answer and explanation

Correct option: C

Triose phosphate is the electron donor, while acetaldehyde is the electron acceptor

Option C (Triose phosphate is the electron donor, while acetaldehyde is the electron acceptor) is correct because during alcoholic fermentation, triose phosphate donates electrons to reduce acetaldehyde to ethanol.

Solution approach

Correct Answer + Core Reason: Triose phosphate is the electron donor, while acetaldehyde is the electron acceptor. This describes the electron transfer in alcoholic fermentation.

Step-by-Step Solution:

Step 1: Alcoholic fermentation: Glucose is converted to ethanol and carbon dioxide.

Step 2: Glycolysis: Triose phosphate is formed.

Step 3: Electron donor: Triose phosphate donates electrons.

Step 4: Electron acceptor: Acetaldehyde accepts electrons and is reduced to ethanol.

Step 5: Conclude: Triose phosphate is the electron donor, and acetaldehyde is the electron acceptor.

Why other options are wrong:
- Option A: There is an electron donor (triose phosphate).
- Option B: Oxygen is not the electron acceptor in alcoholic fermentation.
- Option D: Pyruvic acid is converted to acetaldehyde before accepting electrons.

Key Concepts:
- Alcoholic fermentation
- Electron donors and acceptors

Memory Aids:
- Triose -> Acetaldehyde

Quick Tips:
- Remember the sequence of reactions in alcoholic fermentation.

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Which of the following is necessary for respiration in plants?

View answer and explanation

Correct option: B

Oxygen

Option B (Oxygen) is correct because oxygen is the terminal electron acceptor in aerobic respiration, which is essential for energy production in plants.

Solution approach

Correct Answer + Core Reason: Oxygen. Oxygen is necessary for respiration in plants.

Step-by-Step Solution:

Step 1: Identify the question: What is necessary for respiration in plants?

Step 2: Recall the process of respiration: Respiration requires oxygen to break down glucose and release energy.

Step 3: Consider other options: Carbon dioxide is used in photosynthesis, chlorophyll is used in photosynthesis, and light is required for photosynthesis.

Step 4: Conclusion: Oxygen is necessary for respiration in plants.

Why other options are wrong:
- Option A: Carbon dioxide is a product of respiration and a reactant in photosynthesis.
- Option C: Chlorophyll is used in photosynthesis to capture light energy.
- Option D: Light is required for photosynthesis, not respiration.

Key Concepts:
- Respiration
- Oxygen
- Photosynthesis

Memory Aids:
- Respiration requires oxygen.

Quick Tips:
- Remember the difference between respiration and photosynthesis.

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Among the following, identify the substrate required for the only oxidative reaction that occurs in the process of glycolysis.

View answer and explanation

Correct option: B

Glyceraldehyde 3-phosphate

Option B is correct because Glyceraldehyde 3-phosphate is the substrate that undergoes oxidation in glycolysis, catalyzed by glyceraldehyde-3-phosphate dehydrogenase.

Solution approach

Correct Answer + Core Reason: Glyceraldehyde 3-phosphate. Glyceraldehyde 3-phosphate is oxidized in glycolysis.

Step-by-Step Solution:
Step 1: Recall the steps of glycolysis.
Step 2: Identify the oxidative step: Glyceraldehyde 3-phosphate is oxidized to 1,3-bisphosphoglycerate.
Step 3: Determine the substrate: Glyceraldehyde 3-phosphate is the substrate for this reaction.

Why other options are wrong:
- Option A: 3-phosphoglyceric acid is a product of glycolysis, not a substrate for an oxidative reaction.
- Option C: Fructose-6-phosphate is an intermediate in glycolysis but does not undergo direct oxidation.
- Option D: Glucose-6-phosphate is the initial product of glucose phosphorylation but does not undergo direct oxidation.

Key Concepts:
- Glycolysis
- Oxidation-reduction reactions
- Glyceraldehyde 3-phosphate

Memory Aids:
- Glyceraldehyde 3-phosphate = oxidation in glycolysis.

Quick Tips:
- Focus on the specific reactions in glycolysis to identify the oxidative step.

