Water and ions Flashcards
what is the formula for water?
what percentage of the body is water?
-H2O
-60-70%
why is water described as polar?
water has an unevenly distributed charge due to oxygen atoms being slightly negative and the hydrogen atoms slightly positive
-draw two water molecules next to each other with charges
-what is the bond between them?
hydrogen bond
what are the key properties of water?
- metabolic
- important solvent
- high specific heat capacity
- high latent heat of vapourisation
- strong cohesion between water molecules and surface tension
- liquid at room temperature
- less dense when ice
explain and state the importance of water being liquid at room temp
-hydrogen bonds make it difficult for molecules to escape and become a gas
-liquid for habitats
-support component for tissues
-transport medium e.g blood and vascular tissue
-reaction medium
explain and state the importance of water being metabolic
-around 90% of plasma in blood is water and cytoplasm is largely composed of water
-photosynthesis (used up in)
-produced in respiration
-condensation and hydrolysis
explain and state the importance of water being a solvent.
-able o attract negative and positive parts of solute molecules and so disrupt ionic bonding = form cluster around charged ions= dissolve
-molecules can be transported around living organisms while dissolved e.g glucose, chloride in blood and xylem
explain and state the importance of water having a high specific heat capacity
-lots of energy required to raise the temp of water due to hydrogen bonds
-provides stable environment for aquatic life= so enzymes don’t denature
explain and state the importance of water having a high latent heat of vapourisation
-takes a lot of heat energy to convert liquid to gas due to hydrogen bonds
-this means water provides a cooling effect e.g when humans sweat, large amounts of heat energy from the skin is transferred to water to evaporate = cooling.
explain and state the importance of water being cohesive and having surface tension
-cohesion due to hydrogen bonds
-water molecules at surface hydrogen bond to those below= surface tension = habitat away from predators within water.
- when water moves up xylem due to transpiration it is continuous column of water = transpiration stream
why is water less dense in ice form?
why is it important?
-because it is a polar and molecules align themselves in a latice and so molecules are held further away from eachother than as liquid
-ice forms on top of lakes= stable environment and insulation layer for aquatic organisms
what are the essential cations and their importances?
-Calcium Ca 2+ : nerve impulse transmission, muscle contraction
-Sodium Na+ : nerve impulse transmission, kidney function
-Potassium K+ : nerve impulse transmission, stomatal opening
-Hydrogen + : catalyse reaction, pH determination
-Ammonium NH4^+ : production of nitrate ions by bacteria
what are the essential anions and their importances?
-Nitrate NO3^- : nitrogen supply to plants for amino acid and protein formation
-Hydrogencarbonate HCO3^- : maintenance of blood pH.
-Chloride Cl- : balance positive charges of sodium and potassium ions in cells
-Phosphate PO4^3- : cell membrane formation, nucleic acid and ATP production, bone formation
-Hydroxide OH- : catalyse reactons and pH determination.
