Water - properties and functions, Biology

Assignment Help:

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.

Related Discussions:- Water - properties and functions

Find the equilibrium molality of solute species, Find the equilibrium molal...

Find the equilibrium molality of solute species? Consider a hypothetical system in which two aqueous solutions are separated by a semipermeable membrane. Solution α is prepared

Explain about the term accommodation, Explain about the term accommodation....

Explain about the term accommodation. Normally, the human eye focuses at objects at infinity, without exerting any power. This implies that while a person is observing an objec

How establish a pure-breeding population of brown pigs, Would it be possibl...

Would it be possible to establish a pure-breeding population of brown pigs with a few black spots?

Excluding development, tube feet,stone canal,medreporite and teidman;s body...

tube feet,stone canal,medreporite and teidman;s body notes

Importance of pituitary gland, Importance of pituitary gland Pitutar...

Importance of pituitary gland Pitutary gland is very small and it is about the size of a large pea seed. It is very important as it controls the functions of all the othe

External auditors reports, External Auditors Reports The audit report...

External Auditors Reports The audit report is the final stage in the process of an audit.  The terms 'true and fair'  'present fairly' have special significance in the audit

Explain in brief about unicellular “animals”, Single-cell organisms, protis...

Single-cell organisms, protists, have always been a problem for taxonomists who have trouble describing categories for organisms. Their mixed feeding habits that include being capa

Extensive factor of luria nebraska procedure, Extensive factor of Luria Neb...

Extensive factor of Luria Nebraska procedure Extensive factor analytic studies have been accomplished, and the factor structure of each of the major scales has been recognized.

What is the ability of two oxygens to remove h+ protons, What makes the clu...

What makes the cluster of atoms of carboxylic acid functional group an acid? a) a non-polar O-H bond near another electronegative oxygen. b) an ionic O-H bond near another el

Gradient hypohesis, please give me the expansion for ''gradient hypothesis'...

please give me the expansion for ''gradient hypothesis'' and the two types of gradient hypothesis in deelopment of animals in detailed manner

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