photosynthesis produces oxygen and glucose as the end products whereby the glucose is used as food by plants and oxygen as a byproduct.
cellular respiration produces water and carbon dioxide and the end products and by products where by energy is stored
A reverse reaction is the chemical reaction moving both forward and backwards.
An example of this is Ammonium chloride ⇌ ammonia + hydrogen chloride
This is a symbol for reverse reaction ⇌
Fish don't have ears we can see but they have ear parts inside their heads. They pick up sounds in water through their bodies.