Unit 1 Hydrogen bond Tap / Space to flip
Unit 1 Weak attraction between δ⁺ H of one polar molecule and a δ⁻ atom (usually O, N, F) of another. Underlies water properties and DNA base pairing.
Interactive Deck
184 flashcards.
Filter by unit or priority topic. Tap or hit Space to flip. Arrow keys to navigate. Press K to mark known — your progress saves to this device. Drill a few minutes a day; cram the rest the night before.
— / —
Unit 1 Cohesion vs. adhesion Tap / Space to flip
Unit 1 Cohesion = water-to-water; adhesion = water-to-other-substance. Together drive transpiration in xylem.
Unit 1 Dehydration synthesis Tap / Space to flip
Unit 1 Joins two monomers into a polymer; releases one H₂O molecule.
Unit 1 Hydrolysis Tap / Space to flip
Unit 1 Breaks a polymer using H₂O — reverse of dehydration synthesis.
Unit 1 Saturated fat Tap / Space to flip
Unit 1 No C=C double bonds; fatty-acid tails pack tightly; solid at room temperature.
Unit 1 Phospholipid bilayer Tap / Space to flip
Unit 1 Amphipathic phospholipids self-assemble with hydrophilic heads facing water and hydrophobic tails facing inward.
Unit 1 Primary structure (1°) Tap / Space to flip
Unit 1 Linear amino-acid sequence held together by peptide bonds. Determines all higher levels of folding.
Unit 1 Tertiary structure (3°) Tap / Space to flip
Unit 1 3-D fold from R-group interactions: H-bonds, ionic, hydrophobic, and disulfide bridges.
Unit 1 Antiparallel Tap / Space to flip
Unit 1 The two DNA strands run in opposite 5′→3′ directions, allowing complementary base pairing and replication directionality.
Unit 1 Nucleotide Tap / Space to flip
Unit 1 Pentose sugar + phosphate group + nitrogenous base — the monomer of DNA and RNA.
Unit 1 CHNOPS Tap / Space to flip
Unit 1 The six elements that make up most biomolecules: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur.
Unit 1 Peptide bond Tap / Space to flip
Unit 1 Covalent bond between the carboxyl of one amino acid and the amine of the next. Forms via dehydration synthesis.
Unit 1 Phosphodiester bond Tap / Space to flip
Unit 1 Links nucleotides through the sugar-phosphate backbone of DNA and RNA.
Unit 1 R-group Tap / Space to flip
Unit 1 The variable side chain on an amino acid that determines its chemical properties (polar, nonpolar, acidic, basic).
Unit 1 Denaturation Tap / Space to flip
Unit 1 Loss of higher-order protein structure due to heat, pH, or other disruptors. The active site is destroyed; primary sequence remains.
Unit 2 Endosymbiotic theory Tap / Space to flip
Unit 2 Mitochondria & chloroplasts evolved from once-free-living prokaryotes. Evidence: own circular DNA, 70S ribosomes, double membrane, binary fission.
Unit 2 Fluid mosaic model Tap / Space to flip
Unit 2 The plasma membrane is a fluid bilayer of phospholipids studded with proteins, cholesterol, and glycolipids/glycoproteins.
Unit 2 Aquaporin Tap / Space to flip
Unit 2 Channel protein that selectively conducts water across the membrane.
Unit 2 Hypotonic solution Tap / Space to flip
Unit 2 Lower solute outside the cell — water enters. Animal cells lyse; plant cells become turgid.
Unit 2 Hypertonic solution Tap / Space to flip
Unit 2 Higher solute outside the cell — water leaves. Animal cells crenate; plant cells plasmolyze.
Unit 2 Cell wall (plants) Tap / Space to flip
Unit 2 Rigid cellulose layer outside the membrane; provides structural support and limits over-expansion under turgor.
Unit 2 Cristae Tap / Space to flip
Unit 2 Folded inner mitochondrial membrane. Increases surface area for the electron transport chain & ATP synthase.
