2. Essential Knowledge
2.d.2 Homeostatic mechanisms reflect both common ancestry and
divergence due to adaptation in different environments.
Examples: Osmoregulation in fish, bacteria, and protists.
Osmoregulation in aquatic and terrestrial plants.
3. Osmoregulation in Fish, Bacteria, and Protists
Osmoregulation: regulation of osmotic pressure of an organisms fluid’s
to maintain the homeostasis of the organisms water content
If organisms have similar osmoregulation processes this indicated a
common ancestry.
All regulators and conformers use pumps in order to maintain
homeostatic levels.
4. Osmoregulation in Fish, Bacteria, and Protists
● Osmoregulators vs. Osmoconformers
○ protists and fish are osmoregulators
○ bacteria are osmoconformers
Divergence
● The differences of the processes show divergence
○ protists: Use a contractile vacuole to pump water out preventing themselves
from bursting; unicellular and relies on a single pump mechanism.
○ fish: Marine fish loose water constantly, so they drink water and pump out the
excess salts with their gills. Freshwater fish gain water constantly, they excrete
dilute urine and replenish salts by eating and pumping them through their gills.
○ bacteria: If water is flowing into bacterium, it pumps out salt. If water is flowing
out of the bacterium, it pumps out water. Unicellular and relies on a single
pump mechanism to maintain homeostasis.
6. Osmoregulation in Aquatic and Terrestrial Plants
● Osmoregulation occurs in the stoma of plant; loosing water is crucial in a
plants life, so osmoregulation must be maintained. This proves a common
ancestry.
● Nitrogenous waste is nitrogen gas produced in metabolic processes, also
proving common ancestry.
7. Work Cited
"What Is Osmoregulation?" What Is Osmoregulation? N.p., n.d. Web. 27 Feb. 2015.
http://www.innovateus.net/science/what-osmoregulation
"Osmoregulation in Fish, Protists, and Bacteria." Osmoregulation in Fish, Protists, and Bacteria. N.p., n.d. Web. 27 Feb. 2015.
http://animalphysiologyprojectt.weebly.com/osmoregulation-in-fish-protists-and-bacteria.html
"Homeostasis Prezi." Prezi.com. N.p., n.d. Web. 28 Feb. 2015.
https://prezi.com/kyukg64-hdyn/homeostasis-prezi/
