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

Role of water in metabolism, ROL E OF WATER - In general water cons...

ROL E OF WATER - In general water constitutes 60-90% of protoplasm. Average 80%. It forms 2/3 of human body weight, i.e. 66.66%. Due to electrophillic nature of O, wa

Effects of marasmus on a child, Marasmus is a disease due to the deficiency...

Marasmus is a disease due to the deficiency of both proteins and calories.The child is weaned out before one year of age and is given a diet low in both proteins and carbohydrates.

What are those phyla, Q Beings from four phyla of the animal kingdom "breat...

Q Beings from four phyla of the animal kingdom "breath" (do gas exchange) by diffusion. Which are those phyla? How is this type of respiration associated to features present in tho

Agro industrial-soaking, Soaking Soaking is an another inexpensive proc...

Soaking Soaking is an another inexpensive processing method, which does not require much technical know how, is commonly practiced for improving the palatability of chaffed cro

Difference between spermatid and spermatocyte ii, Q. What is the difference...

Q. What is the difference between spermatid and spermatocyte II? The spermatids (n) are the products of the second division of meiosis (meiosis II) in the male gametogenesis an

Restructured meat products, Re s t r u c t u re d Meat Products ...

Re s t r u c t u re d Meat Products Restructuring technique is used for developing convenience products with texture in between intact steak and a comminuted product.

How is the circulatory system of birds characterized, Q How is the circulat...

Q How is the circulatory system of birds characterized? Like every vertebrate, Birds, have a closed circulatory system. The heart is similar to the mammalian heart, having four

Etiological factor of lactose intolerance, Q. Etiological factor of lactose...

Q. Etiological factor of lactose intolerance? These diseases are referred to as idiopathic (cause unknown) and though the possible mechanism suggested includes genetic factors,

Neural impulse is transmitted from one cell to another, What is the structu...

What is the structure through which the neural impulse is transmitted from one cell to another? What are its parts? The structure by which the neural impulse passes from one c

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