Unit 2 Tight junction Tap / Space to flip
Unit 2 Animal cell-cell junction that seals the space between cells, preventing leakage of extracellular fluid.
Unit 2 Plasmodesmata Tap / Space to flip
Unit 2 Cytoplasmic channels through plant cell walls allowing transport between adjacent plant cells.
Unit 2 Selectively permeable Tap / Space to flip
Unit 2 A membrane that lets some substances cross while excluding others — the basis of cellular homeostasis.
Unit 2 SA:V ratio Tap / Space to flip
Unit 2 Surface-area-to-volume ratio decreases as cells grow, limiting exchange. Foldings (microvilli, cristae, thylakoids) restore SA.
Unit 2 Rough ER Tap / Space to flip
Unit 2 ER studded with ribosomes; site of synthesis for membrane and secreted proteins.
Unit 2 Smooth ER Tap / Space to flip
Unit 2 ER without ribosomes; lipid synthesis, detoxification, Ca²⁺ storage.
Unit 2 Golgi apparatus Tap / Space to flip
Unit 2 Modifies, sorts, and packages proteins received from the ER into vesicles.
Unit 2 Lysosome Tap / Space to flip
Unit 2 Membrane-bound organelle filled with hydrolytic enzymes (low pH) that digest macromolecules and old organelles.
Unit 2 Active transport Tap / Space to flip
Unit 2 Movement of solutes against their concentration gradient. Requires ATP (e.g., Na⁺/K⁺ pump).
Unit 3 Activation energy (Ea) Tap / Space to flip
Unit 3 Energy needed to start a reaction. Enzymes lower Ea by stabilizing the transition state.
Unit 3 Competitive inhibitor Tap / Space to flip
Unit 3 Binds the active site and competes with substrate. Effect can be reversed by adding more substrate.
Unit 3 Noncompetitive (allosteric) inhibitor Tap / Space to flip
Unit 3 Binds an allosteric site, changing the active site's shape. Cannot be reversed by adding more substrate.
Unit 3 ATP Tap / Space to flip
Unit 3 Adenosine triphosphate — the cell's energy currency. Hydrolysis of the terminal phosphate releases usable energy.
Unit 3 Chemiosmosis Tap / Space to flip
Unit 3 ATP synthesis powered by H⁺ flowing down its gradient through ATP synthase.
Unit 3 Photosystem II Tap / Space to flip
Unit 3 Splits water (releasing O₂), captures light energy, and feeds excited electrons into the thylakoid ETC.
Unit 3 Calvin cycle Tap / Space to flip
Unit 3 Light-independent reactions in the stroma; uses ATP & NADPH to fix CO₂ onto RuBP, producing G3P.
Unit 3 RuBisCO Tap / Space to flip
Unit 3 Enzyme that fixes CO₂ to RuBP in the Calvin cycle — the most abundant protein on Earth.
Unit 3 Fermentation Tap / Space to flip
Unit 3 Anaerobic regeneration of NAD⁺ so glycolysis can continue. Net 2 ATP per glucose.
Unit 3 Endergonic reaction Tap / Space to flip
Unit 3 Reaction with positive ΔG; requires energy input. Often coupled to ATP hydrolysis.
Unit 3 ΔG Tap / Space to flip
Unit 3 Change in free energy. ΔG < 0 = spontaneous (exergonic). ΔG > 0 = non-spontaneous (endergonic).
Unit 3 Coupled reactions Tap / Space to flip
Unit 3 Use the energy released by an exergonic reaction (e.g., ATP hydrolysis) to drive an endergonic one.
