Large lava flows can destroy all of the plants in an area. However, rock formed by lava flows often has nutrients that are beneficial to plants. Sediment from this rock can enrich soil.

Some lichens are pioneer species that can grow on rocks. How can lichens help other plants repopulate an area cleared by a large lava flow
va flow?
A.
by protecting other organisms from uncovered rock
B.
by destroying organisms that grow before pioneer species
C.
by breaking down rock into small pieces
D.
by providing competition for resources

 C  by breaking down rock in to small pieces

Explanation:

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.