2018

Question 1

When preparing the cells for observation the scientist placed them in a solution that
had a slightly higher (less negative) water potential than the cytoplasm. This did not
cause the cells to burst but moved the chromosomes further apart in order to reduce
the overlapping of the chromosomes when observed with an optical microscope.
Suggest how this procedure moved the chromosomes apart.

Answer 1

Water moves into the cells/cytoplasm by
osmosis;
2. Cell/cytoplasm gets bigger;

Question 2

The dark stain used on the chromosomes binds more to some areas of the
chromosomes than others, giving the chromosomes a striped appearance.
Suggest one way the structure of the chromosome could differ along its length to
result in the stain binding more in some areas.

Answer 2

Differences in base sequences
OR
Differences in histones/interaction with
histones
OR
Differences in condensation/(super)coiling

Question 3

What is a homologous pair of chromosomes?

Answer 3

(Two chromosomes that) carry the same
genes;

Question 4

Formation of an enzyme-substrate complex increases the rate of reaction.
Explain how

Answer 4

1. Reduces activation energy;
2. Due to bending bonds

Question 5

The genetic code is described as degenerate.
What is meant by this?

Answer 5

More than one codon codes for a single amino
acid;