The world around us

a)… cover about one seventh of the earth's land area. Though it's extremely hot and dry there, deserts are home to a rich variety of plants and animals that have their own strategies for coping with the harsh conditions.

The desert holly, for example, draws up b)… from the ground and releases it onto its leaves. The white salt covers the c)… entirely and helps to reflect some of the daytime heat, in much the same way that white clothes do for humans.

The huge saguaro cactus can live for more than 200 years. This is partly due to its ability to d)… and store water. A giant of the cactus world, the saguaro is a slow grower but it can reach heights of up to 50 feet and weigh as much as 8 tons.

Like plants, deserts e)… are also well equipped to deal with the conditions. The road runner has a long tail, which helps to keep the bird from f)…. It uses the tail very much like a parasol, erecting it over its head to create shade, thus enabling it to keep cool. Birds, of course, also have their g)… to help them. In other, cooler parts of the world, feathers serve to keep body heat in. In the desert, though, their main function is to keep external heat out, and as a result many birds can spend long periods unharmed in the hot desert h)… Mammals tend to avoid the sun, usually coming out only after i)… has fallen. The jack rabbit in America and the fennec fox in the Sahara, however, do go out during the daytime. Their protection against the heat is a pair of extremely large j)…. As well as enabling them to hear better, the ears contain blood vessels which are so close to the surface of the skin that any air, blowing across them, cools the blood that runs through them.

The most archetypal of desert animals, the camel, has a number of useful techniques and devices. Their nose is equipped with k)…, which enable them to close one or both of their nostrils and keep the sand out during sandstorms. Their feet have only two toes which are connected by skin. This spreads out as they walk on soft sand and deeps them from sinking into it. They can also retain vast quantities of water in their stomachs – not their l)… as many people think. As a result they can go without drinking anything for four times longer than a donkey and ten times as long as a man.

2.7 Read and correct the sentences:

1. Deserts are home to plants only.

2. The huge saguaro cactus draws up salt from the ground and releases it onto its leaves.

3. The road runner has long ears, which help to keep the animal from overheating.

4. Mammals tend to lie in the sun all day long.

5. Only the humps and nostrils help the camel not to sink into the sand.