8th Grade Science EOG Review #2

The table lists several statements about oceans and marine resources.

Which statement(s) listed in the table support(s) the fact that oceans are large reservoirs of carbon?

• 1 only

• 3 only

• 1 and 2

• 2 and 3

Biological oxygen demand (BOD) levels measure the oxygen needed by microorganisms to decompose organic matter present in water. The higher the BOD levels, the more organic pollution is present. The graph shows the water quality monitoring results in an area for a period of three years.

What can be correctly concluded from the graph?

• A. Since the overall levels of water pollution are decreasing, some of the water quality laws can be more flexible.

• B. Since the overall levels of water pollution are increasing, stricter water quality laws are needed.

• C. Since the overall levels of water pollution are remaining the same, the water quality laws should remain the same.

• D. Since the overall levels of water pollution are increasing only in the middle range, no changes to the water quality laws are needed.

A researcher recorded the turbidity levels of a lake for three years. He observed that the turbidity levels of the lake have increased every year.

What could be a possible effect on aquatic life if turbidity levels continued to rise?

• A. It would increase the organic content, causing an increase in the fish population.

• B. It would increase the nutrient content, causing an increase in the growth of plants.

• C. It would increase water temperature, causing an increase in dissolved oxygen levels.

• D. It would increase organic pollution, causing harm to aquatic organisms.

The table lists three examples of different levels of organization within an ecosystem (P, Q, and R).

Which model best represents the levels of organization of P, Q, and R?

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What is the likely source of pollution if there are frequent algal blooms in a river?

• A. warm water discharge from nearby factories

• B. fertilizer runoff from nearby farms

• C. acidification of the water from acid rain

• D. oil discharge from a nearby oil rig

A student studies a portion of the periodic table of elements.

Which element is most likely found in a gaseous state at room temperature?

• A. Al

• B. Ar

• C. Ba

• D. Br

The red wolf, found in North Carolina, preys on white­tailed deer. What would be the effect of an increase in the population of the red wolf on the population of white­tailed deer and local vegetation?

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The diagram shows the oceanic zones based on depths and the amounts of sunlight penetration.

Which zone(s) would contain most oceanic plants and animals?

• A. aphotic zone only

• B. aphotic and dysphotic zones

• C. dysphotic and euphotic zones

• D. euphotic zone only

A student is given a blank periodic table and asked to shade the region where nonmetals are located. Which periodic table correctly shows the nonmetals?

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The United States uses a process called dredging to remove layers of sediment at the bottom of an ocean in hopes of finding the valuable minerals. What is a potential danger of dredging an ocean?

• A. Dredging increases the amount of sunlight that reaches plants on the bottom of the ocean, causing their populations to increase.

• B. Dredging disturbs toxic materials that have settled to the bottom of the ocean, causing the toxins to poison the food chain.

• C. Dredging increases the levels of dissolved oxygen at the bottom of the ocean, causing fish populations to decrease.

• D. Dredging disturbs the bedrock at the bottom of the ocean, causing excess magma and minerals to enter the food chain.