Biology Homework Chapter 34: Ecosystems and Aquatic Biomes
Textbook Assignment: Chapter 34: Biomes, sections 1-8.
- 34.1 Until now, we have been studying individual cells and individual organisms. Ecology studies how organisms interact with each other (biotic factors) and their non-living environments (abiotic factors). Members of a species in a given area make up a population; all the populations in the area make up a community. The community and its inorganic environment make up an ecosystem.
- 34.2 The interdependence of living organisms and their interactions with the environment can lead to unforeseen complications when one aspect changes. Studies of the effects of pesticides such as DDT in the 1960s by Rachel Carson and others created the realization that human changes to the environment can endanger species.
- 34.3 Environmentalists track the flow of energy from the sun through producers and consumers to decomposers. The rate of energy flow is affected by sunlight, temperature, and the availability of resources such as water, nitrogen, and phosphorus. Terrestrial and aquatic environments each have special considerations.
- 34.4 Individual traits within a population survive when they give individual organisms an advantage to live and reproduce. Biologists call this evolutionary adaptation of the species to its environment, which includes both other living organisms (biotic factors), and characteristics such as climate and terrain (abiotic factors). Note that such changes do not occur on the individual organism level and do not necessarily involve mutations, just changes in the distribution of particular traits within the species population.
- 34.5 In terrestrial biomes, climate characterizes a region's average temperature (heavily dependent on the amount of sunlight per unit area it receives) and rainfall. These determine the energy and liquid water resources available to organisms. Note that snowfall does not count as rainfall, since snow cannot be utilized by plants and animals but must be melted, an activity requiring energy. Even though they receive precipitation in the form of snow, arctic and tundra areas may be considered deserts because rainfall is below 10" a year. Energy is distributed in the form of heat by both air and water currents. Since water is slow to absorb heat and slow to lose it (review chapter 2), it mitigates temperature changes.
- 34.6 In marine biomes, vertical flow of current distributes sunlight energy through increasing depths: surface areas have the most energy available to support communities that can photosynthesize food or that can prey on producers. Deep water regions are aphotic (lacking light), species poor and have low populations. The intertidal zone where salt and freshwater regions meet is among the most species-rich areas on the plant.
- 34.7 In freshwater biomes, similar dependencies on light govern species populations and diversity. Vertical current flow in lakes may be determined by seasonal change, with water freezing on top but remaining liquid below the insulating layer of ice throughout a winter in many temperate regions. As water heats up in spring, oxygen is redistributed through vertical circulation zones.
Read the following weblecture before chat: The Biosphere
Take notes on any questions you have, and be prepared to discuss the lecture in chat.
Perform the study activity below:
Use the Biome pages at Untamed Science to explore aquatic biomes.
- Start with the Lakes and Ponds Biome. Watch the video on how lakes cycle their water supply, and study the different zones and lake stratification. How are tropical and temperate lakes different?
- Now look at at least one other freshwater zone and one marine (saltwater) zone:
Other Freshwater biomes:
- For each zone that you chose, watch the short video, and study any charts or maps that identify where the zones are found and how they are structured.
Chat Preparation Activities
- Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
- No quiz yet: the Chapter Quiz opens when we finish the chapter.
Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.
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