Comprehensive Biology Chemistry, Biology, Physics, Computer, and Earth Science Notes

Effective Study Strategies and Reviewer Methodology

  • Conceptual Understanding: Mastery of biology, chemistry, computer science, Earth science, and physics requires moving beyond rote memorization. Focus on understanding the meaning of concepts, the mechanisms of why phenomena happen, the interconnections between different subjects, and the practical application of theories to problem-solving.
  • Reviewing Techniques:
    • Concentrate on one subject at a time to ensure depth of focus.
    • Formulas, diagrams, patterns, and comparative tables are critical for visualizing relationships.
    • Utilize active recall by answering check questions without referencing notes.
    • Employ the process of elimination to identify and discard clearly incorrect answer choices during testing.
    • Analyze errors thoroughly; identifying why a mistake occurred is more valuable than simply counting correct answers.
    • Success is built through consistent, incremental progress rather than trying to learn everything at once.

Biological Macromolecules and Cell Chemistry

  • Foundations of Macromolecules: Living organisms rely on large molecules categorized into four major groups: carbohydrates, lipids, proteins, and nucleic acids. These are often polymers—long chains formed from repeating smaller units called monomers.
  • Carbohydrates:
    • Functions: They serve as sources of immediate energy, short-term energy storage, and structural materials.
    • Composition: Composed of carbon, hydrogen, and oxygen, typically in a ratio of approximately 2:12:1 for hydrogen to oxygen.
    • Classification:
      • Monosaccharides: Single sugar units like glucose (cellular fuel), fructose, and galactose.
      • Disaccharides: Two sugars joined together: Sucrose (glucose+fructose\text{glucose} + \text{fructose}), Lactose (glucose+galactose\text{glucose} + \text{galactose}), and Maltose (glucose+glucose\text{glucose} + \text{glucose}).
      • Polysaccharides: Long chains such as Starch (energy storage in plants), Glycogen (energy storage in animals' liver and muscles), Cellulose (plant cell wall strength), and Chitin (fungal cell walls and arthropod exoskeletons).
    • Detection Tests: Benedict’s solution tests for reducing sugars (changing from blue to green, yellow, orange, or brick-red upon heating). Iodine solution detects starch, producing a blue-black color.
  • Lipids:
    • Identity: Includes fats, oils, waxes, phospholipids, and steroids. They are not true polymers because they lack identical repeating monomers.
    • Functions: Long-term energy storage, insulation, organ protection, cell membrane structure (phospholipids), and hormone production.
    • Chemical Nature: Contain carbon, hydrogen, and oxygen (with proportionally less oxygen than carbohydrates). Often composed of one glycerol molecule and fatty acid chains.
    • Saturation: Saturated fats have no carbon-carbon double bonds, straight chains, and are solid at room temperature. Unsaturated fats have one or more double bonds (C=C\text{C}=\text{C}), bent/kinked chains, and are liquid at room temperature.
    • Structure specifics: Phospholipids have a hydrophilic head and hydrophobic tails, forming the bilayer of cell membranes. Steroids (e.g., cholesterol, estrogen, testosterone) consist of four connected carbon rings.
    • Detection Test: The Sudan test identifies lipids, which form a stained red or orange layer.
  • Proteins:
    • Functions: Act as enzymes (amylase), antibodies for defense, hormones, structural components (keratin in hair/nails), transport molecules (hemoglobin for oxygen), receptors, and contractile fibers.
    • Composition: Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. The monomer is the amino acid, consisting of an amino group, a carboxyl group, a hydrogen atom, and a variable R group.
    • Structure Levels:
      • Primary: The linear sequence of amino acids connected by peptide bonds.
      • Secondary: Local folding into alpha-helices or beta-pleated sheets.
      • Tertiary: The overall three-dimensional globular shape.
      • Quaternary: The assembly of multiple polypeptide chains.
    • Denaturation: Loss of shape and function due to high temperature, extreme pH, chemicals, or salt concentration.
    • Detection Test: The Biuret test turns from blue to violet/purple in the presence of proteins.
  • Nucleic Acids:
    • Function: Storing and transmitting genetic information.
    • Composition: Carbon, hydrogen, oxygen, nitrogen, and phosphorus. The monomer is the nucleotide, which contains a phosphate group, a five-carbon sugar, and a nitrogenous base.
    • DNA vs. RNA:
      • DNA (Deoxyribonucleic Acid): Stores instructions; double-stranded; deoxyribose sugar; uses bases Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Base pairs: A−TA-T and C−GC-G.
      • RNA (Ribonucleic Acid): Helps protein synthesis; single-stranded; ribose sugar; uses Uracil (U) instead of Thymine. Base pairs: A−UA-U and C−GC-G.
  • Molecular Reactions:
    • Dehydration Synthesis: Joins monomers into polymers by removing a water molecule (Monomer+Monomer→Polymer+H2O\text{Monomer} + \text{Monomer} \rightarrow \text{Polymer} + \text{H}_2\text{O}).
    • Hydrolysis: Breaks polymers apart by adding water (Polymer+H2O→Monomers\text{Polymer} + \text{H}_2\text{O} \rightarrow \text{Monomers}).

