What group of organisms occupies the second trophic level of an ecosystem?

The oxidizing agent our bodies use to obtain energy from food is oxygen (from the air). if you breathe 15 times a minute (at rest), taking in and exhaling 0.5 l of air with each breath, what volume of air do you breathe each day? air is 21% oxygen by volume. what volume of oxygen do you breathe each day?

The influenza virus cause the flu, but not other diseases. why?

Do you think the gene eef1 alpha1 supports cell theory? explain your response.