LS.4 Level 3

Explain how photosynthesis contributes to the energy flow within a food web. Use specific examples and quantitative data to support your explanation.

• Photosynthesis converts sunlight into chemical energy, which is stored in glucose. This energy is then transferred through the food web as organisms consume plants and each other. For example, a single square meter of leaf surface can produce approximately 10 grams of glucose per hour under optimal conditions.

• Photosynthesis directly provides energy to all organisms in a food web without the need for consumption.

• Photosynthesis only benefits plants and does not affect other organisms in a food web.

• Photosynthesis is a process that occurs only in animals and is unrelated to food webs.

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VA.LS.4.a

Design an experiment to demonstrate the relationship between photosynthesis and cellular respiration in plants. Include a detailed methodology and expected quantitative results.

• Measure the oxygen output of a plant in light and dark conditions, expecting higher oxygen levels in light due to photosynthesis. Quantitatively, you might expect an increase of 20% in oxygen output in light conditions.

• Measure the carbon dioxide output of a plant in light and dark conditions, expecting no change in levels.

• Measure the glucose levels in a plant, expecting them to decrease in light conditions.

• Measure the water intake of a plant, expecting it to increase in dark conditions.

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VA.LS.4.b

Analyze the impact of removing a primary producer from a food web. How would this affect the process of photosynthesis and the overall ecosystem? Provide a detailed analysis including potential quantitative impacts on energy flow.

• The removal would have no significant impact on the ecosystem.

• The removal would lead to a decrease in photosynthesis, reducing energy availability for consumers and potentially collapsing the food web. For instance, a 50% reduction in primary producers could lead to a 30% decrease in energy flow to higher trophic levels.

• The removal would increase photosynthesis as other plants compensate for the loss.

• The removal would only affect herbivores, with no impact on other trophic levels.

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VA.LS.4.a

Evaluate the role of cellular respiration in maintaining the balance of gases in the atmosphere. How does this process complement photosynthesis? Include a discussion of the quantitative balance of oxygen and carbon dioxide.

• Cellular respiration releases oxygen into the atmosphere, complementing photosynthesis by providing more oxygen for plants.

• Cellular respiration consumes carbon dioxide, complementing photosynthesis by reducing atmospheric CO2 levels.

• Cellular respiration releases carbon dioxide, which is used by plants in photosynthesis, maintaining a balance of gases. For example, the amount of CO2 released by cellular respiration is approximately equal to the amount consumed by photosynthesis in a balanced ecosystem.

• Cellular respiration has no role in the balance of atmospheric gases.

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VA.LS.4.b

Propose a model to illustrate the flow of energy from the sun through a food web, highlighting the role of photosynthesis. What key components and quantitative data would you include?

• Include only plants and herbivores, as they are the primary users of solar energy.

• Include the sun, plants, herbivores, carnivores, and decomposers, showing energy transfer at each level. Quantitatively, show that only about 10% of energy is transferred from one trophic level to the next.

• Include only the sun and plants, as they are the only components involved in photosynthesis.

• Include only carnivores and decomposers, as they are the end consumers of energy.

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VA.LS.4.a

Critically assess how changes in environmental conditions, such as light intensity, affect the rate of photosynthesis and cellular respiration in plants. Include quantitative predictions.

• Increased light intensity decreases the rate of photosynthesis and cellular respiration.

• Increased light intensity increases the rate of photosynthesis but has no effect on cellular respiration. Quantitatively, photosynthesis rates can increase by up to 50% with optimal light conditions.

• Increased light intensity increases the rate of photosynthesis and cellular respiration.

• Increased light intensity decreases the rate of cellular respiration but increases photosynthesis.

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VA.LS.4.b

Discuss the interdependence of photosynthesis and cellular respiration in the carbon cycle. How do these processes contribute to the cycle? Include quantitative data to support your discussion.

• Photosynthesis and cellular respiration are independent processes with no impact on the carbon cycle.

• Photosynthesis removes carbon dioxide from the atmosphere, while cellular respiration returns it, maintaining the carbon cycle. Quantitatively, approximately 120 gigatons of carbon are cycled through these processes annually.

• Photosynthesis adds carbon dioxide to the atmosphere, while cellular respiration removes it, disrupting the carbon cycle.

• Photosynthesis and cellular respiration both remove carbon dioxide from the atmosphere, depleting carbon levels.

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VA.LS.4.b

Formulate a hypothesis on how a decrease in plant populations might affect the process of photosynthesis and the structure of a food web. Include potential quantitative impacts.

• A decrease in plant populations would increase photosynthesis and strengthen the food web.

• A decrease in plant populations would decrease photosynthesis, weakening the food web and reducing energy availability. Quantitatively, a 30% reduction in plant biomass could lead to a 20% decrease in energy flow to higher trophic levels.

• A decrease in plant populations would have no effect on photosynthesis or the food web.

• A decrease in plant populations would only affect herbivores, with no impact on photosynthesis.

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VA.LS.4.a

Analyze how the processes of photosynthesis and cellular respiration are essential for the survival of both plants and animals. Provide examples and quantitative data to support your analysis.

• Photosynthesis is essential for animals, while cellular respiration is essential for plants.

• Photosynthesis provides oxygen and glucose for animals, while cellular respiration provides carbon dioxide and energy for plants.

• Photosynthesis provides oxygen and glucose for plants, while cellular respiration provides carbon dioxide and energy for animals. Quantitatively, plants produce approximately 100 billion tons of oxygen annually through photosynthesis.

• Photosynthesis and cellular respiration are not essential for the survival of plants and animals.

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VA.LS.4.b

Evaluate the impact of deforestation on the processes of photosynthesis and cellular respiration. How might this affect global ecosystems? Include quantitative data in your evaluation.

• Deforestation increases photosynthesis and cellular respiration, benefiting global ecosystems.

• Deforestation decreases photosynthesis, reducing oxygen production and increasing carbon dioxide levels, negatively impacting global ecosystems. Quantitatively, deforestation contributes to approximately 15% of global carbon emissions.

• Deforestation has no impact on photosynthesis or cellular respiration.

• Deforestation only affects cellular respiration, with no impact on photosynthesis.

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VA.LS.4.a