Equations, Statistical Tests and Maths

Question 1

What is the method for the Benedict’s Test for reducing sugars?

Answer 1

1. Take a small volume of sample, place in test tube with same volume of Benedict’s solution.
2. Heat in water bath at 70 degrees.
3. Brick red precipitate is a positive result.
4. If Benedict’s remains blue, no reducing sugar present.
   Doesn’t allow comparison.

Question 2

What is the method for the standardised, semi-quantitative Benedict’s Test?

Answer 2

Control Variables- standardised, same volume of sample, Benedict’s solution, temperature and time in water bath. Resulting colour or volume of precipitate can be used to compare volume of reducing sugar.
Difficult to judge colour as colour is subjective, this is an issue.

Question 3

What is the method for the standardised, quantitative Benedict’s Test?

Answer 3

Numerical data obtained, used to compare volume of reducing sugar of different samples objectively.
Same method as semi-quantitative but colour is measured by colorimeter and then plotted on a calibration curve, used to find out unknown quantities of reducing sugar.

Question 4

What is the Benedict’s Test for non-reducing sugars?

Answer 4

1. Carry out Benedict’s test on small sample and confirm negative result.
2. Hydrolyse another sample of substance by heating with dilute HCl.
3. Allow to cool.
4. Neutralise with NaOH.
5. Add same volume of Benedict’s solution and heat in water bath.
6. Positive result (brick red precipitate) indicates non-reducing sugar was originally present.

Question 5

What is the test for Starch?

Answer 5

• Add 2-3 drops of Iodine/potassium iodide solution.
• If starch is present, blue/black precipitate will be produced.
• No starch present, solution remains orange/yellow.

Question 6

What is the test for lipids?

Answer 6

The Emulsion test:
• Small volume of sample placed in test tube with ethanol.
• Shake mixture so fat dissolves.
• Add water.
• Shake again and white emulsion of fat droplets indicate lipids present.

Question 7

What is the Biuret test for proteins?

Answer 7

• Add Biuret agent.
• Purple indicates protein is present.
• If solution remains blue, no protein is present.

Question 8

What are independent, dependent and controlled variables?
What is a control?
Give an example of each from one experiment.

Answer 8

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Question 9

How do you do base calculations?

Answer 9

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Question 10

What is the equation for the synthesis and resynthesis of ATP?

Answer 10

ADP + Pi = ATP

Question 11

What are the two types of ELISA test and what are they used for?

Answer 11

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Question 12

What is the Direct ELISA Test?

Answer 12

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Question 13

What is the Indirect ELISA Test?

Answer 13

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