GED Science Test

The Sahara Desert and the Nile River are the two components of Egypt′s natural environment. In Egypt, 99% of the population lives on only 5.5% of the total area, residing along the banks of the Nile. This small percent represents the only farmland in Egypt. Annual flooding of the Nile supplies water for crop production. Without this water source, civilization in Egypt would be very different.

2

Records indicate that a drought caused the demise of Egypt′s Old Kingdom (2686–2181 BCE). Because of an insufficient water supply, food production decreased, the population suffered from famine, and the political system destabilized. Scientists have recently investigated whether other evidence supports the theory that a shift in climate led to political upheaval in Egypt about 4,200 years ago.

3

One group of researchers removed a sediment core from the Nile delta. The layers within this sediment core allowed researchers to investigate environmental conditions over thousands of years. The researchers hypothesized and observed that periods of low concentrations of pollen from wetland plants and elevated concentrations of microscopic charcoal would occur together, indicating a decrease in vegetation and an increase in natural fires during drought years.

4

A second group of researchers also examined sediment cores by analyzing shifts in the amounts of sediment deposited over time. These researchers hypothesized that a decrease in rainfall would correspond to diminished vegetative cover, which in turn would lead to an increase in erosion. This increase in erosion represented drought-like conditions and could be observed as larger deposits of sediment within the cores.

Use the drop-down menus to complete the hypothesis of the first group of researchers.

During a drought, the decrease in rainfall will reduce the amount of vegetation that can grow and increase the occurrence of natural fires, so an elevation in

charcoal

charcoal and a reduction in

pollen

wetland plants should be found in the cores

Use the drop-down menus to complete the hypothesis of the first group of researchers.

During a drought, the decrease in rainfall will reduce the amount of vegetation that can grow and increase the occurrence of natural fires, so an elevation in

charcoal

charcoal and a reduction in

pollen

wetland plants should be found in the cores

3. Scientists today are studying tidal power as an alternative energy source for generating electricity. Some scientists conclude that tidal power is a good alternative source of energy because it uses a natural process, does not rely on fossil fuels, and does not release greenhouse gases. These scientists recommend building tidal power plants around the United States in locations with high tidal power potential. Other scientists conclude that tidal power is not a good alternative energy source because tidal power plants can negatively impact the surrounding ecosystem by killing marine animals, restricting fish migration, reducing the natural flow of water, and causing silt buildup in waterways. These scientists recommend not building tidal power plants in U.S. waterways.

Both conclusions are based on valid data and scientific reasoning. How can both conclusions be valid?

A.The two groups of scientists believe different theories about the process of generating electricity.

A.

The two groups of scientists believe different theories about the process of generating electricity.

B.The two groups of scientists are looking at different specific aspects of the same scientific problem.

B.

The two groups of scientists are looking at different specific aspects of the same scientific problem.

C. The two groups of scientists collect and analyze data about all types of possible alternative energy sources

C.

The two groups of scientists collect and analyze data about all types of possible alternative energy sources.

D.The two groups of scientists are on opposite sides of the debate on whether the United States needs to find clean alternative energy sources.

D.

The two groups of scientists are on opposite sides of the debate on whether the United States needs to find clean alternative energy sources.

6.

Use the drop-down menus to complete the hypothesis of the first group of researchers.

During a drought, the decrease in rainfall will reduce the amount of vegetation that can grow and increase the occurrence of natural fires, so an elevation in