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The equation of respiration is

View answer and explanation

Correct option: A

{C}_6{H}_{12}{O}_6+6{O}_2 \rightarrow 6{CO}_2+6{H}_2{O}+686\, \mathrm{k\,cal}

Option A (

{C}_6{H}_{12}{O}_6+6{O}_2 \rightarrow 6{CO}_2+6{H}_2{O}+686\, \mathrm{k\,cal}

) is correct because it accurately represents the balanced chemical equation for aerobic respiration, showing glucose reacting with oxygen to produce carbon dioxide, water, and energy.

Solution approach

Correct Answer + Core Reason: ${C}_6{H}_{12}{O}_6+6{O}_2 \rightarrow 6{CO}_2+6{H}_2{O}+686\, \mathrm{k\,cal}$ . This is the correct equation for respiration.

Step-by-Step Solution:

Step 1: Identify the question: What is the equation of respiration?

Step 2: Recall the reactants and products of respiration: Glucose and oxygen are reactants, and carbon dioxide, water, and energy are products.

Step 3: Check the stoichiometry: The equation must be balanced.

Step 4: Conclusion: The correct equation is ${C}_6{H}_{12}{O}_6+6{O}_2 \rightarrow 6{CO}_2+6{H}_2{O}+686\, \mathrm{k\,cal}$ .

Why other options are wrong:
- Option B: The equation is not balanced and uses incorrect reactants.
- Option C: The equation is not balanced and has an incorrect energy value.
- Option D: The equation is not balanced and produces an incorrect number of carbon dioxide molecules.

Key Concepts:
- Respiration equation
- Stoichiometry
- Reactants and products

Memory Aids:
- Glucose + Oxygen -> Carbon Dioxide + Water + Energy

Quick Tips:
- Remember to balance the equation for respiration.

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Which of the following statement is not true for the EMP pathway?

View answer and explanation

Correct option: B

Net 4 ATP gained

Option B (Net 4 ATP gained) is correct because the net ATP gain in glycolysis is 2 ATP, not 4 ATP. While 4 ATP are produced, 2 ATP are consumed in the initial steps.

Solution approach

Correct Answer + Core Reason: Net 4 ATP gained. The net ATP gain in glycolysis is 2 ATP.

Step-by-Step Solution:

Step 1: Recall the ATP production and consumption in glycolysis.
- 2 ATP are used in the initial steps (glucose to glucose-6-phosphate and fructose-6-phosphate to fructose-1,6-bisphosphate).
- 4 ATP are produced during substrate-level phosphorylation.

Step 2: Calculate the net ATP gain.\nNet ATP gain = ATP produced - ATP used = 4 - 2 = 2 ATP.

Step 3: Final Answer\nNet 4 ATP gained

Why other options are wrong:
- Option A (Phospho fructo kinase enzyme is also known as pacemaker enzyme): This statement is true; PFK is a key regulatory enzyme.
- Option C (Two pyruvic acid molecules are formed): This statement is true; glycolysis produces two pyruvate molecules from one glucose molecule.
- Option D (Hexo kinase enzyme is the first enzyme of pathway): This statement is true; hexokinase catalyzes the first step of glycolysis.

Key Concepts:
- Glycolysis
- ATP production
- ATP consumption
- Net ATP gain

Memory Aids:
- Remember that glycolysis has a net gain of 2 ATP.

Quick Tips:
- Distinguish between ATP produced and net ATP gain.

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Assertion: RQ of maturing fatty seeds is

>1

.

Reason: Fats are preferred energy fuels.

View answer and explanation

Correct option: C

If Assertion is true statement but Reason is false

Option C (If Assertion is true statement but Reason is false) is correct because the RQ of maturing fatty seeds is greater than 1 due to the conversion of fats to carbohydrates, but fats are not the preferred energy fuels.

Solution approach

Correct Answer + Core Reason: If Assertion is true statement but Reason is false. The assertion is true, but the reason is false.

Step-by-Step Solution:

Step 1: Evaluate the Assertion. The assertion states that the RQ of maturing fatty seeds is > 1. This is true because during seed germination, fats are converted to carbohydrates, leading to an RQ greater than 1.

Step 2: Evaluate the Reason. The reason states that fats are preferred energy fuels. This is false. Carbohydrates are generally the preferred energy fuels because they are easier to metabolize than fats.

Step 3: Determine the relationship between Assertion and Reason. The assertion is true, but the reason is false. Therefore, the correct answer is that the assertion is true, but the reason is false.

