In which part of the cell does glycolysis occur?

Correct Option: C. Solution: Glycolysis occurs in the cytoplasm of the cell.

Which of the following is the primary location where glycolysis occurs in a cell?

Correct Option: C. Solution: Glycolysis occurs in the cytoplasm of the cell.

What is the main product of glycolysis?

Correct Option: C. Solution: Pyruvic acid is the key product of glycolysis.

Respiration in Plants

Objectives Notes Exam Tips Practice Qs Ask AI

Learning Objectives

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Learning Objectives

Understand the process of respiration in plants.
Differentiate between respiration and combustion.
Explain the steps involved in glycolysis and its significance.
Describe the process of fermentation and its types.
Outline the stages of aerobic respiration and the role of mitochondria.
Define the respiratory quotient (RQ) and its significance in respiration.
Discuss the concept of the amphibolic pathway in respiration.
Identify the differences between aerobic and anaerobic respiration.
Analyze the role of various respiratory substrates in energy production.

Revision Notes & Summary

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Respiration in Plants

12.1 Do Plants Breathe?

Breathing is essential for life.
All living organisms, including plants and microbes, breathe.

12.2 Glycolysis

Energy is required for daily life activities (absorption, transport, movement, reproduction).
Glycolysis is the process where glucose is partially oxidized to form two molecules of pyruvic acid.
Occurs in the cytoplasm of all living organisms.

12.3 Fermentation

Occurs under anaerobic conditions.
Can lead to lactic acid or alcohol fermentation.

12.4 Aerobic Respiration

Takes place in the mitochondria.
Involves complete oxidation of pyruvate, producing CO₂ and ATP.
Key steps:
- Pyruvate enters the mitochondria.
- Oxidative decarboxylation occurs, producing Acetyl CoA.
- Acetyl CoA enters the Krebs cycle.

12.5 The Respiratory Balance Sheet

Net gain of ATP during aerobic respiration of one glucose molecule is 38 ATP.
Assumptions for calculations:
- Sequential pathway functioning.
- NADH from glycolysis is transferred to mitochondria.
- Only glucose is respired.

12.6 Amphibolic Pathway

The respiratory pathway involves both anabolism and catabolism.

12.7 Respiratory Quotient (RQ)

RQ = volume of CO₂ evolved / volume of O₂ consumed.
RQ varies with the type of respiratory substrate:
- Carbohydrates: RQ = 1
- Fats: RQ < 1
- Proteins: RQ ≈ 0.9

Important Processes

Oxidative Phosphorylation: ATP synthesis linked to electron transport.
Electron Transport System (ETS): Located on the inner mitochondrial membrane, crucial for ATP production.

Key Metabolic Pathways

Glycolysis: Converts glucose to pyruvate.
Krebs Cycle: Processes Acetyl CoA to produce CO₂ and energy carriers (NADH, FADH₂).
ATP Synthesis: Involves ATP synthase and proton gradient.

Exam Tips & Common Mistakes

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Common Mistakes and Exam Tips in Plant Respiration

Common Pitfalls

Confusing Respiration with Combustion: Students often confuse the processes of respiration and combustion. Remember, respiration is a biological process that occurs in living organisms, while combustion is a chemical reaction that occurs outside of living systems.
Misunderstanding Glycolysis and Krebs Cycle: Many students struggle to differentiate between glycolysis and the Krebs cycle. Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, while the Krebs cycle occurs in the mitochondria and processes acetyl CoA into CO₂.
Overlooking the Role of Oxygen: Some students fail to recognize the importance of oxygen in aerobic respiration. Oxygen is the final electron acceptor in the electron transport chain, which is crucial for ATP synthesis.
Ignoring the Amphibolic Nature of the Respiratory Pathway: Students may not appreciate that the respiratory pathway is amphibolic, meaning it involves both catabolic and anabolic processes. This can lead to misunderstandings about how substrates are utilized in respiration.

