Honors Biology Final Review - Unit 1

Scientific Method

A systematic process for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.

Observation/Question

The first step in the scientific method where a phenomenon is observed and a question is formulated.

Hypothesis

A suggested solution to the problem - MUST be testable! Can be written as If... then.. statements and predicts an outcome.

Experiment

A procedure to test the hypothesis.

Variable

Factor in the experiment that is being tested.

Valid Experiment

An experiment that will only change ONE variable.

Constants

Factors that the experimenter keeps constant to ensure they do not affect the outcome.

Controls

Experiments that are NOT being tested & used for comparison.

Positive Control

Produces a known and expected response.

Negative Control

Produces no response or no change in result.

Independent Variable

The one factor that is being changed in an experiment.

Dependent Variable

The factor that is measured or observed in an experiment.

Data

Results of the experiment that may be quantitative or qualitative & be organized in charts, tables, or graphs.

Conclusion

The answer to the hypothesis based on the data obtained from the experiment.

Matter

Anything that has mass and occupies space; exists in three states: solid, liquid, and gas.

CHNOPS

The most important elements in biology: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

Atomic Structure

Atoms are the smallest unit of an element, composed of subatomic particles.

Protons

Subatomic particles with a positive charge; weight of 1 atomic unit found in the nucleus.

Neutrons

Subatomic particles with no charge; weight similar to protons, found in the nucleus.

Electrons

Subatomic particles with a negative charge; weight 1/1840th of a proton, found in the electron shell.

Subatomic Particles

Particles that make up atoms, including protons, neutrons, and electrons.

Atomic Symbols

Each element is represented by one or two letters to give them a unique atomic symbol.

Atomic mass

Each atom has its own specific mass.

Atomic number

Proton number.

Atomic mass or mass number

Protons and neutrons.

Isotopes

Atoms of the same element with differing numbers of neutrons, resulting in different atomic masses.

Radioactive isotopes

Some isotopes spontaneously decay, giving off energy in the form of rays and subatomic particles, can be used as tracers, and are mutagenic (can cause cancer).

Electrons and Energy

Atoms normally have as many electrons as protons, resulting in a neutral atom.

Ions

Formed when atoms gain or lose electrons.

Cations

Ions that have lost electrons and have a positive charge.

Anions

Ions that have gained electrons and have a negative charge.

Compound

When atoms of 2 or more different elements bond together.

Chemical Bonding

Bonds between atoms are caused by electrons in outermost shells; the process of bond formation is called a reaction.

Ionic bond

forms when electrons are transferred from one atom to another

Octet Rule

atoms gain, lose, or share electrons to get 8 electrons in outer shell

Covalent bonds

Covalent bonds result when two atoms share electrons, so each atom has an octet of electrons in the outer shell (in the case of hydrogen, 2 electrons)

Nonpolar Covalent Bonds

In nonpolar covalent bonds, sharing of electrons is equal, i.e. the electrons are not attracted to either atom to a greater degree

Polar Covalent Bonds

With polar covalent bonds, the sharing of electrons is unequal, i.e. atoms will have unequal affinity for electrons

Hydrogen Bonds

Hydrogen bonds form between H atoms in one molecule and O/N atoms in another molecule

Water (H2O)

Water is a polar molecule where electrons spend more time with O than H's, making H's slightly positive (+) and O's slightly negative (-)

Heat Capacity

Water has a high heat capacity; when heat is applied, hydrogen bonds restrain molecular bouncing, causing temperature to rise more slowly per unit

Heat of Vaporization

Large numbers of hydrogen bonds must be broken to evaporate water; to raise water from 100 to 101°C, it evaporates to steam

Evaporative cooling

Evaporative cooling is best when humidity is low because evaporation is low humidity

Heat of Fusion

Heat of fusion (melting) explains why ice at 0°C keeps stuff cold much longer than water at 1°C

Properties of Water

Water has unique properties such as high heat capacity, high heat of vaporization, and high heat of fusion

Solvent

Solutions consist of a solvent (the most abundant part) and a solute (less abundant part) that is dissolved in the solvent.

Polar compounds

Readily dissolve; hydrophilic.

Nonpolar compounds

Dissolve only slightly; hydrophobic.

Ionic compounds

Dissociate in water.

Frozen water

Less dense than liquid water - melting ice draws heat.

Ice

Acts as an insulator on top of a frozen body of water.

Cohesion

Hydrogen bonds hold water molecules tightly together, allowing water to flow freely without molecules separating.

Adhesion

Hydrogen bonds form between water and other polar materials, allowing water to be drawn many meters up a tree in a tubular vessel.

High Surface Tension

Water molecules at the surface hold tightly than below.

pH

A measure of the concentration of hydrogen ions.

Acids

Donate hydrogen ions and dissociate in water, releasing hydrogen ions (H+), e.g., HCl → H+ CI.

Strong acid

Dissociation of HCl is almost total.

Bases

Remove hydrogen ions by either taking up hydrogen ions (H+) or releasing hydroxide ions (OH-).

Sodium hydroxide (NaOH)

A solid that dissociates in water into Na+ and OH-.

Strong base

Dissociation of NaOH is almost total.

pH Scale

Used to indicate acidity and alkalinity of a solution, ranging from 0-14.

Acidic solution

Values from 0 to < 7.

Neutral solution

Value of 7.

Basic (alkaline) solution

Values from >7 to 14.

Logarithmic Scale

Each unit change in pH represents a change of 10x.

Monosaccharide

One sugar unit, e.g., glucose (C6H12O6).

Disaccharide

Two sugar units, e.g., sucrose (glucose + fructose).

Polysaccharide

Many sugar units, e.g., starch, glycogen, cellulose.

Lipids

Not soluble in water; soluble in hydrophobic solvents (like oil), e.g., fats, oils, waxes.

Triglycerides

Composed of 1 glycerol and 3 fatty acids.

Proteins (Polypeptides)

Amino acids (20 different types) bonded together by peptide bonds.

Primary Structure

Amino acids bonded together by peptide bonds (straight chains).

Secondary Structure

3D folding arrangement into coils and pleats held together by hydrogen bonds.

Tertiary Structure

Secondary structures bent and folded into the overall shape of the protein.

Quaternary Structure

Composed of 2 or more proteins bonded together, e.g., hemoglobin.

Nucleic Acids

Two types: DNA and RNA, composed of long chains of nucleotides.

Nucleotides

Include phosphate group, pentose sugar (5-carbon), and nitrogenous bases (A, T, U, C, G).