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

Cytogenetics, describe five features of chromosomes used in cytogenetic ana...

describe five features of chromosomes used in cytogenetic analysis?

Why iodine is important for human body, Why Iodine is Important for Human B...

Why Iodine is Important for Human Body? Iodine is an essential constituent of the thyroid hormones: thyroxine (T 4 ) and triiodothyronine (T 3 ), which have a key role in growt

Spermiogenesis - spermatogenesis, Spermiogenesis - Spermatogenesis At ...

Spermiogenesis - Spermatogenesis At the end of the meiosis the spermatids appear as simple spherical cells with a centrally located nucleus. Their differentiation into sperm r

Explain the goal of bcc for a diabetic patient, The overall goal of BCC pro...

The overall goal of BCC programs for diabetes mellitus is to promote behaviors that control diabetes mellitus and prevent complications. These include: Following treatment

Vertebrates, characterstics and classification of vertebrates

characterstics and classification of vertebrates

What will phenotypical feature actually manifested depend, For an individua...

For an individual having a genotype formed of two different alleles that condition different varieties of the same phenotypical trait, upon what will the phenotypical feature actua

What is class crinoidea, What is Class Crinoidea? This Class includes t...

What is Class Crinoidea? This Class includes the sea lilies and the feather stars. What makes them different from the other Echinoderms is the placement of their mouth and anus

Endosperm, 1. What are the examples of helobial endosperm

1. What are the examples of helobial endosperm

Ecology, Benefits of energy pyramids

Benefits of energy pyramids

Thymus gland, THYMU S GLAND Flat, bilobed gland located in the medi...

THYMU S GLAND Flat, bilobed gland located in the mediastinal space in front of heart. Well developed in new born child and grows upto puberty but starts degenerating the

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