g If you look carefully at this organism, you will not see any organs for gathering oxygen or releasing carbon dioxide or ammonia. There is no circulatory system. How does this animal perform these functions

Simple unicellular organisms like Amoeba and some multicellular organisms like Hydra use their cell surface and skin for gaseous exchange with their environment.

Note: The organism in the question was not stated.

Explanation:

The complexity of an animal determines its metabolic needs, and hence, its requirement for specialized structures and functions.

Simple unicellular organisms are able to meet their metabolic needs such as gaseous exchange by simple diffusion through their cell surfaces. Such organisms include amoeba, paramecium, etc.

Some multicellular organisms lack specialized organs for nutrient transport and gaseous exchange such as hearts and blood vessels, etc. Example of such organisms are Hydra and Planaria. They have their cell surfaces in contact with the external environment, and thus use their skin for gaseous exchange by means of diffusion.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

that is wrong, its not thymus.