Droplets of fresh water

1. 1. Person holding a cold sheet of glass LOOK at this demonstration carefully and discuss what you think is happening. Steam Droplets of fresh water Beaker of boiling salt water Bunsen burner and tripod stand DESCRIBE the process in your own words

2. 2. READ the following information about the water cycle Heat from the sun causes water to evaporate (turn from liquid to gas) from the sea, lakes and plants growing on the land. As this water vapour (gas) moves upwards into the atmosphere it gets colder. This makes the water condense (turn from gas to liquid) into droplets and form clouds. Clouds are blown by the wind over the sea and land. If the clouds move upwards further, perhaps to pass over mountains, they become colder. Cold air can hold less water vapour than warm air so more of the water in the cloud condenses and falls as rain or snow. Rain water drains through the soil and into lakes or rivers which flow into the sea. DRAW a picture of what you think is happening in the water cycle Use the information TO EXPLAIN whyone side of a mountain may get more rainfall than the other.

3. 3. The amount of water in the soil which can be used by plants depends on the amount of rainfall and the type of soil. The amount of water that a soil can hold can be measured using the apparatus described below. 1) The top half was cut off a large plastic cool drink bottle. 2) The cap was unscrewed and the hole plugged with cotton wool. 3) A 10cm layer of soil was placed in the upturned bottle. 4) The bottle was rested on a beaker or jug. 5) 250cm3 of water was poured slowly across the soil surface. 6) After one hour the water that had drained through the soil and into the beaker was measured. DRAW a diagram of what you think this apparatus looks like DISCUSS how would you use this apparatus to compare water drainage through three different soils. HAVE REASONS for what you want to do.

4. Sandy soil Garden soil Clay soil LOOK at samples of the soil particles as they are seen under the microscope 4. The table shows some results obtained by using the apparatus for measuing water draining through soil. Three different kinds of soils were compared. CALCULATE how much water was held in each soil which the plants would be able to use. Water in cm3 Clay soil Garden soil Sandy soil 250 250 250 Poured onto top of soil 100 Drained through into beaker 40 220 Held in soil EXPLAIN why different types of soil are able to hold different amounts of water, and how will this effect the plants trying to grow in them?

5. Special xerophyte feature Adaptation to dry environment Thick shiny leaves, swollen stem or roots - store water Old dry leaves do not fall off - cover and protect the stem from heat Leaves joined to the stem without stalks - shade each other / prevent water loss Deep roots - reach water underground Leaves are reduced to spines - do not lose water Stem folded into long grooves - shades part of itself from sun Roots spread wide - to absorb any water in a large area of soil Stem underground - protected from the drying sun and wind Leaves fall off during drought - no water loss Stem has light colour bark or hairs - to reflect the heat and trap moisture 5. In the Great Karoo the rainfall is low and the soil is sandy. Very little water is available for plant growth. Some plants are specially adapted to survive in dry conditions, they are called Xerophytes. DISCUSS these features and choose the ones you think will be best for keeping water in the plant. DESIGN your own plant using these features and draw a picture of it. EXPLAIN how well each of these plants would survive in the Karoo.