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

Explain nephrotic syndrome, Explain Nephrotic syndrome Nephrotic syndr...

Explain Nephrotic syndrome Nephrotic syndrome :- Kidney disease due to degeneration of renal tubule.

Explain about the classification of fungi, Explain about the Classification...

Explain about the Classification of Fungi? The fungi, as you may recall reading above, is now placed in a separate kingdom called Myceteae. Traditionally, fungi were divided in

Procedures for diagnosis - restriction enzyme analysis, R e striction...

R e striction enzyme analysis: The restriction endonuclease analysis of viral DNA fragments or DNA fingerprinting discovered in 1970s has revolutionized the study o

Which mechanism is significant in death of erythrocytes, Of the following, ...

Of the following, which mechanisms are significant in the death of erythrocytes (pron: eh-rith-reh-sites) in human blood? Is it a) Phagocytosis (pron: fag-eh-seh-toe-sis) b)

Explain adverse effects of lactic acidosis, Adverse effects of Lactic acido...

Adverse effects of Lactic acidosis- Lactic acidosis and severe hepatomegaly with steatosis have been reported with use of other nucleoside analogs. The most common adverse effe

Systmetic, Relation between taxonomy and ecology

Relation between taxonomy and ecology

Life as an expression of energy changes, LIF E AS AN EXPRESSION OF ENERGY ...

LIF E AS AN EXPRESSION OF ENERGY CHANGES - Energy is explained as capacity of body to do work. Energy may be as potential (stored) or kinetic (expended) energy. It ex

Crustacea - feeding and digestion in arthropods, Crustacea - Feeding and Di...

Crustacea - Feeding and Digestion in Arthropods Branchiopods (Anacostraca) give a good instance for filter feeding mechanism. The appendages are of foliaceous type (leaf-like)

Carbon dioxide in the atmosphere, Which part of the carbon cycle is respons...

Which part of the carbon cycle is responsible for the enhancing concentration of carbon dioxide in the atmosphere. The burning of fossilized products (coal and oil) of some pla

Foods to be avoided during thyphoid, Foods to be avoided are: High fibr...

Foods to be avoided are: High fibre foods like whole grain cereals and  their products (e.g. whole wheat flour, cracked wheat, whole pulses) Raw vegetables and fruits Fri

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