31 terms

Campbell Essential Biology Chapter 2

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What is matter?
Anything that has mass and occupies space.
What are the three states of matter?
Solid, liquid, gas.
What are elements?
Substances that cannot be broken down into other substances.
How many elements are naturally occurring elements?
92
What are the 4 most important elements to life?
Carbon, hydrogen, nitrogen, oxygen.
What are trace elements
Elements necessary for life in small amounts.
Example of trace element
Iodine (thyroid gland), Iron (Important component of the protein hemoglobin which transports oxygen).
What are compounds?
Substances that contain two or more elements.
What are atoms?
The smallest unit of matter that still retains the properties of an element.
What are the 3 main subatomic particles?
Protons, Electrons, Neutrons.
What does the atomic number tell you?
The number of protons in an element.
How are the chemical properties of an atom determined?
By the number of electrons in the outermost (valence) shell.
What are polar molecules?
Molecules with covalent bonds where the electrons are not shared equally.
Is water polar or nonpolar?
Polar.
What are hydrogen bonds
Weak bonds formed between a Hydrogen and another molecule.
What are reactants?
Substances that react together- the "input" of a chemical reaction.
What are products?
Substances that result from a reaction- the "output" of a chemical reaction.
What molecule is life on earth most dependent on?
Water!
What is some evidence that life is dependent on water?
Life began in water and evolved there for the first 3 billion years. Most living cells are composed of 70-95% water. Adhesion/cohesion in plants.
What are 4 characteristics of water that make it so important for life?
Water is cohesive, water moderates temperature, ice floats, water is an excellent solvent.
What is cohesion?
Tendency of molecules to stick together.
What is surface tension?
Measure of the difficulty in breaking the surface of a liquid.
How does water moderate temperature?
Water has a high specific heat. It takes a lot of energy to change water temperature. This buffers the temperature of organisms and also the earth as a whole.
What does temperature measure?
Measures the average speed of molecules in matter.
How does floating ice support life?
Floating ice allows ponds, lakes, and oceans to maintain life during winter. Sinking ice would build up at the bottom and all bodies of water would become solid ice when cold.
What happens when most liquids freeze?
Molecules move closer together.
What happens when water freezes?
Molecules move father apart as they form crystals.
What is a solution?
Liquid consisting of a mixture of two or more substances.
What is a solvent?
The substance doing the dissolving- usually water.
What is a solute?
The substance being dissolved- usually solids.
Why is the solubility of water important to life?
It dissolves nutrients, minerals and other substances that can then be carried around our bodies (blood).