Unit 3 Feedback inhibition Tap / Space to flip
Unit 3 End product allosterically inhibits an early enzyme in its own pathway (e.g., ATP inhibits phosphofructokinase).
water-potential Water potential (Ψ) Tap / Space to flip
water-potential Free energy of water in a system. Predicts the direction of water flow: high Ψ → low Ψ. Ψ of pure water at 1 atm = 0.
water-potential Ψ = Ψp + Ψs Tap / Space to flip
water-potential Total water potential = pressure potential + solute potential. Both can be positive, negative, or zero.
water-potential Ψs = −iCRT Tap / Space to flip
water-potential Solute potential. i = ionization constant; C = molarity (mol/L); R = 0.0831 L·bar/(mol·K); T = Kelvin (°C + 273).
water-potential Ionization constant (i) Tap / Space to flip
water-potential 1.0 for non-ionizing solutes (sucrose, glucose); 2.0 for NaCl; 3.0 for CaCl₂. Counts dissociated particles.
water-potential R (in water-potential) Tap / Space to flip
water-potential 0.0831 L·bar / (mol·K). The pressure constant on the AP formula sheet.
water-potential Ψ of pure water Tap / Space to flip
water-potential 0 bars at 1 atm. Adding solute always lowers Ψ (Ψs becomes negative).
water-potential Turgid plant cell Tap / Space to flip
water-potential Cell in hypotonic solution: water enters, cell wall pushes back. Ψp > 0.
water-potential Flaccid plant cell Tap / Space to flip
water-potential Cell in isotonic solution: no net water flow. Ψp ≈ 0.
water-potential Plasmolysis Tap / Space to flip
water-potential Plant cell in hypertonic solution: membrane pulls away from the wall as water leaves. Ψp drops to 0 or negative.
water-potential Water flow direction Tap / Space to flip
water-potential Always from higher (less negative) Ψ to lower (more negative) Ψ. Memorize: water flows "down" the Ψ gradient.
cellular-respiration Glycolysis Tap / Space to flip
cellular-respiration Glucose (6C) → 2 pyruvate (3C). Net 2 ATP + 2 NADH per glucose. Cytoplasm. No O₂ required.
cellular-respiration Pyruvate oxidation Tap / Space to flip
cellular-respiration Pyruvate → acetyl-CoA + CO₂ + NADH (×2 per glucose). Mitochondrial matrix.
cellular-respiration Krebs / citric-acid cycle Tap / Space to flip
cellular-respiration Per acetyl-CoA: 3 NADH, 1 FADH₂, 1 ATP, 2 CO₂. ×2 per glucose. Mitochondrial matrix.
cellular-respiration Electron transport chain Tap / Space to flip
cellular-respiration NADH/FADH₂ donate electrons to complexes I/II→III→IV. Energy pumps H⁺ from matrix to intermembrane space. O₂ is final acceptor → H₂O.
cellular-respiration Substrate-level phosphorylation Tap / Space to flip
cellular-respiration Direct enzymatic transfer of phosphate to ADP. Occurs in glycolysis (×4 gross) and Krebs (×2).
cellular-respiration Oxidative phosphorylation Tap / Space to flip
cellular-respiration ATP synthesis via the electron transport chain plus chemiosmosis. Yields ~28 ATP per glucose.
cellular-respiration NAD⁺ / NADH Tap / Space to flip
cellular-respiration Electron carrier. Reduced form (NADH) carries 2 e⁻ to the ETC. ~2.5 ATP per NADH.
cellular-respiration FAD / FADH₂ Tap / Space to flip
cellular-respiration Electron carrier. Enters ETC at complex II, bypassing one proton-pumping site → ~1.5 ATP per FADH₂.
cellular-respiration Final electron acceptor (aerobic) Tap / Space to flip
cellular-respiration O₂ — without it, the ETC backs up, NAD⁺ regeneration fails, and oxidative phosphorylation halts.
cellular-respiration Total ATP per glucose Tap / Space to flip
cellular-respiration ~30–32 ATP (modern estimate) split as: 4 substrate-level + ~28 oxidative phosphorylation.
Unit 4 Ligand Tap / Space to flip
Unit 4 A signal molecule (often hormone or neurotransmitter) that binds to a specific receptor.
