Gaseous exchange in plants

 introduction

       Diffusion is an important process for living organism e.g. Animals and plants

 1) plants need carbon dioxide for photosynthesis. This diffuses from the air into leaves through stomata. Centration of CO2 in air is higher then inside of the leaf. Therefore carbon dioxide diffuses into the leaf.

 2) Oxygen diffuses out of the leaf because the concentration of O2 is higher inside the leaf, as it is a product of photosynthesis. 

3) in animals, exchange of O2 in CO2 occurs in respiration.

 Question.1 What is the difference between (i) gaseous exchange(ii) breathing and(iii) respiration? 

 Ans.(i) Gaseous exchange:

                The process in which gas is diffuse from an area of higher concentration to an area of lower of concentration is called gaseous exchange. 

                      OR 

                The term is used for talking in oxygen and giving out carbon dioxide between an organism and its environment is called gaseous exchange. In plants, gaseous exchange take place during photosynthesis while in animals, gaseous exchange occurs during respiration. 

 (ii)Breathing: 

                 Breathing is inhalation and exhalation of air for the intake of Oxygen and giving out of carbon dioxide. In other words, breathing is used for the movement of air into and out of animal lungs. 

 (iii)Respiration: 

                 The process in which, food molecules are broken down into simple molecules and energy is released by involving different enzymes, is called respiration. OR Respiration is a complex oxidation - reduction reaction process for the release of energy. 

    Question.(2) what is meant by cellular respiration?

 Ans. Cellular respiration: 

                  The process in which, Complex organic molecules like glucose are broken down into simple molecules such as H2O and CO2 with the release of energy at cellular level, is called cellular respiration. 

                        OR

                    The process in which complex organic food is broken down by the action of different enzymes in energy is released within the cell of living organism is called cellular respiration.

 C6 H12 O6 ------》 H2O + CO2 + E 

 Glucose. ------》 water + Carbon dioxide + Energy 

    Question(3). How gaseous exchange occur in plants? 

 Ans. Gaseous exchange in plants:

                      Plants have no special organs change a gases is like gills and lungs of the animals. Every cell of the plant body exchange gases with their environment by its own. Plants have large surface area in proportion to their volume. The exchange of gases occur in the process of diffusion. 

                      The aquatic plants obtain oxygen from water by the process of diffusion the land plant gets oxygen from the air through stomata. The gaseous exchange occurs in young roots through general surface of root by the process of diffusion. 

               Mature woody stem and roots are covered with hard bark. Therefore gaseous exchange occurs through small tiny pores called lenticels in mature steam and roots.


Question(3). What is the mechanism of gaseous exchange in the leaves and young stems?

 Ans. Mechanism of gaseous exchange in leaves and young stem: 

 Gaseous exchange occurs in leaves and young stem through small opening called stomata. Stomata are present on the epidermis of leaves and young stems the inner cell of the leaves (Mesophyll) have air spaces among them, which help in the exchange of gases. Oxygen enters into air spaces where it diffuses into the cells it dissolves in the cell sap and reaches to the respiratory center of the cell called mitochondria where the food molecule is broken down and energy is release carbon dioxide produced in the process may diffuse through stomata are used in photosynthesis.

 (1) during day time both respiration and photosynthesis occurs at same time in plants. In photosynthesis oxygen is produced. Some of it is utilized in cellular respiration while the rest of oxygen is released through stomata. Carbon dioxide produced in cellular respiration is not sufficient for photosynthesis. So more carbon dioxide diffuses into the leaves from surrounding atmosphere.

 (2) during night time, no photosynthesis occurs in plant. Thus the oxygen is not released. Then the plants cells get oxygen from their surrounding air for respiration while carbon dioxide diffuses out through stomata.

 Question(5). What is the difference between photosynthesis and respiration?

 Ans. Photosynthesis: 

(1) it is a constructive process. 

Respiration: 

(1) It is a breaking or destructive process. 

Photosynthesis:

 (2) Raw material for photosynthesis are CO2 and H2O. 

Respiration:

 (2) Raw materials are glucose (C6 H12 O6). 

Photosynthesis: 

(3) Photosynthesis is looking localized  only in green part of the plant. 

Respiration:

(3) Not localized  process. It occurs both day and night in a living cells of an organism. 

Photosynthesis: 

(4) Cellular organelles for photosynthesis are the chloroplast. 

Respiration:

 (4) Cellular organelles for respiration are mitochondria.

 Photosynthesis: 

(5) It depends on solar energy. It take place only during day time. 

Respiration: 

(5) It does not depend on solar system.

 Photosynthesis: 

(6) Photosynthesis is energy absorbing process and plants gain weight.

 Respiration:

 (6) Respiration is energy releasing process and loss in weight occurs. 

Photosynthesis: 

(7) 6CO2 + 6H2O----->C6 H12 O6 + 6O2 

Respiration: 

(7) 6O2 + C6 H12 O6 ----->6O2 + 6H2O 

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