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

Which are the germ layers present in cnidarians, Q. Which are the germ laye...

Q. Which are the germ layers present in cnidarians? Which tissues of the animal do they originate? These beings present endoderm and ectoderm, two germ layers. Animals only wit

Explain neurochemical process, Alertness and sleep are dependent on the act...

Alertness and sleep are dependent on the activity of the brain as a whole, although different levels of consciousness are determined primarily by areas of the brain stem. A key ana

Define measuring body composition- multiple isotope dilution, Define measur...

Define measuring body composition- Multiple isotope Dilution? Multiple isotope dilution (Total and extracellular body water): It is based on the principle that certain substanc

Signs and symptoms of hypothyroidism, Q. What are some signs and symptoms f...

Q. What are some signs and symptoms found in patients with hypothyroidism? In hypothyroidism the production and secretion of T3 and T4 are impaired. Since these thyroid hormone

How does epistasis affect proportion of phenotypical form, In the hybridiza...

In the hybridization of 2 genes (4 different alleles, 2 of each pair) how does epistasis affect the proportion of phenotypical forms in the F2 generation? In the dihybridism wi

Use of syphilis in pregnancy, Syphilis in Pregnancy Syphilis in pregna...

Syphilis in Pregnancy Syphilis in pregnant women should be treated with penicillin in doses appropriate to the stage of the disease. When pregnant women with syphilis are alle

Why superoxide radical scavenging of beverages, Why is Superoxide radical s...

Why is Superoxide radical scavenging of beverages such red wine, grape juice measured at 560 nm?

Aims and applications of epidemiology, Problem 1: Show the aims and app...

Problem 1: Show the aims and applications of Epidemiology. Definition of Epidemiology. List aims of Epidemiology List applicationsof Epidemiology Problem 2

What are the dietary goals for diabetes, Q. What are the dietary goals for ...

Q. What are the dietary goals for diabetes? Well here they are. These are to: 1. Supply optimum nutrition to maintain good health, 2. Provide calories for maintaining ide

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