Which substance can enter a cell by diffusion
without having to be digested?
(1) water (3) starch
(2) protein (4) fat

the element that provides strength to the exoskeletons of clams and oysters is phosphorus.

this is so because calcium carbonate is the main component in the shells. calcium carbonate is strengthened by phosphorus.

explanation:

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explanation:

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the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

i hope this

satellites are frequently used to make observations of the orbit on earth