This chart shows four atoms, labeled W, X, Y, and Z. These atoms can combine with each other to form
molecules.
Which combination of atoms will form a molecule, but
not a compound?
OW and X
0 X and Y
Atom
w
x
Y
Z
Element
oxygen
hydrogen
carbon
oxygen
O W and Z
O Y and Z

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:

the answer would be 2, if crossing over doesn’t occur 2 out of 4 of the daughter cells will have that allele.

hope this : )