For protection from the outside elements & harmful insects I would assume. Unless that's already obvious & they wanted a more in-depth answer.
Answer:
Different things make different vibrations when they hit, and that's why you hear high notes and low notes. Things that vibrate quickly make small waves in the air, and that sounds to you like a high-pitched note. Things that vibrate slowly make longer waves in the air, that sound to you like a low-pitched note.
Answer:
Explanation:
I think it is: acetylcholine (neurotransmitter) - motor neuron - contract
second question: diffusion because of opening of ca2+ channels
Sometimes they're used as drugs. The classic example might be penicillin, a compound made by a fungus and used as the first widely-available antibiotic.
Composting is a form of waste that uses organic materials to put into plants in order to help them grow and flourish. It saves energy, and it doesn't give off many gasses to help the Earth.
However, it is ineffective on the large scale and cannot be mass produced to help Earth instantly because of the large amounts of inorganic materials.
