Page 1 - Lesson notes- Plant Respiration

CBSE Quick Revision Notes

CBSE Class-11 Biology
CHAPTER-14

RESPIRATION IN PLANTS

Respiration is an energy releasing, enzymatically controlled catabolic process which involves

a step-wise oxidative breakdown of food substance inside living cells.

Living organism require energy for all activities like absorption, movement,
reproduction or even breathing. Energy required is obtained from oxidation of food

during respiration.

Cellular respiration is the mechanism of breaking down of food materials within the
cell to release energy for synthesis of ATP.

Breaking down of complex molecules takes place to produce energy in cytoplasm and

in the mitochondria.
Breaking down of C-C bond of complex compounds through oxidation within the cells

leading to release of energy is called respiration. The compounds that get oxidized

are called respiratory substrates.
Energy released during oxidation is not used directly but utilized in synthesis of ATP,

which is broken down when energy is required. Therefore, ATP is called energy
currency of cells.

The process of respiration requires oxygen. In plants oxygen is taken in by stomata,

lenticels and root hairs.
Plants can get along without respiratory organs because:

1. Each plant part takes care of its own gas-exchange needs.

2. Plants do not present great demands for gas exchange.

3. Distance that gases must diffuse in large plant is not great.

4. During photosynthesis O2 is released in leaves and diffuse to other part of leaves.

During process of respiration oxygen is utilized and carbon dioxide and water is
released along with energy molecules in form of ATP.

Respiratory Quotient is the ratio of the volume of carbon dioxide produced to the