Why other options are wrong:
- Option A (If both Assertion & Reason are true and the reason is the correct explanation of the assertion): This is incorrect because the reason is false.
- Option B (If both Assertion & Reason are true but the reason is not the correct explanation of the assertion): This is incorrect because the reason is false.
- Option D (If both Assertion and Reason are false statements): This is incorrect because the assertion is true.

Key Concepts:
- Respiratory Quotient (RQ)
- Seed germination
- Preferred energy fuels

Memory Aids:
- RQ > 1 during conversion of fats to carbohydrates

Quick Tips:
- Remember that carbohydrates are generally the preferred energy source.

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The respiratory quotient of the reaction given below is

2\left(\mathrm{C}_{51} \mathrm{H}_{98} \mathrm{O}_6\right)+145 \mathrm{O}_2 \rightarrow 102 \mathrm{CO}_2+\mathbf{9 0 \mathrm { H } _ { 2 } \mathrm { O } + \text { energy }}

View answer and explanation

Correct option: A

0.703

Option A (0.703) is correct because the respiratory quotient (RQ) is calculated as the ratio of CO2 produced to O2 consumed, which in this case is 102/145 ≈ 0.703.

Solution approach

Correct Answer + Core Reason: $0.703$ . The respiratory quotient is calculated as the ratio of CO2 produced to O2 consumed.

Step-by-Step Solution:

Step 1: Define Respiratory Quotient (RQ). RQ is the ratio of carbon dioxide produced to oxygen consumed: $RQ = \frac{{CO_2 \\ produced}}{{O_2 \\ consumed}}$

Step 2: Identify the number of CO2 molecules produced. From the equation, 102 CO2 molecules are produced.

Step 3: Identify the number of O2 molecules consumed. From the equation, 145 O2 molecules are consumed.

Step 4: Calculate the RQ. $RQ = \frac{{102}}{{145}} \approx 0.703$

Why other options are wrong:
- **Option B ( $0.725$ ): This is incorrect because the correct ratio is closer to 0.703.
- Option C ( $0.960$ ): This is incorrect because the correct ratio is closer to 0.703.
- Option D ( $1.422$ ): This is incorrect because the correct ratio is closer to 0.703.

Key Concepts:
- Respiratory Quotient (RQ)
- Stoichiometry of respiration

Memory Aids:
- RQ = CO2 out / O2 in

Quick Tips:**
- Always check the balanced equation to get the correct stoichiometric coefficients.

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In mitochondria, enzyme cytochrome oxidase is present in

View answer and explanation

Correct option: C

Inner membrane

The correct answer is C (Inner membrane) because cytochrome oxidase, a key enzyme in the electron transport chain, is located in the inner mitochondrial membrane.

Solution approach

Correct Answer + Core Reason: Inner membrane. Cytochrome oxidase is a component of the electron transport chain located in the inner mitochondrial membrane.

Step-by-Step Solution:

Step 1: Recall the location of the electron transport chain (ETC) in mitochondria.

Step 2: The ETC is embedded in the inner mitochondrial membrane.

Step 3: Cytochrome oxidase is a key enzyme complex within the ETC.

Step 4: Therefore, cytochrome oxidase is found in the inner mitochondrial membrane.

Why other options are wrong:
- Option A: The outer membrane is more permeable and contains porins, not the ETC.
- Option B: The perimitochondrial space (intermembrane space) is the region between the outer and inner membranes and does not house the ETC.
- Option D: The matrix is the site of the Krebs cycle, not the ETC.

Key Concepts:
- Mitochondrial structure
- Electron transport chain (ETC)
- Cytochrome oxidase

Memory Aids:
- Inner membrane = ETC

Quick Tips:
- Remember the compartmentalization of mitochondrial functions.

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The reaction which is catalysed by a protein that is not found in the matrix of mitochondria is

View answer and explanation

Correct option: C

Oxidation of Succinic acid

Option C (Oxidation of Succinic acid) is correct because Succinate dehydrogenase, which catalyzes this reaction, is located on the inner mitochondrial membrane, not in the matrix.

Solution approach

Correct Answer + Core Reason: Oxidation of Succinic acid. Succinate dehydrogenase is located on the inner mitochondrial membrane, not in the matrix.

Step-by-Step Solution:

Step 1: Consider the location of the enzyme catalyzing the conversion of pyruvic acid to acetyl coenzyme-A. This enzyme (pyruvate dehydrogenase complex) is located in the mitochondrial matrix.

