Ecosystems

An increase in the population of an organism would most likely be associated with which of the following?

• A series of severe weather events in the habitat

• A decrease in necessary resources available

• An increase in animals that prey on the organism

• An expansion of suitable living space

What data would be most helpful to support the claim that the population of a certain plant is dependent on the rainfall in its habitat?

• Rainfall amounts and number of these plants in a certain habitat over several years

• The average amount of water absorbed by the roots and given off by the leaves of these plants

• The amount of water retained in the soil in the area where the plants live

• The heights and number of leaves produced by these plants under different moisture conditions

Adult monarch butterflies lay their eggs in milkweed, and then caterpillars eat that same plant during their development. Based on the relationship between monarchs and milkweed, which of the following trends would be predicted when looking at data on the populations of these two organisms?

• Population of milkweed should remain constant when monarch butterfly population increases.

• Population decrease in monarch butterflies should follow population decrease in milkweed.

• Population increase in monarch butterflies should follow population decrease in milkweed.

• Population of monarch butterflies should remain constant when milkweed population decreases.

Eagles and grizzly bears live together in the same habitat. There will be competition between the eagles and the grizzly bears only if which of the following is true?

• Grizzly bears hibernate during the winter while eagles remain active.

• Laws prevent humans from being able to hunt eagles or grizzly bears.

• Both grizzly bears and eagles feed on the same species of salmon.

• Pesticides in the fish population affect eagles’ eggs and decrease their population.

An increase in which of the following factors is likely to contribute to competition between two members of the same species living in a certain habitat?

• Overall size of the habitat

• Available food resources

• Annual rainfall

• Population of the species

A student wants to investigate competition between two organisms. For the investigation, it is most important that the student should choose organisms that–

• reproduce at the same rate.

• are both active during the day.

• have the same adaptations.

• require the same resources.

Two species of fish live in the same pond. They eat the same kinds of plants. They are eaten by the same water birds. Which of the following would increase competition between these two species of fish?

• Average habitat temperature increases

• Population of water birds increases

• Number of food plants increases

• Water level in the pond decreases