Name ______Date______

AP Biology – Selections from Chapter 26,29,35,36

Maintaining My Sanitythe Internal Environment

Mechanisms of Homeostasis

Negative and Positive Feedback (and hormones!)

Throughout the text, a common theme has been regulation of homeostasis by feedback loops. There are many examples in the endocrine system with the production of hormones.

  1. Define homeostasis.
  2. Explain how negative feedback works to maintain homeostasis, using the terms “set point”, “stimulus” and “response”.
  3. What are “antagonistic hormones”?
  4. Create a flow chart that shows the negative feedback systems for maintaining blood glucose levels. (Be sure to start with the trigger! Include the hormones and organs/glands involved.)
  5. What is diabetes? What are some of the symptoms?
  6. What are positive feedback loops?
  7. Describe two examples of positive feedback: one for an animal, one for a plant. (Be sure to mention the hormones involved!)

Osmoregulation and Excretion

  1. What is osmoregulation? What is excretion?
  2. In what three forms can nitrogenous waste be excreted? ______
  1. Fish secrete the waste as ______.
  2. Birds and reptiles secrete the waste as ______.
  3. Mammals secrete the waste as ______.

What are advantages/disadvantages to them?

  1. Which organ is responsible for excretion in mammals?
  2. What is the main filtering unit in this organ called?
  3. Create a flow chart that shows the hormones involved in Maintaining Water Levels in the body (Be sure to start with the trigger! Include the organs/glands involved in releasing the hormones.)
  4. Define filtration and reabsorption. Name the substances that are filtered from the blood and are excreted, and which are reabsorbed back into the blood stream.

Thermoregulation

  1. Explain the difference between endotherms and ectotherms (poiklotherm/homeotherm). Which type must expend lots of energy to maintain body temp? How does this relate to metabolic rate?
  2. Create a flow chart that shows the negative feedback system for Maintaining Body Temperature (Be sure to start with the trigger! Include the hormones and organs/glands involved.)Discuss how vasodilation/vasoconstriction are involved in thermoregulation:
  3. Briefly discuss how each of the following are involved in thermoregulation
  4. Fur/feathers, Adipose tissue, Goose bumps, Panting/sweating, Burrowing/sunning
  5. Heat loss in extremities is reduced by countercurrent exchange. Briefly describe how this works in thermoregulation.

Metabolism/Metabolic Rate

  1. What is metabolic rate?
  2. What is basal metabolic rate (BMR)? What is Standard metabolic rate (SMR)? (Include terms ectoderm and endoderm here!)
  3. What is the relationship between BMR and body mass?
  4. What is torpor and what happens to an organism during it?
  5. What are the evolutionary advantages to hibernation/estivation?
  6. Create a flow chart that shows the hormones involved in Maintaining Metabolic Rate (Be sure to start with the trigger! Include the hormones and organs/glands involved.)
  7. Name some metabolic problems (goiter, hypo-, hyperthyroidism) and what causes them? How can they be “fixed”?

Circadian Rhythms

A biological clock is a molecular mechanism that directs periodic gene expression & cellular activity; it is an innate mechanism that controls the physiological activities of an organism that change on a daily, seasonal, yearly, or other regular cycle. Biological clocks drive circadian rhythms.

  1. What is a circadian rhythm?
  2. What factor most directly influences them?
  3. What other factors can affect or disrupt a circadian rhythm?
  4. The hormone that is involved in our circadian rhythm is ______and it is produced by the ______gland in the brain.
  5. What does an increase in this hormone do?
  6. Create a flow diagram that shows the series of events that occurs in the presence of light.
  7. How are levels of light and the hormone mentioned in #29 related?

Plant Regulation

Plant hormones work in conjunction with one another; responses often depend on concentrations of hormone and their ratios to one another.

  1. Without a circulatory system, how do plant hormones work of plant tissues?
  2. Describe the general effects of Auxins (IAA), Gibberellins, Abscisic Acid & Ethylene.

Which hormones are antagonists?

  1. Give a few examples how plant hormones are used in industry.
  2. What is a tropism? What is phototropism? What other stimuli do plants respond to?
  3. Plants also have circadian rhythms. What is photoperiodism? Use short-day plants, long-day plants, and day-neutral plants as an example.