Properties of Water

Cohesion Water is attracted to

other water molecules

Hydrogen bonding

between water

molecules gives it the

cohesive property

Adhesion

Adhesion is attraction

between different

molecules.

Adhesion cont.

Water is not adhesive

to nonpolar molecules

like oil. (Oil and Water

don’t mix)

Capillary Action (Capillarity)

movement of water up a

narrow tube

water is adhesive to the

tube molecules and

cohesive to the other

water molecules

The thinner the tube, the

higher the capillary action

plants use this to pull

water up from roots to

leaves

6

Surface tension•Because of the

cohesion between

water molecules, it

creates surface

tension

•Insects and small

lightweight objects can

rest on top without

disrupting the surface

tension between the

water molecules

Water In Organisms

Organisms usually contain

60% to 90% water.

Lowest- Plant Seed (20%)

Highest- Jellyfish (99%)

Water helps all organisms

with metabolism, and

specifically helps plants

with photosynthesis and

support.

99%

Water

20%

Water

The Versatile Solvent Because the water

molecule is polar, it can dissolve many substances easily, making it a good solvent.

Water As A Way Of Transport

Sap and blood contain high amounts of water making them good solvents.

Being good solvents allows them to dissolve the substances they are transporting.

Tree Sap

Human

Blood Cells

Water As A Reactant

Water, being a good solvent, allows many chemical reactions to occur.

Water As A Way Of Support

When water enters the cell, the water fills up the cell making it turgid(firm)

Water As A Lubricant Many internal organs have fluid

around them to keep them protected.

Examples:

Brain: Cerebro-spinal fluid

Lungs: Pleural Fluid

Eyes: Mix of fluids.

Synovial

Fluid

Water As A HabitatHere are some good reasons why water is a good habitat:

1. Water can provide a good protective layer for organisms in it.

2. Dissolved oxygen can be plentiful in water, for use in cellular respiration.

3. Fertilization (union of egg and sperm cells) is easier in water.

4. Water keeps out UV rays from the sun.

Water In Sexual Reproduction In organisms adapted for

internal fertilization, the sperm is transported in semen which contains mostly water.

Sperm Cells

Animations

Water To stick or not

stick