<span>a. Fish have a single central heart; earthworms have several hearts.
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Multi cellular organisms are made up of billions of cells each specialized to a unique role and these cells are organized into structural and functional units such as tissues and organs.
For each cell and organ to function optimally, it requires oxygen and nutrients and needs carbon dioxide and metabolic waste taken away in a continuous, never ending process.
<span>A mechanism is needed to accomplish the important function of transporting the relevant materials to and from the cell. The circulatory system fits this bill splendidly. It is a specialized organ system which allows blood and lymph to flow through the entire body carrying nutrients such as glucose, amino acids and electrolytes as well as oxygen to each cell, at the same time carting away carbon dioxide and all sorts of metabolic waste over to excretory organs to be expelled from the body.
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Answer:

Explanation:
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In this case, the pH is computed by:
![pH=-log([H^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH%5E%2B%5D%29)
Whereas the concentration of hydrogen ions equals the concentration of the acid for strong acids such as hydrochloric acid (HCl) due to its complete ionization in solution, which means that such concentration is 0.00125 M. Thus, the pH turns out:

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They are very very strong tides they have nothing to do with the season spring they occur when the sun moon and Earth are in a line., the gravitational forces of the Moon and the Sun both contribute to the Tides. spring tides occur during a new moon or full moon
Answer:
Jackels
Explanation:
Domestic dogs and wolves are part of a large taxonomic family called Canidae, which also includes coyotes, foxes and jackals, according to the Integrated Taxonomic Information System (ITIS). Members of this family are called canids.
Answer:
In the process, the carbon dioxide bonds with, then breaks with, a lot of molecules of water. These broken water molecules weaken the ice and make it more brittle.
Explanation:
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