Step 2: Consider the location of the enzyme catalyzing the oxidative decarboxylation of $\alpha$ -ketoglutaric acid. This enzyme ( $\alpha$ -ketoglutarate dehydrogenase complex) is located in the mitochondrial matrix.

Step 3: Consider the location of the enzyme catalyzing the oxidation of succinic acid. This enzyme (succinate dehydrogenase) is located on the inner mitochondrial membrane.

Step 4: Consider the location of the enzyme catalyzing the cleavage of succinyl coenzyme-A. This enzyme (succinyl-CoA synthetase) is located in the mitochondrial matrix.

Step 5: Final Answer: The enzyme catalyzing the oxidation of succinic acid is not found in the matrix.

Why other options are wrong:
- Option A (Conversion of pyruvic acid to acetyl coenzyme-A): The enzyme is in the matrix.
- Option B (Oxidative Decarboxylation of α-ketoglutaric acid): The enzyme is in the matrix.
- Option D (Cleavage of Succinyl coenzyme-A): The enzyme is in the matrix.

Key Concepts:
- Mitochondrial Structure
- Krebs Cycle (Citric Acid Cycle)
- Enzyme Localization

Memory Aids:
- Remember that succinate dehydrogenase is the only Krebs cycle enzyme located on the inner mitochondrial membrane.

Quick Tips:
- Review the location of enzymes involved in cellular respiration.

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NADP, NAD and FAD are acceptors of

View answer and explanation

Correct option: B

Electrons

Option B (Electrons) is correct because NADP, NAD, and FAD are electron carriers that accept electrons during redox reactions.

Solution approach

Correct Answer + Core Reason: Electrons. NADP, NAD, and FAD function as electron acceptors in metabolic pathways.

Step-by-Step Solution:

Step 1: Understand the roles of NADP, NAD, and FAD.

Step 2: Recall that these molecules are coenzymes involved in redox reactions.

Step 3: Recognize that they accept electrons during oxidation reactions.

Step 4: Conclusion: NADP, NAD, and FAD are acceptors of electrons.

Why other options are wrong:
- Option A: Phosphate: While phosphorylation is important, these molecules primarily accept electrons.
- Option C: Oxygen: Oxygen is the terminal electron acceptor, not directly accepted by NADP, NAD, and FAD.
- Option D: Hydrogen: While they carry hydrogen atoms (protons and electrons), their primary role is electron acceptance.

Key Concepts:
- Redox Reactions
- Electron Carriers
- NADP, NAD, FAD

Memory Aids:
- Think of them as "electron taxis".

Quick Tips:
- Remember that these molecules cycle between oxidized and reduced forms.

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During conversion of pyruvic acid into acetyl Co-A, pyruvic acid is

View answer and explanation

Correct option: A

Oxidized

Option A (Oxidized) is correct because pyruvic acid loses electrons during its conversion to acetyl Co-A, which defines oxidation.

Solution approach

Correct Answer + Core Reason: Oxidized. Pyruvic acid loses electrons during conversion to Acetyl Co-A.

Step-by-Step Solution:

Step 1: Recall the conversion process: Pyruvic acid to Acetyl Co-A involves the removal of a carbon atom and electrons.

Step 2: Define oxidation: Oxidation is the loss of electrons.

Step 3: Apply the definition: Since pyruvic acid loses electrons, it is oxidized.

Step 4: Conclude: Pyruvic acid is oxidized during the conversion to Acetyl Co-A.

Why other options are wrong:
- Option B (Reduced): Reduction is the gain of electrons, which doesn't happen to pyruvic acid in this conversion.
- Option C (Isomerized): Isomerization involves rearranging atoms within a molecule, not electron transfer.
- Option D (Condensed): Condensation involves joining two molecules, not electron transfer.

Key Concepts:
- Oxidation
- Reduction
- Oxidative Decarboxylation

Memory Aids:
- OIL RIG (Oxidation Is Loss, Reduction Is Gain) of electrons.

Quick Tips:
- Remember the definitions of oxidation and reduction.

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In oxidative decarboxylation, enzyme used to

View answer and explanation

Correct option: B

Pyruvate dehydrogenase

The correct answer is B (Pyruvate dehydrogenase) because pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA, linking glycolysis to the Krebs cycle.

Solution approach

Correct Answer + Core Reason: Pyruvate dehydrogenase. This enzyme catalyzes the oxidative decarboxylation of pyruvate.

