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Photosynthesis in Ecosystems — Reading Comprehension

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MS-LS1-6
MS-LS2-3

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This comprehensive passage for grades 6-8 explores the fundamental role of photosynthesis in ecosystems, aligning with NGSS MS-LS1-6 and MS-LS2-3 standards. Students will learn how photosynthesis converts solar energy into chemical energy, fueling life and driving ecosystem productivity. The passage explains the photosynthesis equation, distinguishes between gross and net primary productivity, and highlights the most productive ecosystems like rainforests and coral reefs. It also addresses the global impact of photosynthesis on oxygen production and carbon storage, and examines environmental factors that influence these processes. Glossary terms, differentiated and Spanish versions, and multiple-choice and writing activities support diverse learners. Audio integration ensures accessibility, and graphic organizers help students visualize cause and effect and compare different ecosystems. This resource builds scientific literacy and critical thinking while connecting cellular processes to global environmental issues.

CONTENT PREVIEW

carbon storage, vegetation, climate change, photosynthesis — The reactants and products of photosynthesis

Photosynthesis is the fundamental process that transforms solar energy into chemical energy in ecosystems. Every green plant, algae, and some bacteria use photosynthesis to convert sunlight, water, and carbon dioxide into food and oxygen. This process not only supports the growth of individual organisms, but also powers entire ecosystems by providing energy and removing carbon dioxide from the atmosphere. Without photosynthesis, most life on Earth would not exist.

How Photosynthesis Works at the Cellular Level

Inside plant cells, special structures called chloroplasts capture sunlight and use it to drive the chemical reaction: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂. This equation shows that six molecules of carbon dioxide and six molecules of water, with light energy, are transformed into one molecule of glucose (a type of sugar) and six molecules of oxygen. The glucose stores chemical energy that plants use for growth and other life processes. The oxygen is released into the air as a by-product. Photosynthesis is essential for removing carbon dioxide, which helps control Earth's climate.

Photosynthesis and Ecosystem Productivity

Photosynthesis drives primary productivity—the rate at which plants produce useful chemical energy in an ecosystem. Scientists measure this as either gross primary productivity (GPP)—the total amount of energy captured by photosynthesis—or net primary productivity (NPP)—the energy remaining after plants use some for their own life processes. Tropical rainforests, coral reefs, and estuaries are the most productive ecosystems on Earth, with high rates of photosynthesis per square meter. In contrast, deserts and open oceans have much lower productivity due to limited water, nutrients, or sunlight.

Many factors affect photosynthesis and productivity: the amount of sunlight, the availability of water, temperature, and nutrients in the soil or water. For example, tropical rainforests receive plenty of sunlight, warm temperatures, and abundant moisture, leading to high productivity. In contrast, extreme environments like deserts are limited by water, and polar regions are limited by temperature and light.

Global Impact and Importance

Photosynthesis has a global impact far beyond individual plants. It is responsible for producing nearly all the oxygen in Earth's atmosphere, which animals (including humans) need to breathe. It also acts as a major carbon sink by storing vast amounts of carbon in plant tissues, helping to balance Earth’s carbon cycle and slow climate change. Human activities, such as deforestation and pollution, can reduce photosynthesis in ecosystems, leading to higher carbon dioxide levels in the atmosphere.

By studying photosynthesis at both the cellular and ecosystem levels, scientists can better understand how energy flows through living systems and how environmental changes affect life on Earth. Ongoing research explores how to protect or even increase photosynthesis in threatened ecosystems to support a healthy, balanced planet for future generations.

Interesting Fact: The Amazon rainforest produces about 20% of the world’s oxygen through photosynthesis each year!

What is the main function of photosynthesis in ecosystems?

To convert sunlight into chemical energy for living thingsTo provide shelter for animalsTo break down dead organismsTo create rain in the rainforest

Which structures in plant cells capture sunlight for photosynthesis?

VacuolesNucleiChloroplastsMitochondria

According to the passage, what does the photosynthesis equation show?

How plants use sunlight, water, and carbon dioxide to make glucose and oxygenHow animals get energy from foodHow water evaporates from leavesHow ecosystems lose carbon dioxide

What is one reason tropical rainforests have high productivity?

They have low temperaturesThey receive plenty of sunlight and waterThey have very little soilThey are near the ocean

What does 'net primary productivity' mean in the context of ecosystems?

The total energy captured by photosynthesisThe energy left after plants use some for life processesThe energy stored in animal bodiesThe energy lost to the atmosphere

What does the word 'carbon sink' mean as used in the passage?

A place where carbon is removed from the air and storedA river with a lot of carbonA plant that grows in a swampA process that releases carbon dioxide

If a forest is cut down, how might that affect the global carbon cycle?

It would increase carbon dioxide in the atmosphereIt would create more oxygenIt would have no effectIt would reduce animal populations only

Why is photosynthesis important for maintaining Earth's climate?

It controls rainfallIt stores carbon and removes carbon dioxide from the airIt creates new landformsIt provides shelter for insects

True or False: Photosynthesis is responsible for almost all the oxygen in Earth's atmosphere.

TrueFalse

True or False: Only tropical rainforests perform photosynthesis.

TrueFalse