Carbohydrates And Lipids Flashcards
Draw water cell
Refer to page 11 on biological molecules booklet
How does it make hydrogen bonds
Water is polar molecule so it can make hydrogen bonds. This is an attraction between partially positive H on one water molecule with the partially negative charged oxygen on the other water molecule
properties of water
- High specific heat capacity
- high latent heat of evaporation
-Cohesive and adhesive forces - lower density when solid
-Solvent
Cohesive
Attraction of water molecules to each other
Adhesive
The attraction of water molecules to other materials (eg. Water and xylem vessels)
High specific heat capacity
• It takes a lot of heat energy to increase the temperature of liquid water by 1°c.
• This is because it takes a lot of heat energy to break the stable hydrogen bonds between water molecules and force them apart.
•This property of water provides thermal stability for cells (as a major component of cell cytoplasm is water)
• This is important as a lot of cellular reactions take place in the cytoplasm, all of which release energy in the form of heat. If heat were allowed to accumulate, this would damage the cells enzymes.
• So water acts as a ‘temperature buffer, preventing large changes in temperature so enzymes can continue to work at their optimum and reactions can continue at a normal rate.
High latent heat of evaporation
• It also takes a lot of energy to cause liquid water to evaporate because all hydrogen bonds would have to break.
• As the water evaporates, the surface it leaves behind gets cooler.
• In this way, water acts as a coolant.
-Sweating and panting are both ways in which complex organisms lose water vapour from their bodies, removing heat in the process, allowing them to cool down if they overheat.
Cohesive and adhesive forces
• Hydrogen bonds between water molecules.
-Cohesive forces mean that water cannot be compressed.
• Also gives the water a high surface tension.
• This can provide a habitat for small invertebrates, such as the pond skater.
• Also, as water cannot be compressed, it can provide support to large aquatic organisms, such as whales, acting as a hydrostatic skeleton.
Lower density than ice
-Ice is less dense than water as the water molecules make the maximum number of hydrogen bonds when freezing and for this to occur, the water molecules have to spread out. This causes a crystal structure/lattice to form. This traps air in the structure.
• Ice therefore floats on the top of the water forming an insulating layer meaning the water below the ice does not freeze.
• The ice layer can serve as a habitat for organisms such as penguins and polar bears in arctic regions.
• Also, by insulating the liquid water below, this allows aquatic organisms such as fish to continue to move/swim.
-Nutrients and food are also able to continue to circulate and are freely accessible.
Solvent
• lons/minerals are soluble in water as they are charged and water is polar.
This means there is electrostatic attraction between the ions/minerals and the water molecules,
forming hydrogen bonds.
• Organisms can take in nutrients dissolved in water.
• Water is also used as a transport medium, transporting nutrients and waste products around their bodies.
• Water also acts as a medium for chemical reactions and is even used in some reactions.
Carbohydrates
Are polymers made up of monomers called monosaccharides. (Eg. Glucose, fructose, galactose and ribose)
Glucose
Carbon-6
Hydrogen-12
Oxygen-6
What is glucose the monomer for
Monomer for many large carbohydrates
An is called a hexose monosaccharides.
How does glucose form hydrogen bonds
Glucose contains (OH-) bonds which are polar. Hydrogen bonds can form as water is also polar.
Glucose (structure to function)
Small- easily transported across membranes by facilitated diffusion
Polar- dissolve in cytoplasm of a cell and in the liquid transport medium in blood so it can be transported around the body
Easily broken down-To release energy (respiration)
