Water A1.1

IB Biology HL

Cohesion of Water

Water molecules sticking to each other, helping water move up plant stems (xylem) and creating surface tension.

Adhesion of Water

Water sticking to other types of materials, allowing it to move through small spaces like soil and plant cell walls.

Solvent Ability of Water

Water's ability to dissolve nutrients, waste, and gases, making it key for metabolism.

Thermal Stability of Water

Water heats slowly and holds heat, helping to stabilize environments and cells.

Fluidity of Water

Water flows easily, helping substances move inside blood and cells.

Origin of Life in Water

Scientists believe life began in oceans because water provided a stable environment for molecules to dissolve, interact, and support chemical reactions.

Water Polarity and Adhesion

Positive ends of polar water molecules attract negative ends of other surfaces, driving adhesion.

Capillary Action

Water moving upwards through tiny spaces due to adhesive properties, acting stronger than gravity.

Factors Affecting Capillary Action

Tighter pores, smaller soil particles, and increased surface area create more adhesion and better water movement.

Apoplastic Pathway

Water movement in the gaps between plant cells, outside the cell walls.

Symplastic Pathway

Water movement between plant cells through gaps in cell walls called plasmodesmata.

Buoyancy in Water

The upward force liquids place on submerged objects; water's high density makes it buoyant

Viscosity of Water

Water's resistance to flow; because water is more viscous than air.

Thermal Conductivity of Water

The ability to transfer heat quickly, causing aquatic animals to lose body heat fast and require insulation like blubber.

Specific Heat Capacity of Water

The high amount of energy required to increase water's temperature, resulting in very stable aquatic environments.

Buoyancy Biological Consequence

Strong limbs are not needed to support body weight, larger body sizes for movement is allowed

Viscosity Biological Consequence

Aquatic animals need to be streamlined to reduce drag, the shape is enhanced for more effective swimming

Biological Consequence of Thermal Conductivity of Water

There is a risk of hypothermia in which insulation is needed for aquatic animals to maintain body heat

Biological Consequence of Specific Heat Capacity of Water

Since aquatic environments have stable temperatures, a specific evolution takes place

Hydrogen Bonds

Form when bonds are very polar and when polar covalent molecules are attracted to each other, they are fake bonds

Requirements to hydrogen bonding

an electronegative molecule that bonds to hydrogen, which is an asymmetrical molecule shape

Electronegativity

is how much an atom attracts electrons (very big and greedy)

What is FON?

Fluorine, Oxygen, Nitrogen, they are the strongest electronegative bonds

What matters in hydrogen bonds?

Its asymmetrical shape as charges need to be uneven to create polar ends

How to write a partial charge

1. Unique “s” shape with +, -

2. With a funny arrow —>, pointing to negative charge

Why is water a polar molecules?

Due to uneven partial charges

How to recognize a Hydrogen Bond?

1. Look for an FON - H

2. Ensure its asymmetrical

Intramolecular Forces examples

Covalent bonds that share e- between atoms, ionic bonds that transfers e- between atoms (real bonds)

Intermolecular Forces

Hydrogen bonds that is an attraction between molecules (holds it together), does not transfer e-