B12E

B12E In the mid-1980s an aggressive strain of algae known as Caulerpa was accidentally introduced into the Mediterranean Sea when a seaside aquarium cleaned out its tanks. The algae contains a toxin that prevents native herbivores from consuming it. Caulerpa quickly

spread over the sea floor, crowding out many species including sponges, corals, sea fans, and lobsters.

Which statement explains the most likely impact Caulerpa has had on the biodiversity in the Mediterranean Sea?

• The presence of Caulerpa within an ecosystem is an Indicator of the ecosystem's health .

• The spread of Caulerpa improved t he habitat for many species of sea grasses, and increased the biodiversity

• Cau/erpa interbred with native species with the same adaptations with in the ecosystem.

• Caulerpa became dominant within the ecosystem and reduced the biodiversity .

B12E Scientists have observed many types of tropical fish moving beyond their traditional ocean ranges into waters that have historically been more temperate. These fish compete for food with native fish, consuming much from the kelp forests and beds of sea grass.The expansion of the ranges of tropical fish was most likely caused by -

• agricultural runoff that contributes to dead zones In the ocean

• global droughts that raise the salt concentration of ocean waters

• the rising temperatures of ocean waters

• acid rain pollution that lowers the pH of ocean waters

B12E The picture shows a pika, a small mammal found in grassland ecosystems. The vast grasslands of the Tibetan plateau are home to the plateau pika. The numerous pikas are prey for many predators of the grasslands, which serve as a major watershed for much of the area.

The watershed drains large quantities of groundwater during the rainy season, or the monsoon season. Pikas have extensive burrows that help drain groundwater rapidly and are used as nesting sites by many bird species. However, many people advocate the eradication of the plateau pikas because they compete with livestock for grass. Which of these will most likely happen if the plateau pikas are completely removed from the

Tibetan plateau grasslands?

• The ecosystem will become unstable because predators will have fewer prey, the birds will have fewer nesting sites, and the area downriver will become vulnerable to flooding without the burrows to aerate the soil and provide drainage for monsoon rains.

• The ecosystem will become more stable because the pika will be replaced by other species of small mammals that can fill the niche, bird species will adapt to nesting above ground,

  and the soils will become compacted without the burrows.

• The ecosystem will become unstable because the predators will migrate to nearby ecosystems, the birds will nest in nearby trees, and the soils will be aerated by other small mammals.

• The ecosystem will become more stable because the pika will no longer be there to eat the grasses, the birds will migrate to other ecosystems during nesting season, and the soils will be able to absorb more of the monsoon rains without the pika burrows.

B12E Roads are often built through forests for industrial purposes or as land is developed for residential and commercial needs. How would road construction through a forest most likely affect the ecosystem?

• Non-native species would replace native species.

• The number of primary consumers would increase.

• The natural succession of vegetation would change.

• All producers would be eliminated from the community.

B12E Food webs such as the one shown were first used in 1927 by the animal ecologist Charles Elton. The food web below represents the feeding relationships among organisms in an Alaskan ecosystem. An environmental change that removed which of these organisms from the ecosystem would cause the most instability in the ecosystem?

• Auklets

• Foxes

• Salmon

• Zooplankton

B12E Which of the following is most likely to cause the greatest disruption to an ecosystem?

• Emptying an aquarium containing non-native species into a local waterway

• Cutting down a small cedar tree to make holiday decorations

• Cleaning the windshield of a car with an alcohol-based glass cleaner

• Mowing the lawn in a city park

B12E On March 24, 1989, an oi l tanker ran aground on Bligh Reef in Prince William Sound, Alaska, and spilled millions of liters of crude oil. The graph shows pink salmon populations in Prince William Sound from 1970 to 1999 What do these data suggest about the effect the oil sp ll had on pink salmon?

• Pink salmon were nearly eliminated after the oil spill.

• Pink salmon populations steadily declined in the 10 years following the spill .

• Pink salmon populations declined and never fully recovered.

• Pink salmon populations seemed to be minimally affected .

B12E In dry desert areas poor drainage can lead t o a buildup of salt in water supplies. A student performed an investigation to study the effects of salinity on the germination rates of seeds. The student placed seeds in several solutions containing 0% to 3% sa lt. The length of the radicle, which is the root of the germinating seed, ranged from 49 mm in the 0% salt solution 0 mm in the 3% salt solution. The data from this investigation suggest that increased salinity in more areas may lead to a decrease in which of the following?

• Air pollution

• Food production

• Oceanic evaporation

• Nonrenewable resources

B12E Dead zones are low-oxygen areas t hat develop on the seafloor. Scientists hypothesize that phytoplankton blooms cause these dead zones. Phytoplankton blooms occur when excess nutrients are introduced by pollution from fertilizers, sewage plant s, and the burning of fossil

fue ls. Which of the following would most likely cause an increase in these contributors to dead zones?

• Rainfall patterns that increase freshwater runoff from terrestrial ecosystems

• Replacing coal-fired power plants with windmills

• Farming practices that reduce nitrate and phosphate applications

• Constructing efficient water-recovery and treatment plants

B12E Amphibians are dying in large numbers after being infected by an aquatic fungus called Batrachochytrium dendrobatidis. The origin of this fungus is unknown, but scientists suspect

that humans are helping spread it. More than 350 amphibian species have been affected, and at least 200 species of frogs have suffered serious reductions in population or become extinct. The map below shows the worldwide distribution of B. dendrobatidis.

What will be the most likely impact of the decline in frog populations resulting from the fungal infection?

• What will be the most likely impact of the decline in frog populations resulting from the fungal infection?

• Plants will no longer grow in the waters of the affected ecosystems, and fish species will increase.

• The fungus will move on land and destroy reptile and mammal populations in tropical ecosystems.

• Populations of algae and mosquitoes will increase, leading to fish die-offs and potential increases in human malaria cases.