The answer is that <span>all
veins carry blood back to the heart, except for the pulmonary vein. the
vena cava empty into the right side of the heart, so they technically
bring blood to the
</span>main atrium.
That'll be guanine. If you look up "pyrimidine" in google, it will tell you the two nucleotides that are pyrmidines are cytosine and thymine. So that leaves guanine.
<span>Water heats up, changes to water vapor and evaporates, rises into the sky. It cools, condenses, turns back into liquid water forming clouds. Then it falls back to earth as precipitation and runs down hills or mountains during runoff and returns to lakes and oceans.
I think i`m not sure :)</span>
Dichotomous key is the technique which uses a series of criteria and questions referring to physical characteristics to classify species.
<h3>What is Dichotomous key? </h3>
This was created by scientists to help classify different types of species in the ecosystem.
This employs the use of questions to contrast species in order to look for similar features to group them.
Read more about Dichotomous key here brainly.com/question/1726339
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