Water is a universal solvent that is present nearly everywhere on Earth. It has unique thermal, cohesive, and solvent properties that make it essential for life. Water's thermal properties allow it to absorb heat without much change in temperature, acting as a temperature stabilizer for living things that are mostly made of water. Its cohesive properties result from the polar bonding of hydrogen and oxygen atoms, causing water molecules to be attracted to one another. As a solvent, water dissolves many polar molecules found in cells, allowing biochemical reactions to occur in solutions like blood, sap, and cytoplasm.

1. Pearson, Chris, Haziq, Abenazer
3.1
Water is a universal element that is mostly present everywhere on the earth. Water contains properties
that we must include thermal, cohesive, solvent that we must include. Water is the solvent of life. Water
contains hydrogen and oxygen atoms held by polar convent bonds.
Thermal properties
Water can absorb or give off a great deal of heat without changing temperature greatly. All living things
are composed of a great deal of water and thus you can think of water content as a temperature
stabilizer. Water also has a high heat of vaporization. This means that water absorbs a great deal of
heat when it evaporates.
Cohesive Properties
This attraction is due to the polar covalent bonding mentioned earlier. Water molecules have a positive
end and a negative end. Whenever two molecules are near each other the positive pend of one attracts
the negative end of another. When water cools below the freezing point, molecular motion has slowed
to the point where these polar attractions become locked into place and ice crystals. Liquid water has
molecules with a much faster molecular motion and the water molecules are able to influence each
other, but not to the point where molecules stop their motion.
Solvent Properties
Water is a universal solvent. It is an excellent solvent for polar molecules, most of which are found on
the inside and outside of most cells, including carbohydrates, proteins, nucleic acids (DNA and RNA).
Water is also used for most of the cells biochemistry
Because water is an excellent solvent for biochemically important molecules, it is also the medium in
which most of the biochemistry of a cell occurs
Vascular tissue in plants carries water and a variety of dissolved substances.
Xylem carries water and dissolved minerals up from the root system to the leaves of a plant
Phloem then transports dissolved sugars from the leaves to the stems, roots and flowers of a plant.
Blood is the most common transport medium in animals and is largely made up of water
Blood is a transport medium for red blood cells, white blood cells, platelets and a wide variety of
dissolved molecules.

2. Pearson, Chris, Haziq, Abenazer
3.2
Carbohydrates, lipids and proteins
Living things are composed of an amazing array of molecules
Molecules of the same type have certain qualities in common and become fairly easy to
recognize with a little practice.
Molecules can be classified as being either inorganic or organic.
All organic molecules contain the element carbon, although not all carbon-containing molecules
are organic.
Carbohydrates are among the most commonly found biochemical molecules found in both
animals and plants
Carbohydrates exist in different ‘sizes’ – monosaccharide, disaccharides, and polysaccharides.
Lipids are biochemically important molecules that serve many functions; we refer to triglyceride
lipids in solid form as fats. In liquid form, triglycerides are called oils.
If you eat more food than you burn, your body will store much of the excess as fat in adipose
cells
Carbohydrates are also used for storing energy in living organisms.
Lipids are also important for thermal insulation
A special category of lipids called phospholipids makes up the double layer of all cell membrane.
These phospholipids molecules have a polar end turned towards water and a non-polar end
which turns away from water.
Food is chemically digested in your alimentary canal.
The digestive enzymes that accomplish this are hydrolyzing enzymes.
Each reaction is called a hydrolysis and requires a molecule of water as reactant.
Condensation reactions are in many ways the reverse of hydrolysis reactions.
In cells, condensation reactions occur to re-form the larger biochemically important molecules.

3. Pearson, Chris, Haziq, Abenazer
3.3
Avery – Proved Griffith’s transforming principle by removing protein from the experiment.
Griffith – Transforming principle – change in strains
Hershey & Chase – Dyed DNA and surrounding proteins in different colors to prove that DNA
was the genetic material.
Hydrogen Bonds between nucleotides
Covalent bonds between Sugar and phosphate and between nitrogenous bases
DNA nucleotides linked together by covalent bonds
DNA Structure is by four nucleotides A T C G which are connected by hydrogen bonds, with
phosphate and sugar chained linked together forming a double helix structure.