Principles of bio Exam 1

1. Characteristics of life

Living things: are made of cells, use energy, grow, reproduce, respond to environment, maintain homeostasis, and evolve.

2. Levels of biological organization

Atom → molecule → organelle → cell → tissue → organ → organ system → organism → population → community → ecosystem → biosphere

3. Theory vs. Law vs. Hypothesis

  • Hypothesis: testable prediction (lowest certainty).

  • Theory: well‑supported explanation backed by evidence.

  • Law: describes a natural pattern that always happens (highest certainty).

4. Key parts of an experiment

Independent variable, dependent variable, control group, constants, data, conclusion.

5. Control vs. Experimental / Variables

  • Control group: not changed; used for comparison.

  • Experimental group: receives the variable being tested.

  • Independent variable: what the scientist changes.

  • Dependent variable: what is measured.

6. Steps of the scientific method

Observe → question → hypothesis → experiment → collect data → analyze → conclude → repeat

7. Graphs

  • Line graph: change over time

  • Bar graph: compare groups

  • Histogram: distribution of data
    Include title, labels, units, scale, key.

8. Metric measurement

Use meters, liters, grams. Measure with ruler, graduated cylinder, beaker, etc.

Chapter 2 — Basic Chemistry

1. Matter, elements, atoms

  • Matter: anything with mass and volume.

  • Elements: pure substances made of one type of atom.

  • Atoms: smallest unit of matter.

  • Structure: protons (+), neutrons (0), electrons (–).

2. Atomic number vs. mass number

  • Atomic number: number of protons.

  • Mass number: protons + neutrons.

3. Isotopes, radioactivity, bonds

  • Isotope: same element, different number of neutrons.

  • Radioactivity: unstable nuclei releasing energy.

  • Ionic bond: transfer of electrons.

  • Covalent bond: sharing electrons.

  • Polar molecule: unequal sharing.

  • Nonpolar: equal sharing.

4. Properties of water

Cohesion, adhesion, high heat capacity, universal solvent, ice floats, surface tension.

5. Acids and bases

  • Acid: pH 0–6

  • Base: pH 8–14

  • Neutral: pH 7

6. Four organic molecules

Molecule

Monomer

Function

Carbohydrates

monosaccharides

energy

Lipids

fatty acids

energy storage, membranes

Proteins

amino acids

structure, enzymes

Nucleic acids

nucleotides

genetic info

7. Reactions

  • Dehydration: builds molecules by removing water.

  • Hydrolysis: breaks molecules using water.

  • Peptide bond: links amino acids.

Chapter 3 — Cells

1. Why cells are small

Small size allows efficient nutrient and waste exchange.

2. Prokaryotic vs. Eukaryotic

  • Prokaryotic: no nucleus, simple, bacteria.

  • Eukaryotic: nucleus, complex, plants/animals.

3. Main organelles

  • Nucleus: control center

  • Mitochondria: energy

  • Ribosomes: make proteins

  • ER: transport

  • Golgi: packages

  • Lysosomes: digestion

  • Chloroplasts: photosynthesis (plants)

4. Plant‑only organelles

Chloroplasts, cell wall, large central vacuole

5. Mitochondria function

Make ATP (energy).

6. Diffusion vs. Osmosis

  • Diffusion: movement of molecules from high → low concentration.

  • Osmosis: diffusion of water.

  • Active transport: requires energy; moves molecules low → high.

7. Exocytosis vs. Endocytosis

  • Exocytosis: cell releases materials.

  • Endocytosis: cell takes in materials.

Chapter 4 — Cell Membrane

1. Moving down the gradient

Moving from high → low concentration (diffusion).
Osmosis = diffusion of water.

2. Transport that requires energy

Active transport, endocytosis, exocytosis

3. Exocytosis vs. Endocytosis

  • Exocytosis: out

  • Endocytosis: in

4. Plasma membrane structure

Phospholipid bilayer with proteins.
Selectively permeable: only certain substances pass.

5. Water movement

  • Isotonic: equal water movement

  • Hypertonic: water leaves cell

  • Hypotonic: water enters cell

6. Types of membrane proteins

Transport, receptor, enzyme, recognition, attachment

7. Fluid mosaic model

Membrane is flexible with proteins floating in lipids.

8. Functions of membrane proteins

Transport, signaling, recognition, enzyme activity

9. Phospholipid structure

Hydrophilic head + hydrophobic tails → forms bilayer.

10. Diffusion / passive transport

Movement from high → low without energy.

11. Osmosis

Diffusion of water across a membrane.

12. Tonicity terms

  • Hypertonic: cell shrinks

  • Hypotonic: cell swells

  • Isotonic: stays same

13. Animal vs. plant cells in solutions

  • Hypertonic: both shrink; plant = plasmolysis

  • Hypotonic: animal bursts; plant becomes turgid

14. Facilitated diffusion vs. active transport

  • Facilitated diffusion: uses proteins, no energy

  • Active transport: uses proteins and energy