Competition

A forest area of California experienced a wildfire 3 years ago. Since the fire, secondary succession has taken place. Researchers have observed the following numbers of different sized plants. What is the best explanation for the recent decline in the number of grasses on the forest floor?

• The small trees and shrubs now cast shadows on the ground and grasses can no longer get the sunlight they need to thrive

• The grasses can no longer get the amount of water they need to thrive

• The small trees have taken up all the space in the soil

• The average temperatures have risen too high for the grasses to continue to grow

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NGSS.MS-LS1-5

NGSS.MS-LS2-1

NGSS.MS-LS2-4

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

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NGSS.MS-LS1-5

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Which of the following must be true in order for competition to take place (select all that apply)?

• The competing organisms must be a part of the same ecosystem

• Only two individual organisms can compete for the same resource

• The competing organisms must compete for the same limited resource

• The competing organisms must compete for only biotic factors

• The competing organisms must compete for only abiotic factors

Anna recorded the growth of several backyard plants last summer. She noted the amount of sunlight and water needed for each plant. This summer there are strict water restrictions because of a drought. Using the information in Anna's chart, which of the following is the most likely result for her backyard in a drought?

• The Sedges and Rosemary will compete for light resources

• Only the Fountain Grass and Easter Redbud will survive the drought

• The Fountain Grass will replace the Honey Mesquites and Sedges

• The Sedges and Honey Mesquites will be the only plants to survive

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NGSS.MS-LS1-5

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List the steps of the scientific method

d

e

f

c

b

a

Conduct experiment

Communicate results

Analyze results

Ask a question

Draw conclusions

Form a hypothesis

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NGSS.MS-PS2-2

Which letter represents amplitude? (a)  

• A

• B

• C

• D

• E

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NGSS.MS-PS4-1

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

• 5°C to 10° C

• 10° to 15°C

• 15° to 20°C

• 20° to 25°C

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NGSS.MS-LS2-2

An earthworm farmer wanted to grow three species of earthworms, but earthworms can be very picky about the temperature, moisture, and pH balance of their soil. This graph shows the range of soil conditions preferred by three species of earthworms in an earthworm soil bed.
Which of these conditions would cause the most competition for the resources among the three species of earthworms?

• Very warm soil, ph of 6, and dry.

• Very cold soil, pH of 7, and high moisture.

• Moderate temperature, pH of 6.5, and moderate moisture.

• Moderate temperature, pH of 7.0, and high moisture.

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NGSS.MS-LS2-1

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Which organism do the owl and the weasel compete for in the food web?

• Hawk

• Spider

• Grasshopper

• Shrew

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NGSS.MS-LS2-2

Bromeliads are small plants that grow attached to the sides of large trees high above the ground in warm, damp and densely crowded tropical rainforests. Bromeliads do this because they are in competition with other plants for -

• soil.

• heat.

• light.

• water.

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NGSS.MS-LS1-5

NGSS.MS-LS2-1