IB Biology SL A1.1.3 Cohesion of Water Molecules Questions
Practise IB Biology SL A1.1.3 by linking water cohesion and surface tension to xylem transport and insects walking on water.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Exam points
- Distinguish cohesion from adhesion and identify surface tension in water examples.
- Relate cohesion to xylem transport and surface tension to pond-skater support.
IB Biology SL A1.1.3 Cohesion of Water Molecules Questions question 1
[Maximum number: 4]
Water is one of the most abundant molecules on Earth. Living organisms must maintain homeostatic levels of water to survive.
Outline how the cohesive properties of water benefit living organisms.
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 water to move 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 of 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;
4
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