Water acts a transport medium for polar solutes; it is used in movement of minerals to lakes and seas, removal of metabolic wastes such as urea and transport via blood and lymph.
Water volatility is suited to the Earth’s temperatures so that the water cycle of evaporation, transpiration and precipitation is maintained.
Water is a medium for dispersal; it can be used to disperse the larval stages of some terrestrial organisms. It is the medium in which sperm are transferred in mosses and ferns. Osmotic pressure helps disperse the seeds of the squirting cucumber.
Water expands on freezing, this make ice less dense than water so it floats on top of ponds and lakes, providing insulation to organisms in the water below
Importance in plants
Water is essential in osmosis, as it requires the movement of water from a region of lower concentration to a region of lower concentration of water molecules. The weak hydrogen bonds mean that the water molecules can move relatively easily. One of the reasons that this is important is for water to enter cells by osmosis causing the cytoplasm and that it is needed for turgidity of cells to support the plant. The cohesive forces between water molecules mean that it is not easily compressed so it is a great medium for support.
Water is required (it is the reagent) in the photosynthesis reaction, which is also essential as it is the way it produced energy needed to live.
Hydroskeletons are a type of skeleton found in many soft-bodied invertebrates, which consists of water-filled body cavities controlled by muscles. Hydroskeletons are found in echinoderms (starfish, sea urchins), annelids (earthworms), nematodes, and a number of other wormlike invertebrate phyla.
Water is transparent so make photosynthesis possible in shallow aquatic environments.
Without water there would be no plants and therefore no animals either as animals
Importance in animals
Water is a major component of tissues and is an important part of the diet. Most substances in the body dissolve in water. Blood, which is used for transport of substances around the body, is made up of mostly water, which shows how important it is to animals.
Water is the medium in which metabolic reactions take place; molecules in solution can move around water and take part in reactions in the presence of enzymes. All chemical reactions take place in an aqueous medium.
Water is essential in diffusion across surfaces such as the lungs and alimentary canal.
Water is also needed in animals for osmoregulation: the control of the levels of water and mineral salts in the blood.
Water is used hydrolyse macromolecules to their subunits, for example in digestion, such as breaking down proteins into amino acids, fast into fatty acids and glycerol, etc.
Tears contain water, which is protection against bacteria by killing it and as does mucus by trapping it.
Water can help in lubrication in:
- Mucus: lubricates passage of food, colon – easy passage for faeces, penis and vagina during intercourse, used externally in some animals such as snails and earthworms to aid movement
- Synovial fluid: lubricates vertebrate joints
- Pleural fluid: minimizes friction between lungs and ribs during breathing
- Perivisceral fluid: lubricates movement of internal organs, e.g. in peristalsis
- Pericardial fluid: lubricates movement in heart
Water is in amniotic fluid, which protects and supports the fetus of mammals.
Water is important in secretions, most secretions include substances in aqueous solutions such as tears, digestive juices and snake venoms.
The humours of the eye, both aqueous and vitreous are made up of mostly water; it helps maintain the shape of the eye because it is not easily compressed which makes it useful in supporting.
