Biology Chapter 3 Short Answer
How does a food web differ from a food chain?
A food chain is a series of steps in which organisms transfer energy by eating and being eaten. A food web is a feeding relationship among the various organisms in an ecosystem that forms a network of complex interactions. A food web links together all the food chains in an ecosystem.
Explain the differences among the three types of ecological pyramids
A pyramid of energy shows the relative amount of energy available at each trophic level of a food chain or a food web. A pyramid of biomass shows the relative amount of living organic mater available at each trophic level in an ecosystem. A pyramid of numbers shows the relative number of individual organisms at each trophic level in an ecosystem.
Explain, with an example, how the biotic factors in an ecosystem can affect the abiotic factors
A tree by a pond can block the sun from getting to the pond.Therefore the plants in the pond will not be able to get their energy. Because of the loss of energy, less carbon dioxide will be taken, and less oxygen will be put into the water.
Compare and contrast photosynthetic producers with chemosynthetic producers.
Both produce carbohydrates and oxygen and are essential to the flow of energy through the biosphere. They are different because they get their energy from different sources.
Describe three research methods used by ecologists.
Ecologists use observation, experimentation, and modeling. Observation involves asking questions and using senses to gather information. Experimentation is used to test hypotheses. Ecologists use modeling to understand phenomena that are difficult to study directly. Some models are mathematical models based on data gathered through observation and experimentation.
Describe the flow of energy among the following members of an ecosystem:docomposers, autotrophs, heterotrophs, and the sun.
Energy flows from the sun to the autotrophs, and from the autotrophs to the heterotrophs. Energy also flows from the autotrophs and the heterotrophs to the decomposers.
Compare and contrast the flow of energy through an environment with the flow of matter through that same environment.
Energy is captured by producers and then passed in a linear progression from one trophic level to the next. At each level, much of the energy escapes the ecosystem as heat. Unlike this one-way flow of energy, matter is recycled within and between ecosystems. Elements pass from one organism to another and among parts of the non-living environment through closed loops called biogeochemical cycles.
Describe the role of algae in ocean food chains
The algae are autotrophs, the producers at the base of the food chain.
Explain why farmers use fertilizers? Include the concept of limiting factors in your response.
The growth of crop plants is usually limited by one or more nutrients that the plant needs. Fertilizers add large amounts of nitrogen, phosphorus, and potassium which help plants grow better in soil that is low in these nutrients. Some fertilizers also contain other nutrients such as calcium, magnesium, and sulfur in small amounts. Adding all these nutrients in fertilizers makes the soil more productive. In that way farmers can grow better, larger crops and make more money.
Explain the ecological significance of interdependence.
The interactions between organisms produce a web of interdependence. This develops between individual organisms, species, populations, communities, and their environments.
Why might a pyramid of numbers be turned upside down? Explain your answer with an example.
The pyramid might be turned upside down if the consumers are less massive than the organisms they feed upon. For example, thousands of insects may graze upon one tree. The tree has alot more biomass, but itis only one organism. So the base of the pyramid will b smaller than the next level up.
