Biology Study Guide: Core Concepts from Chapters 1-3, 11-14

Humans in the World of Biology

Common Characteristics of Life

Living organisms share several fundamental characteristics that distinguish them from non-living matter.

• Cellular Organization: All living things are composed of one or more cells.

• Metabolism: Organisms carry out chemical reactions to obtain and use energy.

• Homeostasis: The ability to maintain stable internal conditions.

• Growth and Development: Organisms increase in size and undergo changes over time.

• Reproduction: The ability to produce new individuals.

• Response to Stimuli: Organisms can react to environmental changes.

• Evolution: Populations change over generations through adaptation.

Biological Complexity: Levels of Organization

Biological systems are organized in a hierarchy from simple to complex.

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

The Scientific Method

The scientific method is a systematic approach to investigating natural phenomena.

• Observation: Gathering information about the world.

• Hypothesis: Formulating a testable explanation.

• Prediction: Making a logical statement about what will happen if the hypothesis is correct.

• Experiment: Testing the hypothesis under controlled conditions.

• Analysis: Interpreting data to draw conclusions.

• Conclusion: Accepting, rejecting, or modifying the hypothesis.

Example: If plants are given more sunlight, they will grow faster (hypothesis). Predict that plants exposed to 12 hours of light daily will be taller than those exposed to 6 hours.

Chemistry Comes to Life

Elements, Compounds, Isotopes, and Radioisotopes

• Element: A pure substance consisting of only one type of atom (e.g., Oxygen).

• Compound: A substance formed from two or more elements chemically bonded (e.g., H2O).

• Isotope: Atoms of the same element with different numbers of neutrons.

• Radioisotope: An unstable isotope that emits radiation as it decays.

Chemical Bonds

• Hydrogen Bond: Weak attraction between a hydrogen atom and another electronegative atom (e.g., water molecules).

• Ionic Bond: Formed when electrons are transferred from one atom to another, creating charged ions (e.g., NaCl).

• Covalent Bond: Formed when atoms share electrons (e.g., O2).

Structure and Properties of Water

• Polarity: Water is a polar molecule, with partial positive and negative charges.

• Hydrogen Bonding: Leads to cohesion, adhesion, and high specific heat.

• Solvent Properties: Water dissolves many substances, facilitating cellular reactions.

• Example: Water's polarity allows it to dissolve salts and sugars.

pH Scale and Buffers

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic).

• Formula: $\mathrm{pH} = -\log_{10}[\mathrm{H}^+]$

• Buffer: A substance that resists changes in pH by absorbing or releasing H+ ions.

Cellular Macromolecules

• Proteins: Made of amino acids; functions include enzymes, structure, transport.

• Carbohydrates: Made of simple sugars; energy storage and structural roles.

• Fats and Lipids: Made of glycerol and fatty acids; energy storage, membrane structure.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Condensation and Hydrolysis Reactions

• Condensation (Dehydration) Reaction: Joins monomers by removing water to form polymers.

• Hydrolysis: Breaks polymers into monomers by adding water.

Protein Structure

• Primary: Sequence of amino acids.

• Secondary: Alpha helices and beta sheets.

• Tertiary: 3D folding of the protein.

• Quaternary: Multiple polypeptide chains joined together.

DNA vs. RNA

• DNA: Double-stranded, contains deoxyribose, stores genetic information.

• RNA: Single-stranded, contains ribose, involved in protein synthesis.

The Cell

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic: No nucleus, simple structure, bacteria and archaea.

• Eukaryotic: Nucleus present, complex organelles, plants, animals, fungi, protists.

Cellular Constituents (Organelles)

• Nucleus: Contains genetic material.

• Mitochondria: Site of cellular respiration.

• Ribosomes: Protein synthesis.

• Endoplasmic Reticulum: Protein and lipid processing.

• Golgi Apparatus: Modifies and packages proteins.

• Lysosomes: Digestion of cellular waste.

• Plasma Membrane: Controls entry and exit of substances.

Plasma Membrane Structure and Function

• Phospholipid Bilayer: Hydrophilic heads and hydrophobic tails.

• Proteins: Transport, signaling, structural support.

• Carbohydrates: Cell recognition.

• Functions: Selective permeability, communication, protection.

Transport Across Membranes

• Simple Diffusion: Movement of molecules from high to low concentration.

• Facilitated Diffusion: Uses membrane proteins for transport.

• Active Transport: Requires energy to move substances against concentration gradient.

Osmosis and Tonicity

• Hypotonic: Lower solute concentration outside cell; water enters cell.

• Hypertonic: Higher solute concentration outside cell; water leaves cell.

• Isotonic: Equal solute concentration; no net water movement.

Endocytosis

• Endocytosis: Process by which cells engulf substances into a pouch which becomes a vesicle.

Cellular Respiration and Fermentation

• Cellular Respiration: Converts glucose to ATP via glycolysis, Krebs cycle, and oxidative phosphorylation.

• Fermentation: Anaerobic process producing lactic acid or ethanol.

Energy Pathways

• Glycolysis: Occurs in cytoplasm; produces 2 ATP, 2 NADH, 2 pyruvate.

• Krebs Cycle: Occurs in mitochondria; produces 2 ATP, 6 NADH, 2 FADH2, 4 CO2.

• Oxidative Phosphorylation: Produces up to 34 ATP.

Fermentation and Lactic Acid Production

• Role: Allows ATP production without oxygen; produces lactic acid in muscle cells.

Blood and the Cardiovascular System

Composition of Blood

• Plasma: Liquid component, contains water, proteins, nutrients, hormones.

