How is cactus adapted to survive in a desert?

Hint:Cactus belongs to the family Cactaceae and is a plant which is commonly found in deserts. It has spines all over its body and does not have any leaves.

Complete answer:
Adaptation is the process by which a species changes its behaviour and body in order to suit its natural environment. Both plants and animals keep making adaptations to its natural environment in order to survive over the years.
Based on the function and response of species, adaptation is divided into,
a) Structural adaptations
b) Behavioural adaptations
c)Physiological adaptations

In case of cactus, it makes the following adaptations for surviving in a desert.
>The leaves of cactus are modified into spines to prevent additional water loss via transpiration
>It has very long roots so that they can go deep into the soil in order to absorb water, as in deserts there is water scarcity
>The stem of cactus is covered thick waxy layer which also helps in preventing additional water loss
>The stem of cactus is modified into flat green stem to help in conserving water and also to prepare food via photosynthesis
>They are short in size in order to conserve energy

Note:Even animals make adaptive changes in order to survive in the desert. The various animal adaptations are,
>They are nocturnal so as to conserve water
>Camels conserve water by reduced sweating
>They specialized appendages which helps them to dissipate excess heat from their bodies
>They use other sources of water like pollen from flowers, water from cactus, etc