Step-by-Step Solution:

Step 1: Recall the process of oxidative decarboxylation of pyruvate.

Step 2: Pyruvate is converted to acetyl-CoA, releasing $CO_2$ .

Step 3: This reaction is catalyzed by the pyruvate dehydrogenase complex.

Why other options are wrong:
- Option A: Pyruvate decarboxylase is involved in alcoholic fermentation, not oxidative decarboxylation in mitochondria.
- Option C: Pyruvate hydrogeneticase is not a recognized enzyme name.
- Option D: Pyruvate dehydrogeneticase is not a recognized enzyme name.

Key Concepts:
- Oxidative decarboxylation
- Pyruvate dehydrogenase complex
- Krebs cycle

Memory Aids:
- Pyruvate \u2192 Acetyl-CoA = Pyruvate Dehydrogenase

Quick Tips:
- Know the enzymes involved in key metabolic pathways.

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Anaerobic respiration generally occurs in

View answer and explanation

Correct option: A

Lower organism, e.g., bacteria and fungi

Option A (Lower organism, e.g., bacteria and fungi) is correct because anaerobic respiration is more common in these organisms due to their metabolic pathways and environments.

Solution approach

Correct Answer + Core Reason: Lower organism, e.g., bacteria and fungi. Anaerobic respiration is prevalent in lower organisms due to their metabolic adaptations.

Step-by-Step Solution:

Step 1: Define anaerobic respiration: Respiration without oxygen.

Step 2: Identify organisms: Bacteria and fungi are known for anaerobic pathways.

Step 3: Explain prevalence: Lower organisms often thrive in oxygen-deprived environments.

Step 4: Conclude: Anaerobic respiration is common in bacteria and fungi.

Why other options are wrong:
- Option B: Higher organisms primarily use aerobic respiration.
- Option C: While some higher organisms can perform anaerobic respiration under stress, it's not their primary mode.
- Option D: Bacteria and fungi do perform anaerobic respiration.

Key Concepts:
- Anaerobic respiration
- Microbial metabolism

Memory Aids:
- Anaerobic = No air

Quick Tips:
- Remember that bacteria and fungi can survive without oxygen.

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In which part of mitochondria does ATP synthesis occur?

View answer and explanation

Correct option: A

{F_1}

The correct answer is A (

{F_1}

) because ATP synthesis in mitochondria occurs at the

{F_1}

particle of the ATP synthase complex, which protrudes into the mitochondrial matrix.

Solution approach

Correct Answer + Core Reason: ${F_1}$ . ATP synthesis occurs at the ${F_1}$ particle of ATP synthase.

Step-by-Step Solution:

Step 1: Recall the structure and function of ATP synthase.

Step 2: ATP synthase consists of two main components: ${F_0}$ and ${F_1}$ .

Step 3: The ${F_0}$ component is embedded in the inner mitochondrial membrane and acts as a proton channel.

Step 4: The ${F_1}$ component protrudes into the mitochondrial matrix and is the site of ATP synthesis.

Why other options are wrong:
- Option B: ${F_0}$ is the proton channel, not the site of ATP synthesis.
- Option C: Cristae are the folds of the inner mitochondrial membrane, increasing surface area, but not the direct site of ATP synthesis.
- Option D: The inner membrane houses the ATP synthase complex, but the actual synthesis occurs at the ${F_1}$ particle.

Key Concepts:
- ATP synthase structure and function
- Oxidative phosphorylation
- Mitochondrial inner membrane

Memory Aids:
- ${F_1}$ = ATP synthesis

Quick Tips:
- Distinguish between the roles of ${F_0}$ and ${F_1}$ in ATP synthesis.

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Understanding +4 | -1

In animal cells, like muscle, during exercise when

{O_2}

is inadequate for cellular respiration, pyruvic acid is reduced into lactic acid by

View answer and explanation

Correct option: C

Lactate dehydrogenase

Option C is correct because lactate dehydrogenase is the enzyme that catalyzes the reduction of pyruvic acid to lactic acid during anaerobic respiration in muscle cells.

Solution approach

Correct Answer + Core Reason: Lactate dehydrogenase. This enzyme catalyzes the conversion of pyruvic acid to lactic acid.

Step-by-Step Solution:

Step 1: Understand the process of anaerobic respiration in muscle cells.

Step 2: Identify the substrate and product: Pyruvic acid is reduced to lactic acid.

