Answer:
Red blood cells
Explanation:
Hemoglobin carries oxygen in red blood cells
A closed system is a system that makes no physical or chemical exchanges with its environment. Of these systems provided as choices (tree, human, clock, car), only a clock does not make exchanges with the environment, except for energy.
Therefore, of that list, only a clock would be a closed system.
Hope that helped! =)
Yes plant cells do have mitochondira
The capability of both leptin and cholecystokinin in which they
have a similarity when a person has decreased its food intake. A leptin is a
way of helping an individual to regulate energy in means of having to inhibit
its hunger while the cholecystokinin is responsible for having to stimulate
digestions.