Unit 4 Second messenger Tap / Space to flip
Unit 4 Small intracellular molecule (e.g., cAMP, IP₃, Ca²⁺) that propagates and amplifies a signal.
Unit 4 Signal transduction Tap / Space to flip
Unit 4 Series of molecular changes (often a phosphorylation cascade) that converts a signal into a cellular response.
Unit 4 Apoptosis Tap / Space to flip
Unit 4 Programmed cell death — cell shrinks, fragments, and is engulfed without inflammation.
Unit 4 Cell cycle checkpoint Tap / Space to flip
Unit 4 Control point (G1, G2, M) where the cell verifies conditions before proceeding. G1 is the most important.
Unit 4 Cyclin Tap / Space to flip
Unit 4 Regulatory protein whose levels oscillate during the cell cycle; activates Cdks to drive progression.
Unit 4 Proto-oncogene Tap / Space to flip
Unit 4 Normal gene that promotes growth. A gain-of-function mutation converts it to an oncogene → uncontrolled division.
Unit 4 p53 (tumor suppressor) Tap / Space to flip
Unit 4 Halts the cell cycle at G1 in response to DNA damage and triggers apoptosis. Loss-of-function mutations are seen in many cancers.
Unit 4 Negative feedback Tap / Space to flip
Unit 4 Output of a system reduces further output, returning conditions to a set point (e.g., insulin lowering blood glucose).
Unit 4 Quorum sensing Tap / Space to flip
Unit 4 Bacteria gauge their local density via secreted signal molecules; coordinated behavior turns on at threshold.
Unit 4 G-protein-coupled receptor (GPCR) Tap / Space to flip
Unit 4 Seven-transmembrane receptor that activates an associated G-protein on ligand binding. Most common receptor type.
Unit 4 Receptor tyrosine kinase (RTK) Tap / Space to flip
Unit 4 Receptor that dimerizes and autophosphorylates tyrosines on ligand binding, recruiting downstream signaling proteins.
Unit 4 Mitosis (PMAT) Tap / Space to flip
Unit 4 Prophase → Metaphase → Anaphase → Telophase. Produces two genetically identical diploid daughter cells.
Unit 4 Cancer (mechanism) Tap / Space to flip
Unit 4 Loss of cell-cycle control from mutations in proto-oncogenes (gain) or tumor suppressors (loss).
Unit 5 Genotype vs. phenotype Tap / Space to flip
Unit 5 Genotype = genetic makeup; phenotype = observable trait. Phenotype is genotype + environment.
Unit 5 Homozygous Tap / Space to flip
Unit 5 Two identical alleles for a given gene (e.g., AA or aa).
Unit 5 Heterozygous Tap / Space to flip
Unit 5 Two different alleles for a given gene (e.g., Aa).
Unit 5 Test cross Tap / Space to flip
Unit 5 Cross with a homozygous recessive individual to determine an unknown genotype.
Unit 5 Codominance Tap / Space to flip
Unit 5 Both alleles are fully expressed in the heterozygote (e.g., AB blood type).
Unit 5 Incomplete dominance Tap / Space to flip
Unit 5 Heterozygote shows an intermediate phenotype between the two homozygotes (e.g., RR × WW → Rr pink).
Unit 5 Sex-linked Tap / Space to flip
Unit 5 Gene located on a sex chromosome (almost always X). X-linked recessive traits affect more males.
Unit 5 Linked genes Tap / Space to flip
Unit 5 Genes on the same chromosome that tend to inherit together. RF measures their map distance.
Unit 5 Recombination frequency (RF) Tap / Space to flip
Unit 5 % recombinant offspring. ≤ 50%. 1% RF ≈ 1 map unit (centimorgan).
Unit 5 Pleiotropy Tap / Space to flip
Unit 5 A single gene affects multiple, seemingly unrelated traits (e.g., sickle-cell allele).
