CBSE Class 11 Biology HOTs Respiration in Plants

MCQ Questions for NCERT Class 11 Biology Respiration in Plants

 Question. The adjoining diagram refers to mitochondrial electron transport chain. Identify P, Q, R, S, T.

(a) P-Matrix, Q-Outer membrane, R-FADH2, S-NADH+H+, T-2H+
(b) P-Inter membrane space, Q-Matrix, R-NADH + H+, S-NAD+, T-2H+
(c) P-Outer membrane, Q-Cristae, R-NAD,D-NADH + H+, T-H+
(d) P-Cristae, Q-Outer chamber, R-NADH+H+,S-NAD+, T-2H+

Answer : B

Question. Cytochromes are ____ containing compounds.
(a) manganese (Mn)
(b) magnesium (Mg)
(c) iron (Fe)
(d) nickel (Ni)

Answer : C

Question. Select the incorrectly matched pair.
(a) End products of alcoholic – Ethanol + CO2 fermentation
(b) End products of lactic – Lactic acid + CO2 acid fermentation
(c) Obligate anaerobe – Clostridium tetani
(d) Ethyl alcohol fermentation – Rhizopus

Answer : B

Question. Select the incorrect statement regarding an overview of the electron transport system (ETS).
(a) Ubiquinone receives reducing equivalents via FADH2 (complex II) that is generated during oxidation of succinate in the TCA cycle.
(b) As the electrons move down the system,energy is released and used to form ATP.
(c) 2ATPs are formed for every pair of electrons that enters by way of NADH and 3ATPs are formed for every pair of electrons that enters by way of FADH2.
(d) Oxygen, the final e– acceptor, becomes a part of water.

Answer : C

Question. Choose the correct combination of labelling of the molecules involved in the pathway of anaerobic respiration in yeast.   (Img 59 )
(a) A-Ethanol, B-CO2, C-Acetaldehyde
(b) A-Ethanol, B-Acetaldehyde, C-CO2
(c) A-CO2, B-Ethanol, C-Acetaldehyde
(d) A-CO2, B-Acetaldehyde, C-Ethanol

Answer : B

Question. Cells are suspended in a culture medium that contains excess glucose. The graph below shows glucose utilisation under different growth conditions. (A), (B), and (C) in the graph indicate   (Img 59 )

(a) A – Anaerobic respiration
B – Introduction of O2 to culture medium
C – Aerobic respiration
(b) A – Aerobic respiration
B – Introduction of CO2 to culture medium
C – Anaerobic respiration
(c) A – Aerobic respiration
B – Supply of organic triphosphate
C – Aerobic respiration
(d) A – Aerobic respiration
B – Introduction of CO2 to culture medium
C – Anaerobic respiration

Answer : A

Question. Identify A and B in the given reaction.Pyruvic acid + CoA + NAD+A B
(a) PEP CO2
(b) Acetyl CoA CO2
(c) CO2 H2O
(d) Acetyl CoA H2O

Answer : B

Question. During glycolysis, fructose 1, 6-biphosphate splits into
(a) dihydroxyacetone phosphate and 2-phosphoglyceraldehyde
(b) dihydroxyacetone phosphate and 1-phosphoglyceraldehyde
(c) dihydroxyacetone phosphate and 2- phosphoglycerate
(d) dihydroxyacetone phosphate and 3-phosphoglyceraldehyde.

Answer : D

Question. Select the option that correctly fills the blanks in the following statements.
A. Glucose has (i) carbon atoms, pyruvic acid  has (ii) carbon atoms and the acetyl group has (iii) carbon atoms.
B. Electrons enter the electron transport system as parts of hydrogen atoms attached to (i) and (ii) .
A B
(a) (i)-6, (ii)-4, (iii)-3 (i)-NADH, (ii)-FADH2
(b) (i)-6, (ii)-3, (iii)-2 (i)-NADH, (ii)-FADH2
(c) (i)-6, (ii)-3, (iii)-2 (i)-ATP, (ii)-GTP
(d) (i)-6, (ii)-4, (iii)-3 (i)-ATP, (ii)-GTP

Answer : B

Question. R.Q. can vary due to
(a) temperature
(b) respiratory substrate
(c) light and oxygen
(d) respiratory product.

