| Term | Definition |
|---|
| Ecology | the study of relationships between living organisms and between organisms and their environment. |
| Ecosystem | a community and its abiotic environment |
| Population | a group of organisms of the same species who live in the same area at the same time |
| Community | a group of populations living and interacting with each other in an area |
| Species | - a group of organisms which can interbreed and produce fertile offspring |
| Habitat | the environment in which a a species normally lives or the location of a living organism |
| Explain how the biosphere consists of interdependent and interrelated ecosystems. | In an ecosystem, organisms feed off of each other. This relation or interaction of organisms can be in the form of a food chain or a food web. The food chain is a linear and simple feeding relation, where one organism has one type of food and is eaten by one type of organism. However, a food web is a more complex and it includes more variety of organisms, each of which can feed on a variety of other organisms and is fed upon by a variety of organisms. These are not the only interactions that compose the biosphere, however. A remarkable diversity of animal interactions, as well as the work of plants, bacteria, fungus, and protists combine to influence the biosphere. Also, organic cycles such as the water cycle, the recycling of the respiratory products of animals (carbon dioxide) in photosynthesis, and the transpiratory return of water to the atmosphere in plants all play major roles as well. |
| Autotrophs | also known as producers, they can make their own food - main producers are photosynthesizers, which utilize the sun's energy and convert it into chemical energy, which they use to build their bodies. Considered net producers of CO2. |
| Heterotroph | are consumers, they feed on ready made organic material, they cannot synthesize their own food, and they are considered net producers of CO2. |
| Detritovore | organisms that feed by ingesting dead organisms (for example - crabs, earthworms and vultures). |
| Saprotrophs or decomposers | organisms that feed on dead organisms and products of living organisms. They secrete enzymes on these materials that cause decomposition, and then they absorb the resulting simple compounds into their bodies. So they do not ingest whole food, but rather, they absorb decomposed and digested food. Examples are bacteria and fungi. |
| Describe what is meant by a food chain giving three examples, each with at least three linkages (four organisms). | A food chain is a linear and simple feeding relation, where one organism has one type of food and is eaten by one type of organism. For example: |
| Describe what is meant by a food web. | A food web is more complex than a food chain and it includes a larger variety of organisms. Each of which feed on a variety of other organisms and they are in turn fed on by more organisms. Therefore, if one species becomes extinct the ecosystem will still be able to exist. |
| Define trophic level | the division of species in an ecosystem on the basis of their main nutritional source. The trophic level that ultimately supports all others consists of autotrophs, or primary producers. |
| State that light is the initial energy source for almost all communities | Light is the initial energy source for almost all communities |
| Explain energy flow in a food chain. | Energy losses between trophic levels include material not consumed or material not assimilated and heat loss through cell respiration. |
| State that when energy transformations take place, including those in living organisms, the process is never 100% efficient, commonly between 10-20%. | When energy transformations take place, including those in living organisms, the process is never 100% efficient, commonly between 10-20%. |
| Explain what is meant by a pyramid of energy and the reasons for its shape | A pyramid of energy shows the flow of energy from one trophic level to the next in a community. The units of pyramids of energy are therefore energy per unit area per unit time. |
| Explain that energy can enter and leave an ecosystem, but that nutrients must be recycled. | Energy can enter and leave an ecosystem but nutrients must be recycled. Sun light is the main source of energy on this planet. It is absorbed by photosynthesizing organisms, which convert light to chemical energy. Nutrients must be recycled by obtaining them from other organisms or products of organisms. |
| Explain the role of saprotrophic bacteria and fungi (decomposers) in recycling nutrients. | These organisms feed on dead organisms and products of living organisms. They secrete enzymes on these materials that cause decomposition, and then they absorb decomposed and digested foods. Examples include many species of bacteria and fungi. These are essential organisms to an ecosystem, since they cause recycling of materials between biotic and abiotic parts of the ecosystem |
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