Certified Crop Advisor Practice Exam

What is the primary function of phosphorus in plants?

1. Water absorption

2. Protein synthesis

3. Photosynthesis

4. Energy transfer

The correct answer is: Energy transfer

Phosphorus plays a crucial role in energy transfer within plants, which is fundamentally tied to the functioning of adenosine triphosphate (ATP). ATP is a molecule used by plants to store and transport chemical energy necessary for various biological processes. The presence of phosphorus in ATP allows for the transfer of energy during metabolism, including cellular respiration and photosynthesis, enabling plants to synthesize carbohydrates and other vital compounds. While water absorption, protein synthesis, and photosynthesis are all critical processes in plant physiology, they are not the primary functions specifically attributed to phosphorus. Water absorption is mainly facilitated by roots and involves hydrophilic interactions rather than phosphorus directly. Protein synthesis involves various elements, including nitrogen, but phosphorus does not play a direct role in forming the peptides that comprise proteins. Lastly, while phosphorus is involved in photosynthesis indirectly, its most notable role is in the energy transfer processes that occur throughout the plant's cellular activities.