Chapter 8: Living Systems and the Environment

Which is an example of an effect an abiotic factor could have on a population in an ecosystem?

• An insect invasion kills a population of trees.

• An increase in rainfall causes an increase in the population of many plants.

• A fungus infects a population of bats, and many of the bats die.

• An increase in fruit flies leads to an increase in a population of spiders.

Answer explanation

Rainfall is an abiotic factor. TEKS 6.12A

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Examine the image.

Which hierarchical level of organization does the image represent?

• organism

• population

• community

• ecosystem

Answer explanation

The image has various populations of different species in the same area, which is a community. TEKS 6.12C

Which type of relationship includes parasitism and commensalism?

• symbiotic

• predatory

• competitive

• cooperative

Answer explanation

Symbiotic relationships include parasitism, commensalism, and mutualism. TEKS 6.12B

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Nutria are large semiaquatic rodents that were imported from South America to the United States by fur traders. In the late 1940s, a hurricane dispersed nutria throughout southeast Texas. They feed on native seedlings and saplings—native organisms that are naturally found in the ecosystem—and have cleared wide areas of floodplains and marshland along the Gulf Coast.

Which is most likely the effect of the introduction of nutria into southeast Texas ecosystems?

• The nutria depend on native herbivores for food.

• The nutria compete with native organisms for abiotic factors.

• The nutria compete with native herbivores for food.

• The nutria compete with native carnivores for food.

Answer explanation

Nutria are not native organisms. They were brought to the area by a hurricane. They will compete with native herbivores for the food in that area. TEKS 6.12B. 6.12A

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Which is a population?

• all tigers in a refuge

• all the types of fish in a lake

• all the types of reptiles in a zoo

• all the types of rodents on a prairie

Answer explanation

A population is all the organisms of the same species that live in the same area at the same time. TEKS 6.12C

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Predators capture weak members of a population as prey. How does this benefit the population of the prey?

• The remaining members are motivated to fight back against the predator.

• The predators take all of the prey population’s resources.

• More resources become available for the remaining members.

• Less resources become available for the remaining members.

Answer explanation

If predators remove the weak members of a population as prey, there will be more resources available for the remaining members. TEKS 6.12B

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Pink salmon return to the same waters in which they were born to mate. Researchers collected data on the pink salmon returning to Auke Creek and the average water temperature. Table 1 shows the calendar dates of the highest percentage of pink salmon returning to Auke Creek in Juneau, Alaska, to mate in six years spanning from 1971–2010. Table 2 shows changes in the creek during the same time period.

The data in Table 1 and Table 2 show the relationship between salmon and which abiotic factor?

• water availability

• atmosphere

• temperature range

• light availability

Answer explanation

The data supports the statement that salmon depend on specific temperature ranges to reproduce. TEKS 6.12B, 6.12A

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Which statement correctly describes commensalism?

• one organism benefits and the other is harmed in the relationship

• one organism benefits and the other is unaffected in the relationship

• both organisms benefit in the relationship

• both organisms are harmed in the relationship

Answer explanation

In a commensal relationship, one organism benefits and the other is unaffected. TEKS 6.12B

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Bees and flowering plants share a mutualistic relationship. Bees receive the nectar they need to make honey, while the flower is pollinated by the bees. What might happen if all the bees were to disappear?

Answer explanation

They won’t be able to pollinate the flowers, so the flowers may die. TEKS 6.12B

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A shrimp removes and eats the parasites from the gills of a fish. The fish stays healthier because the parasites are removed. What is this relationship an example of?

• commensalism

• mutualism

• parasitism

• competition

Answer explanation

Mutualism is a relationship in which both species benefit, and both the shrimp and the fish benefit. TEKS 6.12B