1 hydrogen bond represented as,
horizontal / vertical, dashed line between O on one molecule and H on the adjacent molecule;
DO NOT CREDIT if >1 H bond is drawn between the same two molecules
2 hydrogen / H, bond label (on any drawn bond between 2 molecules);
3 (delta positive) δ+ on each drawn H
and (delta negative) (2) δ– on each drawn O;
if both molecules drawn, δ+ and δ– on all atoms.
ACCEPT d (lower case) for δ

2. ice floats
P1 (ice less dense because) molecules spread out;
P2 molecules form, crystal structure / lattice / AW;
P3 ice forms insulating layer / clearly described;
e.g. acts as a barrier to the cold
P4 water (below ice), does not freeze / still liquid / remains water / kept at higher temperature;

S1 organisms do not freeze;
DO NOT ACCEPT die (because ‘survival’ stated in stem)
S2 animals / organisms, can still, swim / move;
S3 allows, currents / nutrients, to circulate;

P5 ions / named ion, polar / charged;
P6 ions /named ion, attracted to / bind to / interact with, water;
S4 (named) organisms / plants / animals, uptake / AW, minerals / named mineral / nutrients;
ACCEPT obtain / enters / goes in / gets
S5 correct use of named, mineral / nutrient, in organism;
needs to be more specific than ‘for growth / metabolism’ suitable examples include but are not limited to: nitrates for amino acids / protein / (named) nucleic acid / phosphate for ATP / phospholipids / plasma membrane / magnesium for chlorophyll etc

temperature stability
P7 many / stable, (hydrogen) bonds between molecules;
Many hydrogen bonds between molecules = 2 marks (gets P7 and H)
P8 at lot of energy to, force apart molecules / break bonds;
ACCEPT heat as alternative to energy
P9 high (specific) heat capacity;
DO NOT CREDIT latent heat capacity

S6 temperature does not change much / small variation in temperature;
could refer to organisms or surrounding water
ACCEPT stays cool in summer / stays...

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