A1.1 Water (copy)

Where do most life processes occur?

Water

Where did the first cells originate from?

Water

How are hydrogen bonds formed?

Due to the polarity of covalent bonds in water.

Draw the molecular structure of water (using charges)

Draw the covalent structure of water

What causes polarity?

The unequal distribution of electrons.

What is the charge on oxygen?

Negative

What is the charge on hydrogen?

Positive

Define cohesion

Force by which individual molecules of the same type attract and associate.

What causes cohesion in water molecules?

Hydrogen bonds

How strong are hydrogen bonds? And what is it’s effect on water?

Hydrogen bonds are weak and are therefore always breaking and reforming. But can be strong in large numbers.

Give an example of the cohesive property of water.

Water flows up the inside the xylem vessel under tension due to the transpiration stream.

What other property does a transpiration stream have?

It’s a continuous stream

Define surface tension

Property of the surface of a liquid that allows it to resist an external force, due to the cohesion between water molecules

What does surface tension allow for aquatic life?

It allows smaller organisms to the move along the surface

Give an example of an animal that moves across the surface of a water.

Pondskater

Define adhesion

The force by which individual molecules are able to bond, via hydrogen bonds, to other molecules which are polar, or charged.

Name a molecule that water adheres to in the xylem vessel

Cellulose

Define capillary action

The tendency of a liquid to move up against gravity when confined within a narrow tube, also known as a capillary.

Draw a diagram showing water moving up a xylem vessel, label adhesion and cohesion and describe the process

Water is drawn up narrow tubes in the soil and into the plant via capillary action, when drawn into the plant, the water can move up the vessel through adhesions, by sticking to the walls of the plan.

Define hydrophilic

Attracted to water (e.g. hydrogen bonds are easily formed between a hydrophilic molecule and water)

Define hydrophobic

repelled by water (e.g. cannot form hydrogen bonds)

What is a molecule forming a hydrogen bond with water more commonly known as?

Dissolving

Is a polar molecule hydrophobic or hydrophilic?

Hydrophilic

Is non-polar hydrophobic or hydrophilic?

Hydrophobic

Give an example of cell function dependent on polarity

Phospholipid have hydrophobic hydrocarbon tails form the hydrophobic core of cell membranes

Where do most enzymes catalyse reactions?

In aqueous solution

Where do matabolic reactions take place?

Water

Why do most metabolic reactions take place in water?

Water has a neutral pH, and water can also store large amounts of heat, and water is also electrically neutral

Define buoyancy

The ability of any fluid to provide an upward vertical force on an object placed in or on it.

What is water’s buoyancy?

Water has a high buoyancy (animals can float on water)

Define viscosity

A measure of a fluid’s resistance to flow

What is water’s viscosity?

Water has a high viscosity (it’s easier to walk through air, low viscosity, than through water).

Define thermal conductivity

The measure of how easily heat flows through a specific type of material

What’s water’s thermal conductivity?

Water has a high thermal conductivity (it’s easier to lose heat in water than in air, i.e. you get colder in water)

Define specific heat capacity

The amount of energy required to raise the temperature of 1kg of substance.

What’s water’s thermal heat capacity?

Water has a high thermal conductivity (you need more energy to raise the temperature of water than to raise the temperature of air)

Give two examples of animals that use the properties of water to live

The ringed seal and the black throated loon

Explain how the black throated loon used the properties of water to live

• Thermal conductivity: the loon’s feathers trap a layer of air between it’s feathers to keep in the heat

• Buoyancy: Loons have hollow bones, it solid bones, which allows them to sink beneath the water to catch their prey

• Buoyancy: Loons are covered in a thin layer of oil to allow for better floating

• Viscosity: Loons have webbed feet which allow for quicker movement in water

Explain how the ringed seal uses the properties of water to live

• Buoyancy: Seals live on the ice, as it can float on water

• Viscosity: Seals have flippers that are used to propel themselves

• Thermal conductivity: Seals have a layer of blubber (fat) to keep warm