Download markscheme File

1.
(a)
name of molecule;
function of molecule;
Fe examples:
(b)
hemoglobin;
transports oxygen (in the blood);
myoglobin;
store of oxygen in muscle;
cytochromes / ferredoxin;
electron carrier;
(do not accept avoids anemia)
name of molecule;
function of molecule;
P examples:
2 max
2 max
ATP / ADP;
energy storage and release;
DNA / RNA / nucleotides;
genetic (hereditary) material;
phospholipids
structural component of membrane
[4]
2.
(a)
compounds containing carbon (found in living organisms)
1
(b)
carbon, hydrogen and oxygen
1
(c)
(i)
(ii)
proteins / named protein / DNA / RNA /
chlorophyll / amino acid /
other compound containing nitrogen
1
DNA / RNA / nucleotides / ATP / phospholipids /
GP (glycerate 3 phosphate) /
other compound containing phosphorus
1
[4]
1
3.
Award [1] for each element and its role.
eg C / carbon in forming organic molecules / carbohydrates /
fats / proteins / nucleic acids;
eg H / hydrogen in forming organic molecules / carbohydrates / fats /
proteins / nucleic acids / reducing / fixing CO2 in photosynthesis;
eg O / oxygen in aerobic respiration;
eg N / nitrogen in formation of amino acids / proteins /
nucleotides / ATP / nucleic acids / DNA / RNA;
eg P / phosphorus in formation of nucleotides / ATP /
nucleic acids / DNA / RNA;
eg Ca / Ca2+ / calcium in muscle contraction / nerve transmission /
formation of bones / teeth; eg. Fe / Fe2+ / iron in
formation of hemoglobin / catalase;
eg Na / Na+ / sodium in nerve transmission / osmoregulation;
eg K / K+ / potassium in stomatal opening etc;
[4]
4.
D
[1]
5.
C
[1]
6.
D
[1]
7.
Responses must include reference to coolant, transport and habitat to
receive full marks.
coolant:
lots of energy required to heat water / water has a high specific heat capacity /
hydrogen bonding of water molecules;
when water evaporates energy is used;
cools organism;
eg sweating / panting / transpiration;
transport:
water is polar / universal solvent;
dissolves many organic / inorganic substances;
movement of water carries substances around organism;
eg blood / phloem / xylem / adhesion / cohesion;
medium for external transport (eg gametes);
habitat:
water is transparent;
allows light through for photosynthetic organisms;
2
organisms live in / on water / surface tension for surface creatures / buoyancy;
contains dissolved gases;
fish / aquatic organisms survive under ice at surface;
(Plus up to [2] for quality)
8 max
[8]
8.
Answers must discuss both carbohydrates and lipids to receive full marks.
carbohydrates:
stored as glycogen (in liver);
short-term energy storage;
more easily digested than lipids so energy can be released more quickly;
more soluble in water for easier transport;
3 max
lipids:
stored as fat in animals;
long-term energy storage;
more energy per gram than carbohydrates;
lipids are insoluble in water less osmotic effect;
(Plus up to [2] for quality)
3 max
5 max
[5]
9.
condensation;
involves the removal of water to join monosaccharides together / equation to show this;
catalysed by enzymes;
consists of many monosaccharides linked (glycosidic) to make polysaccharide;
[2]
10.
B
[1]
11.
C
[1]
12.
C
[1]
3
13.
(a)
peptide bonds / peptidic bonds;
1
(b)
alpha-helix / alpha helices;
1
(c)
ionic / polar / hydrogen / hydrophobic / van der Waals’ /
disulfide; (not covalent)
1
linking together of polypeptides to form a single protein;
using the same bonding as for tertiary structure;
linking of a non-polypeptide structure / prosthetic group;
named example of quaternary structure
eg hemoglobin (has four polypeptides);
2 max
(d)
[5]
14.
C
[1]
4