Can blood go backwards from the right ventricle to the right atrium?

yes

Explanation:

as the atrium contracts , blood flows from your right atrium into your right ventricle through the open tricuspid valve. when the ventricle is full, the tricuspid valve shust . this prevents blood from flowing backward into the right atrium while the ventricle contracts

as the atrium contracts, blood flows from right atrium I to your right ventricle through the open tricuspid valve. when the ventricle is full , the tricuspid valve shuts. this prevent the blood from flowing backward into the right atrium while the ventricle contracts. so the answer is no

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

1. is geographic distribution

2 is increasing complexity

3 is transitional forms