This type of molecule is the most common energy source for all cells and enters the cell by facilitated diffusion.

The answer is glucose. Ready energy for any type of cell is glucose. Other molecules may be used for energy, but they are broken down before being used as an energy source. DNA is not used for energy; proteins are used only when an organism is in starvation mode.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the answer is d.) homologous; have mammary glands