Exam Tips

Understand Key Definitions: Be clear on definitions such as respiratory quotient (RQ), oxidative phosphorylation, and amphibolic pathway. These terms often appear in exam questions.
Draw Diagrams: Practice drawing and labeling diagrams of glycolysis, the Krebs cycle, and the electron transport chain. Visual aids can help solidify your understanding and are often useful in exams.
Practice Calculations: Be prepared to calculate the net gain of ATP from glucose oxidation. Understand the assumptions behind these calculations, as they are commonly tested.
Review the Steps of Glycolysis: Familiarize yourself with the steps of glycolysis and the enzymes involved. This is a frequent topic in exams, and knowing the sequence can help you answer related questions accurately.
Connect Concepts: Make connections between different processes, such as how glycolysis leads into aerobic respiration and how fermentation differs from aerobic processes. This holistic understanding can help in application-based questions.

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Practice Test – MCQs, True/False

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Multiple Choice Questions

To act as a substrate in glycolysis

To serve as the final electron acceptor in the electron transport system

To directly produce ATP

To convert glucose into pyruvic acid

Correct Answer: B

Solution:

In aerobic respiration, oxygen serves as the final electron acceptor in the electron transport system, allowing the formation of water.

Lactic acid

Pyruvic acid

Acetyl CoA

Citric acid

Correct Answer: B

Solution:

During glycolysis, glucose is partially oxidized to form two molecules of pyruvic acid.

Fructose

Glucose

Sucrose

Glycerol

Correct Answer: B

Solution:

Glycolysis involves the breakdown of glucose to pyruvic acid.

2 ATP

4 ATP

6 ATP

8 ATP

Correct Answer: A

Solution:

Glycolysis produces a net gain of 2 ATP molecules per molecule of glucose. Although 4 ATP are produced, 2 ATP are used in the initial steps, resulting in a net production of 2 ATP.

Invertase

Hexokinase

Pyruvate decarboxylase

Alcohol dehydrogenase

Correct Answer: B

Solution:

Hexokinase is the enzyme that catalyzes the conversion of glucose to glucose-6-phosphate in glycolysis.

It oxidizes NADH to NAD+.

It transports electrons through the electron transport chain.

It synthesizes ATP from ADP and inorganic phosphate.

It pumps protons across the mitochondrial membrane.

Correct Answer: C

Solution:

ATP synthase is the enzyme responsible for synthesizing ATP from ADP and inorganic phosphate as protons flow through it down their electrochemical gradient.

Acetyl CoA

Lactic acid

Pyruvic acid

Ethanol

Correct Answer: C

Solution:

Pyruvic acid is the main product of glycolysis and its fate depends on the availability of oxygen.

Less than 1

Equal to 1

Greater than 1

Zero

Correct Answer: B

Solution:

The respiratory quotient (RQ) is equal to 1 when carbohydrates are completely oxidized, as the volume of CO₂ evolved is equal to the volume of O₂ consumed.

Mitochondria

Chloroplast

Cytoplasm

Nucleus

Correct Answer: C

Solution:

Glycolysis occurs in the cytoplasm of the cell.

It acts as the initial electron donor.

It serves as the final electron acceptor, forming water.

It is used to phosphorylate ADP to ATP directly.

It is converted into carbon dioxide during the process.

Correct Answer: B

Solution:

Oxygen serves as the final electron acceptor in the electron transport system, where it combines with electrons and protons to form water.

Hexokinase

Phosphofructokinase

Aldolase

Pyruvate kinase

Correct Answer: B

Solution:

Phosphofructokinase is the enzyme responsible for converting fructose-6-phosphate to fructose-1,6-bisphosphate.

Glycolysis

Fermentation

Krebs' cycle

Photosynthesis

Correct Answer: C

Solution:

Krebs' cycle, also known as the citric acid cycle, is responsible for the complete oxidation of glucose to carbon dioxide and water in the presence of oxygen.

1.0

0.9

0.7

1.2

Correct Answer: B

Solution:

When proteins are used as the respiratory substrate, the respiratory quotient (RQ) is approximately 0.9, indicating that less CO2 is produced relative to the amount of O2 consumed.

Fermentation produces more ATP than aerobic respiration.

Fermentation occurs in the presence of oxygen, while aerobic respiration does not.

Fermentation results in the partial breakdown of glucose, while aerobic respiration completely degrades glucose to CO₂ and H₂O.

Fermentation requires the electron transport chain, while aerobic respiration does not.

Correct Answer: C

Solution:

Fermentation results in the partial breakdown of glucose, producing less ATP, while aerobic respiration completely degrades glucose to CO₂ and H₂O, producing more ATP.