Step 3: Identify the enzyme involved: Lactate dehydrogenase catalyzes this reaction.

Step 4: Write the reaction: Pyruvic acid + NADH + $H^+$ -->(Lactate dehydrogenase)--> Lactic acid + $NAD^+$

Why other options are wrong:
- Option A: $O_2$ is not involved in this anaerobic process.
- Option B: Carboxylation is the addition of a carboxyl group, which is not occurring here.
- Option D: Lactate dehydrogenase is directly involved.

Key Concepts:
- Anaerobic respiration
- Lactic acid fermentation
- Lactate dehydrogenase

Memory Aids:
- Lactate dehydrogenase = Lactic acid

Quick Tips:
- Remember that lactate dehydrogenase is key for anaerobic respiration in muscles.

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Which of the following reaction does not take place in the cell organelle, that is referred to as ‘Power house of the cell’?

View answer and explanation

Correct option: B

Glyceraldehyde 3-phosphate dehydrogenation

Option B (Glyceraldehyde 3-phosphate dehydrogenation) is correct because glyceraldehyde 3-phosphate dehydrogenation occurs in the cytoplasm during glycolysis, not in the mitochondria (powerhouse of the cell).

Solution approach

Correct Answer + Core Reason: Glyceraldehyde 3-phosphate dehydrogenation. This reaction occurs in the cytoplasm, not the mitochondria.

Step-by-Step Solution:

Step 1: Identify the location of each reaction.
- Glycine Decarboxylation: Mitochondria
- Glyceraldehyde 3-phosphate dehydrogenation: Cytoplasm
- Fumaric acid hydration: Mitochondria
- Cytochrome oxidation: Mitochondria

Step 2: Determine which reaction does not take place in the mitochondria.\nGlyceraldehyde 3-phosphate dehydrogenation takes place in the cytoplasm.

Step 3: Final Answer\nGlyceraldehyde 3-phosphate dehydrogenation

Why other options are wrong:
- Option A (Glycine Decarboxylation): Glycine decarboxylation occurs in the mitochondria.
- Option C (Fumaric acid hydration): Fumaric acid hydration occurs in the mitochondria as part of the Krebs cycle.
- Option D (Cytochrome oxidation): Cytochrome oxidation occurs in the mitochondria as part of the electron transport chain.

Key Concepts:
- Glycolysis
- Krebs cycle
- Electron transport chain
- Mitochondria

Memory Aids:
- Remember that glycolysis occurs in the cytoplasm, while the Krebs cycle and ETC occur in the mitochondria.

Quick Tips:
- Know the location of the different stages of cellular respiration.

85 Medium

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Remembering +4 | -1

All of the given are reactants of TCA cycle except

View answer and explanation

Correct option: D

Pyruvic acid

Option D (Pyruvic acid) is correct because pyruvic acid is a product of glycolysis and a precursor to acetyl-CoA, which enters the TCA cycle, but it is not a direct reactant *within* the TCA cycle itself.

Solution approach

Correct Answer + Core Reason: Pyruvic acid. Pyruvic acid is a product of glycolysis and a precursor to acetyl-CoA, which enters the TCA cycle, but it is not a direct reactant within the TCA cycle itself.

Step-by-Step Solution:

Step 1: Understand the reactants and products of the TCA cycle.

Step 2: The TCA cycle involves a series of reactions that oxidize acetyl-CoA to produce $CO_2$ , ATP, NADH, and $FADH_2$ .

Step 3: Succinyl CoA, Fumaric acid, and Citric acid are all intermediates within the TCA cycle.

Step 4: Pyruvic acid is converted to Acetyl CoA before entering the TCA cycle. Therefore, it is not a direct reactant of the TCA cycle.

Why other options are wrong:
- Option A: Succinyl CoA is an intermediate in the TCA cycle.
- Option B: Fumaric acid is an intermediate in the TCA cycle.
- Option C: Citric acid is the first product formed in the TCA cycle.

Key Concepts:
- TCA cycle (Krebs cycle)
- Reactants and products
- Intermediates

Memory Aids:
- Remember the key intermediates of the TCA cycle.

Quick Tips:
- Know the sequence of reactions in the TCA cycle.

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Understanding +4 | -1

Which of the following substances yield less than 4 kcal/mol when its phosphate bond is hydrolysed?

