Text Book Back Questions and Answers - Chapter 14 Respiration 11th Biology Botany Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Respiration
Text Book Back Questions and Answers
Question 1.
The number of ATP molecules formed by complete oxidation of one molecule of pyruvic acid is:
(a) 12
(b) 13
(c) 14
(d) 15
Answer:
(a) 12
Question 2.
During oxidation of two molecules of cytosolic NADH $+\mathrm{H}+$, number of ATP molecules produced in plants are:
(a) 3
(b) 4
(c) 6
(d) 8
Answer:
(c) 6
Question 3.
The compound which links glycolysis and Krebs cycle is:
(a) succinic acid
(b) pyruvic acid
(c) acetyl CoA
(d) citric acid
Answer:
(c) acetyl CoA
Question 4.
Assertion (A): Oxidative phosphorylation takes place during the electron transport chain in mitochondria.

Reason $(\mathrm{R})$ : Succinyl CoA is phosphorylated into succinic acid by substrate phosphorylation.
(a) $A$ and $R$ is correct. $R$ is correct explanation of $A$
(b) $A$ and $R$ is correct but $R$ is not the correct explanation of $A$
(c) $A$ is correct but $R$ is wrong
(d) $A$ and $R$ is wrong.
Answer:
(a) $A$ and $R$ is correct. $R$ is correct explanation of $A$
Question 5.
Which of the following reaction is not . involved in Krebs cycle.
(a) Shifting of phosphate from $3 \mathrm{C}$ to $2 \mathrm{C}$
(b) Splitting of Fructose 1,6 bisphosphate of into two molecules $3 \mathrm{C}$ compounds.
(c) Dephosphorylation from the substrates
(d) All of these
Answer:
(d) All of these
Question 6.
What are enzymes involved in phosphorylation and dephosphorylation reactions in EMP pathway?
Answer:
(i) Enzymes involved phosphorylation in EMP pathway:
- Hexokinase
- Phospho - fructokinase
- Glyceraldehyde -3-phosphate dehydrogenase
(ii) Enzymes involved in dephosphorylation in EMP pathway:
- Phospho glycerate kinase,
- Pyruvate kinase
Question 7.
Respiratory quotient is zero in succulent plants. Why?
Answer:

In some succulent plants like Opuntia, Bryophyllum carbohydrates are partially oxidised to organic acid, particularly malic acid without corresponding release of $\mathrm{CO}_2$ but $\mathrm{O}_2$ is consumed hence the $\mathrm{RQ}$ value will be zero.
Question 8.
Explain the reactions taking place in mitochondrial inner membrane.
Answer:
In plants, an additional NADH dehydrogenase (External) complex is present on the outer surface of inner membrane of mitochondria which can oxidise cytosolic NADH + $\mathrm{H}^{+}$. Ubiquinone (UQ) or Coenzyme Quinone (Co Q) is a small, lipid soluble electron, proton carrier located within the inner membrane of mitochondria.
Question 9.
What is the name of alternate way of glucose breakdown? Explain the process involved in it?
Answer:
During respiration breakdown of glucose in cytosol occurs both by glycolysis (about $2 / 3$ ) as well as by oxidative pentose phosphate pathway (about $1 / 3$ ). Pentose phosphate pathway was described by Warburg, Dickens and Lipmann (1938). Hence, it is also called Warburg - Dickens - Lipmann pathway. It takes place in cytoplasm of mature plant cells. It is an alternate way for breakdown of glucose.
It is also known as Hexose monophosphate shunt (HMP Shunt) or Direct Oxidative Pathway. It consists of two phases, oxidative phase and non oxidative phase. The oxidative events convert six molecules of six carbon Glucose -6 - phosphate to 6 molecules of five carbon sugar Ribulose -5 phosphate with loss of $6 \mathrm{CO}_2$ molecules and generation of $12 \mathrm{NADPH}+\mathrm{H}^{+}($not NADH). The remaining reactions known as non - oxidative pathway, convert Ribulose -5 - phosphate molecules to various intermediates such as Ribose 5 - phosphate(5C), Xylulose - 5 - phosphate(5C), Glyceraldehyde - 3 phosphate(3C), Sedoheptulose - 7 - Phosphate (7C), and Erythrose - 4 phosphate (4C). Finally, five molecules of glucose -6 - phosphate is regenerated. The overall reaction is:

The net result of complete oxidation of one glucose $-6-$ phosphate yield $6 \mathrm{CO}_2$ and $12 \mathrm{NADPH}+\mathrm{H}+$. The oxidative pentose phosphate pathway is controlled by glucose -6 - phosphate dehydrogenase enzyme which is inhibited by high ratio of NADPH to NADP+.
Question 10.
How will you calculate net products of one sucrose molecule upon complete oxidation during aerobic respiration as per recent view?
Answer:
When the cost of transport of ATPs from matrix into the cytosol is considered, the number will be 2.5 ATPs for each $\mathrm{NADH}+\mathrm{H}^{+}$and 1.5 ATPs for each $\mathrm{FADH}_2$ oxidised during electron transport system. Therefore, in plant cells net yield of 30 ATP molecules for complete aerobic oxidation of one molecule of glucose. But in those animal cells (showing malate shuttle mechanism) net yield will be 32 ATP molecules. Since sucrose molecule gives, two molecules of glucose and net ATP in plant cell will be $30 \times 2=60$. In animal cell it will be 32 $\times 2=64$.