Distinguish between energy flow and matter cycling as they occur in ecosystems, giving an example for each.

Distinguish between energy flow and matter cycling as they occur in ecosystems, giving an example for each.

• A. Energy flows through food chains and is lost as heat; matter cycles (carbon, water) within the system, moving between organisms and the environment.
• B. Energy and matter both leave the system as heat.
• C. Energy cycles; matter flows.
• D. Matter moves only to the atmosphere.

Answer: (A)

Energy in ecosystems moves in one direction and is gradually transformed and absorbed by living things, with most of it leaving as heat. For example, sunlight powers photosynthesis in plants, which store energy in sugars. When herbivores eat the plants, they use some of that energy to grow and function, and the rest is released as metabolic heat; predators eat herbivores and similarly transfer some energy, with more heat lost to the surroundings. Because of these conversions, energy cannot be reused within the system for another round of work. Matter, by contrast, cycles through the system. Elements like carbon and water move between organisms and the environment and are reused over time. A carbon example: plants take in CO2 from the air to build organic matter, animals eat the plants and incorporate carbon into their bodies, and when organisms respire, decompose, or die, carbon is returned to the atmosphere, soil, or water and can be taken up again by plants. A water example follows the same pattern through evaporation, condensation, precipitation, and transpiration, with water continually moving through air, land, and living things. In short, energy flows from source to organisms to the environment and is lost as heat, while matter cycles and is reused within the ecosystem.

Energy in ecosystems moves in one direction and is gradually transformed and absorbed by living things, with most of it leaving as heat. For example, sunlight powers photosynthesis in plants, which store energy in sugars. When herbivores eat the plants, they use some of that energy to grow and function, and the rest is released as metabolic heat; predators eat herbivores and similarly transfer some energy, with more heat lost to the surroundings. Because of these conversions, energy cannot be reused within the system for another round of work.

Matter, by contrast, cycles through the system. Elements like carbon and water move between organisms and the environment and are reused over time. A carbon example: plants take in CO2 from the air to build organic matter, animals eat the plants and incorporate carbon into their bodies, and when organisms respire, decompose, or die, carbon is returned to the atmosphere, soil, or water and can be taken up again by plants. A water example follows the same pattern through evaporation, condensation, precipitation, and transpiration, with water continually moving through air, land, and living things. In short, energy flows from source to organisms to the environment and is lost as heat, while matter cycles and is reused within the ecosystem.