Answer:
My guess would be H₂O/ water, since osmosis is a form of passive transport and I can't see the model the question references. Gases like O₂/ oxygen, CO₂/ carbon dioxide, and simple sugars like glucose can also pass through a cell membrane with passive transport though.
They are called natural recyclers because they naturally break down dead and decaying matter. I hope this helps!---
It is true that Urban sprawl covers land once used for food
production and destroys ecosystems. Many of the large cities that have come up
were once fertile lands for irrigation or were big jungles. These jungles were
cut down or the fertile lands destroyed to build cities and industries.
By the United States Census Bureau standards, a population
of 1000 people define an urban area is completely false statement. As per the
United States Census Bureau, more than 50000 people define an urban area.
To solve the stability problem, Bohr modified the Rutherford model by making sure that the electrons move in orbits of specific size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. However, radiation can only happen when the electron jumps from one orbit to another.