Name:______________________________________ Period:_____ Date:________________________
Cell Communication / Signals Worksheet
1. How do cells communicate?
2. What is a signal-transduction pathway? What organism was this studied in?
3. What is a local regulator? Explain how it works.
4. What is a hormone? How do they work, and what do they do?
5. What are the 3 stages of cell signaling? Briefly describe each.
6. Most reception sites are proteins found within the cell membrane. What are the 3 major types of
protein receptors, and how do they differ from one another?
7. What is the job of a protein kinase? What is the job of protein phosphatases?
8. Using cAMP as an example, explain how a second messenger works.
9. How are cells able to be so specific in allowing certain signal molecules to bond to them, and how they
respond to them?
10. What is signal amplification?
11. When a signal-transduction pathway involves a phosphorylation cascade, how does the cell’s response
get turned off?
12. What are circadian rhythms?
13. How do circadian rhythms affect body function and health? Give one specific example
14. Do plants have circadian rhythms? Explain
15. Give examples of plant signaling due to stimulation from light.
16. Do plants need hormones? Explain
17. How do fungi, protists and bacteria, use internal and external signals to regulate a variety of
physiological responses that synchronize with environmental cycles and cues?
18. What are antagonistic hormones?
19. Explain feedback mechanism and why are they important in the health of the organism.
20. Give one example of each: negative - positive feedback, and explain how are they different?
21. What is homeostasis?
22. How do the nervous system and the endocrine system regulate homeostasis? (Hint: how are their
signals different and alike)

Name: Period