Solar eclipses occur more often than lunar eclipses because in a lunar eclipse, the moon has to be perfectly aligned with both the earth and the sun.
Solar eclipses occur about 2 to 4 times per year, but the area
on the ground covered by totality is only about 50 miles wide. In any
given location on Earth, a total eclipse happens only once every hundred
years or so, though for selected locations they can occur as little as a
few years apart.
Eclipses of the Moon by the Earth's shadow occur less often than solar eclipses, however, each lunar eclipse is visible
from over half the Earth. At any given location, you can have up to
three lunar eclipses per year, but some years there may be none.
In any
one calendar year, the maximum number of eclipses is four solar and
three lunar.
Your answer is correct (meiosis)
Lederbergs' experiment of the prevalence of mutations before selective culture was proved by replica plating. They spread bacteria on the plate and allowed them to grow. Next, they stamped the growth on the new plate which was already containing penicillin. The bacteria were able to grow on this plate, even when they never exposed to the antibiotic before. This proved that some of the bacteria were already mutated and were not as a result of exposure to selective culture conditions.
