As we explore the wide range of subject material in the biological sciences, one of the fundamental patterns you will see over and over again is the precise and efficient systems of control biological systems use to maintain their function and respond to changes in the environment. This is true at the molecular and cellular level, at the level of the organism, and even at the level of populations. Some have even suggested that the global biosphere regulates itself is this fashion (this is by no means a universally accepted view point however).
Learning Objectives: Successful students will be able to ...
- list and describe specific examples of the "levels of organization" typically used to organize the study of biology.
- define and correctly use the terms "homeostasis" and "negative feedback control" and write short essays detailing examples of each.
- distinguish between and describe examples of "intrinsic" and "extrinsic" factors that regulate homeostatic mechanisms.
- write an essay explaining in detail the occurrence of negative feedback control mechanisms at the cellular, organism, and population levels of biological organization.
- write an essay detailing the anatomical and physiological adaptations of hymenopteran insects that enable them to be endothermic.
Lesson One: Levels Of Biological Organization.
Scientists often restrict their research to narrowly defined areas. This is a practical way of focusing on a limited scope of questions that can be easily (sometimes) addressed using the Scientific Method. Biologist tend to focus their work at one or at most a few levels of organization for this reason. Go to Kimball's Biology Pages and follow the link to "Levels of Organization." Read this material and become familiar with the various levels typically recognized in Biology. Keep in mind that there is nothing magical about this organization scheme; it is totally an artificial construct designed to make the work of biologists easier. Likewise, there are no clear boundaries between these level.
Lesson Two: Homeostasis And Negative Feedback Control Mechanisms.
Homeostasis is a fundamental property of biological systems at every level of organization you studied in the first lesson (some would say with the exception of the biosphere). It will be important all year long that you have a clear understanding of what homeostasis is and how negative feedback mechanisms function. Go to the learning resources of Oklahoma City Community College and go through the pages of their tutorial on homeostasis. Be sure you have a clear understanding of the important role negative feedback mechanisms have in maintaining homeostasis at these different levels of organization. You may want to take the quiz at the end of the tutorial to check your understanding of the material.
Homework, Due 4 August. Define the terms "homeostasis" and "negative feedback mechanism" in your own words. Give a brief example of the role of negative feedback in the maintenance of homeostasis at the molecular, cellular, organism, and population level. Email your answers to me using your Fontbonne Academy account.
Lesson Three: Endothermy In Hymenopteran Insects.
You probably heard the term "warm blooded" to describe animals that maintain a high body temperature independently of the external environment. You may also have learned that mammals and birds (and possibly some dinosaurs) are warm blooded.
Thermoregulation is the ability of an organism to maintain and adjust its internal body temperature despite of (or in response to) changes in the external temperature. This area of physiology is one of the best studied examples of homeostasis. Scientist once divided animals into “warm blooded” species such as mammals and birds or “cold blooded” species such as insects, fish, amphibians, and reptiles. We now know that the picture is much more complicated and subtle than this. A more common distinction is now made between "endotherms" and "ecotherms." Here the difference depends on the presence or absence of internal physiological mechanisms for generating heat. Most endotherms are mammals and birds. However, there are many examples from other groups of animals including fish, reptiles, and insects. Keep in mind that when scientists separate species into distinct categories such as enodtherm and ecotherm, there will always be exceptions (which are often the most interesting examples). Go to this Science-Tech archive if you want to explore some of the confusing terminology associated with this subject.
Homework, Due 11 August. Go to the Internet Lesson on Endothermy. Follow the instructions found on that page and email you answers to me using your Fontbonne Academy account.
Image of wasp from Pest Control Canada
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