Breathing is required for cellular respiration. use the reactions for photosynthesis and cellular respiration to explain why breathing is required.

How does the nervous system affect the excretory system?

In figure 1-2 what is the distance from point b to point c?

According to the rna world hypothesis, rna acted as the genetic material and catalyzed reactions in ancient cells. what conclusion can you draw from this?               a.  this implies that dna and proteins aren't essential in cells today.    b.  this implies that rna can catalyze any chemical reaction that enzymes catalyze.    c.  this implies that if a cell has a problem with its dna, its rna can compensate for the damaged dna.    d.  this implies that dna and proteins evolved after rna.