yacomine_essential biology 03.1 chemical elements and water_6111

8/8/2019 Yacomine_Essential Biology 03.1 Chemical Elements and Water_6111

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Essential Biology 03.1: Chemical Elements and Water

Stephen Taylor Bandung International School http://sciencevideos.wordpress.com

1. What are the four most commonly occurring elements in living things?

The four elements are carbon, hydrogen, oxygen and nitrogen.

2. State some functions of each of these elements in living things:

a. Iron Symbol: Fe Ion: 2+

Function(s): Used to make chlorophyll, used in photosynthesis as ferredoxin, binds with

oxygen for transport and facilitates the movement of electrons in cells.

a. Sulphur Symbol: S Ion: 2-

Function(s): Reactant for chemoautotrophs and produce organic molecules from hydrogen

sulphide, carbon dioxide and oxygen.

b. Calcium Symbol: Ca Ion: 2+

Function(s): Used in the production of exoskeletons of animals and unicellular organisms

and the propagation of an electrical signal along nerves and muscle contraction.

c. Phosphorous Symbol: P Ion: 3-

Function(s): Essential in the formation of the phospholipid layer, an active component of

ATP molecules and make up the backbone of DNA.

d. Sodium Symbol: Na Ion: 1+

Function(s): Essential in generating an action potential for nerve impulses and is the main

cation for blood plasma.

e. Potassium Symbol: K Ion: 1-





Function(s): Plays a role in nerve impulses, has a strong influence in osmosis and is the main

cation in cell cytoplasm.

3. In the space below, draw three water molecules attracted to one another by hydrogen

bonding. Include labels to show the polarity of the molecules.

Annotate: How does H-bonding work?

6. Water has many properties which are essential for life. Complete the table below.

Explanation Significance to living things

Thermal Properties

Water has a high specific heat capacity. This

means it takes a lot of energy for the

temperature of water to change. This is

because there are so many H-bonds.

Most organisms are adapted to a

narrow range of conditions. The slow

heating and cooling of water are ideal

for these organisms there is less risk of extreme changes.

Cohesion

A single hydrogen bond is not very strong. A

large number of hydrogen bonds is very

strong. Molecules of water stick to each other,

and water sticks to other surfaces.

These properties lead to capillary action,

where water will move up xylem against

gravity, and surface tension, where the

surface of water is strong enough to

support insects and causes drops to

form.





Solvent Properties

Water is a good solvent because it is a polar

molecule. It will dissolve polar solutes easily.

Polar attractions cause water molecules

to surround and isolate the solute

molecules.

(include uses as a coolant, medium for metabolic reactions, transport medium)

yacomine_essential biology 03.1 chemical elements and water_6111

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