Question

What are the defining characteristics of desert ecosystems?

1. Annual precipitation exceeding 500 mm is a defining characteristic.
2. Evaporation rates are considerably lower than precipitation levels.
3. The defining feature is that evaporation surpasses precipitation.
4. A common threshold for desert classification is less than 250 mm of annual precipitation.

• A. iii only
• B. i, iii
• C. None of these
• D. iii, iv

Answer 1

Answer:

D. iii, iv

• The Desert is a biome in which evaporation exceeds precipitation.

• A desert is likely to develop where the annual precipitation is less than 250 mm.

• Deserts may be classified into hot and dry deserts, semi-arid deserts, coastal deserts and cold deserts, based on the amount and distribution of temperature and precipitation.

• Sand is commonly found in deserts but all desert landscapes are not dominated by sand. Deserts in which sand is in abundance, completely covering the ground and leading to the formation of dunes that resemble wave-like ridges of the ocean surface, are called erg, meaning a sand sea.

• In other deserts, the wind may blow away all the sand, leaving behind closely packed, inter-locking angular rock fragments. Such a stony desert is known as reg.

• In some deserts the landscape is dominated by boulders and exposed bedrock. Hamada is the name given to such deserts.