Answer:
Flatworms are beings that do not have a heart, veins, arteries, capillaries, hemolymph, or some type of circulatory fluid. Their circulation occurs between cells or intercellularly and they are responsible for transporting substances by diffusion from cell to cell.
Explanation:
Flatworms are considered multicellular eukaryotic organisms. This implies that in their cells they have a cellular nucleus, in which the DNA is contained, structuring the chromosomes. Likewise, they are made up of several types of cells, each one specialized in a specific function. They lack a structured circulatory system as such. Because of this they do not have specialized structures such as a heart or blood vessels, however, the circulation of certain substances is established between their cells. This is done thanks to the diffusion process. Substances pass from one cell to another through this process.This does not apply to all flatworms, since in some species of bog and digenae there is a certain organization and some very small conducting vessels known as the endolymphatic system, the which forms a kind of plexus in the parenchyma.It should also be noted that some species do not even have a digestive system, being the digestive tract the one in charge of digestive functions and the distribution of the nutrients they receive.
The drift explanation states that the people with higher socio-economic status (SES) tend to have better lives. It further states that genetics and biology plays an important role in the socio-economic status so that healthier people can enjoy their SES for longer period of time.
Answer:
For early earth, it was filled with loads of oxygen and could kill humans if they breathed the oxygen that was in the air about 100 million years ago. This massive amount of oxygen cause massive creatures like the dinosaurs to exist. Current earth has an atmosphere with not too much oxygen.
Explanation:
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Answer:
The blood circulatory system delivers nutrients and oxygen.
Explanation:
