CAIE IGCSE Biology 4 Biological Molecules
Practise linking biological molecules to their elements, building blocks, food-test results and DNA base-pair structure.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Covered syllabus points
4. Biological molecules question 1
Antibodies are proteins.
State the chemical elements present in all proteins that are also found in carbohydrates and fats.
4. Biological molecules question 2
Two functions of the alimentary canal are mechanical digestion and chemical digestion.
Substances that are absorbed from the alimentary canal may enter cells and become part of the cells.
State the storage carbohydrate made from glucose in liver cells.
4. Biological molecules question 3
What is the test for protein?
name of the test
heat
colour change
Benedict's
yes
blue to purple
biuret
yes
blue to red
biuret
no
blue to purple
Benedict's
no
blue to red
4. Biological molecules question 4
A DNA molecule has two strands as shown in Fig. 6.1.
Fig. 6.1
Question (a)
(a)
Fill in the boxes on Fig. 6.1 to show the letter of the bases on strand 2 that will pair with the corresponding bases on strand 1.
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Question (b)
(b)
State the name for the structure of a DNA molecule as shown in Fig. 6.1.
When molecules of DNA are used to classify species, only one of the two DNA strands is sequenced.
First the DNA sequence from one strand of a DNA molecule from each species is lined up against one strand from another species.
The bases of the DNA sequences from the same strand can then be compared with each other.
Fig. 6.2 shows a short section from the DNA sequences of eight plant species. There are ten differences between species A and species B. These differences are shown in Fig. 6.2.
Fig. 6.2
Species C: CTCATAGGGT GCAGGCCTAG CCCGTTGACG AATCACATTC CGATT
Species D: CTCATAGGGT GCAGGCCTAG CCCCTTGACG AATCCAATTC CGCTT
Species E: CTCATAGGGT GCAGGCCTAG CCCGTTGACG AATCCAATTC CGCTT
Species F: CTCCTAGGTT GCAGGCCTAG CCCTTTGAAG AATCACATTC CCCAA
Species G: CTCCTCGGGT GCAGGCATAG CCCTTTGACG AATCCCCTTC CGAAA
Species H: CTCCTAGGGT GCAGGCATAG CCCTTTGACG AATCCCCTTC CAAAAT
[ 1 ]
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