Biological soil crusts<span> are communities of living organisms on the </span>soil<span> surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, </span>soil<span> characteristics, climate, plant community, microhabitats, and disturbance regimes.</span>
Answer:
D
Explanation:
because molecule A is only shown on the outside and is not exposed to the acidity on the inside of the cells
What are the questions that go with the model?
Skin prevents the body from getting infections
