They different because there made different and come from different resources
Biological structures like DNA, proteins and cells all depend on molecules. ... Neurotransmitters like epinephrine are pretty simple molecules, but without them our nervous system couldn't work. Oxygen, containing just two oxygen atoms, is a very simple molecule, and it is certainly essential to living things.
What is it I have to give reasons for?
Answer:
photoreceptors are visual
chemoreceptors are smell
mechanical is touch
Explanation:
