A low birth weight infant is an infant that weighs less than 5.5 pounds at birth
Vacuoles <span>can be used by cells to store energy, form biological membranes, and serve as chemical messengers</span>
Because they contain less "built-in" water.
Explanation:
When two glucose molecules 'decide' to bond, they lose a molecule of water:
<span>2<span>C6</span><span>H12</span><span>O6</span>→<span>C12</span><span>H22</span><span>O11</span>+<span>H2</span>O</span>
And this happens at every connection between glucose molecules, so in a long chain a lot of water is lost. The water does not contribute anything to the energy content of the compound.