Intro to Bio (Ch. 1-5)

What is Biology?

The scientific study of life and living organisms.

What are the 7 characteristics that define LIFE?

1. Order/Organization, 2. Sensitivity/Response to environment, 3. Reproduction, 4. Adaptation/Evolution, 5. Energy use/Metabolism, 6. Growth and Development, 7. Homeostasis

What is the MOST BASIC UNIT capable of life?

The cell

What is the MOST BASIC UNIT of matter?

The atom

What are the 3 subatomic particles?

Proton (positive charge, in nucleus), Neutron (no charge, in nucleus), Electron (negative charge, outside nucleus)

What is the CELL THEORY?

All living things are composed of cells; the cell is the basic unit of life; all cells come from pre-existing cells.

WHO coined the term "cells"? What was he looking at and what device did he use?

Robert Hooke; he was looking at cork tissue; he used a light microscope.

What is the hierarchy of biological organization from simplest to most complex?

Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

What is the difference between a PROKARYOTIC and EUKARYOTIC cell?

Prokaryotic: no true nucleus, no membrane-bound organelles, smaller (bacteria/archaea). Eukaryotic: has a true membrane-bound nucleus and membrane-bound organelles, larger (plants, animals, fungi, protists).

Which two domains are prokaryotic?

Bacteria and Archaea

Which domain is eukaryotic?

Eukarya

What are the 4 Kingdoms of Eukarya?

Animalia, Plantae, Fungi, Protista

What organelle is found in BOTH prokaryotic and eukaryotic cells?

Ribosomes

What is found in plant cells but NOT animal cells?

Cell wall, chloroplasts, central vacuole

What is found in animal cells but NOT plant cells?

Centrioles; animal cells also lack a cell wall

What is a VIRUS built of?

A protein coat (capsid) and nucleic acid (DNA or RNA); some have a lipid envelope

Are viruses considered living?

No — they do not meet all 7 characteristics of life (they cannot reproduce independently and do not carry out metabolism on their own)

What is a bacteriophage?

A virus that infects a prokaryotic cell (bacteria)

What are PRIONS? What diseases do they cause?

Prions are misfolded proteins that can cause other normal proteins to misfold. They cause diseases such as mad cow disease (BSE), CJD (Creutzfeldt-Jakob disease), and scrapie.

What are EMERGENT PROPERTIES?

New properties that arise at each level of biological organization that were not present at the level below; the whole is greater than the sum of its parts. Example: water's liquidity arises from H2O molecules.

What is the concept of EVOLUTION by NATURAL SELECTION?

Organisms with heritable traits better suited to their environment survive and reproduce more, passing those traits to offspring; over time populations change.

What two main points did Darwin articulate in "The Origin of Species"?

1. All species descended from common ancestors (descent with modification); 2. Natural selection is the mechanism of evolution.

What is the three-part mechanism of Natural Selection?

1. Variation exists in a population; 2. Some variants are heritable; 3. Organisms with favorable heritable traits survive and reproduce more (differential reproductive success).

What does each TWIG on an evolutionary tree represent?

A species or group of organisms

What do BRANCH POINTS on an evolutionary tree represent?

Common ancestors; points where lineages diverged

What is a SCIENTIFIC HYPOTHESIS?

A testable, falsifiable proposed explanation for an observation; it must be falsifiable (capable of being proven wrong).

Can a scientific hypothesis be proven?

No — hypotheses can only be supported or refuted; science cannot prove, only disprove.

What is the difference between QUANTITATIVE and QUALITATIVE data?

Quantitative: numerical measurements (can be graphed). Qualitative: descriptive observations (e.g., Jane Goodall's field sketches).

What is INDUCTIVE reasoning?

Drawing a general conclusion from specific observations. Example: "Every organism observed requires organic molecules, therefore all organisms do."

What is DEDUCTIVE reasoning?

Drawing a specific conclusion from a general premise. Example: "If all mammals are warm-blooded, and bats are mammals, then bats are warm-blooded."

What is NEGATIVE FEEDBACK?

A regulatory mechanism where the output of a process inhibits the process; keeps conditions stable (e.g., thermostat, blood glucose regulation by insulin).

What is POSITIVE FEEDBACK?

A regulatory mechanism where the output amplifies the process (e.g., childbirth contractions, blood clotting).

What is the SCIENTIFIC METHOD (7 steps)?

1. Observation, 2. Question, 3. Hypothesis, 4. Prediction, 5. Experiment/Test, 6. Data Collection, 7. Conclusion

What is a CONTROLLED EXPERIMENT?

An experiment that keeps all variables constant except the independent variable being tested.

What is the INDEPENDENT variable?

The variable the experimenter manipulates/changes.

What is the DEPENDENT variable?

