Comprehensive Biology: Fungi, Earth History, Animal Diversity, and Physiology

Comprehensive vocabulary flashcards covering fungal biology, geological time and stratigraphy, animal evolutionary history, and comparative animal organ systems and physiology.

Mycology

The scientific study of fungi.

Mycelium

A multicellular, filamentous structure that comprises the vegetative body of multicellular fungi.

Hyphae

Long, narrow branching filaments that make up a mycelium, usually divided into cellular compartments by cross-walls called septa.

Septa

Cross-walls dividing fungal hyphae into distinct cells, containing pores through which organelles and nutrients can move.

Coenocytic

Describing fungal hyphae that lack dividing septa and are multinucleate, with nuclei scattered throughout the continuous cytoplasm.

Basidia

Club-shaped microscopic reproductive structures formed on the gills of mushrooms in the phylum Basidiomycota where spores are produced.

Chitin

A structural polysaccharide found in the cell walls of fungi and the exoskeletons of arthropods.

Saprophytic Fungi

Fungi that feed on dead plant material by performing extracellular digestion via secreted enzymes that digest cellulose and lignin.

Lignin Peroxidase

An enzymatic catalyst secreted by fungi that breaks down complex lignin, exposing cellulose for subsequent enzymatic degradation.

Ectomycorrhizal Fungi (EMF)

Fungi whose hyphae form a dense sheath around plant roots and penetrate between root cells without invading interior host cells.

Arbuscular Mycorrhizal Fungi (AMF)

Fungi whose hyphae penetrate the cell walls of plant root cells and make direct contact with the host plant plasma membrane.

Lichens

Symbiotic mutualistic associations composed of a fungus and a photosynthetic partner (green algae or cyanobacteria), often with an additional basidiomycete yeast.

Plasmogamy

The fusion of the cytoplasm from two distinct fungal mating types without the immediate fusion of their nuclei.

Heterokaryotic

A fungal mycelium containing genetically distinct haploid nuclei from two different mating types within the same cell or hypha.

Karyogamy

The fusion of two haploid nuclei within a fungal cell to form a diploid zygote.

Law of Superposition

A stratigraphical principle stating that in undeformed sedimentary rock layers, younger strata are deposited on top of older strata.

Principle of Original Horizontality

The principle stating that layers of sediment are originally deposited horizontally under the influence of gravity.

Principle of Lateral Continuity

The principle stating that sedimentary layers initially extend outward laterally in all directions until they thin out or terminate against a barrier.

Principle of Cross-Cutting Relationships

The geological principle stating that any body of rock or fault that cuts across a rock stratum must have formed after that stratum.

Principle of Uniformitarianism

The geological doctrine developed by James Hutton stating that physical processes operating today operated similarly in the past.

Index Fossils

Easily identifiable, abundant, geographically widespread fossils present during a relatively brief geologic time span, used to date surrounding strata.

Radiometric Dating

An absolute dating technique based on the ratio of radioactive parent isotopes to stable daughter decay products.

Half-Life

The duration of time required for half of the initial quantity of a radioactive parent isotope to decay into its daughter product.

Molecular Clock

A method using constant rates of DNA sequence substitution across lineages to estimate divergence times among evolutionary clades.

Permineralization

A fossilization mode in which mineral-charged groundwater permeates porous biological tissue, precipitating minerals in cellular spaces.

Trace Fossils

Fossilized indirect physical evidence of an organism's activity rather than body tissue, including footprints, burrows, coprolites, and feeding tracks.

Taphonomy

The scientific study of fossilization processes and the systematic biases involved in the preservation of organisms in the rock record.

Mass Extinction

The rapid loss of $50\text{--}60\%$ or more of diverse global species within a brief interval of less than $1\text{ million years}$.

Cambrian Explosion

The rapid evolutionary radiation approximately $541\text{ mya}$ during which major animal phyla and complex body plans originated.

End-Permian Extinction

A catastrophic mass extinction event occurring $252\text{ mya}$ that eliminated roughly $90\%$ of all existing species.

Diploblasts

Animals that develop from two embryonic germ layers: the ectoderm and the endoderm.

