Which picture?, pls Clip the picture for the answer.
B-Kidneys
The kidneys act as filters that strain urea and excess salts from the bloodstream to release them in the urine.
I believe it relates because as we know the cell membrane is permeable meaning that allows oxygen, carbohydrates, food to enter the cell but it doesn't allow the entrance of large molecules that harm the cells.
After all the movement around it, matters because for example without food the mitochondria won't be able to create the energy and then with that energy, the nucleus to use it to complete the main the activities of the cell.
Hopefully this what you meant when you asked the question. Have a nice day/evening
Answer:
You did not write the concept, so i will try to answer in a general way.
Why sometimes we really need to model concepts?
Well, sometimes the things are really complicated, or we just do not have the knowledge or tools to fully understand them.
Here is where the models came to be handy, we can somewhat "simplify" the things, and explain them with models.
For example, the movement of a particle as the wind pushes it can be really complex, so this can only be explained with a model.
Now, once we have a model (supported by theory and experiments) we can start to investigating furthermore in the given subject.
So for example, we could model how a given therapy acts on a given disease, and with that model, we could extrapolate the effects of the therapy in a similar disease (for example, testing how radiotherapy acts on a given tumor in some organ, can give information on how the same therapy can act on other types of tumors)
Concluding, models simplify some concepts, which allow us to understand them and work better with them
This question is very broad, so one possible answer that's is also very broad is that they can form many other chemical compounds.