By taking careful measurements, scientists have determined that the universe is expanding over time. Individual components of the universe, such as galaxies, continue to travel
through space. This concept is sometimes represented by a balloon as shown below. Each dot on the balloon represents a part of the universe, such as a galaxy.

Based on the information and diagram, which statement best describes the way galaxies move through space over time?

• A. westward
• B. northwest
• C. farther apart
• D. northward
• E. closer together

If a weight with a string attached is swung in a horizontal circular motion around in the air, the path of the weight will appear as shown in the figure at the left.
If the string breaks when the weight is at position A, the weight will fly away in a straight line tangent to the circular path.

In order for the weight to hit an object located at position X, the person should let go of the string when the weight is located at which position?

• A. E
• B. B
• C. C
• D. D
• E. F

The pH of a liquid is a measure of its acidity or its alkalinity. Even small changes in pH of human blood can cause very serious health problems.
Carbon dioxide (CO2), is one of the dissolved gases present in healthy blood. CO2 normally mixes with the water in blood to form a mild acid, carbonic acid, which lowers the blood pH.If a health problem causes the dissolved carbon dioxide to increase or decrease, the blood's pH would change and could produce an unhealthy pH level.
Based on this information, which statement best summarizes the blood condition that might result when an individual has a respiratory condition that causes the blood to contain too much CO2?

• A. The blood will clot more quickly.
• B. The blood's white cell count will be greatly decreased.
• C. The blood pH will be lowered.
• D. The blood pH will remain the same.
• E. The blood will be less acidic.

-- Exhibit -
Since carbon dioxide dissolves in water to form an acid, an acid-base indicator such as bromthymol blue is used to track the acid concentration during plant photosynthesis and respiration. Bromthymol blue turns yellow in an acid solution and remains blue in a basic solution. The color change is reversible. A student used the following procedure to track carbon dioxide.
In an experiment, a student placed a solution of bromthymol blue into each of two flasks, inserted a drinking straw in each flask, and blew through the straw until the solution turned from blue to yellow. Carbon dioxide, a waste product in the student's breath, caused the color change. The student then placed a small Elodea water plant in each flask and closed the flasks with rubber stoppers. Flask A was placed in bright sunlight, while flask B was placed in the dark for 24 hours, as shown in the figure below.

After 24 hours, the bromthymol blue in flask A had turned back to blue, while in flask B it was still yellow.
-- Exhibit -
If living things use oxygen and release carbon dioxide during respiration, what is the most probable reason that the atmosphere does not become depleted of oxygen and become filled with carbon dioxide?

• A. Plants don't use oxygen from the atmosphere in the dark, but they do use carbon dioxide.
• B. The atmosphere supplies large amounts of oxygen and absorbs large amounts of carbon dioxide.
• C. Carbon dioxide is used by many invertebrate animals in place of oxygen during respiration.
• D. Carbon dioxide in the atmosphere breaks down in sunlight to release oxygen and water.
• E. Plants replace the oxygen in the atmosphere and use carbon dioxide during photosynthesis.

Soil is formed when the rock at Earth's surface weathers. Normally, soil develops into three layers, called horizons. The illustration below shows the A, B, and C horizons of a typical soil profile.

Based on the diagram, if the surface vegetation were removed, which would be the likely effect on the soil?

• A. The C horizon would be further buried.
• B. The A horizon would enlarge.
• C. The top 1 or 2 unprotected layers might wash away.
• D. The order of the horizons would be reversed.
• E. The B horizon would disappear entirely.