Why would your muscle cells need to be supplied with more food when there is lack of oxygen that where there is plenty of oxygen present?

Because you would need energy and also food contains oxygen.

Where’s the selection?

The virus is considered to be are living item since they have hereditary material dnas or rnas. they can imitate and change. they respond to boosts, for example, radiation, chemicals, and warmth. they have antigenic properties. they are proficient to duplicate with a same hereditary constituent.