Test her theory. She needs to make sure her hypothesis is true.
During a solar eclipse, when the Moon's shadow falls on the Earth, we stand in the shadow rather than looking at it. Observers standing in the umbra see a total eclipse of the Sun, while observers under the penumbra see a partial eclipse.
Do you mean "why"?
They are the main source for all living organisms because they provide energy, relatively short term, for any creature that consumes them.
<span>s that a single on off switch can control the whole cluster of functionally related genes; these genes are coordinately controlled (ex: when Ecoli must make tryptophan for itself because the nutrient medium lacks this amino acid all the enzymes for the metabolic pathway are synthesized at one time)</span>
