Unit 9: Deserts - Reading

Exercise 1: Fill in each numbered blank with one suitable word or phrase. Desert biomes are the (1) _____ of all the biomes. In fact, the most important characteristic of a desert is that it receives very little (2) _____. Most deserts receive less than 300 mm a year compared (3) __ rainforests, which receive over 2,000 mm. That means that the desert only gets 10 percent of the rain that a rainforest gets! The temperature in the desert can (4) _____ drastically from day to night because the air is. (5) _____ dry that heat escapes rapidly at night. The daytime temperature averages 38°C (6) _____ in some deserts it can get down to -4°C at night. The temperature also varies greatly depending on the (7) _____ of the desert. Since desert conditions are so severe, the plants that live there need to have (8) _____ to compensate for the lack of water. Some plants, such as cacti, (9) _____ water in their stems and use it very slowly, while others like bushes conserve water by growing few leaves or by having large root systems to gather water or few leaves. Some desert plant species have a short life cycle of a few weeks that (10) _____ only during periods of rain.

Exercise 2: Read the passage carefully and choose the correct answer. Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts have been portrayed as fascinating environments of adventure and exploration. These arid regions are called deserts because they are dry. They may be hot. They may be cold. They may be regions of sand or vast areas of rocks with occasional plants. Deserts are natural laboratories in which to study the interactions of wind and sometimes water on the arid surfaces of planets. They contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world. There are many animals in the desert. Some are very large, like the kangaroo or the gazelle. Both are big and have to travel long distances for water at a spring, or an oasis. Another fairly large animal is the addax. The addax is a desert antelope. They live in the Sahara Desert. All addaxes are herbivores. There are less than 200 of them left because of hunting and tourists. Some animals crawl along. Examples of these are snakes and lizards. Snakes rarely drink water; they get their moisture from other prey that they eat. So do others, like the kangaroo rat. Lizards are commonly found in the desert. They stay out of the sun and move as little as possible. There are also other animals in the desert. The fennec lives in northern Africa in the Sahara Desert. They are a relative of the fox. They eat mice, small birds, lizards, and insects. When necessary, they will eat fruit. One more desert animal is the jerboa. The jerboa is a small, long distance jumper that lives in the desert. They are free drinking animals and they eat plants, seeds, and bugs.