Unit 5 Epistasis Tap / Space to flip
Unit 5 One gene's expression masks or modifies another's (e.g., coat color in Labradors).
Unit 5 Polygenic inheritance Tap / Space to flip
Unit 5 Many genes contribute additively to one continuous trait (e.g., height, skin color).
Unit 5 Allele Tap / Space to flip
Unit 5 A variant form of a gene. Different alleles can produce different phenotypes.
Unit 5 Chi-square (χ²) Tap / Space to flip
Unit 5 χ² = Σ (O−E)²/E. Compare to critical value at df = (categories − 1), p = 0.05. Accept H₀ if χ² < critical.
meiosis Homologous chromosomes Tap / Space to flip
meiosis Pair carrying the same genes (one from each parent); same length, centromere position, and gene loci.
meiosis Sister chromatids Tap / Space to flip
meiosis Identical copies of a chromosome joined at the centromere after S-phase replication.
meiosis Tetrad / bivalent Tap / Space to flip
meiosis Paired homologs (4 chromatids total) formed during synapsis in Prophase I.
meiosis Synapsis Tap / Space to flip
meiosis Pairing of homologous chromosomes in Prophase I; required for crossing over.
meiosis Crossing over Tap / Space to flip
meiosis Reciprocal exchange of DNA segments between non-sister chromatids of homologs (Prophase I, at chiasmata).
meiosis Chiasma Tap / Space to flip
meiosis Visible site where crossing over has occurred between non-sister chromatids.
meiosis Independent assortment Tap / Space to flip
meiosis Random orientation of each homologous pair at Metaphase I → 2ⁿ combinations of chromosomes (2²³ in humans).
meiosis Nondisjunction Tap / Space to flip
meiosis Failure of homologs (Meiosis I) or sister chromatids (Meiosis II) to separate properly. Produces aneuploid gametes.
meiosis Aneuploidy Tap / Space to flip
meiosis Abnormal chromosome number from nondisjunction (e.g., trisomy 21 → Down syndrome).
meiosis Reductional vs. equational Tap / Space to flip
meiosis Meiosis I halves the chromosome number (reductional). Meiosis II separates sister chromatids (equational, like mitosis).
Unit 6 Transcription Tap / Space to flip
Unit 6 DNA → mRNA, performed by RNA polymerase. Occurs in the nucleus (eukaryotes) or cytoplasm (prokaryotes).
Unit 6 Translation Tap / Space to flip
Unit 6 mRNA → protein, performed by the ribosome in the cytoplasm (or rough ER for membrane/secreted proteins).
Unit 6 Codon Tap / Space to flip
Unit 6 A 3-nucleotide unit on mRNA that specifies one amino acid (or start/stop signal).
Unit 6 Anticodon Tap / Space to flip
Unit 6 A 3-nucleotide sequence on tRNA complementary and antiparallel to its mRNA codon.
Unit 6 Promoter Tap / Space to flip
Unit 6 DNA region where RNA polymerase binds to start transcription (eukaryotes contain a TATA box).
Unit 6 Operon Tap / Space to flip
Unit 6 Cluster of co-regulated prokaryotic genes sharing a promoter and operator. Includes structural genes downstream.
Unit 6 Inducible operon (lac) Tap / Space to flip
Unit 6 Off by default; an inducer (e.g., allolactose) inactivates the repressor → genes on. Used for catabolic pathways.
Unit 6 Repressible operon (trp) Tap / Space to flip
Unit 6 On by default; a corepressor (e.g., tryptophan) activates the repressor → genes off. Used for anabolic pathways.
Unit 6 Intron / exon Tap / Space to flip
Unit 6 Introns = non-coding sequences removed during splicing. Exons = expressed sequences retained in mature mRNA.
Unit 6 Alternative splicing Tap / Space to flip
Unit 6 Different combinations of exons produce multiple mature mRNAs and proteins from a single gene.
