Pacemakers are devices that keep heart muscles contracting at a steady rate. if a person needs a pacemaker, what does that suggest about his or her heart cells ability to send and receive messages

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.

not sure if this what   you'r looking for would be percent composition

answer; endoplasmic reticulum;