Modes of respiration, Biology

Assignment Help:

Modes of Respiration

Many small organisms obtain oxygen by diffusion through their body surfaces. They do not have any specialised respiratory organs nor do they have blood circulation. Larger and more complex organisms, however, need specialised surfaces for gas exchange and a circulatory system that transports oxygen more readily than that possible by simple diffusion. Calculations based on metabolic demands and rate of diffusion in protoplasm show that simple diffusion is sufficient only to meet the demands of organisms not larger than 1 mm in diameter. These calculations appear reasonable when we see that animals like protozoans and flatworms that meet their respiratory requirements through diffusion are either quite small or have very low metabolic rates.

Giant land planarians may be 50 cm long but they are flat with very large surfaces in relation to mass, therefore, diffusion is sufficient to meet their oxygen demand. Coelentrates, corals and sponges often reach very large sizes but have very modest metabolic demands. Sponges and corals maintain a circulation of water by cilia over the surfaces of cells which line their canal systems. Thus sufficient gas exchange takes place without the aid of a circulatory system or respiratory pigments.


Related Discussions:- Modes of respiration

Myocardial hypertrophy and remodeling, The long term adaptive mechanisms in...

The long term adaptive mechanisms involve myocardial hypertrophy and remodeling which occurs slowly over weeks to months. The capacity of these adaptive mechanisms meant to sust

Rejection reaction, Rejection Reaction For rejection reaction the phys...

Rejection Reaction For rejection reaction the physiological and biochemical processes are set in the pistil by the recognition reaction specific to the type of pollen that lan

The glomerular filtrate in comparison to the blood, What is the main transf...

What is the main transformation presented by the glomerular filtrate in comparison to the blood? Glomerular filtrate is the name given to the plasma after it has passed the glo

fat digestion requires two steps, Fat digestion requires two steps? What a...

Fat digestion requires two steps? What are the steps and what enzymes are used to accomplish each step?

How different are pteridophytes from bryophytes, Q. How different are pteri...

Q. How different are pteridophytes from bryophytes regarding substance transport? Pteridophytes are tracheophyte (vascular) plants that are they have tissues specialized in con

Sharps-hazards in biology laboratory, SHARPS : Cuts due to careless handli...

SHARPS : Cuts due to careless handling of sharps such as sectioning razors, microtome blades etc. are probably the most common cause of injury in the biology lab. The only real re

Define the armamentarium, Define the Armamentarium a) Micro-mirrors (ma...

Define the Armamentarium a) Micro-mirrors (magnification: x 40, Size: 0.5) b) Micro-probe c) Micro-blades, tissue retractors d) Burs e) Retrograde Tips "round bur

Show the examples of arthropods, Q What are the few examples of arthropods?...

Q What are the few examples of arthropods? Ants, crabs, cockroaches, shrimps, flies, spiders and scorpions are examples of arthropods.

Which are the respiratory muscles in mammals, Q. Which are the respiratory ...

Q. Which are the respiratory muscles in mammals? In mammals the muscles that participate in the breathing process are the diaphragm and the intercostal muscles, in respiratory

What is the heterophagic intracellular digestion, Q. What is the heterophag...

Q. What is the heterophagic intracellular digestion and How is this process accomplished? Heterophagic intracellular digestion is the breaking into smaller substances of extern

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