Environmental Changes vs Population Size

A foreign insect is introduced into the Texas. It eats a lot of leaves, and trees start to become leafless. Many different animals feed on the new insect, but even they cannot control its numbers. Eventually, trees begin to die. Why would a rapid increase of the new insect population cause certain species of herbivores to vanish or be fewer in number?

• They would not have enough to eat. 
• They would not have enough space to live.
• They would not have tree bark to eat.

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CCSS.RI.3.3

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A manatee is a water-dwelling herbivore on the list of endangered species. If manatees were to become extinct, what would be the most likely result in areas where they had lived?

• Certain producer organisms would become more abundant in the area.

• The area would not be affected.

• Predators in the area would have more food to eat.

Scientists are concerned about overfishing of shark populations. Sharks feed on rays and rays feed on scallops. Without sharks, rays consume all the scallop beds. This situation demonstrates that:

• humans can improve an ecosystem by removing predators.

• humans can upset an ecosystem by removing species.

• sharks are not important for the stability of the ecosystem.

Raccoons eat aquatic animals. If chemicals entered the lake with rain water and destroyed the plants, how would this impact the raccoon population?

• Raccoons would have more aquatic animals to eat.

• Raccoons would begin eating land plants.

• Raccoons would have less aquatic animals to eat.

A park is home to a large number of robins, squirrels and rabbits. The robins and squirrels live in the park’s trees. The robins feed on earthworms and insects that live on the ground. The squirrels eat the acorns produced by the park’s oak trees. The rabbits hide in the bushes and feed on the grass. Which factor would negatively impact the number of rabbits living in the park?

• Collecting acorns off the ground.

• Planting more trees.

• Removing park bushes.

Which of the following would have a negative impact on an ecosystem

• constructing highways
• planting trees
• recycling paper

What do scientist call organisms that are not native to an ecosystem and cause harm to native organisms?

• native plants
• invaders
• invasive species
• natural species

Which is NOT an example of a short term environmental change?

• flooding

• a hurricane

• a tornado

• climate change

There are many large-mouth bass, a type of fish, living in a small lake near Waco, Texas. How would increased fishing in the lake effect the lake ecosystem?

• Predators of the bass might starve due to loss of a food source

• The population of the bass’ prey would decrease.

• The bass would spend more time swimming near the surface

If a disease destroying barley plants in a field swept through an ecosystem, what would happen to the barley eating bird population in the the field ?

• The bird population would stay the same
• The bird population would increase fast
• The bird population would decrease