The Laws of Conservation of Mass and Energy and Interdependence: A Rabbit's Story

Question

In the natural world, every living organism interacts with its environment in a way that follows the Laws of Conservation of Mass and Energy. One example of a consumer that plays a crucial role in these cycles is the rabbit. Rabbits are herbivores, which means they primarily eat plants.

When a rabbit eats a plant, it consumes leaves, stems, and roots. These plant parts are rich in a sugar called glucose, which is produced through a process known as photosynthesis. During photosynthesis, plants use sunlight, carbon dioxide from the air, and water from the soil to create glucose and oxygen. When the rabbit eats the plant, it breaks down the glucose through a process called cellular respiration, which helps the rabbit convert the stored energy in the glucose into a form it can use for its daily activities, like running, jumping, and staying warm. As rabbits consume glucose, the primary product of photosynthesis, they also breathe in oxygen from the atmosphere, the second product of photosynthesis.

The primary product of cellular respiration, chemical energy (ATP), is released during cellular respiration and powers the rabbit’s movements and bodily functions. Additionally, as rabbits breathe out, they release carbon dioxide, the second product of cellular respiration, back into the atmosphere. This carbon dioxide is then available for plants to use again during photosynthesis, demonstrating the interdependence of living systems.

Eventually, every rabbit will die, just like all living organisms. When this happens, the rabbit's body begins to decay. Decomposers, such as bacteria and fungi, break down the organic matter in the rabbit's body. This decaying process returns nutrients to the soil, enriching it with essential elements that plants need to grow. The carbon contained in the rabbit's body is also released back into the atmosphere in the form of gasses, completing the cycle.

The rabbit's life cycle illustrates the Laws of Conservation of Mass and Energy. Matter is neither created nor destroyed; it simply changes forms. The nutrients from the rabbit’s body (matter) are reused by plants, allowing them to grow and produce glucose once again. Energy is transformed through different processes, but it is always conserved in the ecosystem.

Question 1
Using only information in the passage above, explain how the process of a rabbit eating plants and eventually decaying demonstrates the Laws of Conservation of Matter and Energy. Include specific examples from the passage above that show how matter/energy is conserved (reused/recycled).

Key words to include: photosynthesis, cellular respiration, matter, energy, sunlight, carbon dioxide, oxygen, glucose,

Sentence starters:

The process of photosynthesis shows that matter and energy is conserved because...
The process of cellular respiration shows that matter and energy is conserved because...

Answer 1

The process of photosynthesis shows that matter and energy is conserved because plants utilize sunlight, carbon dioxide from the air, and water from the soil to produce glucose and oxygen. In this process, the carbon dioxide (a form of matter) that plants absorb from the atmosphere is transformed into glucose, which serves as stored energy for both the plants and the consumers that eat them, like rabbits. Thus, the matter is not lost; instead, it changes form from carbon dioxide to glucose, while the energy captured from sunlight is stored in the chemical bonds of glucose.

The process of cellular respiration shows that matter and energy is conserved because when a rabbit consumes glucose, it breaks it down during cellular respiration to convert the stored energy into ATP, which powers its bodily functions. In this process, the rabbit also takes in oxygen (another product of photosynthesis) and exhales carbon dioxide, which is returned to the atmosphere. This illustrates that matter (in the form of carbon dioxide) is recycled back into the ecosystem for plants to use again in photosynthesis. Furthermore, the energy that was in the glucose is transformed into a usable form (ATP), demonstrating that energy is conserved throughout the ecosystem.

Finally, when the rabbit decays after it dies, decomposers break down its body, returning nutrients back to the soil. This nutrient recycling reinforces the conservation of matter, as the organic matter from the rabbit enriches the soil, allowing plants to grow and produce glucose again, thus continuing the cycle. The carbon released back into the atmosphere completes the loop of both matter and energy in the ecosystem.