Modes of respiration, Biology

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.

Posted Date: 1/15/2013 6:32:03 AM | Location : United States

Related Discussions:- Modes of respiration, Assignment Help, Ask Question on Modes of respiration, Get Answer, Expert's Help, Modes of respiration Discussions

Write discussion on Modes of respiration
Your posts are moderated
Related Questions
Antiviral activity

Bacteria The study of bacteria is called bacteriology. Bacteria are unicellular organisms and possess a distinct cell wall. They are included in kingdom Prokaryote. The bacter

What is the main moral problem about the cloning of human individuals? Besides biological perils, a very serious moral problem includes the nucleus transplantation technology c

advantages of spread plate method over pour plate method

Define some Precautions for Estimation of the Amount of Bacteria? 1. Dilution should be made carefully. 2. Use fresh sterile pipette for making each dilution. 3. Aseptic

What was Lamarck's explanation for the succession of fossils in a given location? ps: I want to the idea for the succession of fossils, not the whole difference between Darwin and

Explain the Radiographic Success of Root Canal Treatment Elimination or lack of development of an area of rarefaction (= Radiolocency )  for a minimum of I year after treatment

MOD E OF HORMONE ACTION THROUGH EXTRACELLULAR RECEPTORS - The molecules of amino acid derivatives, peptides or polypeptide (protein) hormones bind to specific receptor molecul

A climate classification system divides regions according to _____?

three types of evidence used by systematic taxonomists