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: C. is your answer
Answer:
b.Movement of phospholipids in the plasma membrane from one monolayer to the other requires the polar or charged head groupd to enter the hydrophobic interior of the lipid bilayer. This process requires a large positive change in free-energy, thus making this type of movement unlikely without an input of energy
The plasma membrane serves a protective function for the cell and is a selective membrane for particles entry
Afferent nerve fibers carry signals from the somatic receptors to the posterior horn of the spinal cord or to the brainstem. So i beleive it is 4 but not too sure. Hope this helped a bit (:
Answer:
The endosymbiotic theory
Explanation:
Protists are the multicellular organisms which possess characteristics of both the prokaryotes and eukaryotes.
The protist can derive nutrition by either heterotrophic mode or photoautotrophic mode. This variation could exist within the same genus and same species.
This variation could be explained with the endosymbiotic origin of the organisms as some species could engulf the photosynthetic bacteria whereas some could have engulfed the chemosynthetic bacteria.
This can be observed in the green and red algae which depend on a different mode of nutrition belonging to the same group.
Thus, the endosymbiotic theory is correct.
