Class 11 Biology - CBSE
Respiration in Plants
The chapter 'Respiration in Plants' explains how plants break down food materials to release energy necessary for cellular activities. It covers cellular respiration, glycolysis, the Krebs cycle, the electron transport system, and the electron transport chain. Students learn the difference between aerobic and anaerobic respiration, fermentation, and the amphibolic nature of the respiratory pathway. Mastering this chapter is crucial for CBSE Class 11 biology exams as it forms the basis for understanding plant metabolism, bioenergetics, and frequent conceptual questions regarding ATP yield.
Start Learning FreeKey Concepts
Glycolysis
The partial breakdown of glucose into two molecules of pyruvic acid in the cytoplasm, producing a net gain of 2 ATP and 2 NADH without using oxygen.
Krebs Cycle
The aerobic pathway in the mitochondrial matrix where acetyl-CoA is completely oxidized to carbon dioxide, releasing NADH, FADH2, and ATP.
Electron Transport System (ETS)
A series of coenzymes and cytochromes located in the inner mitochondrial membrane that transfer electrons, driving oxidative phosphorylation to synthesize ATP.
Fermentation
An anaerobic process where pyruvic acid is converted into lactic acid or ethanol and carbon dioxide, yielding only 2 ATP per glucose molecule.
Amphibolic Pathway
The respiratory pathway is considered amphibolic because it involves both catabolism (breakdown of substrates) and anabolism (synthesis of fatty acids or amino acids).
Important Formulas
Board Exam Info
In the CBSE Class 11 Biology exams, this chapter typically carries around 4 to 6 marks. Common question types include calculating the net ATP yield of aerobic respiration, defining the Respiratory Quotient (RQ) for different substrates, differentiating between cyclic and non-cyclic or aerobic and anaerobic processes, and tracing the steps of glycolysis and the Krebs cycle.
Frequently Asked Questions
What is the net gain of ATP from one glucose molecule in aerobic respiration?
The net gain is theoretically 38 ATP molecules, though practically it is around 30-32 ATP due to transport costs across mitochondrial membranes.
Why is the respiratory pathway called an amphibolic pathway?
It acts as a catabolic pathway when breaking down glucose for energy and an anabolic pathway when its intermediates are used to synthesize fats and proteins.
What is the Respiratory Quotient (RQ) for fats and carbohydrates?
The RQ for carbohydrates is 1.0, while for fats it is less than 1 (typically around 0.7) because they require more oxygen for oxidation.
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