Plant Nutrition Biology CIE
Biology
for sri, danny ebs
Sample Data
| Front | How can we measure the net gas exchange in aquatic plants? |
| Back | We can investigate the effect of light on the net gas exchange in an aquatic plant using a pH indicator such as hydrogencarbonate indicator This is possible because carbon dioxide is an acidic gas when dissolved in waterHydrogencarbonate indicator shows the carbon dioxide concentration in solutionThe table below shows the colour that the indicator turns at different levels of carbon dioxide concentration
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| Front | How can you test leaves for starch? |
| Back | A leaf is dropped in boiling water to kill and break down the cell wallsThe leaf is left for 5-10 minutes in hot ethanol in a boiling tube. This removes the chlorophyll so colour changes from iodine can be seen more clearlyThe leaf is dipped in boiling water to soften itThe leaf is spread out on a white tile and covered with iodine solutionIn a green leaf, the entire leaf will turn blue-black as photosynthesis is occuring in all areas of the leafThis method can also be used to test whether chlorophyll is needed for photosynthesis by using a variegated leaf (one that is partially green and partially white)The white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain chlorophyll stain blue-blackThe areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored
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| Front | What is the function of nitrate ions in plants and what happens if plants develop a deficiency of nitrate ions? |
| Back | Nitrates are a source of nitrogen needed to make amino acids (to build proteins) and if there ois a deficiency of them in a plant, stunted growth is caused and the leaves yellow |
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