The variable that responds to or is measured as a result of the independent variable.

What is a SCIENTIFIC THEORY vs. a hypothesis?

A theory is broader, supported by extensive evidence from multiple studies, makes predictions across many situations; a hypothesis is a single testable explanation for a specific observation.

What 3 types of post-Darwin evidence support evolution?

1. Fossil record, 2. DNA and heredity (molecular biology), 3. Homologous and analogous structures (comparative anatomy)

What is MATTER?

Anything that takes up space and has mass.

What is the difference between MASS and WEIGHT?

Mass is the amount of matter in an object (constant); weight is the force of gravity on that mass (varies with gravitational pull).

What are the 4 STATES of MATTER?

Solid, Liquid, Gas, Plasma

What is an ELEMENT?

A pure substance that cannot be broken down into other substances by chemical reactions (e.g., carbon, oxygen, hydrogen, nitrogen).

What is a COMPOUND?

A substance consisting of two or more different elements combined in a fixed ratio (e.g., H₂O, NaCl).

What 4 elements make up ~96% of living matter?

Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N) — "OCHN"

What are the 11 elements found in living organisms?

C, H, O, N, P, S, Ca, K, Na, Mg, Cl

What is the ATOMIC NUMBER?

The number of protons in an atom's nucleus; unique to each element; in a neutral atom, equals the number of electrons.

What is the ATOMIC MASS?

The total number of protons + neutrons in the nucleus; approximately equals the mass of the atom in daltons.

How do you calculate the number of NEUTRONS in an atom?

Neutrons = Atomic Mass − Atomic Number

For Carbon (C), what is the atomic number and atomic mass?

Atomic number = 6; Atomic mass = 12; therefore 6 protons, 6 electrons, 6 neutrons

What are ISOTOPES?

Atoms of the same element with the same number of protons but different numbers of neutrons (and therefore different atomic masses). Example: Carbon-12, Carbon-13, Carbon-14.

What is a RADIOACTIVE ISOTOPE?

An unstable isotope whose nucleus decays spontaneously, releasing particles and energy. Example: Carbon-14.

What is RADIOMETRIC DATING?

Using the known decay rate (half-life) of a radioactive isotope to calculate the age of a fossil or rock.

What is a HALF-LIFE?

The time it takes for 50% of a radioactive isotope to decay into its daughter isotope. Carbon-14 half-life = 5,730 years.

If only ¼ of Carbon-14 remains, how old is the sample?

Two half-lives have passed: 2 × 5,730 = 11,460 years old.

What is ELECTRONEGATIVITY?

An atom's ability to attract electrons toward itself in a covalent bond. Oxygen has very high electronegativity (~3.44); sodium has very low electronegativity.

What determines an atom's CHEMICAL BEHAVIOR?

The number of electrons in its outermost (valence) shell.

What are VALENCE ELECTRONS?

Electrons in an atom's outermost shell that are available for bonding.

What is the OCTET RULE?

Atoms tend to form bonds so that each atom has 8 electrons in its valence shell (except H and He, which are satisfied with 2).

Why are H and He exceptions to the octet rule?

They only have the first electron shell, which holds a maximum of 2 electrons.

What is a NONPOLAR COVALENT BOND?

A covalent bond in which electrons are shared equally between two atoms of the same or similar electronegativity (e.g., O₂, H₂).

What is a POLAR COVALENT BOND?

A covalent bond in which electrons are shared unequally because the atoms have different electronegativities (e.g., O–H in water). The more electronegative atom gets a partial negative charge (δ−).

What is an IONIC BOND?

A bond formed by the complete transfer of one or more electrons from one atom to another, creating oppositely charged ions that attract each other (e.g., NaCl).

What is a CATION?

A positively charged ion (atom that lost electrons). Example: Na⁺

What is an ANION?

A negatively charged ion (atom that gained electrons). Example: Cl⁻

What is a HYDROGEN BOND?

A weak attraction between a hydrogen atom (with a partial positive charge) covalently bonded to an electronegative atom, and another electronegative atom (usually O or N) nearby. Illustrated with dashed lines.

What are VAN DER WAALS INTERACTIONS?

Very weak, temporary attractions between all atoms/molecules caused by momentary unequal distribution of electrons. Individually weak, but collectively powerful (e.g., gecko feet).

What is the order of bond strength from strongest to weakest?

Covalent bonds > Ionic bonds (in dry state) > Hydrogen bonds > Van der Waals interactions

What are the valences of H, O, N, and C?

H = 1, O = 2, N = 3, C = 4

Why does water form a 2:1 ratio of H to O (H₂O)?

Oxygen has a valence of 2 (needs 2 more electrons); hydrogen has a valence of 1 (needs 1 more electron); so 2 hydrogens satisfy 1 oxygen.

