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

Vitamin - e, VITAMIN - E Also known as beauty vitamin / tocopherol ...

VITAMIN - E Also known as beauty vitamin / tocopherol / antisterlity vitamin . Antioxidant because it inhibits peroxide formation. It stops undesired oxidation. It

Zoonoses disease-cryptococcosis, Cryptococcosis An opportunistic infect...

Cryptococcosis An opportunistic infection, caused by Cryptococcus neoformans is affecting immunocompromised individuals mainly with impaired cell mediated immunity. The disease

What is sarcoplasmic reticulum, An increase in the calcium conductance of a...

An increase in the calcium conductance of all sarcoplasmic reticulum membranes of a skeletal muscle with no external forces on it leads to A. an increase in the amount of calci

Explain in details class hirudenia - leeches, Explain in details Class Hiru...

Explain in details Class Hirudenia - Leeches? This group includes the leeches. Most leeches grow in tropical freshwater habitats, and are familiar to most people as bloodsucker

The permissible use of the technique amniocentesis, The permissible use of ...

The permissible use of the technique amniocentesis is for: 1. detecting sex of the unborn foetus 2. artificial insemination 3. transfer of embryo into the uterus of the su

Phototherapy, Phototherapy As you know exposure of the jaundiced infa...

Phototherapy As you know exposure of the jaundiced infant to blue, white or green light is effective in reducing the serum billirubin level. When bilirubin absorbs light, ser

Why are glucorticoids used in transplant patients, Why are glucorticoids us...

Why are glucorticoids used in transplant patients? Patients with transplanted organs are prone to host versus graft rejection as their own immune system tends to attack the gr

Concept of reproductive isolation and the concept of species, What is the r...

What is the relationship between the concept of reproductive isolation and the concept of species? The Reproductive isolation is an important concept because it defines the con

Nursing diagnosis, Nursing Diagnosis Nursing diagnosis are judgemen...

Nursing Diagnosis Nursing diagnosis are judgements or conclusions reached by you after analyzing the data base that indicate a potential or actual human need that you as

Explain the presumptive test - most probable number test, Explain the Presu...

Explain the Presumptive Test - Most Probable Number Test? The Presumptive test is used to detect and estimate coliform population of a water sample. This test is carried out by

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