Class 11 Biology - KERALA
Respiration in Plants
The chapter 'Respiration in Plants' explores how green plants break down complex organic molecules like glucose to release energy for cellular activities. Students learn about cellular respiration, glycolysis, the Krebs cycle, the electron transport system (ETS), and oxidative phosphorylation. It covers both aerobic and anaerobic pathways, including fermentation. Understanding this chapter is crucial for Kerala SCERT Class 11 board exams as it frequently features direct conceptual questions, pathway diagrams, and numerical problems related to ATP calculation, carrying a weightage of around 6 to 8 marks.
Start Learning FreeKey Concepts
Glycolysis
The first phase of respiration that occurs in the cytoplasm, breaking down one molecule of glucose into two molecules of pyruvic acid with a net gain of 2 ATP and 2 NADH.
Fermentation
An anaerobic pathway occurring in yeast and certain bacteria where pyruvic acid is converted to ethanol and carbon dioxide, or to lactic acid in some tissues, yielding very little energy.
Krebs Cycle (TCA Cycle)
An aerobic pathway taking place in the mitochondrial matrix where acetyl-CoA is completely oxidized to carbon dioxide, producing NADH, FADH2, and substrate-level ATP.
Electron Transport System (ETS)
A series of coenzymes and cytochromes located in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, releasing energy.
Oxidative Phosphorylation
The synthesis of ATP from ADP and inorganic phosphate using the energy released during the electron transport system, driven by a proton gradient.
Respiratory Quotient (RQ)
The ratio of the volume of CO2 evolved to the volume of O2 consumed during cellular respiration, which helps determine the type of respiratory substrate being used.
Important Formulas
Board Exam Info
In the Kerala (SCERT) Class 11 Biology examinations, 'Respiration in Plants' typically carries about 6 to 8 marks. Questions usually include diagrammatic representations of the Krebs cycle or glycolysis, distinguishing between aerobic and anaerobic respiration, calculating net ATP yields, and defining the Respiratory Quotient (RQ) for different substrates.
Frequently Asked Questions
Where does glycolysis take place in the cell?
Glycolysis occurs in the cytoplasm of the cell and does not require oxygen.
Why is the Krebs cycle also known as the Tricarboxylic Acid (TCA) cycle?
It is called the TCA cycle because the first stable product formed after acetyl-CoA condenses with oxaloacetate is citric acid, which is a tricarboxylic acid.
What is the significance of the Respiratory Quotient (RQ)?
RQ helps identify the respiratory substrate being used by the plant, such as carbohydrates (RQ = 1), fats (RQ less than 1), or organic acids (RQ greater than 1).
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