8/9/2019 Answers to Revision Questions

1/2

Answers to S2 Prelim

Knowledge

1. Sand dunes are crescent-shaped deposits of sand. They areformed by winds which tend to blow the sand in the samedirection. The two steep edges of the barchan taperdownwind, to leave a rounded gentler slope facing into thewind. The sand is constantly blown from the front to the backof the barchan. This means that barchans tend to movedownwind.

2.Subsistence farming-they grow food only for themselvesand not for saleSustainable farming-small scale; does no long term

damage to the environment (eg they are not usingchemicals, machinery, cutting down huge areas of land,etc)Hunter gatherer-people who hunt animals (includingfish) and/or collect wild roots, fruits, nuts, honey andother natural produce from the forests.

3. Amazonia has a very low temperature range, with mostmonths around 27 C and only a small difference. Arizona hashotter summers, but winters are cooler, ie there is a greatertemperature range and temperatures are more seasonal.

Understanding

4. Wadis are dried river beds. They can be caused by tworeasons. (1) Sudden downpours of rain can cause temporaryrivers (flash floods) These carve steep sided valleys in the dryland. Once the rain has gone, the rivers quickly evaporate inthe intense heat. (2) they are the remains of very old riverbeds which used to flow when rainfall was heavier.

5. There is heavy rain because there are many rivers and theSun is very strong. It warms the ground, which heats the airabove causing it to expand and rise. Water is evaporated fromthe rivers and plants. When the air gets to a certain height itcools and the water vapour condenses. Clouds form andcontinue to build up during the afternoon. Rain drops growlarger and then it rains, usually in heavy downpours. This iscalled convectional rain.

6. No seasons because the Amazon Basin is on/near the Equator.

This means that the sun is always overhead and its position

8/9/2019 Answers to Revision Questions

2/2

does not change much over the year-unlike places muchfurther from the equator.

7. Phoenix is popular because:

Warm winters, hot summersDry and very sunny (over 4000 hours a year), iehealthy climatePlenty of space so houses have gardens; areas are veryattractiveAmenities like public parks, golfing ideal for retired

people

8. C, as the suns rays are most concentrated (so not B or D) There are no clouds to reflect sun back into space (unlike A)

Applications

9.

Attract touristsBring money and jobs (eg in the construction phase andthe service phase) into the CityButUse up many km2 of desert-make city even biggerGolf courses require millions of gallons of water annually