Practice Exam Questions

Question 1

Describe how you would use the emulsion text to show the presence of oil in a sample of fish

Answer 1

In a test tube, shake the sample of fish with ethanol

Then add the ethanol to water in a separate test tube

If the water turns white then oil is present

Question 2

CH2-CH-CH2
| |
O O

What molecule is this part of a phospholipid formed from?

Answer 2

Glycerol

Question 3

What is the name of the bond between glycerol and a fatty acid chain?

Answer 3

Ester bond

Question 4

How do you know if a fatty acid is unsaturated?

Answer 4

There will be at least one bond between carbon atoms in the hydrocarbon chain of a fatty acid

Question 5

A scientist expressed their results as a % of lipids in plasma membrane by mass. Explain how you would find these values

Answer 5

Divide mass of each lipid by total mass of all lipids

X by 100

Question 6

E.coli has no cholesterol in its cell-surface membrane. Despite this, the cell maintains the same shape.

Why?

Answer 6

Cell unable to change shape because cell has a cell wall and The cell wall is rigid and made up of murein

Question 7

Scientists studying benodigd of breast milk and used cats to test this.

Give 2 reasons why cats were used

Answer 7

Are mammals do are likely to have same reactions as humans

Small enough to keep in a laboratory

Can use a large number of cats