normally penetration of the egg by the sperm cell signals the start of the development process. what can replace this signal when no sperm are involved?

the index of refraction of the second medium is higher. i just took the test trust me !

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

is this a question? wassup

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.