Question

Answer the following.
(a) Why is the camel called the 'Ship of the desert'?
(b) How can the plants like cactus and acacia live in deserts with scarce water?
(c) What is the inter-relationship between adaptations of organisms and their surroundings?
(d) How are organisms classified?

Answer 1

a. Camel is called the "Ship of Desert" because it is the only means of transport found in deserts. The body of a camel has undergone various modifications that help it to survive in the hot and dry conditions of the deserts.

• Camels have very long legs that help them to walk in the sand and prevent the heat of the sand from reaching their bodies.
• They have a prominent back or hump. It stores food which helps it to survive without food in the deserts for several days.
• Another important adaptation that helps the camel to survive in the desert is its ability to conserve water. They do not sweat and excrete only small amounts of water through urine. The camel dung is dry and devoid of water.
• All this helps the camel to conserve water and enables them to live without water for several days.

b. Cactus and acacia plants withstand hot and dry environment of the desert with the help of various modifications. They have thick cuticle on their leaf surface and their stomata are arranged in deep pits to minimise water loss by transpiration. They have special photosynthetic pathway, CAM in which stomata remains closed during day time. Their leaves are reduced to spines to minimise water loss and photosynthetic functions are performed by flattened stems.

c. Adaptation is defined as the modification or change in the organism's body or behaviour that helps it to survive in a particular environment. The environment in which an animal survives consists of many different things and it must learn to adapt to each of these factors in order to survive. These factors can be in the form of climate, the kinds of food plants that grow in it, other animals that may be predators or competitors etc. This fact is evident from the following examples:

• Cactus has thick cuticle on their leaf surface and their stomata are arranged in deep pits to minimise water loss by transpiration. They have special photosynthetic pathway, CAM in which stomata remains closed during day time. Their leaves are reduced to spines to minimise water loss, and photosynthetic functions are performed by flattened stems.
• Camels have very long legs that help it to walk in the sand and prevent the heat of the sand from reaching their bodies. The camel has a prominent back or hump. It stores food which helps it to survive without food in the deserts for several days.

d. The hierarchy of classification was developed by Carolus Linnaeus. It refers to the organisation or classification of organisms in the order of rank or importance. According to this system, kingdom is the highest rank. It is divided into phyla or divisions, which are further subdivided into classes. Further divisions include order, family, genus and species, in that order. Thus, species is the basic unit of classification.