This science reading passage for grades 6-8 explores the connection between photosynthesis and cellular respiration, aligning with NGSS standards MS-LS1-6 and MS-LS1-7. Students learn how these two processes are opposite yet complementary, with the outputs of photosynthesis serving as the inputs for respiration, and vice versa. The passage explains the cycling of carbon and oxygen, the storage and release of energy, and highlights how plants perform both processes to maintain balance in ecosystems. Real-world examples, mechanistic details, and cause-and-effect relationships are emphasized to promote deep understanding. The resource includes a glossary, differentiated and Spanish versions, comprehension questions, writing prompts, and graphic organizers. Audio integration makes the content accessible for diverse learners. This passage is ideal for building foundational biological literacy and supports classroom discussions about energy flow, matter cycling, and human impacts on natural systems.
Written by Workybooks TeamPublished by Workybooks
Preview
Sample passage and quiz content
CONTENT PREVIEW
Expand content preview
Photosynthesis and Respiration Connection
Photosynthesis is the fundamental process that transforms solar energy into chemical energy in ecosystems. This process allows plants, algae, and some bacteria to capture sunlight and convert it into glucose, a type of sugar that stores energy. In contrast, cellular respiration is how living organisms, including plants and animals, release energy from glucose to power life activities. Together, these two processes form a cycle that moves carbon, oxygen, and energy through all living things. Their connection is essential for maintaining the balance of matter and energy in the biosphere.
How Photosynthesis and Respiration Work Photosynthesis occurs mainly in the leaves of plants, within structures called chloroplasts. Using sunlight, plants take in carbon dioxide (CO₂) from the air and water (H₂O) from the soil. Through a series of chemical reactions, they produce glucose and release oxygen (O₂) as a byproduct. The simplified equation is: 6CO₂ + 6H₂O + sunlight → C₆H₁₂O₆ + 6O₂. Cellular respiration, on the other hand, happens in the mitochondria of cells. Organisms use oxygen to break down glucose, releasing energy, carbon dioxide, and water. Its equation is almost the reverse: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP). Thus, the outputs of photosynthesis—oxygen and glucose—become the inputs for respiration, and vice versa.
The Cycle of Matter and Energy This connection creates a powerful cycle. During the day, plants perform photosynthesis, absorbing CO₂ and releasing O₂. At night, when sunlight is unavailable, plants and other organisms rely on respiration, which uses O₂ and releases CO₂. For example, in a forest, the large number of trees help reduce atmospheric CO₂ and increase O₂ during the day. At the same time, animals breathe in O₂ and exhale CO₂, which plants can use again. This cycling of gases helps regulate Earth's atmosphere and supports diverse life forms. Studies show that about 70% of Earth's oxygen comes from photosynthetic organisms in oceans, especially algae.
Real-World Implications and Broader Principles Understanding the link between photosynthesis and respiration reveals how tightly life on Earth is interconnected. Disruptions to this cycle, such as deforestation or burning fossil fuels, can lead to imbalances in carbon and oxygen levels, affecting climate and health. Scientists use this knowledge to develop technologies like artificial photosynthesis and to guide conservation efforts. The relationship between these processes exemplifies the scientific principle that matter and energy are continuously cycled and transformed within ecosystems, supporting all living things.
Interesting Fact: More than 50% of the oxygen you breathe is produced by microscopic algae in the ocean, not by land plants!
What is the main function of photosynthesis in ecosystems?
To transform sunlight into chemical energyTo release carbon dioxide into the airTo break down food for animalsTo absorb water from the soil
Where does photosynthesis mainly occur in plants?
In the rootsIn the mitochondriaIn the chloroplasts of leavesIn the cell nucleus
What gas is produced during photosynthesis and used in cellular respiration?
Carbon dioxideNitrogenOxygenHydrogen
According to the passage, what are the inputs of cellular respiration?
Glucose and oxygenWater and sunlightCarbon dioxide and waterNitrogen and glucose
What is one major result of the cycling of photosynthesis and respiration?
Plants stop growing at nightOxygen and carbon dioxide levels remain balancedAnimals depend only on respirationGlucose is never used
What does the word 'chloroplasts' mean as used in the passage?
Cell structures where photosynthesis happensCell structures that break down foodCell walls of plant rootsA gas in the air
Based on the passage, why is photosynthesis important for animals?
It produces oxygen needed for respirationIt creates soil for plantsIt makes animals grow fasterIt removes energy from the ecosystem
If deforestation increases, what is likely to happen to atmospheric carbon dioxide?
It will decreaseIt will stay the sameIt will increaseIt will turn into oxygen
True or False: The outputs of photosynthesis become the inputs for cellular respiration.
TrueFalse
True or False: Only plants, not animals, perform cellular respiration.