Semipermeable means only certain substances can pass through. I imagine you are talking about cell membranes which are semipermeable. This means vital things like oxygen and nutrients are able to pass through the membrane, while not allowing everything to enter the cell
In a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.
The answer is B. even if you fill out a Punnett Square there is still a possibility that it won't come out that way. for example there could be two dominant traits in a Punnett square instead of just one completely dominant trait. like BB and BB.
A chemical reaction is a process by which atoms or groups of atoms in a particular substance are rearranged from the arrangement within the reactants to a new arrangement within the products.