(a) Distinguish between habitat and ecological niche.

(b) Write characteristics of A-horizon of soil.

OR

(a) What is allelopathy? Give one example.

(b) How is a monoculture disadvantageous?

(a) A habitat is a place where organisms live and interact with their environment.
Ecological niche is the functional role played by an organism in an ecosystem. 

(b) A-horizon soil is the layer which contains organic and inorganic materials of weathering. This is the layer in which true mineral soil begins.

OR

(a) Allelopathy is a common biological phenomenon by which one organism produces biochemicals that influence the growth, survival, development, and reproduction of other organisms.

(b) Disadvantages of monoculture are:
i. Destroys soil nutrients
ii. Harmful chemical accumulation
iii. Groundwater gets polluted
iv. Disturb the ecosystem cycle
v. Require more water for irrigation