The number of chromosomes in a cell
a) is 50
b) varies from spices to spices
c) is haploid
d) is either 25 or 50

I'm not quite sure of the exact answer. But I do know that humans have 46 Chromosomes, so I will assume the correct answer is B. It varies from species to species.

Hope this helps. :) Correct me if I'm wrong.

I’d say a : water molecules

The arrangements of lipids in the membrane makes the cell semi permeable .