Lipids

Question 1

Aim

Answer 1

To test for the presence of lipids in different substances

Question 2

Hypothesis

Answer 2

A substance containing a lipid will leave behind a grease stain after the evaporation of a solvent (ethanol) in which the lipid has dissolved

Question 3

What is left behind on the paper?

Answer 3

A grease spot

Question 4

What conclusion can be made about the experiment?

Answer 4

• The presence of a lipid can be shown by dissolving the substance in ethanol/organic solvent
• If a grease spot remains than the lipid is indicated
• If no spot is left then it is a negative test for lipids

Question 5

The ratio of hydrogen to oxygen is greater than in carbohydrates. what implications does it have for the properties of lipids?

Answer 5

Lipids make excellent fuels because a large portion of their carbon atoms and all their hydrogen atoms can still combine with oxygen to release energy

Question 6

Give 3 functions of lipids

Answer 6

• Source of energy
• Forms part of cell membranes in plant and animal cells
• Contributes waterproofing properties to plant and arthropod cuticles

Question 7

What properties of lipids are used to test for lipids ?

Answer 7

Lipids are soluble in organic solvents like ethanol and beneze