ACT Science Practice Test 60

PASSAGE VI

Carbon monoxide (CO) is a colorless, odorless gas produced by burning material that contains carbon, such as coal or natural gas. Carbon monoxide is the leading cause of accidental poisoning deaths in America. The Centers for Disease Control estimates that carbon monoxide poisoning claims nearly 500 lives and causes more than 15,000 visits to hospital emergency departments annually. Common household appliances produce carbon monoxide. When not properly ventilated, carbon monoxide emitted by these appliances can build up. The only way to detect carbon monoxide is through testing, using a specialized sensing device.

Gas stoves have been known to emit high levels of carbon monoxide. Average carbon monoxide levels in homes without gas stoves vary from 0.5 to 5.0 parts per million (ppm). Levels near properly adjusted gas stoves are often 5.0 to 15.0 ppm and those near poorly adjusted stoves may be 30.0 ppm or higher. CO levels between 0.5 and 15.0 ppm are considered safe.

Table 1 shows the carbon monoxide levels in ppm for each of five homes, with and without gas stoves.

PASSAGE VII

Turf grasses are used throughout the United States in many suburban lawns. Kentucky bluegrass is the most common type of turf grass used in the northern part of the United States. To keep lawns green and healthy, many homeowners apply fertilizer up to five times a year. Inorganic fertilizers are becoming more popular, and contain three common elements - nitrogen, phosphorous, and potassium - for the development of plant color, strength, and health. Most turf grass lawns do not use all of the nutrients provided in the fertilizer, which means that much of the nitrogen, phosphorous, and potassium remains in the soil. When water enters the soil, it accumulates a portion of the excess nitrogen from the soil. This water, now termed leachate, flows into surrounding waterways. The leaching of high concentrations of nitrogen into natural waterways can throw off the environmental equilibrium of the aquatic ecosystem, often resulting in an increase in plant growth that can have a negative impact on the native fish populations.

A study was performed to examine the degree of nitrogen leaching in Kentucky bluegrass turf; 2 one-acre plots of turf were compared. The scientists conducting the study relied completely on natural rainwater to irrigate the test plots. Each plot received fertilizer applications containing different levels of nitrogen two times per week during the months of April and September for 5 years. The plots had a 5% slope to facilitate leaching; leachate was collected in one-liter jugs. The leachate collected from each plot was measured for nitrogen concentration.

Plot A received a low nitrogen application: 98 kilograms of N per acre from 2000 to 2004. Plot B received an initially high nitrogen application: 245 kilograms of N per acre from 2000-2003. In the last year of the study, the amount of nitrogen in the fertilizer was decreased to 196 kilograms of N per acre for Plot B. Table 1 shows the average nitrogen concentration in milligrams per liter (mg/L) in the leachate collected from each plot during each year. Figure 1 shows the percent concentration of nitrogen in the leachate.