Water - properties and functions, Biology

WATER

Occurence

  1. Water is the most abundant substance, covering 70% of earth's surface.
  2. It constitutes 60-90% of living cells.

             5-6% in tooth enamal, 60 - 70% in human adults, 90-92% in brain cells, 90 - 95% in human embryo, 99% in Jelly                   Fish.

  1. 95% of the total water occurs in the free state.
  2. Only 5% is found in bound state.

PROPERTIES

  1. Water freezes at 0oC and boils at 100oC. It remains liquid in between the two temperatures.
  2. Water is colourless and transparent.
  3. Pure water does not have any odour or taste.
  4. All the essential mineral elements dissolve in water. Water is a medium for their availability to organisms.
  5. Water is a very poor conductor of electricity in the pure state. However, it is good conductor of electricity in the presence of ionised chemicals.
  6. Pure water is neutral with a pH of 7.
  7. Water is a small polar molecule having positive and negative charges.
  8. Water has a high dielectric constant which enables the oppositely charged ions of electrolytes to remain suspended in water.
  9. Surface Tension is very high.
  10. Water has the maximum specific heat.  Water has the maximum density at 4oC.

FUNCTIONS OF WATER

  1. Water is a major component of cells and body fluids.
  2. Water is a habitat of numerous animals, plants and other organisms.
  3. Water has the maximum solvent action for both electrolytes and nonelectrolyte polar substances.
  4. Water is also dispersion medium for hydrophilic or reversible colloids.
  5. Water is transport medium in both plants (xylem, phloem) and animals (blood and and lymph).
  6. Excretory products are eliminated mainly in solution form. It helps in homoeostasis.
  7. Water maintains the turgid state of cells and soft organs.
  8. In photosynthesis, water molecules undergo photolysis, evolve O , provide H+ ions and electrons for reduction of CO to organic state.
  9. Water present in tissue fluid, coelomic fluid, pericardial fluid, cerebrospinal fluid, etc. keeps the tissues moist for their optimum functioning. It is also a lubricant of joints.
  10. Seeds and spores require water for their germination.
  11. Cornea is protected from microbe infection and dust by lachrymal fluid. Mucus protects the nasal tract from the same. In both water is the main ingredient for flushing of teh particles.
  12. Heat spreads in water quite repidly due to high thermal conductivity. It distributes heat uniformly and prevents sudden changes in temperature.
  13. Shortage of water on land has been a major selection pressure in evolution of xerophytes, desert animals, seed plants, etc.
Posted Date: 10/9/2012 2:58:45 AM | Location : United States







Related Discussions:- Water - properties and functions, Assignment Help, Ask Question on Water - properties and functions, Get Answer, Expert's Help, Water - properties and functions Discussions

Write discussion on Water - properties and functions
Your posts are moderated
Related Questions
During the last 90 years, man-made materials and devices have been developed to replace parts of living systems in the human body. These special materials function in intimate cont

If the results of an experiment turn out differently then you expected, what does that mean? A. The experiment was a failure B. You did not follow scientific method C. You should e

What is signified by saying that in relation to a given trait conditioned by a gene with two different alleles the gametes are always "pure"? To say so that the gametes are pur

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

Which of the following properties of dsDNA is imprtant for DNA purification? A. Hydrophilic B. Positively charged phosphate backbone C. Can only bind to divalent cations

Q. Explain Rodent Control and pests? In any food establishment, varieties of insects, pests and rodents pose a big threat to the maintenance of hygienic surroundings. They

what the by products of sugarcane

Q. What do you mean by Current Impediments? Given the impressive list of past achievements, we expect that quantitative process to biological problems will continue to repay us

The gene is a distinct portion of a cell's DNA. Genes are coded instructions for making all the body needs, mainly proteins. Human beings have about 25,000 genes. Researchers have

Q. Zonation in the ocean? The oceans play a major role in determining the climate and sustaining life on earth. Oceans help to redistribute the solar energy, through ocean curr