Interdependence and Competition

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.

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Which types of native organisms do feral hogs most likely compete with for food sources?

• Carnivores and producers

• Herbivores and carnivores

• Producers and decomposers

• Decomposers and herbivores

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NGSS.MS-LS2-1

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Giant salvinia is an aquatic plant that floats on water and reproduces rapidly. When these plants die, decomposition by bacteria affects oxygen levels in the water. As more plants die, less oxygen is available in the water. Students observe a pond covered by giant salvinia. Which statement is the best prediction the students can make about the immediate future of the pond?

• The depth of the water in the pond will increase.

• Fish populations in the pond will begin to decrease.

• The amount of bacteria in the pond will suddenly decrease.

• The number of different types of plants around the pond will increase.

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NGSS.MS-LS2-1

NGSS.MS-LS2-4

A scientist added bacteria and a nutrient medium that could support the growth of the bacteria to a sterilized petri dish. No other materials were added. The graph models growth of the bacteria over time. Which of these most likely explains why the bacterial population stopped growing?

• The bacteria competed for nutrients and died after all the nutrients were consumed.

• The bacteria did not reproduce in the system, and eventually each individual died at the end of its life cycle.

• The bacteria mutated from photosynthetic to carnivorous organisms and consumed one another until all the individuals were dead.

• The bacteria became diseased and were unable to survive in the closed system.

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Four students were asked to create a graph representing a typical predator–prey relationship. Which graph shows a situation in which the number of predators in a population depends on the number of prey?

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NGSS.MS-LS2-2

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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

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NGSS.MS-LS1-5

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The Prairies Region and the Cross Timbers are located in north-central Texas. The graph below shows information about eating habits of white-tailed deer in these regions. A Cross Timbers rancher is concerned about competition between the ranch animals and the deer. Based on the graph, which ranch animals compete for the most food with white-tailed deer?

• Cattle that eat grass and feed

• Goats that eat weeds and shrubs

• Turkeys that eat seeds and fruit

• Hogs that eat fruit, seeds, and feed

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NGSS.MS-LS2-1

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Fish in a lake have to compete for space. Different fish have different optimal temperature ranges. The graph below shows the temperature ranges of four fish species. At which temperature range will there be the most competition for space among these fish species?

• 5°C to 10°C

• 10°C to 15°C

• 15°C to 20°C

• 25°C to 30°C

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NGSS.MS-LS2-1

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

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NGSS.MS-LS2-1

Animals from two different species utilize the same source of nutrition in one area. It is most accurate to say that the animals…

• will learn to get along

• will compete for food

• will die because there will not be enough food for both of them

• will learn to eat different foods

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NGSS.MS-LS2-1

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