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

Features of estuaries, Features of Estuaries The physicochemical prop...

Features of Estuaries The physicochemical properties of the estuaries have large variation in several parameters and this often creates stressful environment for organisms. T

Arthropoda phylum, characteristic of spider that makes it the phylum arthro...

characteristic of spider that makes it the phylum arthropoda?

Explain terbinafine, Explain Terbinafine Terbinafine (Lamisil)  -  Ter...

Explain Terbinafine Terbinafine (Lamisil)  -  Terbinafine is a synthetic allylamine approved by the FDA for treatment of onychomycosis of the toenail or fingernail due to derm

Define isolated soybean proteins in cereal products, Define isolated soybea...

Define isolated soybean proteins in Cereal products? ISP is sometimes used instead of, or in combination with isolates and soy flour, in the formulation of milk replacer mixtur

What is respiratory system explain their functionality , What is Respirator...

What is Respiratory System explain their functionality ? The respiratory system is responsible for the transport of oxygen and carbon dioxide from outside the body to and from

Group of the phylum chordata, Q. What is the group of the phylum Chordata t...

Q. What is the group of the phylum Chordata that first colonized the terrestrial environment? From which habitat did they come? Partially aquatic partially terrestrial animals,

Preparation of the laboratory samples, Q. Preparation of the Laboratory Sam...

Q. Preparation of the Laboratory Samples From the primary sample while selecting a representative laboratory sample, we need to consider the following: a) Laboratory sampl

Lactation tetany of mares (eclampsia, Lactation tetany of mares (eclampsia,...

Lactation tetany of mares (eclampsia, transit tetany) Hypocalcaemia in mares causes lactation tetany, which is characterized by abnormal behaviour, in coordination and tetany.

The heart, Ask question #Minimum 100 words adccepted#

Ask question #Minimum 100 words adccepted#

Explain tuberculosis, Tuberculosis Tuberculosis is a chronic infectious...

Tuberculosis Tuberculosis is a chronic infectious disease which is caused by a bacterium - Mycobacterium tuberculosis.  It affects the lungs most commonly but call gel localize

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