1.7/1.8 Water and Inorganic Ions Flashcards
Explain how hydrogen bonds occur between water molecules
● Water is polar molecule
● Slightly negatively charged oxygen atoms attract slightly positively charged hydrogen atoms of other water molecules
Explain 5 properties of water that are important in biology
Metabolite
Used in condensation / hydrolysis / photosynthesis / respiration
Solvent (can
dissolve solutes)
1. Allows metabolic reactions to occur (faster in solution)
2. Allows transport of substances eg. nitrates in xylem, urea in blood
(Relatively) high specific heat capacity
● Buffers changes in temperature
● As can gain / lose a lot of heat / energy without changing temperature 1. Good habitat for aquatic organisms as temperature more stable than land 2. Helps organisms maintain a constant internal body temperature
(Relatively) large latent heat of vaporisation
● Allows effective cooling via evaporation of a small volume (eg. sweat)
● So helps organisms maintain a constant internal body temperature
Strong cohesion between water molecules
1. Supports columns of water in tube-like transport cells of plants eg. transpiration stream through xylem in plants
2. Produces surface tension where water meets air, supporting small organisms (to walk on water)
Where are inorganic ions found in the body?
In solution in cytoplasm and body fluid, some in high concentrations and others in very low concentrations
Describe the role of hydrogen, iron, sodium and phosphate ions
Hydrogen
● Maintain pH levels in the body → high concentration = acidic / low pH
ions (H+)
● Affects enzyme rate of reaction as can cause enzymes to denature
Iron ions
● Component of haem group of haemoglobin
(Fe2+)
● Allowing oxygen to bind / associate for transport as oxyhaemoglobin
Sodium
1. Involved in co-transport of glucose / amino acids into cells
ions (Na+)
2. Involved in action potentials in neurons
3. Affects water potential of cells / osmosis
Phosphate ions (PO43-)
1. Component of nucleotides, allowing phosphodiester bonds to form in DNA / RNA
2. Component of ATP, allowing energy release
3. Phosphorylates other compounds making them more reactive
4. Hydrophilic part of phospholipids, allowing a bilayer to form
