PROJECT
IN
SCIENCE 9

Submitted by: Rogie Marie C. Abecia
Submitted to: Ms. Teresita Nanales

March 20, 2015

THE FLOW OF ENERGY AND MATTER IN ECOSYSTEM
When we think about ecosystems, we need to think both big and small. We need to consider the recycling of atoms between organisms and within their environment and the flow of energy through living organisms and its changes from one form to another. We need to appreciate the relationships between organisms, and between organisms and their environment. We also need to consider the potential effects that these relationships have, not only on individual organisms and their environment, but also on our planet.

WATER
Organisms need water to survive. The good news is that water cycles through ecosystems. The bad news is that, at times, the amount of water available can be too great (as in the case of floods) or too little (as in the case of drought). Some species have adapted to these conditions and possess adaptations that increase their chances of survival. Other organisms are not so fortunate and severe conditions of too much or too little water can result in their death. If too many of a particular type of organism die, then the decrease in their population size can have implications not only for other members of their food web, but also for other biotic and abiotic factors within their ecosystem.

ENERGY

As energy flows through ecosystems, from producers to consumers to detrivores to decomposers, some energy is lost at each level. The Sun is life’s main energy supply. Using energy from the Sun, plants make their own food through the process of photosynthesis. Plants need to use most of the energy from the food they make for everyday life processes, such as growing and producing flowers and seeds. On average, only about one-tenth ( 1 10 or 10%) of a plant’s food energy gets stored as nutrients in the roots, leaves, and other parts of the plant. So, when a plant is eaten by a consumer, such as a deer, only one-tenth of its energy is available to the consumer. Similarly, the deer uses most of the energy from its food (the plant) to support its everyday life functions, such as breathing, moving, and chewing. Energy is also is given off as body heat. Consequently, when the deer is eaten by a consumer, such as a cougar, only about one-tenth of its energy is available to the consumer. Thus, very little energy is passed on from one organism to the next in a food chain.

CONCLUSION

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Flow of Matter and Energy in Ecosystems SciPack. It explores how energy flows through an ecosystem in one direction, from photosynthetic organisms to herbivores to omnivores and carnivores and decomposers. As the energy flows, less and less energy is available to support life.

Plants capture the sun's energy and use it to synthesize complex, energy-rich molecules (chiefly sugars) from molecules of carbon dioxide and water. Because plants and other photosynthetic organisms use energy from the sun and inorganic molecules from the environment to produce organic molecules needed for life, they are called producers. The organisms that consume the producers (called consumers) derive energy and materials from breaking down the producers’ molecules, use them to synthesize their own structures and then may be consumed by other organisms. Decomposers (organisms that break down dead producers and consumers and organic waste) obtain the energy they need to live from chemical bonds of the dead and waste-matter. The energy is transferred both to the decomposer (for growth and development) and to the ecosystem (as heat energy). Food webs and energy pyramids are models or representations that can be used to track the flow of energy in the ecosystem. Food webs detail the flow of energy through the populations in the ecosystems whereas the pyramid model quantifies the flow of energy through various levels in an ecosystem. Unlike matter, as energy flows through an ecosystem in one direction, from photosynthetic organisms to herbivores to omnivores and carnivores and decomposers, less and less energy becomes available to support life. This loss of useable energy occurs because each energy transfer results in the dissipation of some energy into the environment as heat. Continual input of energy from sunlight is necessary to keep ecosystems organized and functioning.