PAPER 2026 QUESTIONS WITH ANSWERS
GRADED A+
◉ (Unit 1:2015) Describe the principles and the limitations of using a
transmission electron microscope
to investigate cell structure. Answer: Principles:
1. Electrons pass through/enter (thin)
specimen;
2. Denser parts absorb more
electrons;
3. (So) denser parts appear darker;
4. Electrons have short wavelength so
give high resolution;
Limitations:
5. Cannot look at living material / Must
be in a vacuum;
6. Specimen must be (very) thin;
7. Artefacts present;
8. Complex staining method /
, complex/long preparation time;
9. Image not in 3D / only 2D images
produced;
◉ (Unit 2:2015) A mutation can lead to the production of a non-
functional enzyme. Explain how. Answer: 1. Change/mutation in
base/nucleotide
sequence (of DNA/gene);
2. Change in amino acid
sequence/primary structure (of
enzyme);
3. Change in hydrogen/ionic/disulfide
bonds;
4. Change in the tertiary
structure/shape;
5. Change in active site;
6. Substrate not complementary/cannot
bind (to enzyme/active site) / no
enzyme-substrate complexes form;
◉ (Unit 4: 2015) On islands in the Caribbean, there are almost 150
species of lizards belonging to the