Electromagnetic waves that are harmful to living things are

high frequency waves
low frequency waves
both high frequency and low frequency waves
neither high frequency nor low frequency waves

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

so whats the answer

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.