• Formed Elements: Red blood cells, white blood cells, platelets.

Formed Elements and Functions

• Red Blood Cells (Erythrocytes): Transport oxygen via hemoglobin.

• White Blood Cells (Leukocytes): Immune defense.

• Platelets: Blood clotting.

Immune System Cells

• Lymphocytes: B and T cells; adaptive immunity.

• Neutrophils, Monocytes: Innate defense.

Red Blood Cells and Hemoglobin

• Hemoglobin: Protein that binds oxygen.

• Function: Transports O2 from lungs to tissues.

Red Blood Cell Life Cycle

• Production: In bone marrow.

• Lifespan: ~120 days.

• Destruction: In spleen and liver.

Anemia

• Definition: Reduced oxygen-carrying capacity.

• Effects: Fatigue, weakness.

• Treatment: Iron supplements, blood transfusions.

Leukemia and Infectious Mononucleosis

• Leukemia: Cancer of white blood cells.

• Infectious Mononucleosis: Viral infection affecting lymphocytes.

Blood Types

• Types: A, B, AB, O; determined by antigens on RBCs.

• Identification: Blood typing tests.

Blood Clotting Overview

• Platelets: Initiate clotting.

• Clotting Factors: Cascade leads to fibrin formation.

Cardiovascular and Lymphatic Systems

Arteries vs. Veins

• Arteries: Thick walls, carry blood away from heart, high pressure.

• Veins: Thin walls, carry blood to heart, low pressure, valves present.

Artery, Arteriole, Capillary Structure and Function

• Artery: Large, muscular, high-pressure transport.

• Arteriole: Smaller, regulate blood flow.

• Capillary: Thin, exchange of gases and nutrients.

Blood Movement in Capillary Beds

• Exchange: O2 and CO2 diffuse across capillary walls.

Venous Return

• Mechanisms: Valves, muscle contractions, low pressure.

Heart Structure and Function

• Components: Atria, ventricles, valves, septum.

• Function: Pumps blood through pulmonary and systemic circuits.

Blood Flow Around the Body

• Path: Heart → arteries → capillaries → veins → heart.

Cardiac Cycle

• Systole: Contraction phase.

• Diastole: Relaxation phase.

Blood Pressure and Health

• Normal: 120/80 mmHg.

• High Blood Pressure: Risk for heart disease.

Lymphatic System Functions

• Fluid Balance: Returns excess fluid to blood.

• Immune Defense: Houses immune cells.

• Absorption: Absorbs fats from digestive tract.

Body Defense Mechanisms

Pathogens and Immunity

• Pathogen: Disease-causing organism (virus, bacteria, fungi).

• Impact: Can cause illness or death.

Active vs. Passive Immunity

• Active: Body produces its own antibodies (infection or vaccination).

• Passive: Antibodies are transferred from another source (mother to child).

Immune System Divisions

• Innate Defense: Physical barriers (skin), chemical barriers (stomach acid).

• Defensive Cells: Phagocytes, inflammation, fever.

• Adaptive Immune Response: Specific, memory-based defense (B and T cells).

Non-Specific vs. Specific Immunity

• Non-Specific: General defense mechanisms.

• Specific: Targeted response to particular pathogens.

Adaptive Immune Response Steps

• Antigen Recognition → Activation → Clonal Selection → Memory Formation

Immunity: Antigens, Antibodies, Vaccines

• Antigen: Foreign substance triggering immune response.

• Antibody: Protein that binds antigens.

• Vaccine: Stimulates active immunity.

Clonal Selection and Memory

• Clonal Selection: Activation and proliferation of specific lymphocytes.

• Memory: Enables faster response upon re-exposure.

B Cell vs. T Cell Response

• B Cells: Produce antibodies.

• T Cells: Directly attack infected cells.

Cytotoxic vs. Helper T Cells

• Cytotoxic: Destroy infected cells.

• Helper: Activate other immune cells.

Autoimmune Disorders

• Impact: Immune system attacks body's own cells.

Allergic Reactions

• Basis: Immune response to harmless substances.

The Respiratory System

Respiratory System Structures

• Upper: Sinuses, pharynx, larynx.

• Lower: Trachea, bronchi, lungs.

Path of Air

• Air enters via nose/mouth → pharynx → larynx → trachea → bronchi → lungs.

Functions of Respiratory Components

• Sinuses: Warm and moisten air.

• Pharynx: Passage for air and food.

• Trachea: Conducts air to lungs.

• Lungs: Gas exchange.

Inhalation and Exhalation

• Inhalation: Diaphragm contracts, air enters lungs.

• Exhalation: Diaphragm relaxes, air exits lungs.

Oxygen and Carbon Dioxide Transport

• O2: Bound to hemoglobin in RBCs.

• CO2: Dissolved in plasma, bound to hemoglobin, or as bicarbonate.

Brain Regulation of Breathing

• Medulla Oblongata: Controls rate and depth of breathing.

Diaphragm and Intercostal Muscles

• Diaphragm: Main muscle for ventilation.

• Intercostal Muscles: Assist in expanding and contracting thoracic cavity.

Oxygen Binding Proteins

• Hemoglobin: Found in blood, transports O2.

• Myoglobin: Found in muscle, stores O2.

Respiratory Disorders

• Common Cold: Viral infection.

• Flu: Influenza virus.

• Bronchitis: Inflammation of bronchi.

Smoking and Lung Disease

• Effects: Damages lung tissue, increases risk of cancer and COPD.