Q1
(a) Insert the most appropriate words in each of the following spaces:
A section of DNA that causes the production of a protein is called a ___________________. Sections of
DNA that do not code for a particular protein are called _____________________________. The protein _______________________________ is responsible for holding the DNA in its highly coiled state. DNA is made up of units called _______________________________. A sequence of three bases is referred to as a ____________________________.
(b) The diagram shows a representation of a section of a DNA molecule. What is represented by each of the letters A, C, D, G, P and T?
A __________________________
C __________________________
D __________________________
G __________________________
P __________________________
T __________________________
(c) What type of bonding exists between the bases? __________________________________
Identify the two purine bases and the two pyramidine bases.
Purine bases ________________________________________________________________
Pyramidine bases ____________________________________________________________
What name is given to the shape of the DNA molecule? _____________________________
(d) State three differences between DNA and RNA.
1 __________________________________________________________________________
2 __________________________________________________________________________
3 __________________________________________________________________________
(e) Write down the sequence of RNA bases that is complementary to the following DNA sequences
TATCGGCA _________________________ ATGCATA _______________________________
20(2) marks

Q2 Give a reason for each of the following steps when isolating DNA from a plant tissue.
Adding salt ___________________________________________________________________
_____________________________________________________________________________
Cooling the mixture after exactly 15 minutes ________________________________________
_____________________________________________________________________________
Filtering the mixture after blending ________________________________________________
_____________________________________________________________________________
Adding protease enzyme ________________________________________________________
_____________________________________________________________________________
Adding cold ethanol ____________________________________________________________
_____________________________________________________________________________
5(3) marks
Q3 What are the three main stages of protein synthesis called?
1 _______________________ 2 __________________________ 3 _______________________
Outline a use for each of the following in proteins synthesis:
RNA Polymerase ______________________________________________________________ tRNA mRNA rRNA
Start codon
Anti-codon
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
Amino acid ______________________________________________________________
10(3) marks
Q4 During what stage of the cell cycle does DNA replication take place? _______________________
Why is it necessary for DNA to make copies of itself? ____________________________________
_______________________________________________________________________________
Name the part of a double stranded chromosome to which spindle fibres attach during cell division
_______________________________________________________________________________
Outline the process of DNA replication in four stages
1 ______________________________________________________________________________
2 ______________________________________________________________________________
3 ______________________________________________________________________________
4 ______________________________________________________________________________
7(2) marks