Module 2: Biological molecules intro

Question 1

State the chemical elements that make up these biological molecules:
Carbohydrate
Lipids 
Proteins 
Nucleic acids

Answer 1

Carbohydrate - Carbon, Hydrogen, Oxygen
Lipids - Carbon, hydrogen, oxygen
Proteins - Carbon, Hydrogen, Oxygen, Nitrogen (R group may contain sulphur)
Nucleic acids - Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous

Question 2

Describe a biological function of these cations:
Ca²+
Na+
K+
H+
NH4+

Answer 2

Ca²+ - Stimulates the vesicles with neurotransmitter to move the presynaptic membrane
Na+ - Involved in transmission of action potentials along a neurone
K+ - Involved in transmission of action potentials along a neurone
H+ - Used in active loading of sucrose into the companion cells
NH4+ Absorbed from the soil by plants. used a source of nitrogen

Question 3

Describe a biological function of these anions:
NO3- :
HCO3- :
Cl- :
PO43- :
OH- :

Answer 3

NO3- : Absorbed from the soil by plants - used as a source of nitrogen.
HCO3- : How the majority of carbon dioxide is carried in the blood.
Cl- : Acta as a cofactor for amylase.
PO43- : Needed for the synthesis of nucleotides.
OH_ : pH determination. Makes solutions alkaline.

Question 4

Describe the difference between a monomer and a polymer. Give an example of each (4 marks)

Answer 4

A monomer is a small, basic molecular unit.
For example, an amino acid, monosaccharide or nucleotide.
A polymer is a large, complex molecule made up of lots of monomers bonded together in a long chain.
For example, proteins, polysaccharides and nucleic acids.

Question 5

Describe what happens in a condensation reaction (4)

Answer 5

Two molecules are bonded together.
A covalent bond is formed.
Water is formed as a by product from the OH from one molecule and the H from the other.

Question 6

Describe what happens in a hydrolysis reaction (4)

Answer 6

A larger molecule is split into two smaller ones.
A covalent bond is broken.
Water is added to form the OH of one molecule and the H of the other.