The circulatory system is ? the respiration system is ?

which molecules are used to produce energy?

molecules of all sizes can enter the cell?
true or false

what are amino acids used for in the cells?

please help it's a text for science

1.The circulatory system is made up of blood vessels that carry blood away from and towards the heart

2.Respiratory system, the system in living organisms that takes up oxygen and discharges carbon dioxide in order to satisfy energy requirements. In the living organism, energy is liberated, along with carbon dioxide, through the oxidation of molecules containing carbon

3.Complex organic food molecules such as sugars, fats, and proteins are rich sources of energy for cells because much of the energy used to form these molecules is literally stored within the chemical bonds that hold them together.

4.True

5.amino acids have many biologically important functions. They are also energy metabolites, and many of them are essential nutrients. Amino acids can often function as chemical messengers in communication between cells.

Explanation:

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