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 nutritional effects of hemicelluloses, Nutritional effects Of Hemic...

Nutritional effects Of Hemicelluloses Hemicelluloses are classified under the category of soluble dietary fibers.  Hemicellulose is an indigestible complex carbohydrate that ab

Spoilage of butter, Q. Spoilage of butter? Butter, which has a high con...

Q. Spoilage of butter? Butter, which has a high content of fat, is subject to rancidity and microbial spoilage due to contaminated cream from which it has been prepared

Define echocardiography, Q. What is Echocardiography in pericardial disease...

Q. What is Echocardiography in pericardial diseases? Ans. One of the earliest clinical applications of echocardiography was in the detection of pericardial effusion and it rema

Describe congenital pulmonary stenosis, Describe Congenital Pulmonary Steno...

Describe Congenital Pulmonary Stenosis? The murmur present since birth. PS may be valvular, sub-valvular, or supravalvular. An obstruction may occur within the RV cavity by an

Artificial kidney, ARTIFICIA L KIDNEY - Dialysis employs the process o...

ARTIFICIA L KIDNEY - Dialysis employs the process of diffusion across a semipermeable membrane to remove unwanted urea . Dialysis is of 2 types - 1. Haemodialysis -

Explain the working of conical flasks, Explain the working of Conical Flask...

Explain the working of Conical Flasks? Conical flasks of different volumes can be used for media preparation and also for culturing large amount of microorganisms in liquid med

Is the neural impulse generated by the stimulus, Q. Is the neural impulse g...

Q. Is the neural impulse generated by the stimulus that triggers the arch reflex restricted within the neurons of this circuit? This is obvious since the person that received t

Northern blot, Northern blot is a technique for analyzing mixtures of RNA ...

Northern blot is a technique for analyzing mixtures of RNA by transfer of size-separated RNA fragments to a synthetic membrane, the presence and rough size of one particular type

ALGAE., HOW ARE THE ORIGIN AND EVOLUTION OF ALGAE..

HOW ARE THE ORIGIN AND EVOLUTION OF ALGAE..

Define the first step to envision the pattern of deformation, Define the fi...

Define the first step to envision the pattern of deformation. The first step in the analysis is to envision the pattern of deformation that would accompany such a failure. In 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