Diffusion in plants and animalsWatch
The way to approach a Q like this is to consider every part of an animal [and different animals] AND plants in turn to remind yourself of each answer, yeah?
lungs ----> a] below.
fish ----> b]
Intestines ---> c]
protists ---> d]
plants ---> e]
a] alveoli/capillary wall and diffusion of oxygen.
b] in fish gills [O2]
c] facilitated diffusion of digested food into villi (tho most absorption occurs by active transport).
d] diffusion of oxygen/nutrients etc into protozoa across cell membrane, and CO2, urea, other waste out.
e] diffusion of O2 from guard cells of leaf into palisade cells
f] diffusion of O2 + nutrients from blood vessels [capillaries] into tissue fluid.
g] diffusion of chemicals [called neurotransmitters] across synapse to act on post-synaptic receptors.
etc etc etc.
Does this help - it should! - not your fault: teachers don't allow you to think these days!
Keep laughing and be safe!