Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

What is a consequence of the phosphorus cycle being disrupted?

1. Increased water temperature

2. Reduced agricultural production

3. Overpopulation of species

4. Decreased rainfall

The correct answer is: Reduced agricultural production

A disruption in the phosphorus cycle primarily impacts the availability of phosphorus, an essential nutrient for plant growth and agriculture. Phosphorus is a critical component of DNA, RNA, and ATP, which are vital for energy transfer and genetic information within living organisms. When the phosphorus cycle is disrupted, it can lead to a shortage of this nutrient in soils, making it difficult for plants to grow and thrive. This directly results in reduced agricultural production, as crops may not receive the necessary nutrients to achieve their full growth potential. The other options pertain to environmental changes that are not directly linked to disruptions in the phosphorus cycle. Increased water temperature is more closely associated with climate change and aquatic ecosystems, overpopulation of species results from ecological imbalances or changes in predator-prey relationships, and decreased rainfall is often tied to broader climatic shifts rather than specifically to nutrient cycles. Thus, the direct link between phosphorus availability and agricultural output makes the answer about reduced agricultural production the most relevant consequence of a disrupted phosphorus cycle.