STAAR Review - Watersheds

Subsidence, the sinking of the surface of the earth, would most likely be caused by which of the following human activities?

• Filtering out pollutants at a water treatment plant
• Storing drinking water in small above-ground basins
• Using toxic chemicals in the manufacturing of goods
• Excess removal of water from underground reserves

A student builds a model to show how pollutants move through an ecosystem. In a plastic tub, the student places a layer of small marbles, covers it with a thick cloth, and then adds a layer of sand. The student sprinkles red powdered paint on top of the soil.
When the student sprays water onto the model, red color appears in the cloth and in the water in the layer of marbles.
Which part of the model represents pollutants introduced by humans?

• Layers of sand
• Red powdered paint
• The thick cloth
• The marbles

The illustration provided shows a river and four cities on that river. When the water from the river was sampled at location X, it was determined to be polluted with various chemicals. What would be the most likely source for this pollution?

• City 1 and City 2
• City 2 and City 3
• City 3 and City 4
• City 1 and City 4

How might runoff from farms adding fertilizer to a pond have a negative effect?

• Rapid growth of algae could cover the pond, cutting off sunlight to other organisms.
• Increased volume in the pond will make it harder for fish to find food.
• Chemicals in the fertilizer could enter the soil around the pond and be trapped there.
• Fertilizers could speed the rate of deposition of sediments in the pond.

Which statement best explains why it is better to use surface water rather than ground water for human use whenever possible?

• Surface water is never contaminated by pollution.
• Aquifer water has a very low phosphorus content.
• Water taken from aquifers is replaced very slowly.
• Surface water has higher levels of dissolved oxygen.