<span> After fertilization, the </span>zygote<span> undergoes cleavage to form the blastula. The blastula, which in some species is a hollow ball of cells, undergoes a process called gastrulation, in which the three germ layers form.</span>
The original source of phosphorus in a terrestrial ecosystem is soil microorganisms. soil becomes deficient in phosphorous leading to ecosystem retrogression. phosphorous can be found in our body, it builds strong bones and teeth.
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The scientist you're looking for is an anthropologist.
Generally nonsense is much much worse. It creates a premature stop code which can throw off the entire chain of codons and makes things much much worse. A good way to remember this is that the nonsense mutations make the codons not make sense.