Cell Biology and Organelles

  • Cell Theory: All living organisms are made of one or more cells; the cell is the basic unit of life; and all cells arise from preexisting cells.
  • Prokaryotic vs. Eukaryotic Cells:
    • Prokaryotic: Lacks a membrane-bound nucleus and organelles; smaller/simpler; DNA in a nucleoid region (e.g., bacteria, archaea).
    • Eukaryotic: Has a nucleus and membrane-bound organelles; larger/complex (e.g., animals, plants, fungi, protists).
  • The Organelles:
    • Cell Membrane: Selective barrier using a phospholipid bilayer described by the fluid mosaic model. Controls homeostasis.
    • Nucleus: Contains DNA and regulates activities; contains the Nucleolus which produces ribosome parts.
    • Ribosomes: Sites of protein synthesis; can be free in cytoplasm or attached to the Rough ER (which modifies proteins).
    • Smooth ER: Synthesizes lipids, detoxifies substances, and stores calcium.
    • Golgi Apparatus: The cell's "packaging and shipping center" that modifies/sorts proteins and lipids into vesicles.
    • Mitochondria: Sites of aerobic respiration; produce ATP; contain their own DNA and double membranes.
    • Chloroplasts: Found in plants/algae; sites of photosynthesis; contain chlorophyll; have their own DNA.
    • Lysosomes: Contain digestive enzymes to break down waste or damaged organelles.
    • Peroxisomes: Break down fatty acids and hydrogen peroxide (H2O2\text{H}_2\text{O}_2).
    • Vacuoles: Storage sacs. Plants have a large central vacuole for turgor pressure.
    • Cytoskeleton: Network of microtubules, microfilaments, and intermediate filaments providing shape and movement.
    • Centrosome/Centrioles: Organize microtubules during animal cell division.
    • Cell Wall: External support. Cellulose in plants, Chitin in fungi, Peptidoglycan in bacteria.
  • Cell Transport:
    • Passive Transport (No Energy): Movement from high to low concentration.
      • Simple Diffusion: Tiny molecules (O₂, CO₂) passing directly through the membrane.
      • Facilitated Diffusion: Using channel/carrier proteins (ions, glucose).
      • Osmosis: Diffusion of water. In Hypotonic solutions, water enters the cell (turgid plants, bursting animals). In Hypertonic solutions, water leaves (plasmolysis in plants, shrinking in animals). In Isotonic solutions, net movement is zero.
    • Active Transport (Energy/ATP Required): Moves substances against the gradient (e.g., Sodium-Potassium pump).
    • Bulk Transport: Endocytosis (phagocytosis/cell eating, pinocytosis/cell drinking) and Exocytosis (releasing materials).

Cell Metabolism and Energy

  • Metabolism Types:
    • Catabolic: Breaking down large molecules to release energy (e.g., cellular respiration).
    • Anabolic: Building molecules, requiring energy input (e.g., photosynthesis, protein synthesis).
  • Enzymes: Biological catalysts that speed reactions by lowering activation energy without being consumed. They bind specific substrates at the active site. Activity is sensitive to temperature, pH, and concentration.
  • ATP (Adenosine Triphosphate): The universal energy currency. Breaking the final phosphate bond (ATP→ADP+Phosphate+Energy\text{ATP} \rightarrow \text{ADP} + \text{Phosphate} + \text{Energy}) powers work like active transport and growth.
  • Cellular Respiration: C6H12O6+6O2→6CO2+6H2O+ATPC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}.
    • Glycolysis: Cytoplasm; splits glucose into smaller molecules; small ATP yield; anaerobic.
    • Krebs Cycle: Mitochondrial matrix; releases CO2CO_2; produces electron carriers.
    • Electron Transport Chain: Inner mitochondrial membrane; uses oxygen to produce most of the ATP.
    • Anaerobic Fermentation: Lactic acid fermentation (muscles/bacteria) or Alcoholic fermentation (yeast; produces ethanol and CO2CO_2).
  • Photosynthesis: 6CO2+6H2O+Light→C6H12O6+6O26CO_2 + 6H_2O + \text{Light} \rightarrow C_6H_{12}O_6 + 6O_2.
    • Light-Dependent Reactions: Thylakoid membranes; split water, release oxygen, produce ATP/NADPH.
    • Calvin Cycle: Stroma; uses carbon dioxide and ATP/NADPH to synthesize sugar.

