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

Differences between genomes in prokaryotes and eukaryotes, What are the dif...

What are the differences between genomes in prokaryotes vs. eukaryotes?

What units are the nucleic acids constituted, Q. Of what units are the nucl...

Q. Of what units are the nucleic acids constituted? What are chemical entities that compose that unit? The Nucleic acids are formed by sequences of nucleotides. Nucleotides

Learning objectives of metabolic diseases, Q. Learning objectives of metabo...

Q. Learning objectives of metabolic diseases? • enumerate the etiological factors and symptoms of gout and few inborn errors of metabolism, • describe the metabolic changes

How are a hypothesis and an experiment related, How are a hypothesis, a pre...

How are a hypothesis, a prediction, and an experiment related? A prediction is a statement made in advance that declares the results that will be get from testing a hypothesis

Explain the economic and social burden of heart diseases, Explain the Econo...

Explain the Economic and Social Burden ? Cardio-vascular diseases pose tremendous economic strain on the population and the countries throughout the world. However there is a d

Enzymatic mutation detection method, This technique utilizes an enzyme reso...

This technique utilizes an enzyme resolvase, endo vii, cloned from the bacteriophage t4. This enzyme has high specificity to find deletions, insertions, and base substitutions muta

Explain how blue white selection works, The plasmids below show the inserti...

The plasmids below show the insertion of the EZH2 gene into the pBluescript plasmid in either sense (forward) or antisense (reverse) orientation. These are the plasmids you will ho

What are intraspecific ecological interactions, What are intraspecific and ...

What are intraspecific and interspecific ecological interactions? Intraspecific ecological interactions are those among individuals of the same species. Interspecific ecologic

Human imapct on the environment, list the long-term and short-term effects ...

list the long-term and short-term effects of forest destruction (a)on hillsides,(b)in the tropics?

Define ailing and failing, Define ailing and failing Clinically unhealt...

Define ailing and failing Clinically unhealthy implants are classified as "ailing" or "failing". It is necessary to distinguish between an ailing versus a failing implant to de

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