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

Explain acyclovir-resistant hsv, Resistance Acyclovir-resistant HSV oc...

Resistance Acyclovir-resistant HSV occurs mainly in immunocom- promised patients treated with the drug; isolates are usually also resistant to valacyclovir and famciclovir. Re

Juxtaglomerular apparatus, Normal 0 false false false E...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What is mendels crosses in genetics explain breifly, What is Mendel's Cross...

What is Mendel's Crosses in genetics explain breifly? Mendel found that if he transferred pollen from a green-seed strain to a yellow-seed strain and vice versa, in a process c

Diagnosis and treatment of myocarditis, Diagnosis X-ray chest show...

Diagnosis X-ray chest shows cardiomegaly.  ECG shows conduction defect, low voltage QRS, atrial and ventricular disrhythrnias.  Echocardiogram - decreased LV cont

Explain bidirectional superior vena cavo, Explain Bidirectional Superior ve...

Explain Bidirectional Superior vena cavo pulmonary shunt bidirectional glenn "This is a palliative produce where blood from superior vena cava is diverted to the pulmonary arter

What is genomics , We are living in an unprecedented age of biological ...

We are living in an unprecedented age of biological discovery and the application of biological knowledge.   Programmed DNA sequencing delivered, in the year of  2001 over the 2.6

Explain the bunsen burner, Explain the Bunsen Burner? It is a type of g...

Explain the Bunsen Burner? It is a type of gas burner that gives very hot flame by allowing air to enter at the base and mix with the gas. It is used - (a) For sterilizing i

What is multi-gated equilibrium radionuclide angiography, Q. What is Multi-...

Q. What is Multi-gated equilibrium radionuclide angiography? Multi-gated equilibrium radionuclide angiography (MUGA) is a very accurate method in measuring ejection fraction. R

Difference between vegetative and generative cell , Difference between Vege...

Difference between Vegetative and Generative Cell The cytoplasm of the vegetative cell and the generative cell is distinctly different. The generative cell is transparent and

Define calcium, Define Calcium, Phosphorus & Vitamin D required for Elderly...

Define Calcium, Phosphorus & Vitamin D required for Elderly? As mentioned earlier, due to the change in skeletal system, vitamin D and calcium needs increase with age. Bone min

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