Essential Biology Concepts and Principles

Biology Study Summary:

Scientific Method and Measurement

• Hypothesis-driven science: Starts with a question or hypothesis. A hypothesis is a tentative, testable explanation or prediction based on observations. A theory has been repeatedly tested and consistently supported.
• Discovery science: Focuses on observations and data ("What do we observe?").
• The meniscus: The curved line on a graduated cylinder used to measure volume. Read from the bottom of the curve (e.g., 5 mL is just below the 5).

Chemistry of Life and Solutions

• pH: A measure of acidity or basicity in a solution.
• Acid: Has an increased concentration of H⁺ ions and decreased OH^- ions.
• Base: Has an increased concentration of OH^- ions and decreased H⁺ ions.
• Buffer: Resists a change in pH.
• Polarity: Molecules have both positive and negative charges.
• Water properties (five key traits):
  • Universal solvent
  • Adhesion (sticks to other substances)
  • Cohesion (sticks to itself; requires more energy to heat)
  • Density (water as a liquid is more dense than as a solid, so ice floats)
  • Polarity

Transport and Diffusion Mechanisms

• Diffusion: The movement of a substance from high concentration to low concentration. Smaller molecules diffuse faster and farther; larger molecules diffuse more slowly and travel a shorter distance.
• Osmosis: The movement of water across a semi-permeable membrane from high to low concentration.
• Plant cell environments:
  • Hypertonic: Salt water; not ideal, plant shrinks (plasmolysis).
  • Isotonic: Equal solute/solvent; not ideal, plant will wilt.
  • Hypotonic: Distilled water; ideal, plant grows upright (turgid).

Cell Biology and Biological Domains

• The three domains:
  • Bacteria: Prokaryotic, no nucleus, small, no membrane-bound organelles.
  • Archaea: Prokaryotic.
  • Eukarya: Eukaryotic, contains a nucleus, organelles, large.
• Eukaryotic cell types:
  • Animal cells: Visible plasma membrane and visible nucleus.
  • Plant cells: Visible cell wall, central vacuole, sometimes visible nucleus, and chloroplasts (green site of photosynthesis).
• Paramecium: A foot-shaped protozoan, which is a single-celled eukaryote.

Enzyme Function and Structure

• Characteristics: Mostly proteins that speed up chemical reactions; highly specific to usually one substrate; not consumed in chemical reactions and can be reused; names usually end in -ase (e.g., lactase, catalase).
• Function and structure: Enzyme function is directly related to its 3D structure, which is ultimately determined by DNA (DNA → RNA → Amino Acids → Enzymes).
• Denaturation: The unfolding of an enzyme's structure, causing it to lose function.

Cellular Respiration and Metabolism

• Chemical reaction: C₆H₁₂O₆ + O₂ → H₂O + CO₂ + ATP + Heat.
• Organisms: Animals, fungi, bacteria, and plants.
• Endotherms: Warm-blooded (e.g., mammals, birds); perform cell respiration continuously to maintain body temperature.
• Ectotherms: Cold-blooded (e.g., snakes, insects); perform cell respiration for ATP while relying on behavior and environment for temperature.
• Factors affecting metabolic rate: Environmental temperature, age, body size, and activity level.
• Lab notes: Padding the bottom of a respiration chamber absorbs CO₂ produced by the organism. Packed ice produces the highest metabolic rate because endotherms must increase cellular respiration to generate heat and maintain core body temperature, resulting in greater oxygen consumption.

Photosynthesis and Light Absorption

• Chemical reaction: CO₂ + H₂O + Sunlight → Glucose (Sugar) + O₂.
• Organisms: Plants, kelp, and cyanobacteria.
• Light absorption: Wavelengths of light primarily absorbed by plants are red and blue.
• Chloroplasts: Organelles where photosynthesis occurs, containing light-capturing pigments like chlorophyll.
• CO₂ uptake indicator lab: Carbon indicators change color based on pH (Orange = no photosynthesis/acidic baseline; Yellow = photosynthetic activity/acidic; Pink = basic).

Biotechnology and DNA Analysis

• Biotechnology: The manipulation of organisms to make useful products for humans.
• Pathogenic: Disease-causing.
• DNA structure: Double-stranded, made up of nucleotides, and negatively charged.
• DNA profiling and gel electrophoresis: Used to identify suspects, find missing persons, or determine parentage.
• Rule of movement: Smaller fragments travel faster and farther through the gel; larger fragments move more slowly and stay closer to the wells.
• Key terms:
  • STR: Short Tandem Repeats.
  • RFLP: Restriction Fragment Length Polymorphisms.
  • PCR: Polymerase Chain Reaction used to copy specific DNA sequences through denaturation, annealing, and extension.

Biodiversity and Organismal Biology

• Nutritional modes: Heterotrophic (must consume organic matter for energy) and Autotrophic/Phototrophs (obtain energy from photosynthesis).
• Microbial and fungal forms:
  • Colony: Population of many genetically identical bacteria.
  • Mushroom: Reproduces via spores produced in gills.
  • Unicellular vs. Multicellular: Single-celled vs. more than one cell type.
  • Bacteria shapes: Spheres (cocci), rods (bacilli), spiral/curved (spirilla).
  • Lichens: Symbiotic relationship between fungi and an algal/cyanobacterial layer.
  • True algae: Photosynthetic and eukaryotic.
  • Fungi: Includes molds and mushrooms with thread-like structures called filaments or hyphae (e.g., on bread mold).
  • Cyanobacteria: Blue-green algae like Nostoc.
• Plant reproduction and life cycles:
  • Gametophyte: A haploid (1n) organism that produces sexual gametes via mitosis.
  • Sporophyte: A diploid (2n) organism that produces spores via meiosis.
  • Haploid (1n): One set of chromosomes (sperm + egg).
  • Diploid (2n): Two sets of chromosomes.
• Challenges of transitioning to land: Desiccation (drying out), reproduction (needing water), gravity (structural support), and access to nutrients.
• Seed plants: Gymnosperms and Angiosperms do not require water for fertilization and produce seeds with a hard protective shell around the embryo. Angiosperms also feature flowers and fruits for protection and pollination.
• Plant vascular tissues: Xylem transports water and minerals (stained blue in labs) and Phloem transports sugars and products of photosynthesis.

Animal Classification and Characteristics

• Basis of classification: Includes fossils, anatomy, and DNA.
• Core animal characteristics: Multicellular, heterotrophic, eukaryotic, and progress from young to adult.
• Body plans:
  • Symmetry: Asymmetrical, radial, or bilateral.
  • Segmentation: Separation into parts.
  • Skeleton types: Exoskeleton for external protection and flexibility (e.g., arthropods) and endoskeleton for internal support (e.g., sharks and mammals).