Living World - [Optional] - Hot Deserts (Paper 1)

Question 1

<p>Define <strong>biodiversity</strong></p>

Answer 1

<p>The variety of plants and animals living in a particular ecosystem</p>

Question 2

<p>What is a hot desert?</p>

Answer 2

<p>A <strong>hot desert</strong>is an area that is very dry (usually receiving less than 250mm of rainfall per year). They also experience very high temperatures of 45°C</p>

Question 3

<p>Where are hot deserts located?</p>

Answer 3

<p>Generally found 30°N and 30°S of the equator in areas of land away from large expanses of coast</p>

Question 4

<p>What is the<strong>climate(temperature and precipitation)</strong>like in a hot desert?</p>

Answer 4

<p><strong>Temperature</strong>: highs of 45°c in the day, lows of 5°c at night</p>

<p><strong>Precipitation</strong>: less than 250mm per year</p>

Question 5

<p>Why is it hot and dry in hot deserts?</p>

Answer 5

<p><strong>Hot</strong>: Close to the equator where suns rays are more concentrated</p>

<p><strong>Dry</strong>: in areas of high pressure where air is sinking</p>

Question 6

<p>What is the<strong>soil</strong>like in a hot desert?</p>

Answer 6

<ul>
	<li>Shallow and dry</li>
	<li>Coarse texture</li>
	<li>Infertile due to lack of leaf litter</li>
</ul>

Question 7

<p>What<strong>wildlife (plants and animals)</strong>would you find in a hot desert</p>

Answer 7

<p>Animalsthat are well adapted to the hot, dry climate, limited vegetation. e.g snakes, lizards</p>

<p>The animals are generally very small in size and tend to sleep through the day time when temperatures are high</p>

<p>Limited plants. Those that do grow are short in height and don't live a long time</p>

Question 8

<p>How have<strong>animals</strong>adapted to hot deserts?</p>

Answer 8

<ul>
<li>Nocturnal - hunt in the cool evenings</li>
<li>Big ears to allow temperature regulation</li>
<li>Can store fat that breaks down into water e.g. camels</li>
<li>Long eyelashes, flat wide feet to cope with sand</li>
</ul>

Question 9

<p>How have<strong>plants</strong>adapted to hot deserts?</p>

Answer 9

<ul>
<li>Long plant roots to reach water deep in soil</li>
<li>Small leaves to reduce moisture loss</li>
<li>Succulent plants (fleshy skin to retain moisture)</li>
<li>Sharp needles on surface to deter predators</li>
</ul>

Question 10

<p>What is the<strong>biodiversity</strong>like of hot deserts?</p>

Answer 10

<ul>
<li>Limited due to extreme climate</li>
<li>This means any changes can have drastic consequences</li>
<li>Global warming is the biggest threat to hot deserts biodiversity</li>
</ul>

Question 11

<p>Why are hot deserts <strong>interdependent</strong>ecosystems?</p>

Answer 11

<p>Plants gain nutrients from soil, animals require energy and nutrients from plants</p>

<p>The climate causes the soil to be infertile and unable to support large amounts of vegetation</p>

<p>Changes to one part of the ecosystem can have huge knock-on impacts on another part e.g. removing vegetation can cause soil erosion</p>

Question 12

<p>What are the<strong>opportunities</strong>in the Thar Desert?</p>

Answer 12

<p><strong>Tourism</strong>: tens of thousands of tourists visit each year. Lots of desert safaris at Jaisalmer and desert festival</p>

<p><strong>Mining</strong>: gypsum (for cement), feldspar (for ceramics), phosphorite (fertiliser)</p>

<p><strong>Energyexploitation</strong>:rich in coal and oil. Opportunities for wind (Jaisalmer Wind Park) and solar power (Bhaleri solar plant)</p>

<p><strong>Farming</strong>: mostly subsistence farming. Irrigation has made commercial farming possible e.g. cotton, wheat</p>

Question 13

<p>What are the<strong>challenges</strong>facing the Thar desert?</p>

Answer 13

<p><strong>Extreme temperatures</strong>: highs of 50°c make it difficult to work outside and plants and animals need large amounts of shade to survive</p>

<p><strong>Inaccessibility</strong>: limited roads to the area due to low population density. Tarmac roads don't cope well in high temperatures.</p>

<p><strong>Water supply</strong>:farming and population increase have put pressure on water use. Low temperatures and high evaporation rates make water scarce</p>

Question 14

<p>What is<strong>desertification</strong>?</p>

Answer 14

<p>Desertification is when land becomes degraded to the point it turns to desert. This tends to happen on the edges of existing deserts</p>

Question 15

<p>Define '<strong>salinisation</strong>'</p>

Answer 15

<p>Salinisation is the accumulation of salts in the soil that occur as a result of rapid evaporation of water</p>

Question 16

<p>What are the<strong>physical</strong>causes of desertification?</p>

Answer 16

<p><u><strong>Climate change:</strong></u></p>

<ol>
<li>Less rainfall- less rainfall in areas that are already dry. This means fewer plants (plants hold soil together) which leads to soil erosion</li>
<li>Higher temperatures- increasing temperatures which causes water to evaporate from ground, in turn, killing plants which hold the soil together</li>
</ol>

Question 17

<p>What are the <strong>human</strong>causes ofDesertification?</p>

Answer 17

<ol>
<li><strong>Overgrazing</strong>- cattle eat too much vegetation which holds the plants together. Soil becomes easily eroded if there is less vegetation.</li>
<li><strong>Over cultivation</strong>- repeated farming exhausts the soil</li>
<li><strong>Population pressures</strong>- more deforestation to make space leads to soil exhaustion</li>
<li><strong>Demand for fuelwood</strong>- removing branches for fuel exposes soil to erosion</li>
</ol>

Question 18

<p>List the<strong>four strategies</strong>used to reduce desertification</p>

Answer 18

<ul>
	<li>Water management</li>
	<li>Soil management</li>
	<li>Tree planting</li>
	<li>Use of appropriate technology</li>
</ul>

Question 19

<p>How can<strong>water and soil management</strong>reduce desertification?</p>

Answer 19

<p>Switching to growing crops that don't require as much water to grow e.g. olives, millet</p>

<p>Drip irrigation means drip-feeding the soil with water rather than over-irrigating the soil at once. This prevents soil degradation</p>

<p>Contour traps - building embankments along contours of a hillside so that soil doesn't slow down hillsides during rainfall</p>

<p>Rotating crop yields and giving a rest period between crop rotations allows soils to recuperate</p>

Question 20

<p>How can<strong>tree planting</strong>reduce desertification</p>

Answer 20

<p>Trees are important in soil health. They can be planted to act as a windbreak to prevent the topsoil from blowing away. They also provide shade for crops to be grown underneath, reducing moisture loss</p>

Question 21

<p>How can<strong>appropriate technology</strong>reduce desertification?</p>

Answer 21

<p>'Appropriate technology' means using technology that is cheap and sustainable for the chosen location. Examples include:</p>

<ol>
<li>Sand fencesthat trap windblown sand</li>
<li>Solar panel cookers reduce the need for fuelwood</li>
<li>Magic stones - lines of stones along contours to prevent water loss from soil. The stones catch the water and retain it</li>
</ol>