Fish breathes through gills which take up dissolved oxygen present in water. When it is kept out of the water, it is unable to respire due to difference in pressure of gas. Hence, it dies.

If an organism fails to adapt to its environment, the possible consequences could be:
(i) The organism will die.
(ii) The species will become extinct

Yes, plants also respond to stimuli. For example, 'touch-me-not' plant (Mimosa pudica) closes its leaves when someone touches them.

Two adaptations of aquatic plants are
(i) The roots of these plants are small just to keep plant in place.
(ii) Stems are hollow with large spaces which help in floating.

A habitat includes
(i) a living component which is called as biotic.
(ii) non-living component called abiotic.

The trees in mountain habitats are usually cone-shaped having sloping branches because this shape of the mountain trees makes the rainwater and snow slide off easily without damaging the branches and leaves.

Desert plants have very small leaves or spines as adaptations to dry conditions. Because of these modifications, the surface of lamina is reduced thereby reducing water loss by transpiration as there is scarcity of water in desert habitat.

Some characters are given below
(i) The birds have hollow bones (light weighted), their forelimbs are modified into wings.
(ii) They have sharp eye sight.
(iii) Their joints are completely fused.

(a) This animal is snow leopard.
(b) The habitat of this animals is mountain where snow is present.
(c) Having a rounded body and small ears keep body surface area of snow leopard to a minimum and hence reduce the heat loss from the body of snow leopard.

We see the following movements in plants
(i) Opening and closing of flower.
(ii) Growth of stem and leaves.
(iii) Growth of stem and twigs towards light and roots towards soil and water.

In grasslands, there are limited number of trees and places for animals to hide. When the enemy attacks an animal, it has to run fast, so as to reach a safe place. if it fails, it has to loose its life. So, speed in such places as grasslands is very important for the survival of animals.

Living things have following common characteristics:
(i) Growth
(ii) Movement
(iii) Reproduction
(iv) Respiration
(v) Adaptation
(vi) Excretion

Cloud is an example of non-living thing which shows following two characteristics of living things:
(i) It increases or decreases in size
(ii) It shows movements.
(Another example can be a car move from one place to another and also requires energy, i.e. petrol).

Non-living things do not need food, air or water. Thus, in the given list plough, sewing machine, radio and boats are non-living.

To survive in a desert, a cactus has the following adaptations:
(i) Leaves modified into spine or absent to prevent water loss through transpiration.
(ii) Stem is modified to perform photosynthesis and covered with a thick waxy layer to retain water.
(iii) The root system of cactus is well developed and grows deep for absorbing water.