Ecosystems 20-21

In a grassland ecosystem, mice and rabbits eat plants. Hawks eat mice and rabbits. Suppose a disease kills many of the rabbits in the grassland. Which of the following is most likely to occur?

• The mice will move to another grassland.

• The hawks will eat more mice.

• The mice will run out of food.

• The hawks will begin to eat plants.

Which population would most likely increase (get bigger) if a chemical was used to kill insects and most of the grasshoppers in the ecosystem died?

• Raccoons

• Grass

• Frogs

• The loss of grasshoppers will not affect other populations in the ecosystem.

Hurricanes usually cause flooding in Eastern North Carolina. Heavy rainfall and runoff cause rivers to carry more freshwater than usual down the river to the salt marshes and estuaries near the coast. The additional freshwater eventually flows into the ocean. How might heavy rainfall and flooding affect ecosystems in Eastern North Carolina?

• Flooding will only affect plants in the salt marshes, estuaries, and shallow areas of the ocean.

• Flooding will affect the organisms and the salinity of the salt marshes, estuaries and shallow areas of the ocean.

• Flooding will only affect animals in the salt marshes, estuaries, and shallow areas of the ocean.

• The flooding will not affect the salt marshes, estuaries, and shallow areas of the ocean.

Rabbits eat filed grains such as wheat and oats. Great horned owls eat rabbits. Bacteria feed on the wastes of organisms and decaying (nonliving) organisms. Which would most likely cause the population of great horned owls to decrease (get smaller)?

• An increase in the number of field grain plants

• A decrease in the number of bacteria

• An increase in the number of rabbits

• A decrease in the number of rabbits

Eelgrass is a flowering underwater plant. It has wide green leaves and its roots anchor the plan in the muddy sand or soil. Eelgrass is a source of food for birds and turtles in an estuary ecosystem. What might happen to the bird and turtle populations in the estuary ecosystem if eelgrass is removed to build a bridge?

• The turtle population might increase and the bird population might decrease.

• The turtle population might decrease and the bird population might increase.

• Both the turtle and bird populations might decrease.

• Both the turtle and bird populations might increase.

Uwharrie National Forest is a forest ecosystem in the Piedmont region of North Carolina. There are balanced populations of plants, animals and fungi. Suppose a flu-like disease kills almost all of the owls and hawks during winter. The owls and hawks that will survive will leave the forest in order to find new mates in the spring. Which of the following is most likely to occur with the owls and hawks gone?

• More young mice will survive and become adults.

• There will be more trees and grass.

• Red foxes will stay for a while then leave to find the owls and hawks.

• The insect population will decrease.

In a forest ecosystem, trees provide a habitat for both birds and squirrels. Acorns from oak trees are an important food source for squirrels. Berries and seeds from shrubs and plants are an import food source for birds. Suppose several trees are cut down and the land is cleared to build a shopping center and parking lot. How much cutting down the trees and clearing the land change the forest ecosystem?

• Squirrels and birds will lost their habitats.

• Soil erosion might occur because trees and other plants are removed.

• There will be less food for squirrels and birds to eat.

• All of the above are possible changes to the forest ecosystem.

An algae bloom is a sudden increase in the algae population. In can disrupt a balanced ecosystem by blocking out sunlight in the shallow areas of the ocean and adding toxins (chemicals) to the water. Suppose a harmful algae bloom kills plankton, fish larvae, and plankton-eating fish. How might the loss of organisms affect other organisms in the ocean ecosystem?

• The tuna will survive by eating sharks.

• Some of the squid will survive, some will die, and some will move to another part of of the ocean in search of a food source.

• The shark population will increase in the part of the ocean.

• The loss of plankton, fish larvae, and plankton-eating fish will have no effect on other organisms.

Suppose the population of tina in a part of the ocean decreases because more tuna are caught by commercial fishers. How might a decreasing population of tuna affect other organisms?

• Some sharks will survive and some will move to another part of the ocean in search of a food source.

• The population of smaller, plankton eating fish and squid might increase in that part of the ocean.

• A smaller tuna population will cause an algae bloom.

• Both answer choices A and B.

What will be most affected if the decomposers in an ecosystem are removed?

• the spread of disease

• the availability of water

• the quality of soil

• the distribution of organisms