• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The role of water in living organisms.

Extracts from this document...

Introduction

The role of water in living organisms Water is one of the most abundant molecules on planet earth; it is found in vast amounts not only in earthly enviroments (oceans, lakes and rivers), but is also present in the atmosphere, and as solid ice in the two poles. Consequently it is rather logical that water plays an important role in biological life: the origins of life occurred in water and life itself wouldn't be able to continue in it's absence . I will now describe the structure of a water molecule. It consists of an oxygen atom covalently bonded to two other atoms of hydrogen. The two bonds form a 105 degrees angle with eachother, but for the reason that oxygen is more electronegative than hydrogen, the shared electron charge of the covalent bond is distributed more towards this atom, making the water molecule weakly polar. ...read more.

Middle

The partial attraction and partial repulsion of the phospholipids to and from water cause them to form interfaces, or membranes, separating the cytoplasm from the external enviroment, and hence defining the cell. Humans themselves are made up of a 70% of water, they are considered the most-solid looking organisms. Without this high water content, waste heat generated from metabolic reactions would soon denature cellular enzymes. The high specific heat capacity, and the high thermal conductivity, of the water in cytoplasm dissipates heat from cellular reactions, preventing thermal damage from occuring. As water warms , some of the molecules gain sufficient energy to detach from liquid water and become vapour. Each water molecule requires a considerable amount of energy for this to occur (i.e water has a high latent heat of vaporisation), due to the need to break H-bonds to free individual molecules. So, as water evaporates from a surface, it carries with it relatively large amounts of heat energy, cooling the surface from which it vaporises Water ...read more.

Conclusion

Adhesion is the tendency to adhere to dissimiliar molecules- in the case of water, to other polar molecules. This adhesive property of water causes capillarity, the ability of water to resist gravitational pull and rise up thin tubes, or form a thin layer around soil particles. Adhesion and cohesion, coupled with the "transpirational pull" generated by evaporation of water from leaves which acts upon the continuos column of water in xylem tissue, allow water and dissolved minerals to be supplied to plant tissues up to 100 metres above the ground. Another property of water is its transparency to visible light. light can penetrate water to a considerable depth, provided the water is free of suspended, particulate matter. Different wavelengths of light penetrate to different depths. Red and yellow light only travel to a maximum of 50 metres depth, whilst blue and violet light can reach 100 metres. This allows large volumes of water to serve as habitats for photosynthetic organisms. On land, light can easily penetrate plant leaf epidermal tissues, which are 90 % water, to reach the underlying photosynthetic cells. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. Marked by a teacher

    The roles water in living organisms and water as a habitat for organisms

    5 star(s)

    Three-quarters of the planet is covered in water. Water itself is a simple molecule made up of 2 hydrogen atoms and one oxygen atom, H20. The hydrogen and oxygen atoms are bonded covalently as shown in the diagram of waters molecular modal.

  2. The Role Of Water In Living Organisms

    Many things will dissolve in it, and more reactions take place while in solution with water. Often in organisms substances must be in solution and water is the solvent. Plants can only obtain mineral salts in solution so require water to live.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work