First 353 words of the document:
The Biological Importance Of Water
Light dependant reaction- Photolysis is the splitting of water. Water is a limiting factor of
photosynthesis, without it a plant cannot produce ATP for growth.
Water is a by product of respiration as oxygen accepts an electron and forms H2O in the electron
Diabetes- Blood sugar levels can affect the water potential causing water in cells to move out of the
cell by osmosis causing the cell to shrivel or to move in causing the cell to burst.
Water is essential to ALL hydrolysis reactions. For example polysaccharides to monosaccharides. Fats
to fatty acids and glycerol. Proteins to amino acids.
Diffusion requires a moist surface.
Water is a good solvent. It is used in blood to transport substances such as glucose. Water is used to
remove excretory products in urea. Cytoplasm in all cells uses water.
The evaporation of water is important in the temperature control of organisms. For example
sweating in mammals.
The loss of chloride ions from the epithelial cells raises their water potential, while the gain of
chloride ions in the lumen of the intestine lowers its water potential. Water flows out of the cells into
the lumen. Water moves from the blood and tissues into the intestines. This causes diarrhoea and
Synovial fluid in joints, Pleural fluid used in lung movement, Pericardial fluid for movements of the
heart, External mucus in snails, Internal mucus for mammals in the gut.
Turgor pressure in plants, aqueous and vitreous humours of the eye, amniotic fluid around a fetus,
hydrostatic skeleton in earthworms.
Water enters a plant through its root hair cells and into the xylem via the symplast or appoplast
pathway. Water moves up a plant against the force of gravity via cohesion and tension and root
pressure. Transpiration is the loss of water from a plants surface, especially the leaves.