Mechanism of respiration in plants - SS2 Biology Lesson Note

The mechanism of respiration in plants differs from that of animals. Plants undergo respiration to produce energy for their cellular processes. Here is an overview of the respiration mechanism in plants:

1.       Cellular Respiration:

·         Plant cells carry out cellular respiration to convert stored energy into ATP (adenosine triphosphate), which is used for various metabolic activities.

·         Cellular respiration takes place in the mitochondria of plant cells.

2.       Glycolysis:

·         The first stage of cellular respiration is glycolysis, which occurs in the cytoplasm of plant cells.

·         During glycolysis, glucose, a six-carbon sugar, is broken down into two molecules of pyruvate, a three-carbon compound.

·         This process releases a small amount of ATP and NADH (nicotinamide adenine dinucleotide) molecules.

3.       Aerobic Respiration:

·         If oxygen is available, pyruvate produced during glycolysis enters the mitochondria, where aerobic respiration takes place.

·         In the mitochondria, pyruvate is further broken down through a series of enzymatic reactions, such as the citric acid cycle and the electron transport chain.

·         These reactions result in the complete oxidation of pyruvate to carbon dioxide and water, releasing a significant amount of ATP in the process.

4.       Anaerobic Respiration:

·         In situations where oxygen is limited or unavailable, some plant cells can undergo anaerobic respiration.

·         Anaerobic respiration in plants often occurs through fermentation, similar to certain microorganisms.

·         During fermentation, pyruvate is converted into other compounds such as ethanol or lactic acid, depending on the plant species.

·         Fermentation generates a small amount of ATP and helps regenerate NAD+ (the oxidized form of NADH) for continued glycolysis.

5.       Gas Exchange:

·         Plant respiration involves gas exchange with the external environment.

·         Oxygen is taken in through small openings called stomata present on the leaves, stems, and other plant parts. Oxygen diffuses into the plant cells for cellular respiration.

·         Carbon dioxide, a byproduct of respiration, diffuses out of the plant cells and is released into the surrounding atmosphere through the stomata.