Cell Division: Mitosis and Meiosis

  • Chromosomal Terms: Chromatin is loose DNA; chromosomes are condensed; sister chromatids are identical copies joined at the centromere; homologous chromosomes are pairs (one per parent) carrying the same gene types but potentially different versions.
  • Cell Cycle: Consists of Interphase (G₁ growth, S DNA replication, G₂ prep) and M phase (division).
  • Mitosis (Somatic Cell Division for Growth/Repair):
    1. Prophase: Chromosomes condense; spindle forms; nuclear envelope dissolves.
    2. Metaphase: Chromosomes line up at the equator (middle).
    3. Anaphase: Sister chromatids move away to opposite poles.
    4. Telophase: New nuclear envelopes form; chromosomes uncoil.
    • Cytokinesis: Cytoplasm divides (cleavage furrow in animals; cell plate in plants). Result: Two identical diploid (2n2n) daughter cells.
  • Meiosis (Gamete Production):
    • Meiosis I: Separates homologous chromosomes. Includes Prophase I where Crossing Over occurs (exchange of DNA for variation).
    • Meiosis II: Separates sister chromatids; resembles mitosis.
    • Result: Four genetically unique haploid (nn) cells. Humans produce gametes with 23 chromosomes to restore the 46 diploid number upon fertilization.

Periodic Trends and Table Organization

  • Basis: Organized by increasing atomic number (number of protons\text{number of protons}).
    • Periods: Horizontal rows; signify number of occupied main energy levels.
    • Groups: Vertical columns; share similar chemical properties due to valence electron counts.
  • Key Families:
    • Group 1 (Alkali Metals): Highly reactive, form +1+1 ions, reactivity increases down the group.
    • Group 2 (Alkaline Earth Metals): Form +2+2 ions, reactive but less so than Group 1.
    • Group 17 (Halogens): Highly reactive nonmetals, form −1-1 ions, reactivity decreases down the group.
    • Group 18 (Noble Gases): Unreactive due to full valence shells.
    • Transition Metals: Center of table; form colored compounds/multiple oxidation states.
  • Trends Summary:
    • Effective Nuclear Charge: Increases across a period, pulling electrons tighter.
    • Shielding: Increases down a group as more energy levels are added.
    • Atomic Radius: Decreases across a period; increases down a group. Largest at bottom-left.
    • Ionic Radius: Cations (++) are smaller than parent atoms; Anions (−-) are larger than parent atoms.
    • Ionization Energy (IE): Energy to remove an electron. Increases across a period; decreases down a group. Highest at top-right.
    • Electronegativity: Attraction for shared electrons. Increases across a period; decreases down a group. Fluorine is highest.
    • Metallic Character: Decreases across a period; increases down a group.

Stoichiometry and Chemical Equations

  • Law of Conservation of Mass: Total mass of reactants must equal total mass of products. Equations must be balanced by changing coefficients, never subscripts.
  • Reaction Types:
    1. Synthesis: A+B→ABA + B \rightarrow AB
    2. Decomposition: AB→A+BAB \rightarrow A + B
    3. Single Replacement: A+BC→AC+BA + BC \rightarrow AC + B
    4. Double Replacement: AB+CD→AD+CBAB + CD \rightarrow AD + CB
    5. Combustion: Hydrocarbon+O2→CO2+H2O\text{Hydrocarbon} + O_2 \rightarrow CO_2 + H_2O
  • The Mole Concept:
    • 1 mol=6.022×1023 particles1\,\text{mol} = 6.022 \times 10^{23}\,\text{particles} (Avogadro's Number).
    • Molar Mass: Mass in grams of 1 mole (e.g., H2O≈18 g/molH_2O \approx 18\,g/mol; CO2≈44 g/molCO_2 \approx 44\,g/mol).
  • Conversions:
    • Mass=Moles×Molar Mass\text{Mass} = \text{Moles} \times \text{Molar Mass}
    • Particles=Moles×6.022×1023\text{Particles} = \text{Moles} \times 6.022 \times 10^{23}
    • Mole Ratio: Determined by balanced equation coefficients (e.g., 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O means 2 mol H2:1 mol O2:2 mol H2O2\,mol\,H_2 : 1\,mol\,O_2 : 2\,mol\,H_2O).
  • Yields:
    • Limiting Reactant: The reagent exhausted first, capping product formation.
    • Percent Yield=Actual YieldTheoretical Yield×100%\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%.

