LO topic 2a - b

Question 1

Describe the structure of an atom; including the characteristics and arrangement of subatomic particles – protons, neutrons and electrons

Answer 1

Atom is the smallest particle of an element made from proton (positive), neutron (neutral) and electron (negative)
As electrons move from shell to shell new bonds are formed the energy is captured and essential to life.
Electrons are in shells which each have specific energy, the further from the nucleus the greater the energy stored.
92 elements occur naturally
2 or more atoms bonded together is a molecule

Question 2

Describe the arrangement of protons, neutrons and electrons within hydrogen, oxygen, carbon and nitrogen; and recognise how this structure is related to their ability to form bonds with other atoms

Question 3

Describe hydrogen bonds; name common compounds where these types of bonds are found

Answer 3

bonds made between hydrogen and oxygen, nitrogen or fluorine (H2O)

Question 4

Describe ionic bonds; name common compounds where these types of bonds are found

Answer 4

Ionic - when two ions of opposite charges form a bond, sharing electrons.
NaCl

Question 5

Describe covalent bonds; name common compounds where these types of bonds are found

Answer 5

Covalent - sharing electrons, stronger than ionic bonds generally they can be polar (unequal sharing of electrons) (H20) or nonpolar (02)

Question 6

Describe the properties of water that enable it to be considered the medium of life

Answer 6

The hydrogen bonds cause cohesion (attraction between the same molecules)
The cohesion and adhesion builds surface tension which builds a resistance to being broken
Good solvent but not completely so fats don’t dissolve
High specific heat capacity
Ice is less dense than water so aquatics won’t freeze.
Water based solutions can be acidic basic or neutral

Question 7

Describe the characteristics of acids, bases and buffers,

Answer 7

Buffers - help retain a constant pH of a solution as is accepts or releases H+ in response to small changes
Acidic - have a higher concentration of H+ ions
Basic - have a higher concentration of OH- ion

Question 8

Describe how the pH scale works

Answer 8

measure the concentration of h+ ions in a solution
0-6 is acidic
7 is neutral
8-14 is basic

Question 9

Define ‘organic molecules’ and ‘functional groups’ and name several examples of important functional groups found in biomolecules

Answer 9

organic - molecule which have a carbon chain backbone popular shapes are, chains, sheets, rings and helices
functional groups - groups of atoms that determine the molecules characteristics,hydroxyl, carbonyl, carboxyl, amino, phosphate, methyl, sulfhydryl

Question 10

Define ‘polymers’, and describe the processes by which they are frequently synthesised or broken apart

Answer 10

Polymers are chains of monomers formed via dehydration synthesis and broken vis hydration (hydrolysis)

Question 11

List the four major groups of organic molecules in organisms and some examples of each – C P N L

Answer 11

Carbohydrates - glucose (monosaccharide) starch (disaccharide) and chitin (polysaccharide)
Proteins - insulin (peptides) haemoglobin (polypeptides)
Nucleic acid - DNA and RNA
Lipids - fats, oils, waxes, phospholipids and steroids

Question 12

Describe the general structure and function of the three main groups of carbohydrates (monosaccharides, disaccharides, polysaccharides), and identify examples of each

Answer 12

Monosaccharides - 3-7 carbon backbone (glucose, fructose, ribose, deoxyribose, galactose),
Disaccharides - two monosaccharides linked via dehydration synthesis (sucrose)
Polysaccharides - many monosaccharides (starch, glycogen, cellulose and chitin)

Question 13

Describe the role of cellulose and chitin as important structural polysaccharides, and explain where each of these compounds would be found

Answer 13

Chitin - structural comprises arthropod exoskeletons and fungal cell walls
Cellulose - structural fo wood and plant cell walls, polymer of glucose

Question 14

Describe the general structure and function of proteins- specifically amino acid structure and bonding, primary, secondary and tertiary & quaternary protein structures and denaturation

Answer 14

Polymers of amino acids each with a central carbon bonded to a hydrogen and three function bonds. Dehydration synthesis forms.
R groups give distinctive properties to the amino acids.
Primary are held via peptide bonds
Secondary helix made via hydrogen bonds
Tertiary folded helix bonded with water
Quaternary polypeptides (2) linked by hydrogen bonds

Question 15

Describe the general structure and function of nucleotides

Answer 15

5 carbon sugar backbone with phosphate group and a nitrogenous base
Energy carrier molecules (ATP), subunit of nucleic acids (DNA), intracellular messengers (cAMP)

Question 16

Provide a brief description of the structure, function and biological importance of DNA and RNA

Answer 16

Deoxyribonucleic acid is a double helix twisted structure, sequence of nucleotides determines genetic code
Ribonucleic acid are single strands of ribose nucleotides and are copies from DNA and directs protein synthesis