View answer and explanation

Correct option: C

Glucose-6-phosphate

Option C (Glucose-6-phosphate) is correct because glucose-6-phosphate has a lower energy phosphate bond compared to the other compounds listed.

Solution approach

Correct Answer + Core Reason: Glucose-6-phosphate. Glucose-6-phosphate has a lower energy phosphate bond.

Step-by-Step Solution:

Step 1: Recall the energy released by hydrolysis of different phosphate bonds.
- ATP: ~7.3 kcal/mol
- ADP: ~7.3 kcal/mol
- Creatine phosphate: ~10.3 kcal/mol
- Glucose-6-phosphate: ~3.3 kcal/mol

Step 2: Identify the substance with the lowest energy release upon hydrolysis.\nGlucose-6-phosphate releases the least energy (less than 4 kcal/mol).

Step 3: Final Answer\nGlucose-6-phosphate

Why other options are wrong:
- Option A (Creatine phosphate): Creatine phosphate releases more than 4 kcal/mol upon hydrolysis.
- Option B (ADP): ADP releases more than 4 kcal/mol upon hydrolysis.
- Option D (ATP): ATP releases more than 4 kcal/mol upon hydrolysis.

Key Concepts:
- Phosphate bond energy
- ATP hydrolysis
- Glucose-6-phosphate

Memory Aids:
- Remember the relative energy levels of different phosphorylated compounds.

Quick Tips:
- Know the approximate energy released by hydrolysis of common phosphate bonds.

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Understanding +4 | -1

Which of the following steps during glycolysis is associated with utilization of ATP?

View answer and explanation

Correct option: D

Both 1 and 2

Option D (Both 1 and 2) is correct because ATP is used in the phosphorylation of glucose to glucose-6-phosphate and fructose-6-phosphate to fructose-1,6-bisphosphate during glycolysis.

Solution approach

Correct Answer + Core Reason: Both 1 and 2. ATP is utilized in the conversion of Glucose to Glucose 6-phosphate and Fructose 6-phosphate to fructose 1,6 diphosphate.

Step-by-Step Solution:

Step 1: Identify the question: Which steps in glycolysis utilize ATP?

Step 2: Recall glycolysis: ATP is used in the initial phosphorylation steps.

Step 3: Glucose to Glucose 6-phosphate: ATP is used.

Step 4: Fructose 6-phosphate to Fructose 1,6-bisphosphate: ATP is used.

Step 5: Conclusion: Both steps utilize ATP.

Why other options are wrong:
- Option A: This is one of the correct steps, but not the only one.
- Option B: This is one of the correct steps, but not the only one.
- Option C: PEP to Pyruvic acid generates ATP, it doesn't utilize it.

Key Concepts:
- Glycolysis
- ATP utilization
- Phosphorylation

Memory Aids:
- ATP is used in the early steps of glycolysis.

Quick Tips:
- Remember the steps of glycolysis and where ATP is used or produced.

88 Medium

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Understanding +4 | -1

Select the correct option w.r.t. increasing order of respiratory quotient of various substrates.

View answer and explanation

Correct option: A

Fats < Protein < Oxalic acid

Option A is correct because the RQ values increase in the order: Fats (0.7) < Protein (0.8-0.9) < Oxalic acid (4.0).

Solution approach

Correct Answer + Core Reason: Fats < Protein < Oxalic acid. The RQ values for these substrates increase in this order.

Step-by-Step Solution:

Step 1: Recall the RQ values for different substrates.

Step 2: RQ value for Fats: Approximately 0.7.

Step 3: RQ value for Protein: Approximately 0.8-0.9.

Step 4: RQ value for Oxalic acid: Approximately 4.0.

Step 5: Compare the RQ values: 0.7 < 0.8-0.9 < 4.0.

Step 6: Arrange in increasing order: Fats < Protein < Oxalic acid.

Why other options are wrong:
- Option B: Malic acid has an RQ of 1.33, which is less than Oxalic acid (4.0) but greater than Fat (0.7).
- Option C: Protein has an RQ of 0.8-0.9, which is less than Fat (0.7) is incorrect.
- Option D: Oxalic acid has an RQ of 4.0, which is greater than Protein (0.8-0.9).

Key Concepts:
- Respiratory Quotient (RQ)
- RQ values for different substrates

Memory Aids:
- Fats < Protein < Carbohydrates < Organic Acids

Quick Tips:
- Memorize the general trend of RQ values for different substrates.

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