8.11BC Preview

A company purchased a large forest and cut the trees for lumber. Sunlight which had not reached the forest floor before was now very bright on the bare ground. Holly ferns began to grow rapidly because of increased access to light and moisture.Which population of organisms would be in direct competition with the Holly ferns for the same resources?

• Spotted owls

• Squirrels

• Hawks

• Wildflowers

Plants need sunlight to perform photosynthesis. In the tropical rainforest, the survival of a plant depends upon its ability to adapt in order to reach sunlight.

Which of the following is an example of one such adaptation?

• Vines that wrap around a tree

• Thin, shallow roots that run across the forest floor

• Numerous small leaves on one stem

• Colorful petals

Which of the following is NOT an example of how biotic factors interact with abiotic factors in an ecosystem?

• A lion preys on a herd of gazelle.

• Plants remove carbon dioxide from the air and add oxygen.

• Animals cause erosion by digging in the dirt.

• A lizard raises its body temperature by using heat from the Sun.

Which organisms are in competition for the same food source?

• Fox and owl

• Spider and fly

• Rabbit and mouse

• Deer and owl

The graph below shows the percent of seeds from two plant species that sprout when grown in water containing different amounts of salt.

Which of the following best summarizes the effect of saltwater on these plant species?

• Species 1 can sprout only in freshwater, and Species 2 can sprout only in saltwater.

• Both species can sprout in freshwater and saltwater, but Species 2 can sprout in a higher salt concentration than Species 1.

• Both species need salt in their water, but Species 2 needs more salt than Species 1.

• Species 1 can sprout only in water with a low salt concentration, but Species 2 is not affected by the salt concentration.

Which organisms in the food web shown above compete for the same food source in this environment?

• Grasshoppers and snakes

• Hawks and frogs

• Frogs and snakes

• Decomposers and grasses

The graph below shows the range of water conditions preferred by three species of fish in an Ozark stream.

Water with which of these conditions would cause the most competition for resources among all three species of fish?

• Very cold, very clear, and very fast

• Very warm, very clear, and very slow

• Mild temperatures, some suspended particles, flows very fast

• Mild temperatures, some suspended particles, flows at a medium speed

A scientist named Joseph Connell studied two species of barnacles on the shore of a Scottish island. In the area between the average tide and the neap high tide, he found that the population of Species A was smaller than that of Species B. He removed Species B from one area but left both Species A and B in a similar area. The graph below shows the results of this study.

Based on these data, which hypothesis was Connell most likely testing?

• The populations of both species of barnacles increase more in warm water than in cool water.

• Barnacles grow larger when they are isolated from other species.

• The two species of barnacles compete with each other for resources.

• The two species of barnacles are closely related to each other.

Black walnut trees produce a nontoxic chemical that becomes highly toxic when it is exposed to air or soil. How does this chemical help black walnut trees compete with plants growing nearby?

• By attracting herbivores to the other plants

• By suppressing the growth of the other plants

• By increasing the photosynthesis rates in the other plants

• By limiting the amount of water available to the other plants

Molly filled up three 2 liter jars with aged water and stuck an aquarium thermometer inside each jar. After a couple of days, she added 1 stalk of Elodea to jar 1, 1 stalk of Elodea and 1 guppy to jar 2, and 1 guppy to the jar 3. Predict what happened in Molly’s experiment.

• Because animals and plants are interdependent, the fish in jar 3 quickly ran out of dissolved oxygen and showed signs of distress.

• The fish in jar 2 showed signs of distress because the production of oxygen by the Elodea was insufficient.

• The temperature in jar 1 dropped too low and the plant died.

• Because there were no fish in jar 1, the plant in jar 1 increased in size.