Aquatic plants can survive in deep waters due to the fact that water is a transparent liquid. As it is transparent, sunlight can reach the plants helping them to photosynthesis and stay alive. This benefits both the aquatic plants as well as the higher order organisms that feed off these plants, as photosynthesis is the process where plants make their food. These sugars are transported to different areas of a plant in water.
Water functions as a transport medium in both animals (including humans) and plants. In humans, water is within the blood substance and because water molecules slide past each other easily blood can be easily transported through narrow capillaries. A vital role because if this were not the case, blood would not be able to transport bodily pigments (e.g. hormones, white blood cells, red blood cells, proteins etc) around the body as efficiently risking vast numbers of health problems. Water also allows waste materials such as urea and urine to be dissolved, transported and excreted, preventing them becoming toxic and harming the organism that has produced them during metabolic activities. A role in the transport of gametes in animals (e.g. sperm in semen) is aided by water, therefore important in fertilisation and the continuance of that specific species. In plants, water and mineral ions are transported through xylem vessels to replace water, lost from leaves in transpiration, and minerals necessary for growth. These properties aid transport and provide support of cells and the stem. Dissolved nutrients that plants need to live are transported in phloem vessels.
A link with the transport of water is the support it provides for marine animals and plants, as well as those living on earth, from the inside and on the outside. In plants, water, being incompressible, means that cells and tissues are filled and turgid. Water provides a hydrostatic skeleton, which allows muscles to be contracted against it, regains the form of organisms e.g. the earthworm.
Having outlined the role of water in excreting toxic waste from metabolic reactions in various organisms, it is important to note the role of cellular constituent in reactions removing or adding water (hydrolysis and hydration).
An example of water being a habitat for organisms is that of pond skaters created by the surface tension of water, the result of inwardly acting cohesive forces between water molecules. For this organism, water is also aiding movement.
In addition to this external role, water is found in the joints of animals to be used as a lubricant. This use reduces the amount of friction at the joint and allows easy movement. Mucus in the mouth of humans has water in it so that it allows easy swallowing of food, the passage then goes to the stomach where water helps with food movement and the dissolving of enzymes to break down the food. The help provided by water in relation to nutrition is vital to organisms’ lives.
The process called homeostasis, which means keeping the organisms’ internal environment working well, can be improved with waters’ coolant functions. For example, when humans release water as sweat, the liquid gets turned into a vapour causing humans to cool down and control our body temperature (a homeostasis process). The cooling functions of water are connected to its high heat capacity nature.
Water has influences on a large number of aspects of organisms’ lives’. From habitat, transport, support, movement, fertilisation, insulator, roles of key processes (photosynthesis and respiration), protection from damage, homeostasis and gas exchange. Enzymes are very important in the body of some / most organisms and catalyse almost every reaction. However, they are soluble and will need water to function, as a result water is very important. Water is an important substrate for chemical reactions as well as product. Around 70% of human mass consists of water, in plants, 95% of mass consists of water.
