This was my answer for the evolution thing:
DNA replication occurs in cells and is important in the mitosis which enables organisms to grow and repair. However, mutations, which is the change of the DNA sequence, can arise during replication. This change may give rise to a new phenotype which makes the individual different from the rest of the population. Mutations that occur during replication form the basis for evolution by natural selection to occur as it provides variation within the population.
Changes in the population can arise as:
1. There exists variation in a population due to mutations in the population.
2. When there is a sudden change in the evironment, those with characteristics that give them a surviving advantage in that new environment survive better than the ones without that characteristic.
3. This enables them to survive and reproduce, passing on their characteristics to their offsprings.
4. After a long period of time change in the population can be seen.
Thus, evolution occurs.
This is essentially what I wrote in the exam. I think may have put a bit for information before the step thing, but yeah...