IG Biology Paper 6

What is an INDEPENDANT variable?

• The variable that is changed by the investigator

• A variable that changes and is measured

• A variable that should be kept constant so as to not affect the result of the dependant variable

What is a DEPENDANT variable?

• The variable that is changed by the investigator

• A variable that changes and is measured

• A variable that should be kept constant so as to not affect the result of the dependant variable

How can you make an experiment more ACCURATE?

• Do it 3 times and then take an average.

• Use the same type of sample.

• Use the same volume of solution.

• Use appropriate apparatus

How many decimal places should you answer with?

• To two decimal places

• A whole number even if the rest of the table is to 1 decimal number.

• To 1 decimal number even if most of the table is to two decimal places

What is the test for Starch?

• Add a few drops of Iodine Solution, gently shake, it should turn from brown/orange to blue/black

• Add a few drops of Biuret Reagent, gently shake, it should turn from blue to mauve/purple

• Add 2cm³ Benedict's Reagent, heat/boil, it should turn from blue to green to yellow to orange to red

• The emulsion test: Add 2cm³ of ethanol to the unknown solution, gently shake, pour into equal volume of distilled water. If present a milky-white emulsion is formed.

What is the test for Reducing Sugars?

• Add a few drops of Iodine Solution, gently shake, it should turn from brown/orange to blue/black

• Add a few drops of Biuret Reagent, gently shake, it should turn from blue to mauve/purple

• Add 2cm³ Benedict's Reagent, heat/boil, it should turn from blue to green to yellow to orange to red

• The emulsion test: Add 2cm³ of ethanol to the unknown solution, gently shake, pour into equal volume of distilled water. If present a milky-white emulsion is formed.

What is the test for Fat (Lipids)?

• Add a few drops of Iodine Solution, gently shake, it should turn from brown/orange to blue/black

• Add a few drops of Biuret Reagent, gently shake, it should turn from blue to mauve/purple

• Add 2cm³ Benedict's Reagent, heat/boil, it should turn from blue to green to yellow to orange to red

• The emulsion test: Add 2cm³ of ethanol to the unknown solution, gently shake, pour into equal volume of distilled water. If present a milky-white emulsion is formed.

What is the test for Vitamin C?

• Add drops of DCPIP to the solution slowly.

• Add methylene blue solution.

• Add Iodine solution.

• Add ascorbic acids solution.

Magnification Equation

• Magnification = Measured / Actual

• Magnification = Actual / Measured

In an experiment to look at the effect of temperature on the number of bubbles of oxygen produced by a plant, what is the independent variable?

• number of bubbles of oxygen produced

• temperature

• type of plant