Cell Structure

Question 1

Skin cells may be studied with a transmission electron microscope or an optical microscope. Explain the advantages and limitations of using a transmission electron
microscope to study cells. (6)

Answer 1

Advantages:
1 Small objects can be seen;
2 TEM has high resolution as wavelength of electrons shorter;
Accept better
Limitations:
3 Cannot look at living cells as cells must be in a vacuum;
4 must cut section / thin specimen;
5 Preparation may create artefact
6 Does not produce colour image;

Question 2

The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how. (4)

Answer 2

1. DNA replicated;
2. (Involving)
   specific/accurate/complementary
   base-pairing;
3. (Ref to) two identical/sister
   chromatids;
4. Each chromatid/ moves/is separated
   to(opposite) poles/ends of cell;