Describe how you would test a sample of food for the presence of starch?
Add iodine/ potassium iodine solution to the food sample, a blue/black indicatesstarch is present.
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What is meant by a saturated fatty acid.
A saturated fatty acid does not have any double bonds between carbons in the hydrocarbon chain.
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Omega-3 fatty acids are unsaturated. what is mesnt by unsaturated?
Double bonds between carbons in the hydrocarbon chain.
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Some seeds contain lipids. Describe how you could use the emulsion test to show that a seed contains lipids.
First crush and grind the seeds with ethanol, then add water and shake. If lipids are present a white emulsion will form.
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what are the differences between a triglyceride and a phospholipid.
fatty acid is removed in a phospholipid and is replaced with a phosphate group.
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Hydrogen bonds are important in cellulose molecules, explain why?
holds chains/cellulose molecules together/ forms cross links between chains, providing strength/ rigidity to cellulose and the hydrogen bons are stron in large numbers.
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The structure of cellulose is related to its role in plant cell walls. Explain how.
long straight/ unbranched chains of glucose are joined together by hydrogen bonds whoch form microfibrils/macrofibrils, whoch provides strength/rigidity/support.
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explain one way in which starch molecules are adapted for their function in plant cells.
They are insoluble so dont affect water potential, helical so they are compact and large molecule so they can not leave the cell.
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A starch molecule has a spiral shape. Explain why this shape is important to its function.
it is compact so it can occupy a small space and is tightly packed.
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name the monosaccharides the make up maltose, lactose and sucrose
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