Triploblasts

Animals whose bodies develop from three distinct embryonic germ layers: ectoderm, endoderm, and mesoderm.

Gastrovascular Cavity

A central digestive chamber with a single opening functioning as both mouth and anus, found in cnidarians and ctenophores.

Cnidocyte

A specialized cell unique to phylum Cnidaria that ejects a venomous or barbed coiled structure to capture prey and defend against predators.

Cephalization

The evolutionary concentration of sensory structures and central nervous processing organs at the anterior end of a bilateral organism, forming a head.

Coelom

An internal, fluid-filled body cavity positioned between the digestive tract and the outer body wall that cushions organs and permits independent movement.

Acoelomate

A triploblastic bilaterian animal that completely lacks an internal fluid-filled body cavity, such as flatworms.

Pseudocoelomate

A bilaterian animal possessing a body cavity that is only partially lined with tissue derived from the mesoderm.

Protostomes

A major lineage of bilaterian animals in which the embryonic blastopore traditionally develops into the mouth before the anus during gastrulation.

Deuterostomes

A major lineage of bilaterian animals characterized by embryonic development wherein the blastopore forms the anus before the mouth.

Lophophore

A specialized ring of ciliated tentacles surrounding the mouth that functions in suspension feeding in certain lophotrochozoan lineages.

Trochophore

A distinct developmental larval stage possessed by many lophotrochozoans that moves and feeds using a wheel-like ring of cilia around its middle.

Chaetae

Stiff bristle-like chitinous structures projecting from the parapodia or body wall of annelids.

Radula

A rasp-like chitinous feeding organ found in mollusks, used to scrape or slice food particles before digestion.

Tagmata

Prominent, specialized body units formed by the fusion of functional segments in arthropods (such as the head, thorax, and abdomen).

Holometabolous Metamorphosis

Complete metamorphosis in insects where the larval stage is morphologically and ecologically distinct from the pupal and adult forms.

Water Vascular System

A hydraulic network of branching fluid-filled tubes and chambers in echinoderms utilized in locomotion, respiration, and feeding.

Keystone Species

A species that exerts exceptional control on community structure and biodiversity disproportionate to its abundance or biomass.

Notochord

A stiff, flexible longitudinal supportive rod composed of specialized cells and located dorsal to the gut in chordates.

Basal Metabolic Rate (BMR)

The minimal rate of oxygen consumption required to sustain life in an endothermic organism at complete rest with an empty stomach under comfortable ambient conditions.

Homeostasis

The array of physiological regulatory mechanisms that actively maintain physical and chemical internal stability despite environmental changes.

Negative Feedback Loop

A self-regulating control loop in which an effector mechanism produces a response that opposes the detected deviation from the homeostatic set point.

Endotherm

An organism that generates internal metabolic heat at high rates to elevate and maintain its own tissue temperature.

Ectotherm

An organism whose body temperature relies predominantly on thermal energy absorbed from its external physical environment.

Countercurrent Exchange

An anatomical arrangement in which two fluids flow antiparallel in adjacent channels, maximizing passive exchange by maintaining a favorable gradient along the entire pathway.

Osmolarity

The total concentration of all osmotically active solute particles contained within a volume of solution, expressed as $\text{Osm/L}$.

Osmoconformers

Organisms that do not actively adjust internal osmotic pressure, maintaining internal osmolarities roughly isosmotic to their surrounding aquatic medium.

Rectal Gland

An epithelial organ located in sharks that concentrates and secretes excess $\text{NaCl}$ into the external environment via active transport.

Malpighian Tubules

Blind-ended excretory organs of insects extending into the hemolymph that generate pre-urine by actively secreting ions and pulling in water.

Nephron

The basic functional microscopic unit of the vertebrate kidney that performs filtration, reabsorption, secretion, and excretion.

Renal Corpuscle

The initial filtration apparatus of the nephron, consisting of a capillary cluster (glomerulus) encased within Bowman's capsule.

Loop of Henle

The hairpin-shaped section of the mammalian renal tubule that generates an osmotic concentration gradient across the medullary interstitial fluid.

