Lecture 2

Question 1

describe 3 parts of an atom and why electrons are the most important

Answer 1

Protons , neurons, electrons. electrons is most important because electrons = energy in the outer ring.

Question 2

explain how an atom becomes an ion

Answer 2

in order to become stable some substances need an extra electron or need to give away an electron.

Cations: a positively charged ion, give an electron away eg. Na+

anions: a negative charged ion, gain an extra electron eg. Cl-

Question 3

describe the difference between ionic, non-polar and polar covalent bonds

Answer 3

covalent bonds occur when atoms share electrons instead of giving or receiving them.
eg. water is polar
oil is not polar; cannot break bonds between water molecules and stays separate

Question 4

compare and explain the difference between hydrophilic and hydrophobic substances and give examples

Answer 4

hydrophilic ‘water-loving’ (polar molecules)

• electrolytes
• protein
• sugar
• most hormones

hydrophobic ‘water-hating’ (non- polar)

• oils and fats
• cholesterol
• some hormones

Question 5

list 3 macromolecules that cells use and describe what they use them for

Answer 5

Carbohydrates, Lipids, Proteins.
carbohydrates- glucose and other monosaccharides
lipids- fatty acids and glycerol
proteins - amino acids and polypeptides

this is for the production of ATP (energy source for most cellular processes)

Question 6

list and describe the different ways substances can enter or exit a cell and the processes involved

Answer 6

cellular transport = the process of substances entering or exiting the cell

passive= no energy required
active= energy required 

endocytosis= cell membrane deforms to eat a substance 
exocytosis= cell membrane deforms to release a substance 

cellular transport happens due to DIFUSSION, this is the movement of particles down a gradient and eventually results in equal concentration in all areas.

different kind of difussions

• down a concentration gradient: particles always diffuse down their concentration gradient
• electrical gradient: charged particles move towards the opposite charge- they attract
• Osmosis (diffusion of water)- water moves from high water concentration to low water concentration