Download 1. The table shows the number of carbon atoms contained in some

1.
The table shows the number of carbon atoms contained in some substances.
Substance
Number of carbon atoms
Amino acid
2 - 11
Glycerol
Glucose
6
Pyruvate
Starch
(a)
Large and variable number
Complete the table to show the number of carbon atoms in glycerol and pyruvate.
(2)
(b)
Explain why the number of carbon atoms
(i)
may vary from 2 to 11 in an amino acid molecule;
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(1)
(ii)
may be described as variable in a starch molecule.
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(1)
(c)
Explain why the type of chemical reaction in which glucose is converted to starch may be
described as condensation.
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(2)
(Total 6 marks)
The Queen Katherine School
1
2.
The diagrams show five molecules A to E.
B
A
CH 2 OH
R
H2N
C
H
COOH
O
H
OH
H
OH
H
H
OH
H
OH
D
C
H
H
C
OH
H
C
OH
H
C
OH
H
E
Which molecule, A to E,
(a)
is one of the monomers which combine to form starch;
....................
(b)
contains peptide bonds:
....................
(c)
could be an oil;
....................
(d)
is one of the molecules that form a triglyceride?
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(4)
(Total 4 marks)
The Queen Katherine School
2
3.
The diagrams show four types of linkage, A to D, which occur in biological molecules.
Amino acid
H
C
H
S
S
A
Amino acid
H
O
H
C
C
N
B
H
O H H
O
C
(a)
H
H
C
O
O
C
R
D
Name the chemical process involved in the formation of linkage B.
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(1)
(b)
Give the letter of the linkage which
(i)
occurs in a triglyceride molecule;
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(1)
(ii)
might be broken down by the enzyme amylase;
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(1)
(iii)
may occur in the tertiary, but not the primary structure of protein.
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(1)
(c)
Describe how a saturated fatty acid differs in molecular structure from an unsaturated
fatty acid.
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(2)
(Total 6 marks)
The Queen Katherine School
3