Molecular weight of 60s sub unit = 2.7 x 10^6 units
Molecular weight of 40s sub unit = 1.3 x 10^6 units
Densities are same and both are spherical
Relative size = Molecular weight of 60s / molecular weight of 40s
= 2.7 x 10^6 / 1.3 x 10^6 = 27/13 = 2.0769
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Crossing over at prophase I results in the linked genes (those on the same chromosome) becoming unlinked and separated. Prophase I is this first stage of meiosis, the chromosomes condense, form tetrads<span>, and exchange DNA. The nucleolus and nuclear envelope disappear.</span>
Answer: Option B.
Geographic separation.
Explanation:
It is geographic separation that is common to both of them because
Sympatric speciation to occur when certain populations of species isolate reproductively from the the main populations because they can not longer interbreed with each other and they inhabit the same geographical location.
Allopatric speciation occur when two populations of the same species separate from each other geographically which can be as a result of one group of population move to another geographical location.