Assertion (A): In plants, there is no need for specialised respiratory organs.
Reason (R): Plants do not have great demands for gaseous exchange.
a) Both A and R are true and R is correct explanation of the assertion.
b) Both A and R are true but R is not the correct explanation of the assertion.
c) A is true but R is false.
d) A is false but R is true.
Answers
Answer: option C
Explanation:
Plants, unlike animals, have no specialised organs for gaseous exchange. Gaseous exchange in plant occurs by diffusion through stomata and lenticels. There are various reason for the absence of repiratory organs in plants. Each part of plant takes care of its own gas exchange needs. There is little transport of gases from one part to another. Plants do not require much demands for gas exchange. Thus the distance that gases must diffuse is not large.
Assertion (A): In plants, there is no need for specialised respiratory organs.
Reason (R): Plants do not have great demands for gaseous exchange.
From the given statements, c) A is true but R is false.
Respiratory organs in animals serve the function of gaseous exchange in which oxygen is inhaled from the surroundings while carbon dioxide is exhaled into the atmosphere.
Do plants need specialised respiratory organs?
The answer is no, because-
- Plants have stomata and lenticels for gaseous exchange.
- Each part of the plant can fulfil its own respiratory needs, so not much gaseous transport is required.
- Unlike animals, many of the part plants do not have great respiratory need all the time. Respiratory needs of stems, roots, and leaves is much low when photosynthesis does not take place.
- During the process of photosynthesis, gaseous exchange is more. However, the leaf can overcome this need on its own. Furthermore, oxygen is released during photosynthesis that can be utilised.
- Even in huge and bulky plants, the gases can easily diffuse from one cell to another as the cells are close to the surface. The cells in stems underneath bark have lenticels while the inner cells are mostly dead providing mechanical support.
In the given question,
- From the above explanation, we can conclude that plants do not need specialised respiratory organs.
- This does not mean plants do not have great demands for gaseous exchange.
- Thus, assertion is true, but reason is false.