Answer:
The circulatory system has evolved over time from simple diffusion through cells, in the early evolution of animals, to a complex network of blood vessels that reach all parts of the human body. Made of specialized and unique cardiac muscle, it pumps blood throughout the body and to the heart itself.
Claps shut at birth. Evolutionary changes in the vertebrate heart are tied to change from single to double-circuit heart, with increased separation of oxygenated and deoxygenated blood, allowing more efficient respiration and circulation to fuel high activity and increased oxygen demands associated with endothermy.
First eliminate choices C and D since they both mention that fact 1 is crossing over ( which is also referred to as genetic recombination) . So you're left with A and B and the correct answer is B .
B. Subgroups
<span>When constructing a dichotomous key, the first step is to look at the group of objects or organisms and separate them into two groups based on a single distinguishing characteristic. Then continue to separate each of the groups until each object has its own separate set of characteristics.</span>
We know, DNA is the main molecule by which scientists can learn about evolution by comparing the DNA structure between two different organisms.
But, in addition to DNA (which is most helpful & important) still, there are 3 molecules that can help us, They are:
1) RNA : - It is found in cytoplasm, as DNA transfers it's codes into RNA during Central dogma, it can help us in evolution studies.
2) Proteins: - Another helpful feature, into which RNA transforms in Central Dogma.
3) Pseudogenes: - It is also known as "Non-coding DNA" It is extra <span>DNA in a genome that do not get transcribed into RNA to synthesize proteins. They can also help us in Evolutionary studies.
Hope this helps!</span>
this is true. when it is warmer the plant and insects can migrate to these other places so they do not have to die or hibernate through winter
