AS Level Biology A
H020/02 Depth in biology
Monday 4 June 2018 – Afternoon
Time allowed: 1 hour 30 minutes
You must have:
• the Insert
... [Show More] (inserted)
You may use:
• a scientific or graphical calculator
• a ruler (cm/mm)
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*H02002*
Last name
First name
Candidate
number
Centre
number
2
© OCR 2018
Answer all the questions.
1 (a) Fig. 1.1 shows the general structure of an amino acid.
U
V
H
H H
O O
H
C
R group C
N
Fig. 1.1
(i) State the names of the groups labelled U and V.
U ........................................................................................................................................
V ........................................................................................................................................
[1]
3
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(ii) Fig. 1.2 shows a representation of a short polypeptide chain made from three amino
acids.
Valine
Alanine
Glycine
Bond W
Fig. 1.2
Name bond W and state what type of reaction takes place to form this bond.
Name of bond W ...............................................................................................................
Type of reaction .................................................................................................................
[1]
(b) Pepsin is a protease enzyme with a polypeptide chain containing 327 amino acids.
Titin is the largest known protein. It has a polypeptide chain containing at least 92 times more
amino acids than pepsin.
(i) DNA sequences in genes code for polypeptide molecules such as pepsin and titin.
Explain why a process known as transcription is necessary for polypeptide synthesis.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(ii) Calculate the minimum length of [Show Less]