Autotroph + heterotroph cells respire w/ oxygen, from photosynthesis
Only photoautotrophs are photosynthetic
Day (Spring/Summer, temperate climates); Photosynthesis rate > Respiration rate, CO_2 diffuses in and O_2 out and Night; Only respiration, CO_2 diffuses out and O2 in
Dawn + dusk (low light); Photosynthesis rate = Respiration rate so no net diffusion of O_2 and CO_2 (compensation point)
O_2 made by photosynthesis in chloroplasts diffuses out, into mitochondria, for respiration or diffuses into leaf air spaces to be stored for diffusion
CO_2 made by respiration in mitochondria diffuses out into chloroplasts, for photosynthesis or diffuses into leaf air spaces to be stored for diffusion