Answer : B

Ques. Conversion of glucose to glucose-6-phosphate, the first irreversible reaction of glycolysis, is catalysed by
(a) phosphofructokinase
(b) aldolase
(c) hexokinase
(d) enolase. 

Answer: C

Ques. What is the role of NAD+ in cellular respiration?
(a) It functions as an enzyme.
(b) It functions as an electron carrier.
(c) It is a nucleotide source for ATP synthesis.
(d) It is the final electron acceptor for anaerobic respiration. 

Answer: B

Ques. In glycolysis, during oxidation electrons are removed by
(a) ATP
(b) glyceraldehyde-3-phosphate
(c) NAD+
(d) molecular oxygen. 

Answer: C

Ques. At the end of glycolysis, six carbon compound ultimately changes into
(a) ethyl alcohol
(b) acetyl Co-A
(c) pyruvic acid
(d) ATP. 

Answer: C

Ques. The first phase in the breakdown of glucose, in animal cell, is
(a) fermentation
(b) Krebs’ cycle
(c) glycolysis
(d) ETS. 

Answer: C

Ques. End product of glycolysis is
(a) acetyl CoA
(b) pyruvic acid
(c) glucose 1-phosphate
(d) fructose 1-phosphate. 

Answer: B

Ques. In which one of the following processes CO2 is not released?
(a) Aerobic respiration in plants
(b) Aerobic respiration in animals
(c) Alcoholic fermentation
(d) Lactate fermentation

Answer: D

Ques. The energy-releasing metabolic process in which substrate is oxidised without an external electron acceptor is called
(a) glycolysis
(b) fermentation
(c) aerobic respiration
(d) photorespiration.

Answer: B

Ques. In alcohol fermentation
(a) triose phosphate is the electron donor while acetaldehyde is the electron acceptor
(b) triose phosphate is the electron donor while pyruvic acid is the electron acceptor
(c) there is no electron donor
(d) oxygen is the electron acceptor. 

Answer: A

Ques. The end product of fermentation are
(a) O2 and C2H5OH
(b) CO2 and acetaldehyde
(c) CO2 and O2
(d) CO2 and C2H5OH.

Answer: D

Ques. Which of the following products are obtained by anaerobic respiration from yeast?
(a) Beer and wine
(b) Alcohols
(c) CO2
(d) All of these 

Answer: D

Ques. When yeast ferments glucose, the products obtained are
(a) ethanol and CO2
(b) methanol and CO2
(c) ethanol and water
(d) water and CO2.

Answer: A

Ques. The number of substrate level phosphorylations in one turn of citric acid cycle is
(a) zero
(b) one
(c) two
(d) three.

Answer: B

Ques. Where is respiratory electron transport system (ETS) located in plants ?
(a) Mitochondrial matrix
(b) Outer mitochondrial membrane
(c) Inner mitochondrial membrane
(d) Intermembrane space 

Answer: C

Ques. Which of these statements is incorrect?
(a) Enzymes of TCA cycle are present in mitochondrial matrix.
(b) Glycolysis occurs in cytosol.
(c) Glycolysis operates as long as it is supplied with NAD that can pick up hydrogen atoms.
(d) Oxidative phosphorylation takes place in outer mitochondrial membrane. 

Answer: D

Ques. Which statement is wrong for Krebs’ cycle?
(a) There is one point in the cycle where FAD+ is reduced to FADH2.
(b) During conversion of succinyl CoA to succinic acid, a molecule of GTP is synthesised.
(c) The cycle starts with condensation of acetyl group (acetyl CoA) with pyruvic acid to yield citric acid.
(d) There are three points in the cycle where NAD+ is reduced to NADH + H+. 

Answer: C

Ques. Oxidative phosphorylation is
(a) formation of ATP by transfer of phosphate group from a substrate to ADP
(b) oxidation of phosphate group in ATP
(c) addition of phosphate group to ATP
(d) formation of ATP by energy released from electrons removed during substrate oxidation.

Answer: D

Ques. Cytochromes are found in
(a) cristae of mitochondria
(b) lysosomes
(c) matrix of mitochondria
(d) outer wall of mitochondria.

Answer: A

Assertion & Reasoning Based MCQs

For question numbers 51-60, two statements are given-one labelled Assertion and the other labelled Reason.
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.

Question. Assertion : Krebs’ cycle is a high energy producing process.
Reason : 2 ATP molecules are produced itself in Krebs’ cycle.

Answer : D

Question. Assertion : Respiratory quotient provides important information regarding the nature of respiratory substrate being respired.
Reason : RQ of germinating seeds of cereal is less than unity.

Answer : C

Question. Assertion : Krebs’ cycle occurs in aerobic respiration.
Reason : Krebs’ cycle occurs in mitochondria.

Answer : B

Question. Assertion : Glycolysis is the first step of respiration in which glucose is completely broken into CO2 and H2O.
Reason : In this, there is net gain of eight molecules of ATP.

Answer : D

Question. Assertion : Terminal oxidation occurs at terminal step of respiration.
Reason : Terminal oxidation occurs both in aerobic and anaerobic conditions.

Answer : C

Case Based MCQs

Case I : Study the following passage and
given figure and answer the questions from 41 to 45.
The inner mitochondrial membrane contains groups of electron and proton acceptors. Each of these groups are arranged in specific sequence forming electron transport chain or system.   (Img 60)

Question. What does c represent in the given figure?
(a) Succinate - UQ - reductase complex
(b) Cytochrome c oxidase complex
(c) NADH - UQ reductase complex
(d) UQH2 - Cytochrome c reductase complex

Answer : D

Question. Electron transport chain includes
(a) FMN
(b) coenzyme-Q
(c) cytochromes
(d) all of these.

Answer : D

Question. Consider the first reaction of TCA cycle.
Acetyl CoA + OAA + H2O A + CoA
What is true about compound A?
(a) First product of TCA cycle
(b) Tricarboxylic acid and six carbon compound
(c) It undergoes reorganisation in the presence of enzyme aconitase to form cis-aconitate
(d) All of these.

Answer : D

Question. Which component of this system is not a protein?
(a) Cytochrome
(b) Ubiquinone
(c) Cytochrome oxidase
(d) All of these

Answer : B

Important Questions for NCERT Class 11 Biology Respiration in Plants

Very Short Answer Type Questions  

Question. What is the respiratory quotient when fats are used in respiration?

Answer. If the respiratory substrate is fat, then RQ of the respiring cells will be less than one because the volume of CO2 evolved is quite less in comparison to the volume of O2 being consumed.

Question. Name the unit of oxidative phosphorylation.

Answer. Oxysomes, or F0 – F1 particles are present on inner mitochondrial membrane.

Question. Mention the number of protons that passes through complex V for the synthesis of 2 molecules of ATP.

Answer. Two pairs of protons (i.e., 4) passes through complex V for the synthesis of two molecules of ATP.

Question. How many NADH2 molecules are produced form one molecule of acetyl CoA in TCA cycle?

Answer. 3NADH2 molecules are produced from one molecule of acetyl Co-A in TCA cycle.

Question. What are the end products of alcoholic fermentation?

Answer. Ethyl alcohol and CO2 are the end products of alcoholic fermentation.

Short Answer Type Questions

Question. How many ATP are produced during cellular respiration during - Glycolysis, Oxidative decarboxylation and Krebs’ cycle? What is the net production of ATP?

Answer. Complete aerobic breakdown of one molecule of hexose result in the release of ATP molecule. The number of ATP molecule released during : – Glycolysis : Two molecules of NADPH are released during glycolysis. The glycolysis also yields 4 ATP molecules out of which 2 ATP molecules are consumed. Thus, the glycolysis contributes a total of 2 + 4 = 6 ATP molecule. – Oxidative decarboxylation : Two molecules of NADH are released during the oxidative decarboxylation and synthesis of acetyl CoA from pyruvic acid. Thus, number of ATP molecules will be 2 × 3 = 6. – Krebs’ cycle : This cycle releases 6 molecules of NADPH and 2 molecules of FADH2. The Krebs’ cycle also releases 2 ATP molecules thus total number of ATP molecules produced during Krebs’ cycle are 2 + 2 × 2 + 6 × 3 = 24 molecules Net production of ATP molecules is 36 or 38.

