1. Unit II Cell Energy and Communication Learning Goal 3 Explain how organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis.

2. I.Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes A. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.

3. Operons in gene regulation http://www.youtube.com/watch?feature=play er_detailpage&v=iPQZXMKZEfw http://www.youtube.com/watch?feature=play er_detailpage&v=iPQZXMKZEfw

4. Temperature regulation in animals

5. Plant responses to water limitations

6. B. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set-point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces system change.

7. Lactation in mammals

8. Onset of labor in childbirth

9. Ripening of fruit

10. C. Alteration in the mechanisms of feedback often results in deleterious consequences.

11. Diabetes mellitus in response to decreased insulin

12. Dehydration in response to decreased antidiuretic hormone (ADH)

13. Graves disease (hyperthyroidism)

14. Blood clotting

15. II. Organisms respond to changes in their external environments. A. Organisms respond to changes in their environment through behavioral and physiological mechanisms.

16. Photoperiodism and phototropism in plants.

17. Hibernation and migration in animals

18. Taxis and kinesis in animals

19. Chemotaxis in bacteria http://www.youtube.com/watch?feature=play er_detailpage&v=1wW2CZz6nM4 http://www.youtube.com/watch?feature=play er_detailpage&v=1wW2CZz6nM4

20. Sexual reproduction in fungi

21. Nocturnal and diurnal activity: circadian rhythms

22. Shivering and sweating in humans