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

Social determinants of health - social exclusion, Social Determinants of He...

Social Determinants of Health - Social Exclusion Given that absolute poverty is a major determinant of ill-health, the resultant social exclusion is ‘psychologically damaging,

What are the values of dpd for plant cells under hypertonic, What are the v...

What are the values of DPD for plant cells under hypertonic, isotonic and hypotonic media? In plant cells under hypertonic medium there is loss of water for the exterior, SF >

What do biomass pyramids represent, What do biomass pyramids represent? ...

What do biomass pyramids represent? Biomass pyramids show the sum of the masses of the individuals that participate in each trophic level of a food chain.

Define role of polyunsaturated fatty acids - gene expression, Define Role o...

Define Role of polyunsaturated fatty acids - Gene Expression? In contrast, polyunsaturated fatty acids (PUFA) inhibit G6PD in both intact animals and in primary hepatocytes in

Chlamydiosis-clinical manifestations, Clinical manifestations Since the...

Clinical manifestations Since the disease due to Chlamydia involves many organs/systems, system-wise descriptions of clinical signs is described as under: Genital infectio

Explain the biomechanics of cantilevers, Explain the biomechanics of cantil...

Explain the biomechanics of cantilevers The biomechanics of cantilevers need to be understood. It has been found that when a three unit prosthesis is supported by two implants

What is a nutrient, What is a nutrient? A nutrient is it substance used...

What is a nutrient? A nutrient is it substance used in the metabolism and which is acquired from the diet. Such as, vitamins and necessary amino acids are nutrients.

Ribosomes, Ribosomes:     are minute nonmembranous  and dense spheroidal p...

Ribosomes:     are minute nonmembranous  and dense spheroidal particles or  granules. First observed by   electron   microscopy by palade 1955. Being only about 200 to 250 a in di

What are the hormones produced by the testicles, What are the hormones prod...

What are the hormones produced by the testicles and the ovaries? The testicles make androgenic hormones, the major of them being testosterone. The ovaries make estrogen and pro

Define streptomycin, Define Streptomycin Streptomycin  causes ototoxici...

Define Streptomycin Streptomycin  causes ototoxicity (usually vestibular disturbance) and, less frequently, renal toxicity.  Amikacin  and kanamycin  commonly cause tinnitus an

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