Glucose

NADH

Oxaloacetic acid

FADH₂

Correct Answer: C

Solution:

Oxaloacetic acid is regenerated in the citric acid cycle to allow the cycle to continue.

Less than 1

Equal to 1

Greater than 1

Zero

Correct Answer: B

Solution:

The respiratory quotient (RQ) is equal to 1 when carbohydrates are used as the substrate and are completely oxidized, as equal amounts of CO₂ and O₂ are evolved and consumed, respectively.

Lenticels facilitate gaseous exchange in woody stems.

Lenticels are involved in the transport of nutrients.

Lenticels store water in plant tissues.

Lenticels are responsible for photosynthesis in non-green parts.

Correct Answer: A

Solution:

Lenticels are openings in the bark of woody stems that allow gases to diffuse into the inner tissues of the plant, facilitating respiration.

Correct Answer: C

Solution:

Theoretically, there is a net gain of 38 ATP molecules during aerobic respiration of one molecule of glucose.

1.0

0.9

Less than 1

Greater than 1

Correct Answer: C

Solution:

When fats are used as the respiratory substrate, the RQ is less than 1 because the volume of CO₂ evolved is less than the volume of O₂ consumed.

It is located on the inner membrane of the mitochondria.

Oxygen acts as the ultimate electron acceptor.

It directly synthesizes glucose from pyruvate.

It involves oxidative phosphorylation.

Correct Answer: C

Solution:

The electron transport system does not synthesize glucose from pyruvate; it is involved in oxidative phosphorylation.

Nucleus

Mitochondria

Cytoplasm

Endoplasmic reticulum

Correct Answer: C

Solution:

Glycolysis occurs in the cytoplasm of the cell.

Krebs' cycle

Glycolysis

Electron transport chain

Oxidative phosphorylation

Correct Answer: B

Solution:

Glycolysis is the process that occurs in the cytoplasm, leading to the formation of pyruvate from glucose.

Conversion of glucose to glucose-6-phosphate

Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate

Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate

Conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate

Correct Answer: C

Solution:

In glycolysis, ATP is directly synthesized during the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate.

Correct Answer: C

Solution:

The theoretical yield of ATP from the complete oxidation of one molecule of glucose during aerobic respiration is 38 ATP molecules.

Succinyl-CoA

Fumarate

Malate

Citrate

Correct Answer: A

Solution:

During the conversion of succinyl-CoA to succinic acid, a molecule of GTP is synthesised, which is a substrate-level phosphorylation.

It occurs in the absence of oxygen and produces lactic acid or ethanol.

It occurs in the mitochondria and requires oxygen to proceed.

It produces ATP and NADH without the need for oxygen.

It involves the complete oxidation of glucose to carbon dioxide and water.

Correct Answer: C

Solution:

Glycolysis is considered anaerobic because it does not require oxygen to produce ATP and NADH. It takes place in the cytoplasm and can occur in both aerobic and anaerobic conditions.

Invertase

Hexokinase

Alcohol dehydrogenase

Lactate dehydrogenase

Correct Answer: B

Solution:

Hexokinase is the enzyme responsible for converting glucose into glucose-6-phosphate during glycolysis.

Hexokinase

Invertase

Alcohol dehydrogenase

Pyruvate decarboxylase

Correct Answer: B

Solution:

Invertase is the enzyme that converts sucrose into glucose and fructose, which then enter the glycolytic pathway.

Complete breakdown of glucose

Higher ATP yield

Partial breakdown of glucose

Requires oxygen

Correct Answer: C

Solution:

Fermentation accounts for only a partial breakdown of glucose, unlike aerobic respiration which completely degrades it to CO₂ and H₂O.

Krebs' cycle

Electron Transport System

Fermentation

Oxidative phosphorylation

Correct Answer: C

Solution:

Fermentation occurs under anaerobic conditions in many prokaryotes and unicellular eukaryotes.

It only involves the breakdown of glucose.

It is exclusively anabolic, synthesizing complex molecules.

It involves both the breakdown (catabolism) and synthesis (anabolism) of molecules.

It is a pathway that only occurs in plants.

Correct Answer: C

Solution:

The respiratory pathway is considered amphibolic because it involves both catabolic processes (breakdown of substrates for energy) and anabolic processes (synthesis of molecules using intermediates from the pathway).

