Respiration in plants: Review

Welcome Learners to the most conceptual and interesting content “cbse class 11 biology respiration in plants notes”. Open your Geeta of Biology-NCERT BIOLOGY XI and dive into the facts embeded in this chapter. Read every NCERT line most carefully to understand what it says.

However respiration is the multi steps dehydrogenation, where a respiratory substrate is oxidised into carbon dioxide and metabolic water and energy.

Understanding the Basics:

In Plant respiration we will discuss only about the physiology of respiration. In otherwords you can call it as cellular respiration. On the basis of definition respiration is the breakdown of C-C energy rich bnds to release energy as main product. Respiration is the reverse process of photosynthesis.

On the basis of respiratory substrate involved in respiration, there are two main types of respiration.

Floating respiration, in which respiratory substrate is carbohydrate or lipid.

Protoplasmic respiration, in which RS is the protein.

Protoplasmic respiration is harmful respiration.

Key Concepts:

Overview of Plant Respiration:

Respiration in plants

PLant doesn’t have respiratory system. Every organ of plant carry gaseous exchange. Like other organisms, Plans also carry out cellular respiration in the seme steps.

Glycolysis, the First Step:

Respiration in plants

Glycolysis is a 10 step process. !0 important enzymes catalise the steps. Most of the steps are reversible except steps like 1,3,10. Some main enzymes of glycolysis are Hexokinase, PFK, Isomerase, Phosphoglycerokinase, Enolase and Pyruvate kinase.

The substrate of glycolysis is Glucose or fructose and the end products are two molecules of pyruvic acids. Glycolysis is anaerobic respiration and takes place in the cytoplasm. In this process, less than 7% of the total energy of respiration is released.

Aerobic Respiration starts with the oxidation of Pyruvate inside mitochondria. There are three steps of aerobic respiration such as Link reaction, Kreb’s cycle and Terminal Oxidation.

During link reaction, Pyruvic acid is oxidised by oxidative decarboxyllation to form Acetyl CoA.

The Krebs Cycle Unveiled:

Kreb’s cycle is the main step or pathway of aerobic respiration. It is the energy sink as maximum energy is released here. It is also called as the amphibollic pathway because it is mainly a breakdown process but is also associated with anabolism synthesizing some metabolites from its intermediates.

Electron Transport Chain and ATP Synthesis:

Respiration in plants

I have already told you that the final step of aerobic respiration is the terminal oxidation. Terminal oxidation involve ETS and ATP synthesis by chemiosmosis. This step is completed on inner membrane of mitochondria.

Electron transport system is the oxidation of reduced powers like NADH2 and FADH2 to release electrons and protons in matrix of mitochondria. The electrons are transported on inner membrane through 4 complexes and finally accepted by oxygen to release metabollic water.

One NADH2 release 3ATP while one FADH2 release 2ATP during ETS. ATP is synthesized due to a sequence of phenomena like ETS, Proton gradient and finally proton diffusion

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Respiration is the only key source of energy for organism. Whether it is anaerobic respiration in yeast and prokaryotes or Aerobic respiration in plants and animals, it produces the energy for activities of life.

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Where glycolysis occurs?


Where link reaction occurs?

matrix of mitochondria

What is the site of TCA cycle?

matrix of mitochondria



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