Chemical Bonding and Molecular Geometry

  • Octet Rule: Atoms gain, lose, or share electrons to reach 8 valence electrons.
  • Bond Types:
    • Ionic: Transfer of electrons from metal to nonmetal. High melting points, brittle, conduct when dissolved.
    • Covalent: Sharing of electrons between nonmetals. Polar covalent bonds have unequal sharing (δ+\delta+ and δ−\delta-) due to electronegativity differences. Multiple bonds (triple > double > single) are stronger and shorter.
    • Metallic: Valence electrons are delocalized in a "sea," allowing conductivity and malleability.
  • Molecular Geometry (VSEPR Theory): Electron groups repel to maximize distance.
    • Linear: 2 groups, 180∘180^{\circ} (e.g., CO2CO_2).
    • Trigonal Planar: 3 groups, 120∘120^{\circ} (e.g., BF3BF_3).
    • Tetrahedral: 4 groups, 109.5∘109.5^{\circ} (e.g., CH4CH_4).
    • Trigonal Pyramidal: 3 bonds, 1 lone pair, 107∘107^{\circ} (e.g., NH3NH_3).
    • Bent: 2 bonds, 2 lone pairs, 104.5∘104.5^{\circ} (e.g., H2OH_2O).
  • Intermolecular Forces (IMF): Forces between molecules (weaker than bonds).
    • London Dispersion: Universal; temporary dipoles.
    • Dipole-Dipole: Between polar molecules.
    • Hydrogen Bonding: H bonded to N, O, or F; strongest dipole interaction.
    • Ion-Dipole: Ions interacting with polar molecules (solubility).

Internal Computer Hardware Identification

  • Motherboard: The main circuit board connecting all components; contains BIOS/UEFI firmware chips and the CMOS battery (which preserves clock settings).
  • CPU (Central Processing Unit): The processor executing instructions. Measured by clock speed (Hz) and cores. Requires thermal paste and a heat sink for cooling.
  • Memory:
    • RAM (Random Access Memory): Volatile, temporary working memory for active programs.
    • ROM (Read-Only Memory): Traditionally permanent instructions; allows the Power-On Self-Test (POST).
  • Storage:
    • HDD (Hard Disk Drive): Magnetic spinning disks; high capacity, slower, mechanical parts.
    • SSD (Solid-State Drive): Flash memory; no moving parts, faster, quieter. Form factors include 2.5-inch and M.2 (using SATA or NVMe protocols).
  • GPU (Graphics Processing Unit): Renders images/video. Can be integrated (sharing RAM) or dedicated (on a PCIe card with its own VRAM).
  • PSU (Power Supply Unit): Converts AC from the wall to DC for components. Measured in Watts.
  • Network Interface Card (NIC): Allows Ethernet (RJ-45) or wireless connection.

Computer Science Data Conversions

  • Units:
    • 1 byte=8 bits1\,\text{byte} = 8\,\text{bits}
    • 1 nibble=4 bits1\,\text{nibble} = 4\,\text{bits}
  • Binary Conversions (Standard School Use):
    • 1 KB=1,024 bytes1\,\text{KB} = 1,024\,\text{bytes}
    • 1 MB=1,024 KB1\,\text{MB} = 1,024\,\text{KB}
    • 1 GB=1,024 MB1\,\text{GB} = 1,024\,\text{MB}
    • 1 TB=1,024 GB1\,\text{TB} = 1,024\,\text{GB}
    • Note: Manufacturers often use decimal base (1,0001,000), while Operating Systems use binary (1,0241,024).
  • Data Rates: Mbps (megabits) is distinct from MBps (megabytes). To convert megabits per second to megabytes per second, divide by 8.

Earth Science: Crustal Deformation and Geology

  • Stress and Strain:
    • Compression: Squeezes rock (Convergent boundaries); leads to folding and reverse faults.
    • Tension: Pulls rock apart (Divergent boundaries); leads to rift valleys and normal faults.
    • Shear: Slides rock past each other (Transform boundaries); leads to strike-slip faults.
    • Deformation Types: Elastic (temporary), Ductile (bending/flowing), and Brittle (breaking/fracturing).
  • Geological Structures:
    • Folds: Anticline (upward arch, oldest rock in center) and Syncline (downward fold, youngest rock in center).
    • Faults:
      • Normal: Hanging wall moves down (Tension).
      • Reverse: Hanging wall moves up (Compression).
      • Thrust: Low-angle reverse fault.
      • Strike-Slip: Horizontal movement (e.g., Right-lateral or Left-lateral).
  • Mountain Building (Orogeny): Occurs through collisions (Andes-style subduction vs. Himalayan-style continental collision), volcanism, or faulting (Horsts are uplifted blocks, Grabens are dropped blocks). Isostasy describes the buoyancy balance of the crust.

