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

What is hmp pathway, What is HMP pathway? Give any two points of its signif...

What is HMP pathway? Give any two points of its significance The HMP  is an alternate oxidative pathway for the metabolism of glucose. The significance of the pathway  is that

Explain classification of lipids, Classification of lipids  A general c...

Classification of lipids  A general classification of lipids based on their structural components is presented in table. Such a classification, however, is possibly too rigid f

Locomotion in arthropoda, Locomotion in Arthropoda The Arthropods are...

Locomotion in Arthropoda The Arthropods are characterized by the existence of some special features which can be considered key to their success. These involve a rigid exoske

Water absorption, Water Absorption Water status of a plant is determin...

Water Absorption Water status of a plant is determined by two major factors: i) water absorption and ii) water loss. We deal with water absorption in this section and water lo

How does the depolarization of the neuronal membrane start, Q. How does the...

Q. How does the depolarization of the neuronal membrane start? The primary cause of the neuronal depolarization is the binding of neurotransmitters released in the synapse by t

Explain the competitive behaviour of social animal group, Explain the Compe...

Explain the Competitive behaviour of social animal group dominance behaviours removal of individuals to other groups which minimises inbreeding eg lions, apes.

Enumerate the anatomic consequences of edentulism, Q. Enumerate the anatomi...

Q. Enumerate the anatomic consequences of edentulism? The anatomic consequences of edentulism include the effect of edentulism on bone and soft tissues. Basal bone forms the de

Vertebrates, characterstics and classification of vertebrates

characterstics and classification of vertebrates

Describe class ophiuroidea in general way, Describe Class Ophiuroidea in ge...

Describe Class Ophiuroidea in general way? Brittle stars have a central disc with five long, thin, flexible arms that can be detached from the body at will in times of danger.

List what organelle is responsible, List what organelle is responsible for ...

List what organelle is responsible for each of these cellular functions. -production of energy (ATP) for the cell -synthesizing proteins -cellular digestion.

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