QUESTION 1 [10]
Look carefully at the electron micrographs in Figure 1.
1.1. Describe the differences between the cell that died by (A) necrosis and the one that died by
(B) apoptosis. (6)
1.2. How do the pictures confirm the differences between the two processes? Explain your answer (4)
Figure 1: Cell death by (A) Necrosis and (B) Apoptosis
QUESTION 2 [15]
2.1. Explain how the lac operon is both positively and negatively controlled. (2)
2.2. A mutation within the promoter region can alter transcription of a gene. Describe how this can
happen. (3)
2.3. Summarize the negative repressible feedback mechanism when operated by an operon. (5)
2.4. Describe the process of repression in the trp operon. (5)
QUESTION 3 [15]
3.1. List and explain four (4) ways in which new genes can be generated from pre-existing genes. (8)
3.2. Write a brief description of the three (3) main types of non-covalent bond. (3)
3.3. Describe the two (2) main classes of membrane transport proteins. (4)
QUESTION 4 [20]
4.1. Draw the chemical structure of DNA including the complementary base pairs in the DNA double
helix. (10)
4.2. Describe how the complementarity of DNA provides the mechanism for heredity and how DNA
acts as a template for its own duplication. (10)
QUESTION 5 [20]
5.1. In your own words, explain the principle of how gel electrophoresis of DNA separates the
molecules according to size. (5)
5.2. Discuss the cloning laboratory technique. (5)
5.3. Explain the importance of polymerase chain reaction (PCR) during the DNA sequencing
process. (10)
QUESTION 6 [20]
6.1. Discuss why gene regulation is important. (6)
6.2. Describe how controlling gene expression will alter the overall protein levels in the cell. (6)
6.3. List the differences in the regulation of gene expression of prokaryotic and eukaryotic
organisms.