Vasa Recta

A specialized hairpin loop network of capillaries that parallels the loop of Henle, reclaiming reabsorbed water and ions without dissipating medullary hyperosmolarity.

Antidiuretic Hormone (ADH)

A peptide neurohormone secreted by the posterior pituitary that inserts aquaporins into collecting duct epithelial membranes, promoting water reabsorption.

Aldosterone

A steroid hormone secreted by the adrenal cortex that stimulates $\text{Na}^+/\text{K}^+$ pumps in distal tubules, conserving sodium and water.

Cloaca

A common cavity at the terminus of the digestive tract in reptiles, amphibians, and birds receiving urinary, reproductive, and digestive effluents.

Partial Pressure

The hypothetical pressure exerted by an individual component gas within a gaseous mixture, defined by $P_X = P_{\text{Total}} \times F_X$.

Tracheal System

A respiratory system of internal branching tubes in terrestrial arthropods that delivers gases directly between tissues and outside air via spiracles.

Alveoli

Microscopic, thin-walled terminal air sacs in mammalian lungs enveloped by capillaries where gas exchange with blood occurs.

Hemoglobin

An iron-containing respiratory pigment protein packaged in erythrocytes that reversibly binds and transports up to four oxygen molecules.

Cooperative Binding

A conformational phenomenon where the binding of an oxygen molecule to one hemoglobin subunit increases the oxygen affinity of remaining vacant subunits.

Open Circulatory System

A circulatory system where hemolymph leaves vessels and directly percolates through open sinus cavities before returning to the heart.

Closed Circulatory System

A circulatory system in which blood remains enclosed entirely within a continuous circuit of specialized transport vessels.

Sinoatrial (SA) Node

A specialized group of modified cardiac myocytes in the right atrium that acts as the primary electrical pacemaker of the heart.

Systole

The physiological phase of the cardiac cycle during which ventricular muscle actively contracts to eject blood into arterial circuits.

Diastole

The relaxed filling phase of the cardiac cycle between ventricular contractions.

Baroreceptors

Specialized sensory stretch receptors located in the walls of the heart and major arteries that detect changes in systemic blood pressure.

Autonomic Nervous System

The division of the peripheral nervous system controlling involuntary physiological processes via smooth muscles, cardiac muscle, and secretory glands.

Resting Potential

The steady negative electrical voltage difference across an unexcited neuronal membrane, typically measured between $-65\text{ mV}$ and $-80\text{ mV}$.

Action Potential

A rapid, transient, all-or-none reversal and repolarization of membrane potential propagated down an axon.

Depolarization

A shift in membrane electrical potential that drives the interior voltage toward zero and into positive values relative to resting potential.

Refractory Period

A short post-action-potential interval during which inactivated voltage-gated $\text{Na}^+$ channels prevent immediate re-excitation.

Excitatory Postsynaptic Potential (EPSP)

A graded, depolarizing postsynaptic membrane potential change that increases the likelihood of firing an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A graded, hyperpolarizing postsynaptic membrane potential change that decreases the likelihood of triggering an action potential.

Hormone

A chemical signaling molecule synthesized by secretory cells, released into extracellular fluid or blood, and active at distant target cells in low concentrations.

Signal Transduction

The biochemical cascade that converts an extracellular chemical signal into a specific intracellular response following cell-surface receptor binding.

Juvenile Hormone (JH)

An insect hormone whose presence suppresses pupation and adult metamorphosis, directing molts toward subsequent larval instars.

Ecdysone

A steroid hormone that coordinates cellular events inducing periodic cuticular shedding (ecdysis) and metamorphosis in arthropods.

Fission

An asexual reproductive mode in which an adult animal divides transversely or longitudinally into two separate, genetically identical offspring.

Parthenogenesis

A form of asexual reproduction in which females produce viable offspring without any genetic fertilization by male gametes.

Spermatophore

A specialized, gelatinous capsule containing packets of sperm transferred by biological males to females during internal fertilization.

Ovoviviparous Development

An internal developmental mode where embryos develop inside yolk-filled eggs retained within the female reproductive tract until hatching.