Worksheet 2.1
Biological molecules
Use your Coursebook to help you answer the following questions.
Extension
Answer the following questions without reference to the Coursebook.
1
2
a
Name the three chemical elements present in a triglyceride.
[1]
b During digestion, triglycerides are hydrolysed to form two other compounds.
Name these compounds.
[2]
c
[2]
State two functions of triglycerides in living organisms.
d Name two elements which are present in proteins but not in triglycerides or starch.
[2]
Copy and complete the table below, giving the chemical nature and one function of each
carbohydrate in the table.
[8]
Carbohydrate
Chemical nature
glucose
monosaccharide (hexose)
One function
ribose
maltose
energy source in germinating seeds
starch
storage of carbohydrate in plants
glycogen
cellulose
3
polysaccharide of -glucose
The diagram below shows the structural formulae of two different amino acids. R1 and R2 represent
the variable side chains of the amino acids.
Cambridge International AS and A Level Biology Teacher’s Resource © Cambridge University Press 2013
1
Worksheet 2.1
a
The two amino acids can be linked together during protein synthesis.
i
ii
Copy the diagram and draw a circle around the atoms that are removed when
the two amino acids are linked together.
[1]
On your diagram, draw a line showing the position of the new bond that forms
between the two amino acids.
[1]
iii What is the name given to this type of bond?
[1]
b The amino acid cysteine has an R group containing sulfur. Use diagrams to explain
why this is important in forming the tertiary and quaternary structure of a protein.
[3]
c
[4]
Distinguish between a globular and a fibrous protein.
d Explain why the protein haemoglobin is said to have a quaternary structure.
e
4
[1]
The most abundant amino acid in the polypeptide chains of the protein collagen is glycine.
Explain the significance of this fact.
[2]
Solution X may be a solution of a reducing sugar, a solution of a non-reducing sugar, or a
mixture of both. Describe how you would test solution X to find out what it contains.
Total:
34
[6]
Score:
%

Cambridge International AS and A Level Biology Teacher’s Resource © Cambridge University Press 2013
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