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Infection and response
Organisation
Cell biology
Biological molecules
Homeostasis and response
Responding to change (a2 only)
Energy transfers (a2 only)
The control of gene expression (a-level only)
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
Britain & the wider world: 1745 -1901
Inter-war germany
World war one
2n revolution and dictatorship: russia, 1917-1953
World war two & the holocaust
1l the quest for political stability: germany, 1871-1991
The cold war
2j america: a nation divided, c1845-1877
Medieval period: 1066 -1509
The fight for female suffrage
2m wars and welfare: britain in transition, 1906-1957
2d religious conflict and the church in england, c1529-c1570
Britain: 1509 -1745
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22/10/2023
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Food tests practicles: 4 Benedict's test (sugars). 4 lodine test (starch). Biure+ test (proteins). "Sudan 3 test (lipids) also emulsion test (EDEXCEL only) what these tests have in common: 14 GCSE practicles: 4 • Need to prepare your food sample. Steps: Get your piece of food and break it up using a water and pestle. Need to put this crushed food into a beaker with some distilled water and stir with a glass rod until some of it dissolves. & Filter out the solution using a funnel that's been lined with filter paper to get rid of the sold bits of food that we don't need. The solution we end up with will be our sample that we can use for the food tests. Benedict's test (sugars): •Sugars are the small units that all carbohydrates are made of Can split into two types. •Reducing (Benedict's test only tests on reducing sugars) •Non-reducing First prepare your food sample Transfer 5cm³ of the food sample into a test tube Prepare a water bath and set it 10 75 °C once the water bath is ready, you aad about 10 drops. of benedict solution to your test tube Piace the test tube into the water bath for 5 minutes. "use a test tube holder to place the test tube into the water bath. If no reduang sugars are present then the solution will stay blue • If there are...
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reducing sugars present then the solution should change to green, yellow or even brick red depending on the concentration. lodine test (starch) •Starch is a carbohydrate but it's a much larger and more complex molecule. Take Scm³ of your food sample in a test tube 2 Add a few drops of jodine solution in the test tube This will turn the solution a browny - orange colour Give a gentle shake If the sample did contain starch the solution would change from that browny - orange colour to a blue - black colour. Biuret test (proteins) Ondd 2cm³ of food sample in a test tube.. Add 2cm³ of Bid ret solution to your sample This solution will turn to blue 3 Give a gentle snake if the sample did contain protein ine solution would change from blue to pink or purple EDEXCEL Content ONLY: instead of just adding directory agent (biuret solution). Add potassium hydroxide followed by copper sulfate Sudan III (3) test (lipids) Not filtered QAdd 5cm³ of food sample in a test tube Add 3 drops of the sudan 3 stain solution to the test tube. Gently shake it. if the lipid was present it should get stained by the sudan 3 solution As the lipid seperates from the water (not soluble) you'll see there's a bright red layer at the top. EDEXCEL Content ONLY: Emulsion test (upids) 0 Take your food sample in a test tube. Add 2cm³ ethand 6 Shake it vigorously Add 2cm³ distilled water • If it goes a cloudly while colour it means that lipid was present. 6 If there isn't any cloudy white colour then there wasn't any lipid.