Ecosystems and Food Webs25 Study Guide

As an insect population decreases, which would most likely also decrease?

• hawk population

• vulture population

• sparrow population

• hummingbird population

Answer explanation

As insect populations decrease, sparrows, which primarily feed on insects, would likely decline due to food scarcity. In contrast, hawks and vultures have broader diets, and hummingbirds rely on nectar, making them less directly affected.

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Under which condition would a population most likely increase?

• The carrying capacity exceeds the habitat area

• The number of deaths exceeds immigration rate.

• The number of deaths exceeds the number of births

• The amount of available resources exceeds the carrying capacity

Answer explanation

A population is most likely to increase when the amount of available resources exceeds the carrying capacity, as this allows for more births and less competition for resources, supporting growth.

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Which of these is an abiotic element of a desert environment?

• sand

• cactus

• lizard

• scorpion

Answer explanation

Sand is an abiotic element of a desert environment, as it is a non-living component. In contrast, cactus, lizard, and scorpion are all biotic elements, as they are living organisms.

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Which does every organism in an ecosystem need for survival?

• animals

• plants

• water

• soil

Answer explanation

Every organism needs water for survival as it is essential for various biological processes, including hydration, nutrient transport, and temperature regulation. While plants and animals are important, water is a fundamental necessity for all life.

Estuaries often have marsh grasses that act as a safe nursery for young fish. Which limiting factor, provided by estuaries, does this describe?

• food

• space

• shelter

• predators

Answer explanation

The marsh grasses in estuaries provide shelter for young fish, protecting them from predators and harsh environmental conditions. This safe nursery environment is crucial for their growth and survival.

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After a forest fire, plants come back in abundance. Which limiting factor to plant growth is removed?

• food

• prey

• space

• water

Answer explanation

After a forest fire, the removal of trees and other plants creates more space for new growth. Thus, the limiting factor of space is removed, allowing plants to thrive in the newly available area.

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If wolves prey on deer for food, what will most likely happen to the deer population if wolves are removed from an area where deer live?

• The population of deer will increase

• The population of deer will decrease

• The population of deer will remain the same

• The population of deer will become extinct

Answer explanation

If wolves, the primary predators of deer, are removed from an area, there will be less predation on deer. This reduction in predation pressure will likely lead to an increase in the deer population.

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Which best describes a parasitic relationship?

• Both organisms benefit

• Neither organism benefits

• One organism benefits, while the other is unaffected

• One organism benefits, while the other organism is harmed

Answer explanation

A parasitic relationship is characterized by one organism benefiting at the expense of another. In this case, the parasite gains resources or advantages while harming the host organism.

What type of relationship exists between wolves who hunt together for food

• cooperation

• mutualism

• parasitism

Answer explanation

Wolves that hunt together exhibit cooperation, as they work as a team to increase their chances of successfully capturing prey. This mutual effort benefits all involved, distinguishing it from mutualism or parasitism.

In a beehive, different bees have different jobs which help to ensure the survival of the hive. Which is being demonstrated?

• communsalism

• cooperation

• competition

Answer explanation

The different jobs performed by bees in a hive, such as foraging, nursing, and defending, illustrate cooperation. Each bee contributes to the hive's survival, demonstrating how working together benefits the entire colony.