Unit 6 PCR Tap / Space to flip
Unit 6 Polymerase chain reaction. Cycles of denature → anneal → extend (Taq polymerase) amplify a specific DNA fragment exponentially.
Unit 6 Restriction enzyme Tap / Space to flip
Unit 6 Endonuclease that cuts DNA at a specific recognition sequence (e.g., EcoRI at GAATTC).
Unit 6 Silent mutation Tap / Space to flip
Unit 6 Point mutation that produces the same amino acid (due to redundancy of the genetic code). No protein effect.
Unit 6 Missense mutation Tap / Space to flip
Unit 6 Point mutation changing one amino acid. Effect ranges from neutral to severe.
Unit 6 Nonsense mutation Tap / Space to flip
Unit 6 Point mutation creating a premature stop codon — usually produces a truncated, nonfunctional protein.
Unit 6 Frameshift mutation Tap / Space to flip
Unit 6 Insertion or deletion of bases that is not a multiple of 3, shifting the reading frame for all downstream codons.
Unit 6 Transcription factor Tap / Space to flip
Unit 6 Protein that binds DNA (often at enhancers/promoters) to regulate transcription.
Unit 6 DNA methylation Tap / Space to flip
Unit 6 Addition of methyl groups (often to cytosine in CpG islands). Generally silences gene expression.
Unit 6 Histone acetylation Tap / Space to flip
Unit 6 Adds acetyl groups to histone tails, loosening chromatin (euchromatin) and activating transcription.
dna-rna-replication Semi-conservative replication Tap / Space to flip
dna-rna-replication Each daughter DNA molecule has one old (parent) strand + one newly synthesized strand. Demonstrated by Meselson-Stahl (1958).
dna-rna-replication Helicase Tap / Space to flip
dna-rna-replication Unwinds and separates the DNA double helix at the replication fork.
dna-rna-replication Topoisomerase Tap / Space to flip
dna-rna-replication Relieves supercoiling ahead of the fork by transiently cutting and rejoining DNA.
dna-rna-replication Single-strand binding proteins (SSBs) Tap / Space to flip
dna-rna-replication Bind separated DNA strands to keep them apart and prevent re-annealing during replication.
dna-rna-replication Primase Tap / Space to flip
dna-rna-replication Synthesizes a short RNA primer that DNA polymerase III uses to start synthesis.
dna-rna-replication DNA polymerase III Tap / Space to flip
dna-rna-replication Main replicative polymerase in prokaryotes. Extends RNA primers 5′→3′. Has 3′→5′ proofreading.
dna-rna-replication DNA polymerase I Tap / Space to flip
dna-rna-replication Removes the RNA primer and replaces it with DNA in prokaryotes.
dna-rna-replication DNA ligase Tap / Space to flip
dna-rna-replication Seals the nicks between Okazaki fragments on the lagging strand by forming phosphodiester bonds.
dna-rna-replication Okazaki fragments Tap / Space to flip
dna-rna-replication Short DNA pieces synthesized discontinuously on the lagging strand, each with its own RNA primer.
dna-rna-replication Leading strand Tap / Space to flip
dna-rna-replication Synthesized continuously toward the replication fork in the 5′→3′ direction.
dna-rna-replication Lagging strand Tap / Space to flip
dna-rna-replication Synthesized discontinuously away from the replication fork as Okazaki fragments.
dna-rna-replication Telomerase Tap / Space to flip
dna-rna-replication Reverse-transcriptase enzyme that extends telomere repeats. Active in germline and stem cells; mostly off in somatic cells.
dna-rna-replication 5′ cap Tap / Space to flip
dna-rna-replication Modified guanine added to the 5′ end of pre-mRNA. Protects from degradation and aids ribosome binding.
dna-rna-replication Poly-A tail Tap / Space to flip
dna-rna-replication ~50–250 adenines added to the 3′ end of pre-mRNA. Stabilizes mRNA and assists nuclear export.