Oxygen

NAD+

FAD

Water

Correct Answer: A

Solution:

In oxidative phosphorylation, electrons are transferred through the electron transport chain and are finally accepted by oxygen, which combines with protons to form water.

Succinyl-CoA

Citrate

Oxaloacetate

Malate

Correct Answer: A

Solution:

The conversion of succinyl-CoA to succinic acid involves substrate-level phosphorylation, resulting in the synthesis of GTP.

2 ATP

12 ATP

38 ATP

100 ATP

Correct Answer: C

Solution:

Theoretical calculations suggest that 38 ATP molecules can be gained from the complete oxidation of one molecule of glucose during aerobic respiration.

Conversion of succinyl-CoA to succinic acid

Conversion of fumarate to malate

Conversion of isocitrate to alpha-ketoglutarate

Conversion of citrate to isocitrate

Correct Answer: A

Solution:

The conversion of succinyl-CoA to succinic acid is associated with substrate-level phosphorylation, resulting in the synthesis of GTP.

It directly synthesizes ATP from ADP.

It transports electrons from NADH and FADH₂ to oxygen, releasing energy to pump protons across the mitochondrial membrane.

It converts pyruvate into acetyl CoA.

It splits glucose into two molecules of pyruvate.

Correct Answer: B

Solution:

The electron transport system (ETS) facilitates the transfer of electrons from NADH and FADH₂ to oxygen, releasing energy used to pump protons across the mitochondrial membrane, which ultimately drives ATP synthesis.

Glycolysis

Fermentation

Krebs' cycle

Photosynthesis

Correct Answer: C

Solution:

The Krebs' cycle, also known as the citric acid cycle, occurs in the mitochondria and involves the complete oxidation of pyruvic acid.

Photosynthesis

Glycolysis

Respiratory pathway

Fermentation

Correct Answer: C

Solution:

The respiratory pathway is considered an amphibolic pathway as it involves both anabolism and catabolism.

Oxygen acts as an initial electron donor.

Oxygen is the final electron acceptor and gets reduced to water.

Oxygen is used to phosphorylate ADP to ATP.

Oxygen is not involved in the electron transport system.

Correct Answer: B

Solution:

In the electron transport system, oxygen acts as the final electron acceptor and is reduced to water, allowing the process of oxidative phosphorylation to occur.

Krebs' cycle

Electron transport system

Glycolysis

Oxidative phosphorylation

Correct Answer: C

Solution:

Glycolysis occurs in the cytoplasm of the cell and involves the partial oxidation of glucose to form pyruvic acid.

Correct Answer: D

Solution:

There can be a net gain of 38 ATP molecules during aerobic respiration of one molecule of glucose.

It acts as a substrate for glycolysis.

It is the ultimate acceptor of electrons.

It is converted into glucose.

It is used to synthesize NADH.

Correct Answer: B

Solution:

In the electron transport system, oxygen acts as the ultimate acceptor of electrons and is reduced to water.

Hexokinase

Invertase

Pyruvate decarboxylase

Lactate dehydrogenase

Correct Answer: B

Solution:

Invertase is the enzyme that converts sucrose into glucose and fructose.

Hexokinase

Invertase

Pyruvate decarboxylase

Alcohol dehydrogenase

Correct Answer: B

Solution:

Invertase is the enzyme that catalyzes the hydrolysis of sucrose into glucose and fructose, which then enter the glycolytic pathway.

Hexokinase

Phosphofructokinase

Pyruvate kinase

Aldolase

Correct Answer: A

Solution:

Hexokinase is the enzyme that catalyzes the conversion of glucose into glucose-6-phosphate during glycolysis.

NADH

FADH₂

GTP

Lactic acid

Correct Answer: D

Solution:

Lactic acid is not a product of the citric acid cycle. It is produced during anaerobic respiration.

Aerobic respiration

Lactic acid fermentation

Alcoholic fermentation

Glycolysis

Correct Answer: C

Solution:

Alcoholic fermentation occurs under anaerobic conditions and results in the production of ethanol and CO₂.

ATP

GTP

NADH

FADH₂

Correct Answer: B

Solution:

During the conversion of succinyl-CoA to succinic acid, a molecule of GTP is synthesized.

