Contractile vacuoles - excretion, Biology

Assignment Help:

Contractile Vacuoles - Excretion

Contractile vacuoles are always found in freshwater protozoans and sponges, but are frequently absent in their marine counterparts. Since a freshwater animal is hyperosmotic to the medium (freshwater) and its surface is permeable to water, it should continually endeavour to pump out the excess water that enters osmotically. When a freshwater protozoan is transferred to dilute sea water, the vacuolar activity decreases. In those marine species that have a contractile vacuole (e.g., some ciliates), vacuolar output increases with dilution of the sea water.

The fluid present in the contractile vacuole of freshwater protozoans is hypoosomotic to the surrounding cytoplasm, though still hyperosmotic to freshwater. These observations are consistent with the hypothesis that contractile vacuoles are primarily organs of water balance and function as pumps to remove excess osmotic water. Any role they might play h the excretion of nitrogenous wastes, which is mainly ammonia-in protozoans and sponges, is considered to be secondary.


Related Discussions:- Contractile vacuoles - excretion

CYTON, WHAT DOES CYTON HAVE TO DO WITH NEURON

WHAT DOES CYTON HAVE TO DO WITH NEURON

Deficiency diseases-thiamine deficiency (hypothiaminosis), Thiamine deficie...

Thiamine deficiency (hypothiaminosis) Thiamine deficiency is characterized by signs of nervous system. The primary  thiamine deficiency is not common in animals. However, seco

Draw the organic chemistry notation, I know that in organic chemistry notat...

I know that in organic chemistry notation , it is assumed that the end of a line or the point where two lines meet is a carbon atom and that Hydrogen atoms are not labelled as it i

Osmotic stress, when microbial culture must be harvested after giving osmot...

when microbial culture must be harvested after giving osmotic stress to analyze osmotolerant genes?

Fission - asexual reproduction, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Living matter, LIVING MATTER Since at the subatomic level, all matter i...

LIVING MATTER Since at the subatomic level, all matter is basically similar, the fundamental chemical and physical principles are equally applicable to all objects in nature; y

Explain the nucleic acid is the transforming agent or not, Fredrick Griffit...

Fredrick Griffith published a series of experiments that collectively were dubbed "The Transforming Principle" in 1928. Which of the following prevented him from being able to decl

Enumerate about the diseases insomnia, Enumerate about the diseases Insomni...

Enumerate about the diseases Insomnia The results from studies of people, who claim that they do not sleep, or wake up frequently from sleep show that their insomnia can have m

How is carbon dioxide released by cellular respiration, How is carbon dioxi...

How is carbon dioxide released by cellular respiration transported from the tissues to be eliminated through the lungs? In vertebrates almost 70% of the carbon dioxide is trans

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd