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

Define the historical process of spatial processes, Define the Historical P...

Define the Historical Process of Spatial processes? In year 1952 Alan Turing developed his theory of the generation of pattern in systems of reaction diffusion equations, now k

Describe the timing of surgery and intervention, Describe the Timing of Sur...

Describe the Timing of Surgery and Intervention For Various Congenital Heart Diseases ? The timing of surgical or trans-catheter intervention for congenital heart disease (CHD

Biological species concept, Is the biological species concept subjective or...

Is the biological species concept subjective or objective? How about the phylogenetic species concept or is it subjective or objective?

Enumerate the term - clinical neuroscience, Enumerate the term - Clinical n...

Enumerate the term - Clinical neuroscience Clinical neuroscience concerns the study of clinical populations both to well understand neuroanatomy and to test psychological theor

Explain about the hypokalemia, Explain about the Hypokalemia? Normal s...

Explain about the Hypokalemia? Normal serum K ranges from 3.5-5 mM/L. Hypokalemia or low plasma K levels can occur with a net shift of K from the plasma to the cells. This shi

Limerick, how do we write a limerick spell?

how do we write a limerick spell?

Explain the adsorption or binding ability, Explain the Adsorption or Bindin...

Explain the Adsorption or Binding Ability? Some fibre components have the ability to bind (adsorb) substances in the gastrointestinal tract. Wheat bran, guar gum, mannan and is

Amoeboid protozoan, Amoeboid Protozoan Amoeboid protozoan are distingu...

Amoeboid Protozoan Amoeboid protozoan are distinguished by the presence of flowing extensions of their body known as pseudopodia. These are used for feeding and locomotion. Th

Entamoeba histolytica, Entamoeba Histolytica Losch (1875), for the fir...

Entamoeba Histolytica Losch (1875), for the first time, described the disease symptoms of infection of Entamoeba histolytica. However, it was only in 1903 that Schaudin gave t

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