Acetyl CoA

Lactic acid

Pyruvic acid

Citric acid

Correct Answer: C

Solution:

Pyruvic acid is the key product of glycolysis.

Acetyl CoA

Pyruvic acid

Lactic acid

Citric acid

Correct Answer: B

Solution:

The main product formed at the end of glycolysis is pyruvic acid.

To act as a substrate for glycolysis.

To serve as the final electron acceptor in the electron transport chain.

To phosphorylate glucose.

To convert pyruvate into lactic acid.

Correct Answer: B

Solution:

Oxygen serves as the final electron acceptor in the electron transport chain, where it combines with electrons and protons to form water.

It ensures that all energy is released as heat.

It allows the energy to be trapped in ATP.

It prevents the formation of carbon dioxide.

It increases the rate of glycolysis.

Correct Answer: B

Solution:

The step-wise release of energy in respiration allows the energy to be trapped in ATP, making it useful for the cell.

It directly produces a large number of ATP molecules.

It regenerates NAD+ and FAD from NADH and FADH2.

It occurs in the cytoplasm of the cell.

It generates NADH and FADH2 which are used in the electron transport chain.

Correct Answer: D

Solution:

The citric acid cycle generates NADH and FADH2, which are crucial for the electron transport chain where ATP is produced. It does not directly produce a large number of ATP molecules, nor does it regenerate NAD+ and FAD.

Acetyl CoA

Pyruvic acid

Citric acid

Lactic acid

Correct Answer: B

Solution:

The primary product of glycolysis is pyruvic acid.

NADH

FADH₂

O₂

CO₂

Correct Answer: C

Solution:

In the electron transport system, O₂ is the ultimate acceptor of electrons and it gets reduced to water.

NAD+

FAD

Oxygen

Carbon dioxide

Correct Answer: C

Solution:

In aerobic respiration, oxygen acts as the final electron acceptor in the electron transport chain, where it gets reduced to form water.

It only involves the breakdown of glucose.

It involves both anabolic and catabolic processes.

It solely synthesizes ATP.

It is restricted to the mitochondria.

Correct Answer: B

Solution:

The respiratory pathway is considered amphibolic because it involves both the breakdown of substrates (catabolism) and their synthesis (anabolism).

To act as a substrate for glycolysis

To serve as the final electron acceptor in the electron transport chain

To directly phosphorylate ADP to ATP

To break down glucose into pyruvate

Correct Answer: B

Solution:

In aerobic respiration, oxygen acts as the final electron acceptor in the electron transport chain, where it combines with electrons and protons to form water.

Fermentation completely oxidizes glucose to CO₂ and H₂O.

Fermentation occurs only in the presence of oxygen.

Fermentation results in a net gain of two ATP molecules per glucose molecule.

Fermentation produces a large number of ATP molecules.

Correct Answer: C

Solution:

Fermentation results in a net gain of two ATP molecules per glucose molecule.

NADH

FADH₂

O₂

CO₂

Correct Answer: C

Solution:

In the electron transport system (ETS), O₂ is the ultimate acceptor of electrons, which gets reduced to water.

True or False

Correct Answer: True

Solution:

The electron transport system (ETS) is a part of aerobic respiration, where electrons are transferred to oxygen, the final electron acceptor.

Correct Answer: True

Solution:

During the conversion of succinyl-CoA to succinic acid in the citric acid cycle, GTP is synthesised through substrate-level phosphorylation.

Correct Answer: True

Solution:

Glycolysis involves the partial oxidation of glucose to produce two molecules of pyruvic acid.

Correct Answer: True

Solution:

In the citric acid cycle, there is one point where FAD+ is reduced to FADH₂, contributing to the electron transport chain.

Correct Answer: True

Solution:

In aerobic respiration, oxygen acts as the final electron acceptor in the electron transport system, where it is reduced to water.

Correct Answer: False

Solution:

Fermentation results in the partial breakdown of glucose, not complete oxidation.

Correct Answer: False

Solution:

The respiratory quotient (RQ) for carbohydrates is typically 1, as equal volumes of CO₂ are evolved and O₂ are consumed.

Correct Answer: True

Solution:

Glycolysis takes place in the cytoplasm and is a universal process present in all living organisms, where glucose is partially oxidized to form pyruvic acid.

