Answers to questions from section 1.5 – Ecology
1) In your own words, define the term “ecology.” Ecology is defined as the study of all the interactions in the biosphere.
2) List four biotic and four abiotic factors in:
a) A freshwater ecosystem such as a lake: – biotic – fish, snails, frogs, dragonfly larvae, water lilies, phytoplankton, etc; abiotic – water, rocks, sand, dissolved oxygen, minerals, etc.
b) A terrestrial ecosystem such as a forest: -biotic – maples, trilliums, bracket fungus, squirrels, red fox, earthworms, etc; abiotic – rocks, soil, sunlight, wind, temperature, etc.
3) Describe how a population differs from a community, using examples: The animals of plants of a specific species make up a population (frogs in a pond), while the various animals and plants in the pond make up a community.
4) Describe how an ecosystem differs from a community using your own examples. Both the biotic and abiotic factors in a community comprise an ecosystem (the community of organisms plus its physical environment).
5) Predict whether you would find more species in a forest, an open field, or the forest-grassland ecotone between them. Explain your prediction. More species are found in ecotones that border two ecosystems because the organisms from both ecosystems are found in the ecotone.
6) Make predictions from the graphs on page 23 in the text:
a. The population of Species 1 of the paramecia in Beaker A grows until it reaches a “steady state” or constant level. The population of Species 2 of the paramecia in Beaker B takes a little longer to begin to increase, but once it does, the population reaches a higher number than Species 1 before reaching a steady state.
b. An increase in the population of paramecium 1 corresponds to a decrease in the population of paramecium 2. This suggests that paramecium 1 has a negative effect on paramecium 2. Perhaps they compete for the same food source.
c. In Beaker C, Species 2 increases in number before Species 1 begins to increase in number. Species 2 begins to decrease in number while Species 1 continues to increase beyond the level of Species 2 and then levels off. One could conclude that the presence of Species 1 has a negative effect on Species 2. (Remember that an answer such as Species 1 feeds on Species 2 or Species 1 is able to compete for food more successfully than Species 2 are inferences that cannot be supported without further study.)