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

Ask an Expert

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

Write your message here..

Related Questions

Importance of nutritional interaction, Importance  of nutritional interact... Importance  of nutritional interaction :- Now  being  realized.  Some  nutrients  are antagonistic to each other whereas others act synergistically. Examples of uniquely related

Define significance of plants and animals on human life, Define Significanc... Define Significance and Impact of Plants and Animals on Human Life? Plants and animals both have a great significance and unparalleled impact on human life. Most of our needs a

Explain the postoperative nutritional care, Explain the Postoperative Nutri... Explain the Postoperative Nutritional Care? The therapeutic goal for the post-operative patient is rapid recovery to normal function and well being, minimum complications and e

How are the male gametophytes formed in angiosperms, Q. How are the male ga... Q. How are the male gametes and the male gametophytes formed in angiosperms? In the anthers of every stamen there are pollen sacs. Inside the pollen sacs there are microspore m

Define pseudo-yeasts, Q. What are the Pseudo-yeasts? These are like tru... Q. What are the Pseudo-yeasts? These are like true yeasts but do not form spores. All the members of this group are particularly unsuitable for fermentation purposes as they p

Adp-atp system of energy exchange, ADP-ATP system  of energy  exchange : ... ADP-ATP system  of energy  exchange : In 1929 Lohmann, Fiske and  subbarow  published  their  discovery  that the energy  exchanges  compounds in all biological  systems  are t

Which equipments are required for stress laboratory, The stress lab must ha... The stress lab must have the following equipment: 1) A mercury Blood Pressure apparatus. 2) A Bed so that the patients ECG can be recorded in the recovery period in supine po

Heteroduplex dna, Heteroduplex Dna  is generated by the base pairing betwee... Heteroduplex Dna  is generated by the base pairing between complementary single strands derived from the different parental duplex molecules; heteroduplex DNA molecules occuring du

Urinary system, Structures that l pyramidenaform the r Structures that l pyramidenaform the r

Q- fever, Q- fever Q-fever or query fever is primarily a disease of animal... Q- fever Q-fever or query fever is primarily a disease of animals transmitted to human through inhalation. It is also known as Balkan influenza, Abattoir fever or Coxiellosis. It