BR 11/18/24

A scientist hypothesizes that increasing the concentration of carbon dioxide will increase the rate of photosynthesis in a particular plant species. Which of the following describes an appropriate method to test this hypothesis?

• Measure the growth rate of the plant over several months without altering the carbon dioxide levels.

• Compare the rate of photosynthesis in plants exposed to different concentrations of carbon dioxide while keeping other variables constant.

• Change the light intensity and observe its effect on the rate of photosynthesis.

• Record the amount of water absorbed by the plant and correlate it with photosynthesis rate.

Answer explanation

The correct method is to compare the rate of photosynthesis in plants exposed to different concentrations of carbon dioxide while keeping other variables constant. This directly tests the hypothesis about CO2 concentration's effect.

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NGSS.MS-LS1-6

Anton decided to get an aquarium, but he didn’t want to add fish to it. So, he kept it with just aquatic plants. He wanted to make sure the plants were healthy, so he decided to use a respirometer to measure the rate of cellular respiration and photosynthesis in his aquarium plants. He noticed that after he turned the lights on in the morning, he saw a greater amount of Oxygen just a few hours later. A few hours after he turns the lights off for the night, he sees an increase in Carbon Dioxide. How do Anton’s observations demonstrate the Law of Conservation of Energy?

• Energy is created during photosynthesis and cellular respiration, violating the Law of Conservation of Energy.

• The Law of Conservation of Energy does not apply to biological processes such as photosynthesis and cellular respiration.

• Energy is transformed and transferred between chemical bonds during photosynthesis and cellular respiration, but the total energy remains constant.

• The Law of Conservation of Energy only applies to physical systems and not biological processes.

Answer explanation

Anton’s observations show that energy is transformed during photosynthesis (producing oxygen) and cellular respiration (producing carbon dioxide), but the total energy remains constant, illustrating the Law of Conservation of Energy.

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Genevieve’s science class performed an investigation to test the Law of Conservation of Mass as it relates to Cellular Respiration. They were split into groups of four. Their results are shown below. Which of the following groups performed the investigation correctly?

• Jack, Ariana, Sam

• Genevive, Tad, Mary

• Mason, Sarah, Beck

• Tory, Jenelle, Arden

Answer explanation

Mason, Sarah, and Beck correctly demonstrated the Law of Conservation of Mass in their investigation by accurately measuring the mass before and after cellular respiration, showing that mass is conserved.

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NGSS.MS-PS1-5

Kendall plants flower seeds and places caterpillar larvae in a sealed container with enough light, soil, moisture, and gases to thrive. When she observes the container two weeks later, she finds that the flowers have sprouted, and caterpillars have eaten some of their leaves. Kendall plotted the results of her experiment on the graph below. What does the graph show that Kendall found?

• The total amount of carbon increased.

• The total amount of carbon decreased.

• The total amount of carbon was constant throughout the experiment.

• The total amount of carbon decreased before and increased after the flowers sprouted.

Answer explanation

Kendall's experiment showed that the total amount of carbon remained constant throughout the experiment, indicating a balance between the carbon uptake by the flowers and the carbon released by the caterpillars.

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NGSS.MS-LS1-6

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The Home Owners Association (HOA) of a particular neighborhood noticed the plants and grass in the common areas in their neighborhood were dying. They recruited the help of a local scientist. This scientist uses a few tests he has on hand and determines that the plants are not being plagued by any diseases. The scientist hypothesizes that the HOA is preventing the plants from performing photosynthesis by restricting their access to one of the reactants. What is the best research method that would help the scientist test this hypothesis?

• a survey asking residents about their observations of the local plants and how well they feel they can breathe

• a collection device in the area that counts the amount of glucose in the air

• a controlled field experiment where the scientist sections off three parts of the common area and gives each section a different amount of water

• a three-month case study observing the behavior of animals that pollinate the common area

Answer explanation

A controlled field experiment is best to test the hypothesis about water affecting photosynthesis. By varying water levels in sections, the scientist can observe plant responses, isolating the effect of water on their health.

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NGSS.MS-LS1-6

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Alex’s science teacher assigns them a project to create a model that demonstrates the relationship between Cellular Respiration and Photosynthesis. He talks to his classmates, and comes up with four options. Which of the following models best demonstrates the interconnectedness of the two processes?

• He can write out the equations for photosynthesis and cellular respiration and use different colored beads to show how the products of photosynthesis become the reactants for cellular respiration, and vice versa.

• He can use a device that measures his Carbon Dioxide output while he works out, showcasing that the mitochondria in his cells are performing cellular respiration to produce ATP.

• He can split his class into two groups: Mitochondria and Chloroplasts. He could then give the Mitochondria group glucose to trade with the Chloroplasts for Water to perform Cellular Respiration with.

• He can build a scale model of a chloroplast, then use marbles to show how the chlorophyll in the chloroplast captures solar energy to produce glucose and oxygen.

Answer explanation

The correct choice effectively illustrates the interdependence of photosynthesis and cellular respiration by using equations and colored beads to show how their products and reactants are connected, making the relationship clear.

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About a week later, Alex’s science teacher assigns them another project, this time to create a model that demonstrates the Carbon Cycle. He talks to his classmates, and draws the model shown below. Which of the following statements best explains why this is an inaccurate model?

• The diagram is showing that the carbon cycle has a definite beginning and end where carbon eventually cannot be reused

• The diagram is showing producers are getting carbon from the decomposers

• The diagram is showing that carbon does not flow in a linear fashion

• The diagram fails to show that carbon is depleted over time as it is used by different organisms

Answer explanation

The correct choice explains that the model inaccurately suggests the carbon cycle has a definite beginning and end, implying carbon cannot be reused, which contradicts the continuous nature of the carbon cycle.

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NGSS.MS-LS2-3