What agents of erosion are assisted by the force of gravity

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?

If a robot fixed another robot is it a engineer or doctor?

Consider this plant cell which organelle is labeled g