Answer: Leaf is a flat, thin, green, lateral structure borne on the stem at a node. It usually has a stalk called petiole and a pair of very small leaves at the base of the petiole called stipules. The broad expanded green part of the leaf is called lamina, which has a thick midrib at the centre.

Answer: The constant flow of water from the Earth to the atmosphere and back to the Earth is known as the water cycle. The two main steps involved in water cycle are evaporation and condensation. Then, it condenses (condensation) to form tiny water droplets that further join together to form clouds.

Photosynthesis is the process by which plants and some microorganisms make substances like carbohydrates. It is an endothermic (takes in heat) chemical process that uses sunlight to turn carbon dioxide into sugars. The sugars are used by the cell as energy, and to build other kinds of molecules.

A habitat is a place where an organism makes its home. A habitat meets all the environmental conditions an organism needs to survive. For an animal, that means everything it needs to find and gather food, select a mate, and successfully reproduce. The main components of a habitat are shelter, water, food, and space.

(i) It has long roots that go deep inside the soil for absorbing water. (ii) Its leaves are in the form of spines to prevent water loss through transpiration. (iii) Its stem is covered with a thick waxy layer to retain water. 3.

The land is very dry and has very little water. The roots of plants in the desert may go deep as much as 18 to 20 meters to absorb water deep under the surface of the soil. Some of the plants found in deserts, store water in their stems or leaves. These are also called succulents.

The streamlined shape of sea animals is an adaptation for swimming in water. (2) Most of the sea-animals have gills which enable them to use oxygen dissolved in water for breathing. So, the presence of gills in sea-animals is an adaptation for breathing inside the water.