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अध्याय 12: पादप में श्वसन

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CBSE • कक्षा XI • Biology • अध्याय 12

अनुमानित समय: 45 Mins

प्रगति: अध्ययनरत

पादप में श्वसन

In Class 11 Biology, "Respiration in Plants" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्याय CBT ऑनलाइन टेस्ट दें सभी अध्याय देखें

प्रस्तावना अध्याय अवधारणाएँ अध्याय सारांश स्व-मूल्यांकन अभ्यास टेस्ट दें

🔥 Have You Ever Wondered?

How does a tiny microscopic cell break down glucose to generate 38 molecules of ATP without bursting into flames like an open fire? Cellular respiration dismantles chemical bonds in controlled steps across the cytoplasm and mitochondria.

यह अध्याय क्यों महत्वपूर्ण है

In Class 11 Biology, "Respiration in Plants" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्ययन से पूर्व (आवश्यक ज्ञान)

Mitochondria structure from Chapter 8.
Cellular respiration from Class 10.
ATP and energy currency.

इस अध्याय के लक्ष्य

Distinguish Aerobic respiration and Anaerobic respiration (Fermentation: Alcoholic vs Lactic acid).
Trace Glycolysis (EMP Pathway, 10 enzymatic steps in cytoplasm, net yield: $2\text{ ATP} + 2\text{ NADH}$).
Explain the Link Reaction: Oxidative decarboxylation of Pyruvate to Acetyl-CoA by Pyruvate Dehydrogenase.
Trace the Tricarboxylic Acid (TCA / Krebs) Cycle in the mitochondrial matrix.
Explain the Electron Transport System (ETS) and Oxidative Phosphorylation: Complexes I to V in inner mitochondrial membrane.
Calculate Respiratory Quotient (RQ): Carbohydrates ($1.0$), Fats ($0.7$), Proteins ($0.9$).

अध्याय रूपरेखा एवं प्रगति

1 1. Glycolysis (EMP Pathway)

2 2. The Krebs Cycle (TCA Cycle)

3 3. Electron Transport System (ETS)...

सम्पूर्ण सैद्धांतिक एवं वैचारिक अध्ययन

1. Glycolysis (EMP Pathway)

Discovered by Embden, Meyerhof, and Parnas. Occurs in the cytoplasm of all living cells (anaerobic, requires zero oxygen):
• 1 Glucose ($6C$) is phosphorylated and cleaved into two molecules of Pyruvate ($3C$).
• Key regulatory enzyme: Phosphofructokinase (PFK).
• Net Yield: Consumes 2 ATP; produces 4 ATP → Net $+2\text{ ATP}$ and $+2\text{ NADH}$.

2. The Krebs Cycle (TCA Cycle)

Inside the mitochondrial matrix:
• Link Reaction: $\text{Pyruvate} + \text{CoA} + \text{NAD}^+ \xrightarrow{\text{PDH}} \text{Acetyl-CoA} + \text{CO}_2 + \text{NADH}$.
• TCA Cycle: $2C$ Acetyl-CoA condenses with $4C$ Oxaloacetate to form $6C$ Citric acid. Per glucose (2 turns): produces $\mathbf{6\text{ NADH} + 2\text{ FADH}_2 + 2\text{ GTP/ATP} + 4\text{ CO}_2}$!

3. Electron Transport System (ETS) & RQ

In the inner mitochondrial membrane, electrons from NADH and $\text{FADH}_2$ cascade through Complexes I to IV to the final electron acceptor: Oxygen (forming $\text{H}_2\text{O}$)! Protons pumped into the intermembrane space drive Complex V (ATP Synthase):
• $1\text{ NADH} \implies 3\text{ ATP}$ (or $2.5\text{ ATP}$).
• $1\text{ FADH}_2 \implies 2\text{ ATP}$ (or $1.5\text{ ATP}$).
• Respiratory Quotient: $\mathbf{RQ = \frac{\text{Volume of } \text{CO}_2 \text{ evolved}}{\text{Volume of } \text{O}_2 \text{ consumed}}}$.

