Describe one problem that scientists must overcome to develop a vaccine for HIV

Responding to the environment is a characteristic of life best shown by which example? O O O a human shivers on a cold day a horse trots in a field a dog swims in a pond a cat licks its paws

Which are a result of tectonic plate movement? Check all that apply. o causes craters in Earth's surface causes continents to move to different parts of Earth causes some organisms to die causes new species to develop causes ice ages to begin

The more motor units excited the ___ the contraction

Ralph is looking at a blood vessel under a microscope as part of his study about the cardiovascular system. He notices that the vessel contains blood and has valves. Determine the blood vessel being observed.

N Stage 1 of his lab, Gunther adds 20 mg of solute into a solution. He stirs it and it completely dissolves. In Stage 2, he adds 20 mg more of solute and stirs, but this time, some settles out.

Why do we can't sneeze without closing our eyes.

What begins when a neuron is stimulated by another neuron or by a stimulus in the environment?

8. Referring to Figure 2-1, the coyotes would be considered a. herbivores c. second-order consumers b. third-order consumers d. decomposers

Why do most scientists believe that all life on earth evolved from a single-celled ancestor?

Everyone has two alleles for blood type. where do these two alleles come from?