Describe the possible effects of a mutation on an organism. describe an example for each effect you mention.

1) No real change in a the phenotype
The genetic code of an organism is very long, and not all segments correspond to a phenotype. Often, a mutation in an organism will result in no noticeable change in any phenotype, meaning there will be no visible effect of the mutation on the organism. 

2) A small change in a phenotype. 
Somtimes a mutation will render a very small change in the phenotype of an organism. One example is a certain type of birthmark, which is caused by a single mutation. 

3) A significant change in the phenotype. 
A mutation can also lead to significant changes in the phenotype of the organism. One example is a mutation that causes bacteria, or other organisms, to become resistant to viruses or antibiotics. This mutation causes a huge change in the organism's survivability (fitness), and thus will cause it to be passed on often to new organisms. 

Generally travels west to east but often shifts to north and south