Activity 2: Biology to Go

1. Living organisms are affected by one another in competing for food, for light, for types of soil, for water, for mates, for places to live, and in many other ways. They may affect each other adversely or may interact in ways that are helpful to one another. When one organism in a community is affected, it directly or indirectly affects all others.

2. The decomposers in a biological community return the chemical compounds of the bodies of dead organisms, and of the waste products of living organisms to the environment in a form usable by other organisms.

3. A food chain is a straight-line feed path in an ecosystem. For example, a plant is eaten by a rabbit, which is eaten by an owl. A food web links together a whole community of living things in a complex relationship of feeding paths. For example, a plant is eaten by a rabbit, deer, mice, caterpillars. Owls eat mice, rabbits, and caterpillars.

4. a) Autotrophs are able to obtain their energy directly from the physical envi-ronment. They can produce their own food, hence they are called producers.
b) Heterotrophs must obtain their energy from autotrophs or other heterotrophs. Therefore, they consume other organisms to survive.

5. Students will answer that they are either omnivores or herbivores. Their answers must indicate that they understand that omnivores eat both plants and animals, whereas herbivores eat only plant material.

6. Student answers will vary. Suggest that students who are vegetarians nonetheless include some second-order consumers in their food webs.

7. The removal of one organism would have the greatest effect on an Arctic eco-system. There is much less biodiversity in the Arctic, and therefore food webs in this region are not as stable. A deciduous forest has considerable biodiversity.