Which statement best helps explain the formation of the hydrogen bond represented in the figure?

• A. The oxygen has a partial positive charge, and the nitrogen has a partial negative charge.

• B. The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

• C. The hydrogen attached to the oxygen has a partial negative charge, and the nitrogen also has a partial negative charge.

• D. The nitrogen has a partial positive charge, and the hydrogen attached to the oxygen also has a partial positive charge.

Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?

• A. Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles to form under the feet of the insect.

• B. Ionic bonds between molecules at the surface of the water provide an electric charge, which attracts the feet of the insect, keeping it on the surface.

• C. Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the weight of the insect.

• D. Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

The diagram shows how water can adhere to the xylem in the stems of plants, which contributes to water movement in the plant. Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves?

• A. Water is polar, and the walls of the xylem are nonpolar. Water molecules have the ability to form hydrogen bonds with one another but not with the xylem walls.

• B. Water is nonpolar, and the walls of the xylem are polar. Water molecules are able to form hydrogen bonds with the xylem walls, and they are pulled up the xylem.

• C. Water and the xylem are both nonpolar. Water molecules have the ability to form hydrogen bonds with one another but not with the xylem walls.

• D. Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process?

• A. The high specific heat capacity of water allows the body to absorb a large amount of excess heat energy

• B. The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.

• C. The high surface tension of water contributes to the physical process by which water leaves the body.

• D. The high melting temperature of water allows the body to remove excess heat through a phase change of water from solid to liquid.

Tags

NGSS.HS-LS1-3

Scientists want to determine whether the rapid economic growth in China between 1950 and 2000 caused a mass extinction of animal species during that time period. The scientists collected data on the number of extinctions of selected vertebrate species in China between 1950 and 2000, as shown in Table 1.

Which of the following is the null hypothesis most relevant for evaluating the data in Table 1 ?

• A. There is no significant difference between the extinction rates of mammals, birds, amphibians, and reptiles in China.

• B. Because of climate change, habitat loss, pollution, and excessive exploitation of resources, China experienced a mass extinction event between 1950 and 2000.

• C. There is no significant difference between the extinction rate of animals between 1950 and 2000 in China and the background extinction rate.

• D. There is no significant difference between the extinction rates of mammals, birds, amphibians, and reptiles in China.

Tags

NGSS.HS-LS4-5

To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the pH of the cultures at 5

-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

Which of the following was the dependent variable in the researcher’s experiment?

• A. Time

• B. pH

• C. Glucose Concentration

• D. Lactic Acid Concentration

Tags

NGSS.HS-PS1-5

Discuss THREE properties of water

Property and Description (2 points jointly)

Tags

NGSS.HS-ESS2-5

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes.

Which of the following must remain the same for all trials of this experiment?

• A. The initial concentration of the substrate

• B. The final concentration of the product

• C. The three-dimensional structure of the enzyme

• D. The temperature of the aqueous buffer solution

Scientists are studying the two primary vocalizations made by Belding’s ground squirrels (Urocitellus beldingi). The trill call consists of a series of medium-pitched notes given rapidly, while the whistle call consists of a single high-pitched note. The objective of the experiment is to determine the function of each vocalization. Recordings of the calls were played to four different groups of squirrels, and the response of each individual squirrel was documented. The responses are summarized in Table 1.

Which of the following correctly identifies the dependent variable and the independent variable for the experiment?

• A. The independent variable is the percent of squirrels responding, and the dependent variable is the type of alarm call.

• B. The independent variable is the percent of squirrels responding, and the dependent variable is the type of response.

• C. The independent variable is the group of squirrels, and the dependent variable is the percent of squirrels responding.

• D. The independent variable is the type of alarm, and the dependent variable is the percent of squirrels responding.

For following group of questions first study the description of the situation or data and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below.

In graphing the data from this experiment, the sampling time would be shown on the x-axis because

• A. cell components were shown on the y-axis

• B. radioactivity level shows the most variation

• C. time values are always located on the horizontal axis

• D. all quantitative values are represented on the x-axis

• E. sampling time is the independent variable