سؤال قراءة ستيب محلول — الإشارة والمرجعية (تدريب 5852)

(1) Deserts are some of the most widespread yet explored biomes. They cover about 1/3 of the earth’s surface and are found in 60 of the world’s nations. The largest hot desert biome (the Sahara) stretches over 3.5 million square miles or 9 million square kilometers, However, Antarctica, which is a polar desert, is the largest desert overall. Many people assume that deserts cannot support any form of life, but they actually house about 4,000 different plants and animal species. Since desert biomes receive little precipitation per year, the conditions are very hostile for plants and animals. (2) A desert biome is a collection of habitats that develop in arid (dry) environments as a result of little rainfall (50cms per year) or no rainfall at all. Desert biomes are classified into four, with each having its own unique features, yet sharing great similarities regarding living and nonliving composition. They include hot and dry deserts, semi-arid deserts, coastal deserts and cold deserts. In the midst of these 4 deserts exist numerous deserts in many areas across the globe. (3) The Australian deserts consist of a collection of lowland arid eco-regions in the heartland of Australia. They are hardly inhabited, and their average population density is lower than one person per square kilometer. Of all the deserts in the world, Australian deserts have the lowest human population, by far. (4) The Afrotropic desert biomes are located in Sub Saharan Africa, including the southern fringe of the Arabian Peninsula. The biome receives a lot of pressure from humans, particularly in Madagascar and the Home of Africa. (5) The Indo-Malay region consists of two hot lowlands including the Indus Valley and the Thar. These deserts top the world’s deserts when it comes to human footprint. (6) The Nearctic deserts cover an estimated area of 1.04 million square miles in North America. Due to the expansion of urban conurbations like Phoenix in the U. S. their average population is relatively high.