Explain how one celled organisms get oxygen in water.

n unicellular organisms, oxygen diffuses across the cell membrane into the cell. Carbon dioxide diffuses out of the cell once the concentration of carbon dioxide is higher inside the cell than it is outside of the cell. Some micro-organisms, including some bacteria and fungi, can survive without oxygen.

Explanation:

the answer is trees if i'm not mistaken

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .