Class 11 Biology - TAMILNADU
Respiration in Plants
The chapter 'Respiration in Plants' in Class 11 Tamil Nadu Samacheer Kalvi Biology explores how plants break down complex organic compounds like glucose to release energy in the form of ATP. You will study both aerobic and anaerobic respiration, covering major pathways such as Glycolysis, the Krebs Cycle (Tricarboxylic Acid Cycle), and the Electron Transport Chain (ETC). The chapter also introduces the concept of the Respiratory Quotient (RQ) and amphibolic pathways. This is a high-scoring unit in board exams, with frequent questions focusing on metabolic pathways, site of reactions, and net energy yields.
Start Learning FreeKey Concepts
Glycolysis (EMP Pathway)
The breakdown of one glucose molecule into two molecules of pyruvic acid in the cytoplasm, yielding a net gain of 2 ATP and 2 NADH without requiring oxygen.
Krebs Cycle (TCA Cycle)
The enzymatic oxidation of acetyl-CoA inside the mitochondrial matrix, producing carbon dioxide, NADH, FADH2, and substrate-level ATP.
Electron Transport Chain (ETC) and Oxidative Phosphorylation
A series of protein complexes in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, generating a proton gradient used by ATP synthase to produce ATP.
Fermentation (Anaerobic Respiration)
The incomplete oxidation of glucose under anaerobic conditions, leading to the formation of ethanol and carbon dioxide in yeast, or lactic acid in certain bacteria and tissues.
Respiratory Quotient (RQ)
The ratio of the volume of CO2 evolved to the volume of O2 consumed during respiration, which helps determine the type of respiratory substrate being used.
Important Formulas
Board Exam Info
In Tamil Nadu Samacheer Kalvi Class 11 Biology exams, this chapter typically carries around 6 to 8 marks. Questions usually include 1-mark objective questions, 2 or 3-mark short answers (such as defining RQ or the site of the Krebs cycle), and 5-mark long-answer questions explaining Glycolysis, the Krebs Cycle, or the Electron Transport System in detail.
Frequently Asked Questions
What is the difference between breathing and cellular respiration?
Breathing is a physical process of taking in oxygen and giving out carbon dioxide, whereas cellular respiration is a biochemical pathway inside cells that oxidizes food molecules to release energy as ATP.
Why is the Krebs cycle considered an amphibolic pathway?
Because it acts as both a catabolic pathway (breaking down acetyl-CoA for energy) and an anabolic pathway (providing intermediates for the synthesis of fatty acids, amino acids, and chlorophyll).
How many ATP molecules are produced from one glucose molecule?
A net of 36 to 38 ATP molecules are produced during aerobic respiration, depending on the shuttle system used to transport electrons from NADH into the mitochondria.
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