Most of the Dry Weight of a Plant is Derived

Question

Most of the dry weight of a plant is derived from
A) NO₃ and CO₂.
B) K and CO₂.
C) PO₄ and K.
D) H₂O and K.
E) H₂O and CO₂.

Accepted Answer

The dry weight of a plant is derived mainly from water and carbon dioxide through the process of photosynthesis. Although plants also require nutrients such as nitrogen, potassium, and phosphorus, these elements do not contribute significantly to the plant's dry weight. Therefore, choices A, B, and C can be eliminated. Choice D includes water as a limiting factor, but it is not a significant contributor to the plant's dry weight. Only choice E correctly identifies water and carbon dioxide as the main sources of a plant's dry weight.