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! =)
Answer:
Yes they do.
Explanation:
Both plant and animal cells contain ribosomes. Some may be found floating in the cytoplasm while others may be found in the rough Endoplasmic Reticulum.
Yes, it is a weak acid called the citric acid
