AP Biology Osmoregulation Worksheet

AP Biology
Osmoregulation Worksheet
This worksheet approaches the subject of osmosis using evolution, homeostasis and regulation.
Use your knowledge of osmosis and your text (Focus 1e: Ch.32.2-4) / Campbell 7e: Ch.32.3) to describe how
homeostasis is maintained in these organisms using these features to survive. Use one or two sentences for each.
Also, note whether each organism is an osmoconformer or an osmoregulator. Which is more evolutionarily
advanced? Page and figure references are for Biology in Focus, 1e.
1.
Define osmoconformer:
2.
Define: osmoregulator:
3.
Kingdom Protista: paramecia (contractile vacuoles, fig. 5.12)
4.
Phylum: Platyhelminthes: planaria (flame cells or protonephridia,
fig. 32.18)
5.
Phylum: Annelida: earthworms (nephridia, Google it)
6.
Phylum: Arthropoda: grasshoppers (malpighian tubules, p.656)
7.
Phylum Mammalia: lions (kidney/nephron, fig. 32.19)
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Use your textbook to look up the structure of a nephron, the functional unit of a kidney. (Bio in Focus: Fig. 32.21)
8. Explain how the osmolarity of the kidney changes as the filtrate in the tubule moves from the cortex to the outer and inner
medulla.
9.
Describe how the nephron uses the osmolarity of the interstitial fluid in the kidney to reabsorb water back into the blood
stream by osmosis. (p.657)
10. How is the high osmolarity of the kidney maintained?
11. The marine environment is strongly dehydrating due to the high salt concentration. Fish, like sharks, drink large amounts
of water and excrete ions and nitrogenous waste in urine that is low in volume and highly concentrated in urea
(hyperosmotic urine). How would freshwater fish maintain their water balance? (fig. 32.15)
12. Kangaroo rats live in the desert and get their water through the food they eat. A mammal with typical kidneys (like a
humans) would not be able to survive. How has the Loop of Henle adapted in kangaroo rats to give them the ability to
survive with so little water? (p.661)
Homeostasis
13. Which part of the body monitors the osmolarity of blood? (fig.32.23)
14. What is the condition called when the body has too little water due to sweating, for example?
15. Which part of the body produces the hormone that controls the reabsorption of water by the kidneys?
16. Which hormone causes the body to conserve water? (p.661) _______________, a.k.a.: _________________ .
17. How does an antidiuretic hormone bring about the reabsorption of water from the filtrate of the nephron?
18. Are alcohol and caffeine diuretic or antidiuretic substances? Explain.
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(4 pts) Correctly arrange the labels in the boxes.
Response/effector
Sensor/receptor
Stimulus: Change in internal variable
Control Center
Using the information that you found to answer questions 12-17 under the heading Homeostasis, superimpose the specific
answers onto the generalized model above.
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