IB Biology HL A1.1 Water Questions

a. similar water molecule drawn with oxygen on one molecule facing hydrogen on the other water molecule;
b. one hydrogen bond drawn as a dotted/dashed line between the two water molecules and labelled;

O and H do not need to be labelled but must be positioned correctly

eg:

a. cohesion is caused by the polarity of water

OR

water molecules have a negative and positive end;

b. water molecules are attracted to each other

OR

water molecules are linked by hydrogen bonds;

c. (cohesion) enables transport of water along stems/xylem

OR

enables a continuous column of water in transpiration/transpiration pull;

d. surface tension provides a habitat for some organisms

OR

some insects can walk on water surface because surface tension/other verified example

OR

cohesion is related to buoyancy allowing organisms (like ringed seal) to float;

e. helps animals regulate body temperature (through evaporative cooling);

f. (cohesion causes high specific heat) so maintains a stable temperature in aquatic environments

OR

water is liquid at a wide range of temperatures supporting many aquatic habitats;

a. water has greater viscosity than air;
b. thermal conductivity is higher in water than in air;
c. specific heat capacity is higher in water than in air;
d. water is denser/has more buoyancy than air;

The physical property must be named. Comparative terms are expected, making reference to both eg: accept higher in water, but not high in water.

Marking guidance: