CBSE Questions for Class 11 Medical Biology Respiration In Plants Quiz 2 - MCQExams.com

• Aerobic respiration involves Glycolysis, Krebs' cycle and ETS.
  
• 1 molecule of glucose (6 C) forms 2 molecules of pyruvic acid (3 C) as end product of glycolysis. In the process, 2 molecules of NAD+ are reduced to NADH+H+ and 2 ATP is produced. So a total of 8 ATP is produced.
• 2 molecules of pyruvic acid forms 2 molecules of acetyl CoA by the link reaction. Another 2 molecules of NADH2 is produced in that reaction which releases 6 ATP through ETS.
• 2 molecules of acetyl CoA produce 24 ATP ( 6 NADH2, 2 FADH2 and 2 GTP) as it completes one cycle of Krebs' cycle.
• So a total of 38 ATP is produced from 1 molecule of glucose.
• So the answer is '38 ADP molecules into 38 ATP molecules'.

• in certain conditions such as starvation when sufficient amount of glucose is not present in the blood the foremost priority of the body is to provide brain with the sufficient amount of glucose.
• So for the other body parts the energy that is to be provided can be done by the use of other substrates instead of glucose.
• First alternative of glucose is fatty acid which is stored in the body. These fatty acid molecules are converted to acetyl coA by the process of beta oxidation and used in the kerbs cycle to provide the cell with energy.
• Glycerol is also a fatty acid which is used as the other fatty acid in the kerbs cycle.
• Amino acids are the part of protein molecules which are usually not stored in the body but can be used in the kerbs cycle whenever they are provided to the cell.
• Therefore the answer 'all of these' is correct.

• The role of coenzyme A in the respiration process is to react with the pyruvate molecule (released by the process of glycolysis) and from an 2 carbon molecule that is acetyl CoA which will enter the Kerb's cycle.
• While reacting to produce acetyl coA a carbon dioxide molecule is also released.
• The coenzyme also reaction with the fatty acid to for acetyl CoA so that the fatty acid can also be used in the cellular respiration.
• The acetyl CoA after being produced enters the Kerb's cycle where it reacts with the oxaloacetic acid and then goes on in a cycle of reaction where it produces 4 NADH + 4H, one FADH and I ATP and also releasing 3 molecules of carbon dioxide (one before entering the cycle and 2 during the cycle) per molecule of pyruvate.
• The NADH and FADH produced during the cycle under go oxidative phosphorylation to produce ATP in presence of oxygen in inner mitochondrial membrane.
• The kerb cycle provides the phosphorylation reaction with substrate for electron transport chain and it clearly does not facilitate the reaction chain.
• Therefore the above sentence is false and the option 'False' is correct.
  

• TCA or Tricarboxylic Acid Cycle or Krebs cycle oxidizes the compounds like acetyl-CoA obtained from carbohydrates, fats, and proteins and leads to the production of carbon dioxide and energy in form of GTP, NADH$$_2$$, and FADH$$_2$$.

A.Correct option B
B.Explanation for correct option:

• The respiratory quotient is the ratio, which defines the amount of CO2CO2 eliminated to that of O2O2 consumed. 
• Thus it is evident that it solely depends on the nature of the substrate.
• For example, hexose sugar will have a value of RQ = 1, and fats have an RQ less than one. 
• During the oxidation of carbohydrates, the amount of oxygen used is equal to the amount of carbon dioxide produced.

• Kreb's cycle only produces 1 molecule of ATP from every pyruvate molecule during the conversion of succinyl-CoA to succinate in the presence of enzyme Succinyl CoA synthetase. 
• One molecule of glucose undergoes glycolysis to produce 2 pyruvate molecules which enter Kreb's cycle simultaneously.
• Thus, overall 2 ATP are produced from Kreb's cycle through substrate-level phosphorylation when one glucose undergoes aerobic respiration.

• The respiratory quotient is less than one if respiration is aerobic and the respiratory substrate is either fat or protein. 
• Maize contains carbohydrates and groundnut seeds have fatty acids. RQ of carbohydrates is 1.0 and of fats is less than 1. 
• So, the RQ of this mixture would be less than 1. 

• The respiratory quotient (RQ) is defined as the ratio of the volume of carbon dioxide released to the volume of oxygen utilized during the process of respiration. 
• At the compensation point, there is no net exchange of gases in plants, that is, the release of $$O_2$$ in photosynthesis is equal to its utilization in respiration. 
• Therefore, the exchange of $$CO_2$$ and $$O_2$$ is equal and RQ becomes one.

• Respiratory materials that are more oxidized require less number of oxygen for their complete oxidation. 
• They have higher respiratory quotients. For example, glucose has high respiratory quotients. 
• Similarly,  respiratory materials that are less oxidized require more number of oxygen for their complete oxidation. 
• They have lower respiratory quotients. For example, fatty acids have low respiratory quotients. 
• Triolein has the lowest respiratory quotients. It has an RQ of 0.7. 
• RQ of malic acid, tartaric acid, and oleic acid are 1.3, 1.6, and 0.71 respectively.
• Hence, triolein requires the highest number of oxygen molecules for its complete oxidation.

• The respiratory quotient is the value obtained by dividing the number of CO$$_{2}$$ molecules eliminated to that of O$$_{2}$$ molecules consumed. 
• Most energy sources are food containing carbon, hydrogen, and oxygen such as fats, carbohydrates, and proteins. Therefore, the value of RQ depends on the respiratory substrate.