E-Reticulocyte b. Peter went for an expedition to climb Mount Everest. Explain a mechanism that occurs to
maintain his body's oxygen level during the expedition.
[5 marks]

you need more balloons

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.