3.1 : Biological Molecules

Question 1

What is an element? What sets them apart? What are the four primary elements?

Answer 1

Elements : different types of atoms
They are distinguished by the number of protons.
The primary elements are Carbon, Hydrogen, Oxygen and Nitrogen.

Question 2

Define molecule and covalent bond

Answer 2

Molecule - 2 or more atoms bonded together

Covalent bond - a shared pair of electrons

Question 3

What is an ion? Cation and anion?

Answer 3

An atom or molecule where the total number of electrons is not equal to the total number of protons.

Cation : a positive ion that has lost electrons
Anion : a negative ion that has gained electrons

Question 4

How does ionic bonding work?

Answer 4

One atom in the pair donates the electrons and one receives. This forms positive and negative ions that are held together by the attraction of opposite charges.

Question 5

List some cations and their roles. ( not part of spec )

Answer 5

Calcium ions ( ca2+) : nerve impulse transmission, muscle contraction
Sodium ions ( na+) : nerve impulse transmission , kidney function 
Potassium ions ( K+) : nerve impulse transmission, stomatal function  
Hydrogen ions ( H+) : catalysis of reactions, pH determination 
Ammonium ions ( NH4+) : production of nitrate ions by bacteria

Question 6

List some anions and their roles ( not part of spec )

Answer 6

Nitrate ions ( No3-) : nitrogen supply to plants for amino acid and protein formation

Hydrogen carbonate ions ( HCO3-) : maintenance of blood pH

Chloride ions ( Cl-) : balance positive charge of sodium and potassium ions in cells

Phosphate ions ( PO43-) : cell membrane formation, nucleic acid and ATP formation, bone formation

Hydroxide ions ( OH-) : catalysis of reactions , pH determination

Question 7

What are the four main biological molecules?

Answer 7

Carbohydrates
Lipids
Proteins
Nucleic acids