The simple mathematical equations of these relationships effectively allow scientists to 13) __ summary_ the dimension of cells and cell walls based on the thickness of a leaf. In most cases, the relationships the team found were 14) __________.
By contrast, a leaf's 15) __________ is unrelated to the sizes of the cells inside. This allows plants to produce leaves with a huge range of surface areas without the need for larger cells, which would be 16) __________, the researchers said. Variation in the number of cells arranged vertically cannot be large because light can penetrate only so many layers of cells. On the other hand, the number of cells arranged horizontally in the leaf continues to 17) __________ as leaves expand, regardless of the size of the individual cells.