Activity 7: Biology to Go

1. The processes in the water cycle and their description are:

• Evaporation occurs when liquid water is turned into water vapor.
• Condensation occurs when water vapor is turned into liquid with very low temperature.
• Precipitation occurs when water from the atmosphere returns to the Earth’s surface as either liquid or solid in the form of rain, snow, hail, or sleet.
• Life processes involve the living organisms that contribute water into
  the atmosphere through cellular respiration and transpiration.

2. The Sun is the energy source that drives the water cycle.

3. People in the United States live where there is water. This excludes the desert
because of the scarcity of water. With modernization, however, water is made available even in the desert areas like Las Vegas. Preference for areas where
there are large bodies of water is also seen. These areas provide milder climates and temperatures that are not extreme.

4. If the water cycle or hydrologic cycle stopped functioning, then life would cease
to exist. With the loss of 1200 km3 of water each day from the ocean, land plants, and ice caps, water would eventually disappear and would never get to be replenished. With no formation of precipitation, drought would become common and death to all living things would result.

• With increasing human population, there is more demand on the freshwater resource, which remains constant. The big demand caused by the increasing population will result in very scarce freshwater resource.
• With increasing population, an increase in the number of industries results, which produces more domestic, agricultural, and industrial wastes. These can overload water supplies with hazardous chemicals and bacteria.
• With the clearing of forested areas for human purposes, natural drainage patterns are replaced by road drains, sewer systems, and paved land. These factors put increased pressure on the water cycle.
• Pollutants discharged into the air from fossil fuel burning, automobile combustion, and nitrogen fertilizer processing, release sulfur and nitrous oxides. These oxides enter the atmosphere where they combine with water droplets and form acids. They return to the Earth in the form of acid precipitation.