1. Make an observation- use senses- leads to questions. Inferences- logical interpretation based on what is already known.
2. Hypothesize- Come up with a testable explanation.
3. Experimentation- test the hypothesis (test only 1 variable at a time)
Parts of a controlled experiment:
a) Control- your standard of comparison. You don’t do anything to your control group. (nothing is changed in order to see what is different)
b) Constants- factors that stay the same
c) Independent variable- what IS changed. It is what you test.
d) Dependent variable- what change occurs. The result caused by the independent variable.
4. Gather data- 2 main types of data
a) Quantitative- numerical
b) Qualitative- descriptive
5. Analyze data- draw conclusions. Uses tools to collect and analyze data.
7. Publish & chare results
(Know your metric card- K.H.D.L.M.D.C.M)
(Know lab safety)
Atoms- basic building blocks of all matter
Structure- nucleus which is made up of:
Protons + positive charge
Neutrons no charge
Electrons surround the nucleus – negative charge. They create a cloud
Electrons and protons have the same amount
Compound- a substance made of 2 or more different elements in a definite proportion
Ex: H2O- water NaCl- salt
Isotopes- atoms of the same element with same # of protons, but different #s of neutrons
Uses of Isotopes:
Determine the age of rocks & fossils (carbon 14)
Detection & treatment of cancer
Killing bacteria in food
Used as “tracers” to follow the movement of substances through an organism
Bonds- bonds hold atoms of a compound together. Electrons that form bonds are called valence electrons
Two main types of bonds:
1. Ionic- transfer electrons Forms ions (charged atoms)
2. Covalent- share electrons
Water- the most important compound in living things. It makes up 60%-95% of most organisms
It is a polar molecule
Slight positive charge
Oxygen has a stronger attraction for electrons than hydrogen
Slight negative charge
Uneven distribution of electrons
Hydrogen bonds- attraction between a hydrogen atom on one molecule and the oxygen atom of another water molecule.
Hydrogen bonding- responsible for water properties:
1) Universal solvent- can break down almost anything
2) Cohesion- the attraction of molecules of the same substance. Creates surface tension
3) Adhesion- attraction of molecules of different substances to each other.
Ex: water in a graduated cylinder
Capillary action- water can rise in a tube against the force of gravity
Ex: drawing water up from the roots of a plants
4) Heat capacity- amount of heat and energy from the roots of a plant’s temperature is high. Large bodies of water can absorb heat with only small charges in temperature. Organisms living in water don’t have to deal with drastic changes in temperature.
Mixtures- two or more elements(substances) mixed but not chemically joined to make a new substance
1. Solution- liquids- even distribution of patriots
Solute- what gets dissolved
2. Suspensions- parts separate out
Ex: Italian salad dressing
3. Colloid- particles remain spread out in solvent
Ex: whipped cream
Acids & Bases form ions when they dissolve in water. pH scale(potential of Hydrogen) measurements that shows the concentration of hydrogen ions (H+) in solutions:
0-6 is an acid. Acids produce H+ ions in solutions
7 is neutral
9-14 is a base. Bases produce hydroxide ions (OH-) in solutions
Macromolecules- large molecules
4 major groups of macromolecules:
Carbohydrates- C, H, O. Stores & releases energy.
Lipids- fats, oils, waxes. Stores a lot of energy. Insoluble in water. Will dissolve in alcohol.
Nucleic acids- large and most complex of organic compounds. Contains
Proteins- C, H, O, N
-Made from amino acids (there are 20)
Enzymes-proteins that act as…