To Determine Where Plants Obtain the Raw Materials Needed for Growth

question 14

Essay

To determine where plants obtain the raw materials needed for growth, van Helmont collected data on the growth of a willow tree for over 5 years. He measured the amount of soil in a pot, planted the tree in the soil, and then watered the tree with rainwater. After 5 years, he weighed the soil and the tree. He concluded that the tree did not gain its mass from the soil, but incorrectly concluded that the tree had gained its mass from the water. What are two critical problems with this study design? How could you redesign the study to fix these two study design problems?

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Definitions:

Chemical Signals

Molecules released by cells that have the effect of altering the metabolism, growth, or activity of other cells that possess receptors for the signal.

Electrical Signals

Impulses generated by the movement of ions, essential for the functioning of neurons and the communication within and between neural circuits.

Glycocalyx

A glycoprotein and glycolipid covering that surrounds the cell membranes of some bacteria, epithelia, and other cells.

Glycolipids

are lipids with a carbohydrate attached by a glycosidic linkage, primarily involved in cell recognition and membrane structure.