Changes in Environment-Human Impact 22

Primary succession occurs when pioneer species move into an area that has no plants. Which organisms are common pioneer species?

• Conifer trees & tall grasses with roots that loosen the soil

• Mosses lichens that can grow on rocky surfaces

• Mosses lichens that can grow on rocky surfaces

• Vines and shrubs that help prevent the erosion of shallow soil

Both primary and secondary succession begin with pioneer species that-

• Change the area and make it safer from predatory organisms

• Invade the area so that new organisms cannot be established

• Modify the area and allow larger and more complex organisms to appear

• Use up all the existing resources and prevent establishment of non-native organisms

Some students take care of a vegetable garden. When it is time to plant in the spring. the students leave part of the garden empty in order to observe ecological succession. Which of these will most likely occur first?

• Development of top soil

• Growth of weeds and grasses

• Growth of trees and shrubs

• Development of a stream

Researchers are studying lichens growing on trees in a forest ecosystem. At the beginning of the study, the researchers identified twelve lichen species in the forest. Later a forest fire happened in the study area. The researchers return to the area and found only six lichen species. Which inference is best supported from the researchers observations?

• Most lichen species are unaffected by forrest fire

• The biodiversity in a forest increases after a fire

• Certain lichen species are better adapted to survive forest fires than others

• Forest fires will permanently remove certain species from the ecosystem

Parus major is a bird species that depends on caterpillars as a food source for its young. Caterpillars are most abundant during spring. The yearly increase in temperatures during springtime has gradually shifted, resulting in caterpillars developing approximately two weeks earlier than in the past. How will the changes in the availability of caterpillars most likely affect future populations of P. major?

• P. major will change their food source to plant leaves.

• P. major will lay their eggs earlier in the year

• P. major will decrease the number of eggs laid at a time.

• P. major will hunt caterpillars earlier in the day when temperatures are cooler.

A student observes several species of plants growing in a drainage ditch. Some species have short roots, will others have long roots. During periods of heavy rainfall, the ditch fills with fast moving-water, which uproots more plants that have short roots than long roots. Which short term effect will most likely result from a year with more heavy rain than normal?

• Most plants in the ditch will be plants with long roots.

• Most plants in the ditch will be plants with short roots.

• There will be no change in the numbers of plants with ling roots and short roots.

• There will be an equal number of plants in the ditch with ling roots and short roots.

An environment change drastically reduced the population of milkweed plants in an area. the milkweed plants provided the only source of food for a nearby population of monarch butterfly caterpillars. Which statement describes the most likely effect of this environmental change on it population of monarch butterflies?

• The number of monarch butterflies will decrease because their caterpillars will not have enough food.

• The number of monarch butterflies will stay the same because butterflies reproduce so rapidly their populations can withstand most food shortages.

• The number of monarch butterflies will stay the same because their caterpillars will begin consuming nectar from different types of flowers.

• The number of monarch butterflies will increase because their reproduction rate will increase to ensure some individuals survive.

A student's model of an area near the city depicts many activities that affect the quality of water in the area. How does the agricultural activity most likely affect the surface water of the area?

• Crops absorb pure water form the soil, causing the remaining water to contain more salt.

• Excess crop material on the riverbanks, slowing the movement of the river water.

• Crops reduce erosion, increasing the amount of soil entering the river.

• Excess crop fertilizer is carried by runoff into the river, causing excess growth of water plants.

A student drew a model below to represent a part of a watershed and some human activities that affect the watershed. How do the industrial, agricultural and residential activities of humans most likely affect the ground water in the area?

• The activities prevent most of the water from evaporating into the atmosphere.

• The activities replace the ground water used.

• Pollutants from the activities percolate through the soil and enter the water table.

• All of the above.

Some areas of the ocean are known as dead zones. these zones form when excess organic material decomposes. This increased decomposition uses up the oxygen from the water. Which human activity is most affected by the increasing number of dead zones in the ocean?

• Off shore oil drilling, because water in dead zones is toxic.

• Commercial fishing, because fish cannot survive with out oxygen.

• Commercial shipping, because dead zones change the course of ocean currents.

• Sand mining, because oxygen is not available to form the sands on ocean beaches