GED Science TestLife ScienceMedium
A farmer observes that one of his fields consistently yields crops with stunted growth and yellowing leaves, despite adequate watering and sunlight. A soil test reveals very low levels of phosphorus. Which of the following is the most likely reason for these symptoms?
- AExcess calcium hindering nutrient uptake.
- BLack of nitrogen for protein synthesis.
- CLimited phosphorus for energy transfer and nucleic acid formation.
- DInsufficient potassium for water regulation.
Show answer & explanationAnswer & explanation
Correct answer: C. Limited phosphorus for energy transfer and nucleic acid formation.
Phosphorus is a crucial macronutrient for plants, essential for ATP (energy transfer), DNA, and RNA (nucleic acids). A deficiency directly impacts growth and overall plant health, often presenting as stunted growth and discolored leaves.
Why the other options are wrong
- A. Excess calcium can cause issues, but a low phosphorus level is the direct cause of the observed symptoms related to essential nutrient function.
- B. Nitrogen deficiency also causes yellowing, but specifically affects older leaves first and is primarily for protein synthesis, while phosphorus is critical for energy and genetic material.
- D. Potassium deficiency affects water balance and disease resistance, typically showing as yellowing at leaf edges and reduced fruit quality, not the primary cause of stunted growth.
Phosphorus in Plants
An essential macronutrient for plants, crucial for energy storage and transfer, and as a component of nucleic acids and cell membranes.
- Component of ATP (energy currency).
- Essential for DNA and RNA synthesis.
- Deficiency leads to stunted growth, dark green or purplish leaves, and poor root development.
Memory trick: N-P-K: Nitrogen for leaves, Phosphorus for roots/flowers, Potassium for overall health.