Respiration

a) Cells respire to produce energy

b) Oxygen is absorbed and carbon dioxide is released slowly via tiny holes (stomata) in leaves (see a magnified view of stomata, below)

Magnification of plants as they respire carbon dioxide and absorb oxygen

a) Cells respire to produce energy

b) Oxygen from air is inhaled via lungs (below), and CO₂ breathed out

Image of a humans respiratory system