<span>Soils rich in organic material are always highly fertile.</span>
The atria and ventricles work together, alternately contracting and relaxing to pump blood through your heart. ... The electrical activity spreads through the walls of the atria and causes them to contract. This forces blood into the ventricles. The SA node sets the rate and rhythm of your heartbeat.
The correct answer is:
fixation
Explanation:
Nitrogen fixation is a method by which nitrogen in the Earth's atmosphere is converted into ammonia or other molecules prepared to living organisms. Nitrogen fixation is carried by a diversity of bacteria, both as free-living organisms and in symbiotic association with plants. Because it is the primary source of the nitrogen in the soil, nitrogen that plants need to grow, nitrogen fixation is one of the most critical biochemical processes on Earth