Correct Answer: True

Solution:

The electron transport system is located on the inner membrane of the mitochondria where it facilitates oxidative phosphorylation.

Correct Answer: False

Solution:

Fermentation accounts for only a partial breakdown of glucose, unlike aerobic respiration.

Correct Answer: False

Solution:

Glycolysis involves the partial oxidation of glucose to form two molecules of pyruvic acid, not complete oxidation to carbon dioxide and water.

Correct Answer: True

Solution:

The respiratory quotient is defined as the ratio of the volume of carbon dioxide evolved to the volume of oxygen consumed during respiration.

Correct Answer: True

Solution:

Only cells containing chloroplasts, which are usually located in the superficial layers, carry out photosynthesis. Non-green parts need food for oxidation.

Correct Answer: True

Solution:

During aerobic respiration, pyruvic acid is transported into the mitochondria where it is converted into acetyl CoA.

Correct Answer: True

Solution:

During the conversion of succinyl-CoA to succinic acid, a molecule of GTP is synthesized, which is a substrate-level phosphorylation.

Correct Answer: False

Solution:

Oxidative phosphorylation occurs in the mitochondria, not in the cytoplasm.

Correct Answer: True

Solution:

The respiratory pathway is involved in both the breakdown (catabolism) and synthesis (anabolism) of molecules, making it an amphibolic pathway.

Correct Answer: False

Solution:

Fermentation accounts for only a partial breakdown of glucose, not a complete one.

Correct Answer: True

Solution:

When fats are used as a respiratory substrate, the RQ is less than 1 because the volume of CO₂ evolved is less than the volume of O₂ consumed.

Correct Answer: False

Solution:

Oxidative phosphorylation occurs in the mitochondria, specifically in the inner mitochondrial membrane.

Correct Answer: True

Solution:

Glycolysis takes place in the cytoplasm of the cell in all living organisms, including plants.

Correct Answer: False

Solution:

Glycolysis occurs in the cytoplasm of the cell, not in the mitochondria.

Correct Answer: True

Solution:

Glycolysis occurs in the cytoplasm of the cell and is present in all living organisms, where glucose undergoes partial oxidation to form pyruvic acid.

Correct Answer: True

Solution:

In the citric acid cycle, there are three points where NAD+ is reduced to NADH + H+.

Correct Answer: False

Solution:

Photosynthesis occurs only in cells containing chloroplasts, which are most often located in the superficial layers of green plants. Non-green parts of the plant do not photosynthesize and require food for oxidation.

Correct Answer: True

Solution:

Lenticels are openings in the stems of plants that facilitate gaseous exchange.

Correct Answer: True

Solution:

The complete combustion of glucose produces CO₂ and H₂O as end products, yielding energy.

Correct Answer: True

Solution:

The respiratory pathway is amphibolic as it partakes in both the breakdown (catabolism) and synthesis (anabolism) of molecules.

Correct Answer: True

Solution:

The electron transport system, located in the inner mitochondrial membrane, facilitates ATP synthesis through oxidative phosphorylation.

Correct Answer: False

Solution:

Fermentation results in the partial breakdown of glucose, not complete oxidation to carbon dioxide and water.

Correct Answer: False

Solution:

The electron transport system (ETS) is located on the inner membrane of the mitochondria.

Correct Answer: True

Solution:

Green plants and cyanobacteria trap light energy and convert it into chemical energy stored in carbohydrates through photosynthesis.

Correct Answer: True

Solution:

The respiratory quotient for carbohydrates is 1 because equal amounts of carbon dioxide are evolved and oxygen is consumed.

Correct Answer: True

Solution:

The citric acid cycle involves three points where NAD+ is reduced to NADH + H+.

Correct Answer: True

Solution:

When carbohydrates are used as substrate and are completely oxidised, the RQ is 1 because equal amounts of CO₂ and O₂ are evolved and consumed.

Correct Answer: True

Solution:

Glycolysis is a universal process occurring in the cytoplasm of all living organisms, including plants.

Correct Answer: True

Solution:

During aerobic respiration, one molecule of glucose can theoretically yield a net gain of 38 ATP molecules.

Correct Answer: False

Solution:

Glycolysis involves the partial oxidation of glucose to form two molecules of pyruvic acid, not complete oxidation to carbon dioxide and water.

Correct Answer: True

Solution:

In the electron transport system (ETS), oxygen is the ultimate acceptor of electrons and it gets reduced to water.

Correct Answer: False

Solution:

Fermentation results in the partial breakdown of glucose, producing either lactic acid or ethanol and carbon dioxide, not complete breakdown to carbon dioxide and water.

Correct Answer: False

Solution:

Glycolysis occurs in the cytoplasm of the cell, not the mitochondria.

Respiration in Plants

Learning Objectives

Learning Objectives

Revision Notes & Summary

Respiration in Plants

12.1 Do Plants Breathe?

12.2 Glycolysis

12.3 Fermentation

12.4 Aerobic Respiration

12.5 The Respiratory Balance Sheet

12.6 Amphibolic Pathway

12.7 Respiratory Quotient (RQ)

Important Processes

Key Metabolic Pathways

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips in Plant Respiration

Common Pitfalls

Exam Tips

AI Learning Assistant

Practice Test – MCQs, True/False

Multiple Choice Questions

Q1.What is the main role of oxygen in aerobic respiration?

Correct Answer: B

Q2.In the process of glycolysis, glucose is converted into which of the following?

Correct Answer: B

Q3.What is the primary substrate for glycolysis?

Correct Answer: B

Q4.During glycolysis, how many net ATP molecules are produced per molecule of glucose?

Correct Answer: A

Q5.In glycolysis, which enzyme catalyzes the conversion of glucose to glucose-6-phosphate?

Correct Answer: B

Q6.Which of the following best describes the role of ATP synthase in the mitochondria?

Correct Answer: C

Q7.What is the main product of glycolysis that can undergo further metabolic processes depending on the availability of oxygen?

Correct Answer: C

Q8.What is the respiratory quotient (RQ) when carbohydrates are completely oxidized during respiration?

Correct Answer: B

Q9.In which part of the cell does glycolysis occur?

Correct Answer: C

Q10.In the electron transport system (ETS), what is the role of oxygen?

Correct Answer: B

Q11.Which enzyme is responsible for converting fructose-6-phosphate to fructose-1,6-bisphosphate during glycolysis?

Correct Answer: B

Q12.Which of the following processes is responsible for the complete oxidation of glucose to carbon dioxide and water in the presence of oxygen?

Correct Answer: C

Q13.What is the respiratory quotient (RQ) when proteins are used as the respiratory substrate?

Correct Answer: B

Q14.What is the primary difference between fermentation and aerobic respiration?

Correct Answer: C

Q15.In the citric acid cycle, which molecule is regenerated to allow the cycle to continue?

Correct Answer: C

Q16.What is the respiratory quotient (RQ) when carbohydrates are used as the substrate and are completely oxidized?

Correct Answer: B

Q17.In the context of plant respiration, which of the following statements best describes the role of lenticels?

Correct Answer: A

Q18.During aerobic respiration, how many ATP molecules are theoretically gained from one molecule of glucose?

Correct Answer: C

Q19.What is the respiratory quotient (RQ) when fats are used as the respiratory substrate?

Correct Answer: C

Q20.Which of the following is NOT a characteristic of the electron transport system (ETS) in mitochondria?

Correct Answer: C

Q21.Which of the following is the primary location where glycolysis occurs in a cell?

Correct Answer: C

Q22.Which of the following processes occurs in the cytoplasm of the cell and leads to the formation of pyruvate?

Correct Answer: B

Q23.In the process of glycolysis, which of the following steps directly results in the synthesis of ATP?

Correct Answer: C

Q24.During aerobic respiration, the complete oxidation of one molecule of glucose yields how many ATP molecules theoretically?

Correct Answer: C

Q25.In the citric acid cycle, which molecule is directly involved in substrate-level phosphorylation?

Correct Answer: A

Q26.Which of the following statements best describes why glycolysis is considered an anaerobic process?

Correct Answer: C

Q27.Which enzyme is responsible for converting glucose into glucose-6-phosphate during glycolysis?

Correct Answer: B

Q28.Which enzyme is responsible for converting sucrose into glucose and fructose in the glycolytic pathway?

Correct Answer: B

Q29.Which of the following is a characteristic of fermentation compared to aerobic respiration?

Correct Answer: C

Q30.Which of the following processes occurs under anaerobic conditions?