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New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
Book E4, Chapter 1
p.1/4
Suggested answers to Exercise
Chapter 1
Traditional and modern biotechnology
Exercise
Multiple-choice questions (p. 39)
1
6
B
B
2
7
B
C
3
B
4
D
5
A
Short questions (p. 39)
8
a
b
9
a
b
c
10
a
b
People produced cheese / yoghurt / wine by fermentation.
1m
They did not understand the principles.
1m
The techniques were practised on a small scale.
1m
Biotechnology is any technological application that involves the use of organisms,
biological systems or processes in producing goods or providing services.
1m
The making of cheese / yoghurt / wine involves the use of microorganisms and is thus
considered as an early biotechnology.
1m
Restriction enzyme / endonuclease
DNA fragments move towards the positive terminal because they are
negatively-charged.
DNA fragments move at different rates related to their sizes.
i
It is a piece of single-stranded
DNA
that is complementary to / binds to known base sequence / gene.
ii DNA is invisible on the gel.
Radioactive DNA probes allow detection.
Restriction enzyme / endonuclease
Sticky ends / staggered ends
are complementary and can be joined by hydrogen bonds.
1m
1m
1m
0.5m
0.5m
1m
1m
1m
1m
1m
1m
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
Book E4, Chapter 1
p.2/4
c
Plasmid with foreign DNA joined in ring
1m
Ring with plasmid only
1m
Ring of foreign DNA only
1m
11
HKALE Biology 2005 I Q8
12
a
b
c
d
e
f
13
a
b
c
Genetically identical cells / individuals
Mitotic cell division
No differentiation at this stage / same genes being expressed
It is brown because the DNA comes from the nucleus of a brown frog.
The embryo cell is diploid whereas the egg cell is haploid.
The nuclei contain different alleles of the colour gene.
Damage to the nucleus / cells
1m
1m
1m
1m
1m
1m
1m
The hydrogen bonds between complementary bases are broken
1m
by heating.
1m
i
To allow the DNA polymerase to attach. / To start the addition of nucleotides. /
To mark the start and end of the sequence to be copied. / To prevent the strands
from re-joining.
1m
ii It is because the sequences at the ends of the target sequence are different. 1m
8/7
1m
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
Book E4, Chapter 1
p.3/4
Structured questions (p. 41)
14
a
i
ii
iii
iv
b
i
ii
15
a
b
c
d
e
Plasmid
1m
The bacteria divide, producing many copies of desired gene. /
Bacteria divide to cover the agar.
2m
Plant tissue that has antibiotic resistance survives.
1m
To identify plant tissue which has the desired gene.
1m
To clone plants with the gene / characteristic.
1m
To produce large numbers of offspring quickly.
1m
The toxin is present all the time. / Save costs of buying or application of spray. /
No spray drifts onto other fields or insects.
1m
Harmless or useful insects that feed on wild plants are killed. / Food chains
starting with wild plants are damaged.
1m
Heating breaks down the hydrogen bonds between the bases.
1m
Each strand acts as a template against which free nucleotides combine.
1m
Any two from:
1m x 2
Nucleotides are arranged in place opposite the exposed bases on each strand
according to the complementary base pairing (A–T, C–G, T–A, G–C).
The complementary bases are held together by hydrogen bonds.
The sugar of one nucleotide is joined to the phosphate group of the next nucleotide.
A condensation reaction forms the bond.
This ensures that multiple copies of the DNA are manufactured.
1m
i
Suspect 1
1m
ii To ensure that the DNA specimen is not that of the victim.
1m
16
HKALE Biology 2004 I Q11
17
a
c
Deoxyribose / 5-carbon sugar
1m
Phosphate / phosphoric acid
1m
i
On the diagram, write ‘–’ at the top and ‘+’ at the bottom.
0.5m
DNA fragments move towards the positive electrode.
0.5m
ii Correct answer = 710 to 890 base pairs (in range) 2m
OR
X = 4.45 to 4.7 cm → 1500 to 1600 base pairs /
1m
Y = 6.4 to 6.65 cm → 710 to 790 base pairs
1m
iii A DNA molecule consists of two chains that are joined by the linking of 2 bases
(A with T and G with C).
1m
Bases are a constant distance apart. / Nucleotides occupy constant distance. /
Each base pair is of the same length. / Sugar-phosphate is a constant distance.
1m
4
1m
a
DNA is cut using a restriction enzyme.
b
18
1m
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
b
c
d
Book E4, Chapter 1
p.4/4
DNA fragments are separated according to their lengths / mass using gel
electrophoresis.
1m
Southern blotting is used to transfer the DNA fragments to a nylon membrane. 1m
The DNA fragments are made single-stranded.
1m
Radioactive / fluorescent DNA probes are added.
1m
Reference to tandem repeats
1m
i
All bands in the cub which do not come from the mother
1m
must be in the father’s DNA fingerprint.
1m
ii Select pairs with dissimilar DNA fingerprints.
1m
i
Cells (from panda) in faeces / gut cells / blood cells
1m
ii To increase the amount of DNA as only a small amount is present initially. 1m
iii Primers have a specific base sequence.
1m
They are designed to bind to panda DNA by complementary base pairing. 1m
Any two from:
1m x 2
Taking samples from the animals causes stress / injury to them.
It is difficult to find the animals.
Pandas pose threats to humans.
Reading to learn (p. 46)
1
Any two from:
2m x 2
The mosquito may not have fed on the blood of dinosaurs.
The mosquito may have fed on the blood of more than one species of dinosaurs.
This makes it difficult to identify which DNA comes from which.
The DNA may have been digested by the mosquito.
2
Enzymes
1m
3
Yes / No
With suitable explanations
1m
2m