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

What is the primary outcome of the water cycle for living organisms?

1. Photosynthesis

2. Respiration

3. Excretion

4. Source of hydration

The correct answer is: Source of hydration

The primary outcome of the water cycle for living organisms is the provision of hydration, essential for survival. Water is a critical resource for all forms of life, as it plays a vital role in various biological processes, including cellular function, nutrient transport, and temperature regulation. Through the water cycle, which involves processes such as evaporation, condensation, precipitation, and infiltration, water moves continuously through the environment, replenishing freshwater sources. This availability of water enables organisms to carry out essential life functions. While photosynthesis, respiration, and excretion are important biological processes, they depend on water availability to occur efficiently. Photosynthesis requires water as a raw material, and respiration involves water as a metabolic byproduct. Excretion also involves water in the removal of waste products from the body. However, these processes are secondary to the direct and fundamental need for hydration that arises from the water cycle. Thus, the primary outcome remains the provision of hydration, which is crucial for sustaining life.