How would the body wave affected if red blood cells have low levels of hemoglobin

Aprocedure done under controlled conditions to test a hypothesis is an inquiry.

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled

Which statement describes the punctuated equilibrium theory?