Biological Molecules - Exam Questions

Maltose is hydrolysed by the enzyme maltase.
Explain why maltase catalyses only this reaction.
(3 marks)

Describe how a saturated fatty acid differs in molecular structure from an unsaturated
fatty acid.
(2 marks)

Describe the role of DNA polymerase in DNA replication.
(1 mark)

Describe how you would test a sample of food for the presence of starch.
(2 marks)

The concentration of glucose in the blood rises after eating a meal containing
carbohydrates. The rise is slower if the carbohydrate is starch rather than sucrose. Explain why.
(3 marks)

Describe the structure of proteins.
(5 marks)

Explain one way in which starch molecules are adapted for their function in plant cells.
(2 marks)

Explain how cellulose molecules are adapted for their function in plant cells.
(3 marks)

Explain the difference in the structure of the starch molecule and the cellulose molecule.
(2 marks)

The enzyme sucrase catalyses the breakdown of sucrose into monosaccharides. What
type of reaction is this breakdown?
(1 mark)

Describe a biochemical test to find out if the solution collected from the apparatus
contains the products of the hydrolysis of sucrose.
(2 marks)

Describe a biochemical test to find out if the solution collected from the apparatus
contains the enzyme used.
(2 marks)

Some seeds contain lipids. Describe how you could use the emulsion test to show that a
seed contains lipids.
(3 marks)

The structure of a phospholipid molecule is different from that of a triglyceride.
Describe how a phospholipid is different.
(2 marks)

In a piece of DNA, 34% of the bases were thymine. What are the names and percentages of the other bases.
(2 marks)

A polypeptide has 51 amino acids in its primary structure. What is the minimum number of DNA bases required to code for the amino acids in this polypeptide?
(1 mark)

DNA helicase is important in DNA replication. Explain why.
(2 marks)

Name the monosaccharides of which the following disaccharides are composed:
-Sucrose
-Lactose
(2 marks)

Explain what is meant by a polymer.
(1 mark)

Complete the equation of the reaction:
Lactose + ............... --> Glucose + ...............
(2 marks)

What bond holds cellulose molecules together side by side?
(1 mark)

On each template strand, DNA polymerase works in opposite directions. Use your knowledge of enzyme action to explain why.
(4 marks)

Write a simple equation to show how ATP is synthesised from ADP
(1 mark)

Give two ways in which the properties of ATP make it a suitable source of energy in biological processes.
(2 marks)

Give and explain two properties of water that are important in the cytoplasm of cells.
(4 marks)

Compare and contrast the processes by which water and inorganic ions enter cells.
(3 marks)

Name the two enzymes that play an important role in DNA replication.
(2 marks)

Explain what effect phosphorylation has on a reaction.
(1 mark)

Describe how DNA is replicated
(6 marks)

Name the type of bond that joins amino acids together in a polypeptide.
(1 mark)