dna-rna-replication Spliceosome Tap / Space to flip
dna-rna-replication snRNP complex that catalyzes removal of introns and joining of exons in pre-mRNA processing.
dna-rna-replication Start codon Tap / Space to flip
dna-rna-replication AUG — codes for methionine and signals the start of translation.
dna-rna-replication Stop codons Tap / Space to flip
dna-rna-replication UAA, UAG, UGA — recruit release factor; do not encode an amino acid.
dna-rna-replication A / P / E sites Tap / Space to flip
dna-rna-replication Aminoacyl (incoming tRNA) → Peptidyl (growing polypeptide) → Exit (deacylated tRNA leaves) on the ribosome.
dna-rna-replication Ribozyme Tap / Space to flip
dna-rna-replication Catalytic RNA. The rRNA in the large ribosomal subunit catalyzes peptide bond formation.
Unit 7 Natural selection Tap / Space to flip
Unit 7 Differential survival and reproduction based on heritable variation. Drives adaptation.
Unit 7 Fitness Tap / Space to flip
Unit 7 Relative reproductive success — the number of offspring that themselves reproduce.
Unit 7 Genetic drift Tap / Space to flip
Unit 7 Random change in allele frequencies due to chance. Strongest in small populations.
Unit 7 Bottleneck effect Tap / Space to flip
Unit 7 Drastic population reduction reduces genetic diversity by chance (e.g., overhunted cheetahs).
Unit 7 Founder effect Tap / Space to flip
Unit 7 A small group colonizes a new area, carrying only a subset of the original gene pool.
Unit 7 Hardy-Weinberg Tap / Space to flip
Unit 7 Null model of no evolution. p² + 2pq + q² = 1 holds when 5 conditions are met (no mutation/migration/drift/selection, random mating).
Unit 7 Directional selection Tap / Space to flip
Unit 7 Favors one phenotypic extreme; shifts the population mean (e.g., antibiotic resistance).
Unit 7 Stabilizing selection Tap / Space to flip
Unit 7 Favors intermediate phenotypes; reduces variance (e.g., human birth weight).
Unit 7 Disruptive selection Tap / Space to flip
Unit 7 Favors both extremes against the mean; can promote speciation.
Unit 7 Allopatric speciation Tap / Space to flip
Unit 7 New species forms when a geographic barrier isolates populations.
Unit 7 Sympatric speciation Tap / Space to flip
Unit 7 New species forms in the same area without geographic isolation — often via polyploidy in plants.
Unit 7 Homologous structures Tap / Space to flip
Unit 7 Similar structures inherited from a common ancestor (different functions). Evidence of common ancestry.
Unit 7 Analogous structures Tap / Space to flip
Unit 7 Similar function but different ancestry — convergent evolution.
Unit 7 Cladogram Tap / Space to flip
Unit 7 Branching diagram of evolutionary relationships based on shared derived characters.
Unit 7 Gene flow Tap / Space to flip
Unit 7 Movement of alleles between populations via migration. Reduces between-population differences.
Unit 7 Prezygotic isolation Tap / Space to flip
Unit 7 Reproductive barrier acting before fertilization — habitat, temporal, behavioral, mechanical, gametic.
Unit 7 Postzygotic isolation Tap / Space to flip
Unit 7 Reproductive barrier acting after fertilization — reduced hybrid viability or fertility (e.g., mules).
Unit 7 Mutation Tap / Space to flip
Unit 7 Heritable change in DNA sequence. The ultimate source of new alleles, and therefore of all variation.
Unit 7 RNA world hypothesis Tap / Space to flip
Unit 7 Self-replicating RNA preceded DNA-based life. Supported by ribozymes and tRNA-amino acid linkages.
Unit 8 Carrying capacity (K) Tap / Space to flip
Unit 8 Maximum population size the environment can sustain given resources, predation, and disease.
