The Guam rail is a flightless bird found on the island of Guam. It builds a shallow nest on the ground and lays eggs throughout the year. There are no native species of snakes on Guam, so the Guam rail had no experience with snake predators until the brown tree snake was accidentally introduced sometime between 1944 and 1952. These snakes, which eat a wide variety of animal species, quickly established a large population on Guam. How was the Guam rail most likely affected by the introduction of the brown tree snake?

The main parts of a working clothes dryer are shown in the diagram. This appliance dries clothes primarily by converting —

An athlete is trying to lift some weights. He successfully lifts 200 N weights, but when he tries to lift 400 N weights, he is unsuccessful. Which of these correctly compares the amount of work the athlete does on the weights?

A student drew the picture of a human body system shown below. The student labeled some of the organs of the system. The main function of this human body system is to —

A phase of the moon is shown below Which pair of diagrams shows the moon’s phase immediately before and immediately after this phase?

Many Texas caves provide a habitat for animals that live in total darkness. The caves are damp and cool, and most of the caves are rich in the mineral calcite. The diagram below shows the relationships of some organisms involved in a cave ecosystem. Based on the diagram, which of the following statements is valid?

A student wants to use a spinning basketball to model the day-and-night cycle on Earth. What should the student do in order to best model the cause of the day-and-night cycle?

Thunderstorms are more common in some areas than in others. The map shows the average number of thunderstorms per year in different parts of the United States. Why are there significantly more thunderstorms in Florida than in California?

During a demonstration of Newton’s laws of motion, a student used the setup shown in Figure 1. The student flicked the index card with a fingertip, and the coin fell straight down into a plastic cup as shown in Figure 2. Which of these best explains why the coin fell straight down into the cup instead of remaining on the index card?

For an investigation a student records data about four unknown substances. The student then calculates the densities of the unknown substances and compares them with the table of densities of known substances shown below. Which unknown substance is most likely carbon?

The image shows a plate boundary. Arrows have been added to indicate the movement of the plates. What plate boundary feature is also shown?

Two stars are identified on the Hertzsprung-Russell diagram below. Based on this diagram, how do the characteristics of Star 1 and Star 2 compare?

The partial food web shown below is found in an aquatic environment. This type of environment has many organisms in the same trophic levels. Which two types of organisms in this aquatic food web have a producer–consumer relationship?

The graph below shows the range of water conditions preferred by three species of fish in an Ozark stream. Water with which of these conditions would cause the most competition for resources among all three species of fish?

The periodic table is organized into groups and periods of elements. The characteristics of a certain group of elements are listed below. Which of these elements is in this group?

A student drew the diagram below to show the movement of water through a hydroelectric dam. The student used the diagram to describe changes in the potential and kinetic energy of the water. At which location is the gravitational potential energy of the water the greatest?

The satellite photo below shows San Francisco, California, which has many miles of coastline and an inland bay. Which area of the coastline has most likely experienced the greatest effect of erosion from waves over hundreds of years?

Which of these formulas contain equal numbers of nitrogen atoms?

A student examines the winged insect shown below. Based on the dichotomous key, in what order should this insect be classified?

Quasars are extremely distant celestial bodies. Investigators using a special telescope determined that a certain quasar was emitting waves with a frequency of 1 4. 1 × 109 Hz. An electromagnetic spectrum is shown. The investigators were most likely using a telescope that detects —

Scientists are studying the effects of climate change on the Baltic Sea. Some scientists predict that if current trends continue, the Baltic Sea will become less salty, and it will contain less dissolved oxygen. As a result of these changes, the Baltic Sea will have less biodiversity. The location of the Baltic Sea is shown on the map below. Which statement best explains why biodiversity in the Baltic Sea could decrease if these changes occur?

On July 4, 1776, the American colonies declared their independence. The table shows the lunar phases for June 1776. What lunar phase occurred on July 4, 1776?

The map below shows the locations of four active volcanoes in the Caribbean Sea. What do these volcanoes indicate about plate tectonics in the region?

A student stands at the point marked X on the topographic map below. What height in meters must the student climb in order to reach the top of the hill? Be sure to use the correct place value.

In the summer many people enjoy going to the beach. The photograph shows a beach in Argentina, which is located in the Southern Hemisphere. Which diagram shows the position of Earth when it is summer in Argentina?

Barnacles are marine organisms that live attached to surfaces as adults. A scientist studies two barnacle species that live on rocks on a coast in Scotland. In some rocky areas Species A is found alone. In other rocky areas Species B is found alone. In still other rocky areas both species are found together. The diagram below shows the two barnacle species on rocks in their habitats. If Species B were removed from the rocky areas it shares with Species A, Species A would most likely inhabit —

A student jumps off a sled toward the west after it stops at the bottom of an icy hill. Based on the law of action–reaction, in what direction will the sled most likely move as the student jumps off?

Some students are studying the relationships between organisms in a food web.How many predators shown in this food web are omnivores? Be sure to use the correct place value.

The weather map shows the weather conditions for one day across the United States. Based on the weather map, which city will most likely experience decreasing temperatures during the next 24 hours?

For an investigation a student poured a blue solution of CuSO into a beaker. The student 4 placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes. The student inferred that a chemical reaction occurred. What evidence supports this inference?

Three cousins have a similar appearance but different face shapes. Which of these cell components are most involved in determining the basic shape of each girl’s face?