Respiration in Plants - Key Biological & Anatomical Model

अध्याय का सार संक्षेप एवं 10 मुख्य निष्कर्ष

मुख्य बिंदु 1

EMP Glycolytic Cascade: Cytoplasmic anaerobic breakdown producing 2 net ATP and 2 NADH.

मुख्य बिंदु 2

Link Reaction: Mitochondrial gateway converting pyruvate to acetyl-CoA and releasing CO2.

मुख्य बिंदु 3

Krebs Cycle: Matrix enzymatic furnace producing reducing power equivalents NADH and FADH2.

मुख्य बिंदु 4

Complex V ATP Synthase: Rotary nanomachine harnessing intermembrane proton motive force.

मुख्य बिंदु 5

Respiratory Quotient (RQ): Gas exchange volumetric ratio diagnosing metabolised fuel substrate.

स्व-मूल्यांकन अभ्यास (Check Your Understanding)

मूल वैचारिक स्पष्टता की जांच के लिए नैदानिक प्रश्न। पहले स्वयं हल करें, फिर उत्तर देखें।

Trace the sequential enzymatic reactions of Glycolysis (EMP Pathway). What is the net yield of ATP and NADH?

उत्तर एवं व्याख्या देखें

उत्तर: Ten reactions in cytoplasm: Glucose is phosphorylated to Glucose-6-phosphate by hexokinase → isomerized to Fructose-6-phosphate → phosphorylated to Fructose-1,6-bisphosphate → cleaved into DHAP and PGAL → oxidized to 1,3-bisphosphoglycerate → dephosphorylated to 3-phosphoglycerate → 2-phosphoglycerate → PEP → Pyruvate. Net yield: 2 ATP and 2 NADH per glucose molecule.
10-step cytoplasmic cascade; net yield of 2 ATP and 2 NADH per glucose.

What is the final electron acceptor in aerobic cellular respiration? What product is formed?

उत्तर एवं व्याख्या देखें

उत्तर: Molecular Oxygen ($O_2$) is the terminal electron acceptor at Complex IV (Cytochrome c oxidase) of the electron transport system. It combines with protons ($H^+$) and electrons to form metabolic Water ($\text{H}_2\text{O}$).
Oxygen is the terminal electron acceptor, forming water.

Define Respiratory Quotient (RQ). Calculate the RQ value for: (i) Glucose, (ii) Tripalmitin (fat).

उत्तर एवं व्याख्या देखें

उत्तर: RQ is the ratio of the volume of $\text{CO}_2$ evolved to the volume of $O_2$ consumed during cellular respiration: $RQ = \frac{\text{Volume of CO}_2}{\text{Volume of O}_2}$. (i) For glucose: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \to 6\text{CO}_2 + 6\text{H}_2\text{O} \implies RQ = 6/6 = 1.0$. (ii) For tripalmitin: $2\text{C}_{51}\text{H}_{98}\text{O}_6 + 145\text{O}_2 \to 102\text{CO}_2 + 98\text{H}_2\text{O} \implies RQ = 102/145 = 0.7$.
RQ = CO2 / O2; Glucose = 1.0, Tripalmitin = 0.7.

Why is the Krebs cycle also called the Amphibolic pathway?

उत्तर एवं व्याख्या देखें

उत्तर: Because it is involved in both catabolism (breakdown of carbohydrates, fats, and proteins to release energy) and anabolism (intermediates like $\alpha$-ketoglutarate, oxaloacetate, and succinyl-CoA are constantly withdrawn for synthesizing amino acids, fatty acids, and chlorophyll).
Serves dual roles in both catabolic breakdown and anabolic synthesis.

What is the major difference between Fermentation and Aerobic Respiration regarding energy release and NADH oxidation?

उत्तर एवं व्याख्या देखें

उत्तर: Fermentation is an anaerobic partial breakdown of glucose yielding only 2 ATP with slow oxidation of NADH to $\text{NAD}^+$ without an ETS; Aerobic respiration is complete oxidation of glucose to $\text{CO}_2$ and $\text{H}_2\text{O}$ yielding 36-38 ATP with rapid, vigorous oxidative phosphorylation through an electron transport system.
Partial oxidation with 2 ATP (Fermentation) vs complete oxidation with 36-38 ATP (Aerobic).

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