Unit 8 Logistic growth Tap / Space to flip
Unit 8 Population growth that slows as N approaches K. S-shaped curve. dN/dt = rN[(K−N)/K].
Unit 8 Exponential growth Tap / Space to flip
Unit 8 Unconstrained growth: dN/dt = rN. J-shaped curve, only sustainable in unlimited resource environments.
Unit 8 Keystone species Tap / Space to flip
Unit 8 Species whose impact on its community is disproportionately large relative to its biomass (e.g., sea otters).
Unit 8 Niche Tap / Space to flip
Unit 8 The sum of an organism's use of biotic and abiotic resources — its role in the community.
Unit 8 Mutualism (+/+) Tap / Space to flip
Unit 8 Symbiosis where both species benefit (e.g., mycorrhizae and plant roots).
Unit 8 Commensalism (+/0) Tap / Space to flip
Unit 8 Symbiosis where one species benefits and the other is unaffected.
Unit 8 Trophic level Tap / Space to flip
Unit 8 Position in a food chain — producer, primary consumer, secondary, tertiary. Energy flows up the levels.
Unit 8 10% rule Tap / Space to flip
Unit 8 Only ~10% of the energy at one trophic level is incorporated into the next; the rest is lost as heat.
Unit 8 Primary succession Tap / Space to flip
Unit 8 Community development on bare rock (no soil). Pioneer species like lichens initiate soil formation.
Unit 8 Secondary succession Tap / Space to flip
Unit 8 Community recovery after disturbance where soil remains intact (e.g., after fire).
Unit 8 Eutrophication Tap / Space to flip
Unit 8 Nutrient overload (often N, P from runoff) → algal bloom → bacterial decomposition → O₂ depletion → fish kill.
Unit 8 GPP vs. NPP Tap / Space to flip
Unit 8 Gross primary productivity = total photosynthesis. Net primary productivity = GPP − producer respiration.
Unit 8 Biomagnification Tap / Space to flip
Unit 8 Persistent toxin (e.g., DDT, mercury) increases in concentration up the food chain.
Unit 8 Kin selection Tap / Space to flip
Unit 8 Helping close relatives improves an organism's inclusive fitness (passes on shared alleles).
Unit 8 r- vs. K-selected Tap / Space to flip
Unit 8 r-selected: many offspring, little care, unstable env. K-selected: few offspring, much care, stable env.
Unit 8 Adaptive radiation Tap / Space to flip
Unit 8 Rapid diversification of one ancestor into many ecologically distinct species (e.g., Galápagos finches).
Unit 8 Competitive exclusion Tap / Space to flip
Unit 8 Two species with identical niches cannot stably coexist; one will outcompete the other.
Unit 0 Sodium-potassium pump Tap / Space to flip
Unit 0 3 Na⁺ pumped out / 2 K⁺ pumped in per ATP. Maintains resting membrane potential and gradients.
Unit 0 Gibbs free energy ΔG Tap / Space to flip
Unit 0 ΔG = ΔH − TΔS. Negative = spontaneous; positive = requires input.
Unit 0 Negative vs. positive feedback Tap / Space to flip
Unit 0 Negative: returns to set point. Positive: amplifies response (childbirth, blood clotting).
Unit 0 Plasmid Tap / Space to flip
Unit 0 Small circular bacterial DNA carried separately from the chromosome. Used as cloning vector.
Unit 0 CRISPR-Cas9 Tap / Space to flip
Unit 0 Bacterial defense system repurposed to edit DNA at a sequence specified by a guide RNA.
Unit 0 Gel electrophoresis Tap / Space to flip
Unit 0 Separates DNA fragments by size; smaller fragments travel farther through agarose toward the + electrode.
Unit 0 Lytic vs. lysogenic Tap / Space to flip
Unit 0 Lytic: virus replicates immediately and lyses host. Lysogenic: viral DNA integrates as prophage and replicates with host.
Keyboard: ← / → to move · Space to flip · K mark known · S shuffle.