Short & Long Term Environmental Changes STAAR Bootcamp W9

Farmers spray insecticides to protect their crops from herbivorous insects. What is the most likely effect of spraying the same insecticides continuously for many years?

• The number of crops that carry a trait for insect resistance will increase.

• The number of crops that do not carry a trait for insect resistance will increase.

• The number of crops that are resistant to these insecticides will increase.

• The number of insects that are not resistant to these insecticides will increase.

Answer explanation

Continuously spraying the same insecticides will lead to the development of resistance in crops, increasing the number of crops that are resistant to these insecticides.

Buffelgrass is an invasive species of grass from Africa that out competes native Texas grasses for space and water. Which long-term change to a Texas grassland would most likely occur due to the introduction of buffelgrass?

• The population of native grasses will increase.

• The population of native grasses will decrease.

• Buffelgrass offspring will develop traits like those of native grasses.

• Buffelgrass offspring will develop traits like those of other invasive species.

Answer explanation

The population of native grasses will decrease as buffelgrass outcompetes them for space and water, leading to a decline in their numbers over time.

A student observes several species of plants growing in a drainage ditch. Some species have short roots, while others have long roots. During periods of heavy rain, 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 long roots and short roots.

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

Answer explanation

The heavy rain will uproot more plants with short roots, leaving mostly plants with long roots in the ditch.

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 returned to the area and found only six lichen species.

Which inference is best supported from the researchers' observations?

• Most lichen species are unaffected by forest 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.

Answer explanation

Certain lichen species are better adapted to survive forest fires than others, as indicated by the decrease in lichen species after the forest fire.

An environmental change drastically reduced the population of milkweed plants in an area. The milkweed plants provided the only source of food for nearby population of monarch butterfly caterpillars.

Which statement describes the most likely effect of this environmental change on this 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.

Answer explanation

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

To fight a bacterial infection, a patient was given an antibiotic to take for 10 days. After the patient finished taking the antibiotics as directed, almost all the bacteria were killed. After another 10 days, the patient was sick again with the same type of infection.

What most likely happened?

• A few bacteria survived the antibiotics and stopped reproducing.

• The patient's high fever inactivated the antibiotic, allowing the surviving bacteria to grow rapidly.

• The antibiotic slowed the life cycle of the bacteria.

• Some of the bacteria were resistant to the antibiotic, and they reproduced.

Answer explanation

Some of the bacteria were resistant to the antibiotic, and they reproduced.

DDR is a pesticide that was once widely used to control agricultural pests and mosquitoes. However, this pesticide caused the eggshells of certain birds, including the brown pelican, to become fragile and thin. The adults would then accidently crush the eggs while trying to incubate them.

What happened to brown pelican populations as a result of DDT use by humans?

• The populations increased much more slowly.

• The populations decreased as fewer eggs survived long enough to hatch.

• The population remained stable over time.

• The population increased as pelicans laid more eggs so that more offspring would survive.

Answer explanation

The populations decreased as fewer eggs survived long enough to hatch due to the thin and fragile eggshells caused by DDT pesticide.

Trees lose water through transpiration, when water evaporates from leaves. The list describes types of tree leaves that help reduce the amount of transpiration.

Which of these is most likely observed in an area experiencing a long-term drought?

• Trees with broad leaves will be more healthy than trees with needlelike leaves.

• Trees with leaves that have waxy coverings will be more healthy than trees without wax-covered leaves.

• Trees with broad leaves will be more healthy than trees with small, flat leaves.

• Trees with leaves without any hairlike structure will be more healthy than trees with leaves covered by hairlike stuctures.

Answer explanation

Trees with leaves that have waxy coverings will be more healthy during a long-term drought as the wax helps reduce transpiration.

There is a range of beak depths in a population of a certain species of seed-eating bird. Scientists observed the feeding behavior of the seed-eating birds and recorded their observations in the table.

Which statement best predicts the change in subsequent populations of these seed-eating birds if the availability of small seeds decreases?

• Birds with a large beak depth will require less food in order to survive and reproduce.

• Birds with a large beak depth will have an advantage over birds with a small beak depth and will be better able to survive and reproduce.

• Birds with a small beak depth will have an advantage over birds with a large beak depths and will be better able to survive and reproduce.

• Neither birds with a small beak depth nor birds with a large beak depth will have a reproductive advantage.

Answer explanation

Birds with a large beak depth will have an advantage over birds with a small beak depth and will be better able to survive and reproduce.

The house sparrow was first introduced to New York in 1851. It is now distributed across most of North America. As the species expanded its range, it began to live in environments that were different from its original habitat. The birds now vary in size, depending on their geographic location. The map shows the distribution of house sparrows by size.

What is the most likely explanation for the body-size distribution of house sparrows shown on the map?

• Cold temperatures, in the North favored the survival of populations of larger sparrows over populations of smaller sparrows.

• High elevations in the West provide a survival advantage for populations of larger sparrows over populations of smaller sparrows.

• Warm temperatures in the South allowed populations of larger sparrows to survive over populations of smaller sparrows.

• Coastal environments in the East tended to give a survival advantage to populations of larger sparrows over populations of smaller sparrows.

Answer explanation

The most likely explanation for the body-size distribution of house sparrows shown on the map is that cold temperatures in the North favored the survival of populations of larger sparrows over populations of smaller sparrows.