exam practice

Question 1

The dark stain used on the chromosomes binds more to some areas of the
chromosomes than others, giving the chromosomes a striped appearance.
Suggest one way the structure of the chromosome could differ along its length to
result in the stain binding more in some areas.

Answer 1

• Differences in base sequences
• Differences in histones/interaction with
  histones
• Differences in condensation/(super)coiling

Question 2

Formation of an enzyme-substrate complex increases the rate of reaction.
Explain how.

Answer 2

1. Reduces activation energy;
2. Due to bending bonds

Question 3

Compare and contrast the structure and properties of triglycerides and phospholipids.

Answer 3

1. Both contain ester bonds (between glycerol and
   fatty acid);
2. Both contain glycerol;
3. Fatty acids on both may be saturated or
   unsaturated;
4. Both are insoluble in water;
5. Both contain C, H and O but phospholipids also
   contain P;
6. Triglyceride has three fatty acids and
   phospholipid has two fatty acids plus phosphate
   group;
7. Triglycerides are hydrophobic/non-polar and
   phospholipids have hydrophilic and
   hydrophobic region;
8. Phospholipids form monolayer (on
   surface)/micelle/bilayer (in water) but
   triglycerides don’t;

Question 4

where in the cell would lactose be attached to a
polypeptide to form a glycoprotein?

Answer 4

golgi apparatus