Water

BIOL 1101L

Fall 2015

WATER AND LIFE

Water’s importance to life on earth cannot be overstated. It is a required component of living systems, and its

unique properties provide the basis for the many processes necessary in cells.

A water molecule has a very simple structure: 2 atoms of hydrogen, each covalently bonded to an oxygen atom.

These covalent bonds are polar, meaning that the electrons are more attracted to the nucleus of the oxygen

atom than to the nucleus of the hydrogen

atom.

Water molecules are attracted to each other

due to the partial charges on each molecule.

The partial negative end of one water

molecule is attracted to the partial positive

end of another water molecule, resulting in a

hydrogen bond (a weak attraction between 2

polar molecules). While a single hydrogen

bond is not very strong, when you group

many of these bonds together, the result can have an impressive impact. Hydrogen bonds give water some of

its unique properties and make it an important component of living systems.

List the four major properties making water important to life and living systems:

1. _______________________________________

2. _______________________________________

3. _______________________________________

4. _______________________________________

Experiment 1: Demonstration of cohesion/adhesion

1. Remove a small piece of the stalk of the celery by using the scalpel. To remove the piece make an incision

about ½ inch from the bottom of the stalk and halfway through the diameter of the celery. Your celery

should look like:

missing piece

2. Put the bottom of the celery stalk in the beaker of methylene blue.

3. Allow it to sit in the methylene blue while you complete Experiments 2, 3, and 4.

BIOL 1101L

Fall 2015

4. Remove the celery from the methylene blue and dry it on a paper towel by dabbing it on the towel.

5. Look at the bottom of the celery stalk (the part that was immersed in the methylene blue). What do you...