Question. (i) Where is the respiratory electrons transport system located in a cell?
(ii) What compound is the terminal electron acceptor in aerobic respiration?

Answer. (i) On the inner membrane of mitochondria. (ii) Oxygen.

Question. Give examples of organisms where anaerobic respiration serves as exclusive mode of respiration.

Answer. Anaerobic respiration is an exclusive mode of respiration that occurs in prokaryotes, unicellular eukaryotes, moulds and some parasitic worms.

Question. Differentiate between glycolysis and fermentation.

Answer. Differences between glycolysis and fermentation are as follows:  (Tvble 68)

Question. How many ATP molecules are generated from oxidative decarboxylation of 2 molecules of pyruvate?

Answer. 6 ATP (Since oxidation of 2 pyruvate yields 2NADH and each NADH molecule is equivalent to almost 3 ATP molecules, hence 3 × 2 = 6 ATP).

Question. In which type of fermentation no CO2 is released? Name the enzyme required for it. Give its complete reaction.

Answer. In lactic acid fermentation, no CO2 is released. The enzyme required for this reaction is lactic dehydrogenase. Pyruvic acid + NADH Lactic dehydrogenase FMN, Zn2+ Lactic acid + NAD+

Question. Give an account of four complexes and their respective components present in an electron transport chain (ETS). What is the significance of each of these complex in ETS?

Answer. The electron transport chain is comprised of four complexes and two mobile electron carriers i.e., coenzyme Q, a non–protein part of the chain (except this all the members of the chain are proteins) and cytochrome c. Complex I consists of flavoproteins of NADH dehydrogenase of which FMN is the prosthetic group. Combined with the flavoprotein is non-heme iron of NADH dehydrogenase. This complex spans inner mitochondrial membrane and is able to translocate protons across it from matrix side to outer side. Complex II consists of flavoprotein of succinate dehydrogenase, of which FAD is the prosthetic group. Combined with the flavoprotein is non-heme iron of succinate dehydrogenase. Between complexes II and III is the mobile carrier – coenzyme Q (CoQ) or ubiquinone (UQ). Complex III consists of cytochrome b and cytochrome c1. Associated with cytochrome b is non-heme iron of complex III. Between complexes III and IV is the mobile carrier cytochrome c. Complex IV consists of cytochrome a and cytochrome a3 and bound copper that are required for this complex reaction to occur. This cytochrome also called cytochrome oxidase, is the only electron carrier in which the heme iron has a free ligand that can react directly with molecular oxygen. The electrons either follow the pathway of complexes I, III and IV or II, III and IV depending upon the substrates from Krebs’ cycle.

Questions. Why less energy is produced during anaerobic respiration?

Answer. Following are the reasons:
• Incomplete breakdown of respiratory substrate.
• Some of the products of anaerobic respiration can be oxidized further to release energy which
  shows that anaerobic respiration does not liberate the whole energy contained in the respiratory substrate.
• NADH₂ does not produce ATP as electron transport is absent.
• Oxygen is not utilized for securing electrons and protons.

Questions. What is the importance of FoF1 particles in ATP production during aerobic respiration?

Answer. ATP synthatase consists of F0F1 particles. Fo acts as channel through which H+ passes.
F1 contains the site for synthesis of ATP.

Questions..Define respiratory quotient and mention the value for the proteins and fats.

Answer. It is ratio of volume of CO2 evolved and volume of O2 consumed.
           R.Q. = Volume of CO2 evolved / Volume of O2 consumed 

           For proteins: R.Q. remains 0.9 and the R.Q. for fat is 0.7

          2C₅₁H₉₈O₆ + 145O₂→ 102CO₂ + 98H₂O + Energy
          R.Q. = 102/ 145 = 0.7