Answer:
for 16 it is heart.
Explanation:
for 17 it is kidney to bladder
Answer:
photosynthesis produce food for plants
<span>In the "all or none" law of muscle contraction, it states that when the stimulus applied exceeds threshold then the the nerve sending signals to a few muscle fibers will give a complete response; contraction. Graded response is dependent on how many motor units have been recruited. The more motor units, the greater the force in the contraction.</span>
