Bio Test Chapter 2

Consider a food web in which snakes eat mice; toads eat beetles; owls eat mice; eagles eat rabbits, snakes, and owls; cougars eat deer; and foxes eat rabbits and mice. What animal occupies (gets energy in) more than one trophic level? Explain.

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What events typically contribute to an algal bloom in a lake or ocean?

A large input of nutrients, such as nitrogen or phosphorus. Can cause the algae to grow and reproduce more quickly.

Compare and contrast the ways carbon and water cycle through the biosphere.

Answers will vary but should include that both carbon and water are found together in the biotic parts of the biosphere. The major reservoir for carbon is the atmosphere and oceans, while the major reservoir for water is the oceans. Students may describe or draw the water and carbon cycles.

Ecologists study the attributes of a biological community to learn about how it works. These attributes include the number of species and the number of different kinds of species interactions. What attributes would an ecologist study about a population to understand it?

Answers will vary. Attributes of a population include its size, growth rate, and distribution or range.

Briefly describe the habitat and niche, highlighting their differences, of a mallard duck.

Answers will vary. The habitat of the duck is a freshwater environment such as a lake, marsh, or river and the nearby shore area (in temperate North America). The niche includes all of the things the duck requires to survive and reproduce, such as certain kinds of plants, algae, insects and other arthropods to eat, an ideal temperature range to successfully live and reproduce in, suitable land areas to make and use a nest undisturbed, and so on.

If you increase the nitrogen content of soil in a forested area, what is likely to change about the water cycle in that area?

Assuming the addition of nitrogen increases plant growth rates, but does not change the composition of the community, the rate of transpiration will increase, so water will cycle faster.

Compare and contrast photosynthetic producers with chemo synthetic producers.

Both reproduce carbohydrates and oxygen are essential to the flow of energy through the biosphere. Different because they get their energy from different sources.

Why are decomposers the final consumers in every food chain.

Decomposers break down dead organisms and return the nutrients to the soil. After this process is complete, the food chain starts over.

What is the connection between ecology and economics?

Ecological economics recognize that people are not only consumers, but are also citizens: not only buy products, but have the ability to respond to ethical problems and considerations.

Compare and contrast a food web and a food chain.

Food chains and food webs are models that show how food and matter pass through organisms at different trophic levels. A food chain shows only one organism at each trophic level. A food web can show many different organisms at different trophic levels. Food webs are better representations of reality because many organisms may consume the same organism, and one organism may consume many others.

Why might a pyramid of numbers be turned upside down?

If the organisms are less massive than the organisms they feed upon. For example, thousands of insects may graze upon a tree. The tree has a lot more biomass, but it is only one organism. So the base of the pyramid will be smaller than the next level up.

Compare the movement of energy in the biosphere with the movement of matter through the biosphere.

Matter is recycled within and between ecosystems. Energy flow is a one-way flow.

List and describe various levels of biological organization that may be studied by an ecologist.

Students should describe the levels of the individual organism, populations, communities, ecosystems, and the biosphere. Each level should be related to the levels above and below. Examples of each level might also be given. (Organelle, cell, tissue, organ, organ system, organism, population, species, community, ecosystem, biome, biosphere).

Most food webs are drawn with arrows between organisms that are all the same thickness. Why might you want to draw a food web with arrows of differing thickness and what would these differences represent?

The arrows with different thicknesses would represent the amount of energy that moved from one organism to another. So, for example, if three quarters of the diet of a snake were mice (three quarters of the weight of food it ate) and one quarter were frogs, then the arrow between the mouse and the snake would be three times as thick as the arrow from the frog to the snake. This would improve the information given by the food-web model and allow you to see where most of the energy was flowing in the ecosystem.

Explain why graphs of the amount of energy at each trophic level in a community forms a pyramid.

The graph is a pyramid because there is a loss of energy reaching each trophic level from the one below it. That energy is lost as heat or in waste and is not available for the next trophic level to incorporate into its own tissues. Because of this at each higher trophic level there is less and less energy, making the graph look like a pyramid, wide at the bottom, narrow at the top.

Explain the ecological significance of interdependence.

The interactions between organisms produce a food web of interdependence. This develops between individual organism species, populations, communities and their environments.

When a grouse (a type of bird) eats berries, the berry seeds are eliminated as waste materials and may be dropped in another part of the forest where they may sprout and eventually grow into new berry plants. How would you classify the relationship between the berry and the grouse? Explain your reasoning.

The relationship is one of mutualism as the grouse benefits by getting food energy from the berries and the berry plant benefits by having its seeds dispersed; thus, its reproduction is aided.

Explain how the biogeochemical cycling of oxygen, carbon, nitrogen and hydrogen are important to living systems.

Without these cycles, the living things on Earth may not be able to function the way they do with these cycles, because these cycles are an essential part in order for living organisms to survive.