Identify the choice that best completes the statement or answers the question

200 A major reservoir for oxygen is the atmosphere. Which of the following processes adds oxygen to the atmosphere?

201 Which of the following is an example of emigration?

202 Sea otters are small marine mammals that prey on fish, clams, crabs, and sea urchins. Sea otters’ natural predators include bears, sharks, and killer whales, but humans have also threatened sea otter populations. Hunting of sea otters for their fur severely reduced sea otter populations in the 18th and 19th centuries. After laws and programs were put into place to protect sea otters, their populations started increasing. Some sea otter populations in Alaska are now decreasing again. Which of the following is the most likely cause of these decreases?

203 A picture of a horseshoe crab is below. Horseshoe crabs are arthropods, related to crustaceans, insects, and spiders.

In the 1990s, the harvesting of horseshoe crabs for fishing bait and biomedical use led to a significant decrease in the size of horseshoe crab populations on the Mid-Atlantic coast of the United States. Recovery efforts for the horseshoe crab populations are most challenged by which of the following?

204 Which processes are part of the carbon cycle?

205 Which causes the most loss of biodiversity on Earth?

206 Which biotic factor affects the number of animals in a population?

207 Which is a benefit of planting different crops on the same land throughout the year?

208 Which would most help to protect an endangered species?

209 What will most likely happen if the human population continues to grow at the current rate?

210 What is the function of autotrophs in the carbon cycle?

212 A sea turtle has washed up on a remote section of a beach. This is known as a “stranding.” Stranding occurs when a dead, sick or injured sea turtle washes up on the shoreline. Which statement best explains why “stranding” should be reported immediately to local authorities?

213 The yucca plant releases a strong scent at night when the yucca moth is active. The yucca moth, attracted by the scent, gathers pollen from the yucca flower. The yucca moth then deposits her eggs and the pollen on another plant. This ensures that the plant will be cross-pollinated and that the yucca moth larvae have a steady food supply. Which relationship does this best illustrate?

214 The construction of a new coal-burning power plant would have the greatest impact on which environmental issue?

215 A field ecologist wants to determine the interactions of various populations of organisms living in a large grassland field. Which method is best for conducting this study?

216 Which environmental factor would cause the greatest decrease in the number of species of plants and animals living in some of the lakes in the United States?

217 Blackberry plants are found in forest edge habitats. How could blackberry plants limit the population of salmonberry plants growing in the same habitat?

218 Which event might be evidence that a forest edge habitat is in equilibrium instead of a disturbance?

219 Which of the diagrams below shows an example of secondary succession in an ecosystem?

A
B
C
D

220 The biome populated by cone-bearing trees such as pine, spruce, and fir is the

221 The graph below shows changes in truffle harvesting in an oak forest over a period of 40 years.

Which statement BEST describes the relationship between the oak forest and the truffle population?

222 Which of the following correctly describes the way animals get their nutrition?

223 Look at the diagram below.

Which of the following is the correct flow of energy?

224 Which of the following is an example of how a change in climate can affect the equilibrium of an ecosystem?

225 Mold and mushrooms are organisms that help recycle materials within an ecosystem.

How would an ecosystem with few recycling organisms be affected?

226 By drilling sediment cores from the ocean floor and studying them, scientists have learned much about ancient carbon dioxide levels and climate. A study in 2004 found that the waters around the North Pole 55 million years ago were as warm as the waters in today’s tropics. The researchers also found that the concentration of carbon dioxide 55 million years ago was 2,000 parts per million (ppm), whereas today, the concentration is 380 ppm. Which hypothesis does this finding support?

227 Examine the energy pyramid shown below.

Each level of the energy pyramid above contains about 90% less energy than the level below it. The energy that is not passed on to the organism above it is used in the life processes of the organism or released into the environment. A certain sample of plants contains 490 joules (J) of energy. Based on the energy pyramid above, approximately how much of that energy remains in the level containing rats?