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

Define effect of caffeine on athletes, Define effect of Caffeine on athlete...

Define effect of Caffeine on athletes? Caffeine is found in coffee, tea, colas and chocolates. Its doses at 3- 6 mg/d have been known to increase muscle contractility and aerob

Need for microbiological analysis of environment sample, Explain Need For M...

Explain Need For Microbiological Analysis of Environment Samples? Once the food is harvested, it passes through various operating steps before reaching the consumer. These step

Determine the medical history - assessment, Determine the Medical History -...

Determine the Medical History - Assessment  A child's medical history often contains predictors of neuropsychological functioning. Perhaps the most obvious predictor is the pre

Write the factorson on which metaboilc changes depend, The metaboilc change...

The metaboilc changes would depend on the  following  factors: a)  Nature of infection b)  Severity of the infection c)  Duration of the infection d)  Presence or abse

Define freeze concentration, Define Freeze Concentration? This process ...

Define Freeze Concentration? This process has been known for many years and has been applied commercially to orange juice. However, high processing costs due largely to losses

Explain gelation - function of proteins, Explain Gelation - Function of pro...

Explain Gelation - Function of proteins Gelation  refers to the process where denatured molecules aggregate to form an ordered protein network. Proteins  can form a well-order

Zoology, give an account of specific characters of phylum porifera

give an account of specific characters of phylum porifera

Taxonomy, Agroup of realated genera are classified as-?

Agroup of realated genera are classified as-?

Hybridization, Hybridization  is the reaction by which pairing of the compl...

Hybridization  is the reaction by which pairing of the complementary strands of nucleic acid happens. DNA is usually double-stranded, and when these strands are separated form each

Explain herbicide tolerant crops in evolutionary way, Explain Herbicide to...

Explain Herbicide tolerant crops in Evolutionary way Increased use of herbicide can result in increase in development of weed resistance to that herbicide either through

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