Earth Science: Atmosphere and Weather

  • Humidity:
    • Absolute Humidity: Mass of vapor per volume.
    • Relative Humidity: actual vapor / maximum vapor capacity at that temperature. Increases if air cools even if vapor stays constant.
    • Dew Point: Temperature where air reaches saturation (100% RH100\%\,\text{RH}).
  • Adiabatic Process: Rising air expands due to lower pressure and cools (Adiabatic Cooling). Sinking air compresses and warms.
  • Lifting Mechanisms: Convectional (ground heat), Orographic (mountains—leads to rain shadows), Frontal (warmer air over colder air), and Convergence (flowing together).
  • Clouds:
    • Cirrus: High, wispy, ice crystals.
    • Cumulus: Puffy, cotton-like.
    • Stratus: Layered, sheet-like.
    • Nimbus: Precipitation-bearing (e.g., Cumulonimbus storm clouds).
  • Precipitation Processes: Collision-coalescence (warm clouds) and Bergeron/Ice-crystal process (cold clouds).
  • Forms of Water:
    • Sleet: Frozen ice pellets formed before hitting ground.
    • Freezing Rain: Supercooled liquid that freezes upon contact with a cold surface.
    • Hail: Produced by updrafts in thunderstorms.

Physics: Waves and Sound

  • Mechanical Waves: Require a medium (cannot travel in a vacuum). Transverse (perpendicular movement) and Longitudinal (parallel movement, e.g., sound).
  • Wave Properties:
    • Speed: v=fλv = f \lambda.
    • Frequency (ff): Cycles per second (Hertz).
    • Wavelength (λ\lambda): Distance between crests.
    • Amplitude: Max displacement; relates to sound loudness.
  • Sound: Travels fastest in solids, slowest in gases. Pitch depends on frequency. Doppler Effect is the pitch shift when a source moves relative to an observer (approaching = higher pitch).
  • Behaviors: Reflection (echo), Refraction (bending due to speed change), Diffraction (bending around obstacles), and Interference (Constructive vs. Destructive).

Physics: Light and Electrostatics

  • Nature of Light: Electromagnetic wave (travels through vacuum at c≈3.00×108 m/sc \approx 3.00 \times 10^8\,m/s). Exhibits wave-particle duality (photons).
  • Spectra: From radio (long wave) to gamma rays (short wave/high energy). Visible spectrum: Red (long) to Violet (short).
  • Optics:
    • Reflection: Angle of incidence equals angle of reflection (measured from the normal).
    • Refraction: Light bends toward the normal in slower media (higher index nn). n=c/vn = c/v.
    • Dispersion: Separation of white light (e.g., prism, rainbows).
    • Lenses/Mirrors: Convex lenses converge light (farsightedness/cameras). Concave lenses diverge (nearsightedness).
  • Electrostatics: Like charges repel; opposites attract.
    • Charging: Friction (rubbing), Conduction (contact), Induction (no contact, redistribution via grounding).
    • Coulomb’s Law: Force between charges is F=k∣q1q2∣r2F = \frac{k|q_1q_2|}{r^2}. Doubling distance reduces force to 1/41/4.
    • Electric Field (EE): Direction is defined by a positive test charge; lines point away from positive and toward negative.

Questions & Discussion

  • Biological Comparison: Why are lipids not true polymers? They are not composed of long chains of identical, repeating monomers like the other groups; they are typically discrete molecules of glycerol and fatty acids.
  • Chemistry Problem: Moles in 4 moles of Oxygen for water synthesis? In the equation 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O, the ratio is 1:21:2. Therefore, 4 mol of O24\,\text{mol of } O_2 produces 8 mol of H2O8\,\text{mol of } H_2O.
  • Computer Science Calculation: How many bits in 64 bytes? 64×8=512 bits64 \times 8 = 512\,\text{bits}.
  • Earth Science Identification: What is a rain shadow? It is the dry area on the leeward side of a mountain where air sinks and warms after losing moisture on the windward side.
  • Physics Logic: Why does frequency remain unchanged during refraction? Frequency is determined by the source. When light enters a new medium, its speed and wavelength change, but its oscillations per second remain constant.
  • Final Tip on Test Strategy: Pay attention to "NOT" or "EXCEPT" in questions. Use unit tracking in calculations to verify if multiplication or division was done correctly.