Natural and artificial selection — practice question

Write the most suitable term in each space. When humans deliberately apply selection ........................................ to members of a population, the process is called artificial selection. For instance, people have attempted to ‘improve’ cattle for thousands of years. It is desirable for a dairy farmer to have cows with a high milk yield. The farmer will choose cows with high milk yields and mate them with bulls whose ........................................ have high milk yields. Some of the ........................................ responsible for high milk yield are passed to their female offspring, who are then selected for breeding. This will continue for many ........................................ . Artificial selection can have drawbacks such as ........................................ depression, which can cause infertility.