SB1 - Key Concepts in Biology

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10 Terms

1
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What is resolution ?

Resolution means how well a microscope distinguishes between two points that are close together.

2
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Formula for magnification.

Magnification = image size

                         actual size

3
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What are the units of measurement used in microscopes and in what order ?

Millimetre (mm)

Micrometre (μm)

4
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How to test the effect of pH on enzyme activity ?

  1. Place a drop of iodine solution into every well of the spotting tile.

  1. Place a Bunsen burner on a heat-proof mat, and a tripod and gauze over the Bunsen burner. Heat a beaker of water until it is 35o C.

  2. Use a syringe to add 3 cm3 of amylase solution and 1 cm3 

5
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What enzymes break down starch, proteins and lipids?

  1. Starch is broken down by amylase and is broken down into simple sugars.

  2. Protein is broken down by protease enzymes into amino acids.

  3. Lipids is broken down by lipase enzymes into glycerol and 3 fatty acids

6
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What is the test for the presence of sugars ?

Add Benedict’s solution to a sample in a boiling tube and then heat in a hot water bath (75o C), if sugars are present the solution will turn orange or brick red.

7
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What is the test for starch ?

Add iodine to the sample if starch is present, the sample changes from browny-orange to blue-black.

8
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What is the test for lipids ?

Shake the test substance with ethanol until it dissolves.

If there are any lipids present, they will precipitate out of the liquid and show up as a milky emulsion.

9
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What is the test for protein ?

Add Biuret solution, if there’s no protein the colour will stay blue, if there is protein the colour will turn purple.

10
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How to investigate osmosis?

  1. Prepare sucrose solutions of different concentrations.

  2. Cut same sized potatoes.

  3. Measure the potato slice make sure they weigh the same.

  4. Place 3 potato slices in each beaker of sucrose solution.

  5. Leave the solution for the same time for each (40 mins)

  6. Remove the slices and pat down gently with a paper towel.

  7. Record the final mass and calculate the percentage difference.