What type of bond is WITHIN a water molecule?

Polar covalent bond (between O and H)

What type of bond forms BETWEEN water molecules?

Hydrogen bonds (between the partial + H of one molecule and the partial − O of another)

Why is water a POLAR molecule?

Oxygen is more electronegative than hydrogen, so shared electrons spend more time near the oxygen, giving it a partial negative charge (δ−) and the hydrogens partial positive charges (δ+). The molecule has distinct positive and negative ends (V-shape).

How many hydrogen bonds can one water molecule form?

Up to 4 hydrogen bonds (2 from the H atoms, 2 from the lone pairs on O)

What is a CHEMICAL REACTION?

The making and breaking of chemical bonds, leading to changes in the composition of matter. Matter is conserved — atoms are rearranged but not created or destroyed.

What are REACTANTS vs. PRODUCTS?

Reactants: the starting materials of a chemical reaction. Products: the resulting materials after the reaction.

What is CHEMICAL EQUILIBRIUM?

The point where the forward and reverse reaction rates are equal, so relative concentrations of reactants and products stop changing (dynamic equilibrium).

What is PHOTOSYNTHESIS (summary equation)?

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Why is water so important to life?

1. Universal solvent

2. Cohesion/surface tension

3. High specific heat (temperature moderation)

4. High heat of vaporization (evaporative cooling)

5. Ice is less dense than liquid water (floats, insulates)

What is COHESION in water?

The attraction of water molecules to each other via hydrogen bonds, creating surface tension. Allows insects to walk on water.

What is ADHESION in water?

The attraction of water molecules to other substances (e.g., water sticking to glass or plant cell walls). Enables capillary action.

What is CAPILLARY ACTION?

The movement of water up a narrow tube (or plant vessel) due to adhesion overcoming gravity.

What is the SPECIFIC HEAT of water?

1 cal/(g·°C) — one of the highest known; water resists temperature change because hydrogen bonds must be broken/formed. Moderates Earth's and organisms' temperatures.

What is HEAT OF VAPORIZATION?

The energy required to convert 1g of liquid water to gas (~580 cal/g at 25°C). High because many H-bonds must be broken. Explains evaporative cooling (sweating).

How does sweating cool the body?

The most energetic (hottest) water molecules evaporate first, carrying heat away and leaving the body cooler (evaporative cooling).

Why does ICE float on liquid water?

In ice, water molecules form a rigid crystalline lattice held by hydrogen bonds, making ice ~10% less dense than liquid water. Less dense = floats.

What would happen if ice sank?

Bodies of water would freeze solid from the bottom up; only the top few inches would thaw; aquatic life as we know it could not exist.

What is a SOLVENT?

The dissolving agent in a solution (e.g., water is the solvent of life).

What is a SOLUTE?

The substance that is dissolved in a solvent (e.g., salt or sugar in water).

What is an AQUEOUS SOLUTION?

A solution in which water is the solvent.

Why is water called the "universal solvent"?

Because it is polar and can dissolve ionic compounds and polar molecules by forming hydration shells (surrounding ions with partial charges), breaking apart ionic bonds.

What is HYDROPHILIC?

"Water-loving" — polar or charged molecules that interact with and dissolve in water (e.g., sugar, salt).

What is HYDROPHOBIC?

"Water-fearing" — nonpolar molecules that do not interact with water and are excluded from it (e.g., oils, fats). Polar likes polar; nonpolar likes nonpolar.

What is HYDROPHOBIC EXCLUSION?

The tendency of nonpolar molecules to cluster together and be excluded by water because they cannot form hydrogen bonds with it. Basis for cell membrane structure (lipid bilayer).

What is a MOLE?

A unit of measurement equal to the molecular weight of a substance expressed in grams; contains 6.02 × 10²³ molecules (Avogadro's number).

What is AVOGADRO'S NUMBER?

6.02 × 10²³ — the number of molecules in 1 mole of any substance.

What is MOLARITY?

The concentration of a solution expressed as moles of solute per liter of solution (mol/L or M).

How many grams is 1 mole of sucrose?

342 grams (molecular mass of C₁₂H₂₂O₁₁ = 12×12 + 22×1 + 11×16 = 144+22+176 = 342 daltons).

What is WATER IONIZATION (dissociation)?

H₂O spontaneously dissociates into H⁺ (hydrogen ion/proton) and OH⁻ (hydroxide ion). Occurs because oxygen is so electronegative it sometimes steals the electron from hydrogen completely.

What is the concentration of H⁺ and OH⁻ in a NEUTRAL solution?

Both equal 10⁻⁷ mol/L at pH 7

What is an ACID?

A substance that increases the H⁺ concentration of a solution (donates protons). Example: HCl → H⁺ + Cl⁻