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

Landslides: measures to be taken during landslides, Protection of our prope...

Protection of our property:                  ·          If any our property lies in an area prone to landslides, we should seek advice of experts in earth movement and take cor

Sex-limited traits, can u show the different activities on the topic

can u show the different activities on the topic

Glucose rehydration therapy, The movement  of Na + and glucose  from the l...

The movement  of Na + and glucose  from the lumen  of the intestine  across  the epithelial  cell to the blood  sets up a dissimilarity  in osmotic  pressure  across  the cell. As

Explain the peripheral nervous system in detail, Explain The Peripheral Ner...

Explain The Peripheral Nervous System in detail? The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system. The somatic nervous

How to calculate the requirements for the calcium in body, How to Calculate...

How to Calculate the Requirements for the Calcium in Body? Requirements for calcium depend upon the rate at which calcium is incorporated into bone; they are therefore highest

Why is iodine important for human beings, Why is iodine important for human...

Why is iodine important for human beings? Iodine is a fundamental chemical element for the proper functioning of the thyroid since it is part of the hormones produced by this g

What is plant coleoptile, What is plant coleoptile? Why does the removal of...

What is plant coleoptile? Why does the removal of the coleoptile extremity disallow plant growth? Coleoptile is first (one or more) aerial structure of the sprouting plant that

Evolutionary Biology-Genetic Drift, Imagine a population evolving by geneti...

Imagine a population evolving by genetic drift in which the frequency of allele K is 0.65. What is the probability that at some point in the future allele K will drift to a frequen

Endoplasmic reticulum, ENDOPLASMIC RETICULUM (ER) Eucaryotic celIs have t...

ENDOPLASMIC RETICULUM (ER) Eucaryotic celIs have two major compartments- nucleus and cytoplasm. Cytoplasm was known to have no structure until the discovery of electron micrsscop

Scientific american article suggests some improvement, The human skeleton h...

The human skeleton has evolved from that of four-legged animals. Unfortunately, the adaptation is far from perfect; thus, our upright posture causes problems like back age and 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