Biology Chapter 3

Evaporative cooling

the property of a liquid whereby the surface becomes cooler during evaporation, owing to a loss of highly kinetic molecules to the gaseous state. this contributes to the stability of temperature of lakes and ponds which provides organisms from overheating.

Why are "apparently" small changes in pH so important in biology

The pH is measured logarithmically. If pH varies by one it actually varies by 10. So, even a slight change in pH can be harmful to the chemical processes in a cell, killing the cell.

Heat of vaporization

The quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state. To evaporate 1g of water at 25 degree C, about 580 cal of heat is needed. This is another property of hydrogen bonds, which must be broken before the molecule can make a departure from the liquid.

Hydrophilic

any molecule that has an affinity or an attraction to water

Hydrophobic

any molecule that has no attraction to water

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid. The hydrogen atoms in water bond to the hydrogen atoms in the air, creating a greater surface tension than most other liquids. This describes how some animals can run, walk, or stand on water.

Solute

A solute is a substance that is dissolved in a solution

Solvent

A solvent is what a solute is dissolved in

Colloid

A substance that constists of particles dispersed through another substance, like smoke.

What defines an acid and a base

An acid is something that increases the hydrogen ion concentration of a solution and a base is something that decreases the hydrogen ion concentration

Aqueous solution

An aqueous solution is a solution in which water is the solvent

Molarity

Molarity is the amount of solute per each liter of a solution.

Cohesion

Occurs when hydrogen bonds together. This allows water to become more structured. Water molecules that are evaporating from the leaves on plants help pull up new molecules from the roots and ground to help keep the plant supplied with the proper amounts of water.

High specific heat

The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree Celsius. The specific heat of water is 1 [[#|calorie]] per gram per degree Celsius. Water has a high specific heat because of its hydrogen bonding (heat must be absorbed in order to break hydrogen bonds, and heat is released when hydrogen bonds form). In nature, a large body of water can absorb and store a large amount of heat from the sun, which can later be used to warm up the air as it cools down at night and during the winter. This creates a favorable environment for marine life.

Adhesion

The clinging of one substance to another. It occurs because the polar bonds allow the water to cling onto other substances. Water adheres to the walls of cells to help counter the downward pull of gravity when water leaves the roots to go to the leaves.

Hydration shell

The hydration shell is the water molecules surrounding a dissolved ion.

Why is water considered a polar molecule

Water is considered a polar molecule because one side of the molecule is a different charge then the other side of the molecule.