Lignin makes cellulose more rigid.

protection
support
transporting materials
reproduction

What substance acts to prevent sudden ph changes in bodily fluids?

The law of thermodynamics states that energy can't be created or destroyed. to natural sources of energy on earth are the

Ruby is conducting an investigation. an advantage of her design is that she can use a large range of variables, with that she can not be sure that one variable is the cause of another. what kind of investigation is ruby most likely conducting?