A1.1 Water

Question 1

Adhesion

Answer 1

Adhesion between water molecules and the walls of thin tubes, such as those found in plant xylem or in blood capillaries, helps in the movement of fluids. This is vital for the transport of water and nutrients against gravity in plants and for the distribution of blood in animals.

Question 2

Cohesion

Answer 2

1. Water molecules are polar and form hydrogen bonds with each other, which is a type of cohesive force.
2. As water evaporates from the surface of the leaves during transpiration, it creates a tension (negative pressure) at the top of the xylem. This tension is akin to a pulling force exerted on the water column.
3. Due to the cohesive properties of water, when molecules at the top are pulled out during transpiration, they in turn pull on the molecules below them. This chain reaction continues all the way down to the roots, pulling water upwards.

Question 3

What is a

Solvent?

Answer 3

Able to dissolve other substances.