Biology Unit 2 Lecture Review: Chapters 25–34 and Entropy

Complete set of vocabulary flashcards covering origins of life, viruses, prokaryotes, protists, seedless and seed plants, fungi, animal diversity, protostomes, deuterostomes, and entropy.

Stromatolites

Fossilized structures that provide evidence of ancient microbial life dating back about $3.5\text{ billion years ago}$.

RNA-World Hypothesis

Hypothesis proposing that RNA may have originally stored genetic information and catalyzed early biochemical reactions.

Ribozyme

An RNA molecule capable of catalyzing a biochemical reaction.

Endosymbiosis

Evolutionary process by which eukaryotic organelles, specifically mitochondria and chloroplasts, evolved from engulfed aerobic and photosynthetic bacteria.

Capsid

The protein coat enclosing the genetic material of a virus.

Viral Envelope

An optional outer lipid membrane surrounding the capsid in certain viruses, such as influenza and HIV.

Prion

An infectious, misfolded protein responsible for diseases such as BSE and kuru.

Viroid

A small, circular infectious RNA molecule that infects plants.

Reverse Transcriptase

An enzyme found in retroviruses like HIV that synthesizes DNA from an RNA template.

Bacteriophage

A virus that specifically infects and replicates within bacteria.

Lytic Cycle

A viral replication cycle in which new viral particles are produced, culminating in the bursting and lysis of the host cell.

Lysogeny

A viral life cycle in which phage DNA integrates into the host bacterial chromosome as a prophage and can later excise to enter the lytic cycle.

Prophage

Bacteriophage DNA that has integrated into the bacterial host chromosome.

Bacterial Capsule

An outer layer that aids in bacterial attachment and provides protection against environmental threats.

Fimbriae

Hair-like appendages on bacterial surfaces used primarily for attachment to surfaces and hosts.

Pili

Bacterial surface structures that facilitate the direct transfer of DNA between cells during conjugation.

Endospore

A highly resistant, dormant structure formed by certain bacteria allowing long-term survival in harsh environmental conditions.

Gram-Positive Bacteria

Bacteria possessing a thick peptidoglycan cell wall that retains crystal violet stain, appearing purple in a Gram stain.

Gram-Negative Bacteria

Bacteria with a thin peptidoglycan layer surrounded by an outer membrane that stain pink or red in a Gram stain.

Transformation

The horizontal gene transfer process where a bacterium takes up free foreign DNA directly from its surroundings.

Transduction

The transfer of bacterial DNA from one host cell to another mediated by a bacteriophage.

Conjugation

The direct transfer of genetic material between two bacterial cells connected by a pilus.

Excavata

A major protist group that includes organisms such as Giardia, Trichomonas, Euglena, and Trypanosoma.

SAR Supergroup

A major eukaryotic clade containing stramenopiles, alveolates, and rhizarians, including brown algae, dinoflagellates, apicomplexans, and ciliates.

Archaeplastida

A major eukaryotic group comprising red algae, green algae, and land plants.

Amoebozoa

A major eukaryotic lineage characterized by amoeboid movement and including amoebas and slime molds.

Opisthokonta

A broad eukaryotic clade that includes choanoflagellates, fungi, and animals.

Cuticle

A waxy outer coating on land plants that reduces water loss.

Stomata

Specialized microscopic pores on plant surfaces that open and close to regulate gas exchange.

Lignin

A rigid polymer integrated into vascular plant cell walls that provides structural support.

Xylem

Vascular tissue responsible for conducting water and dissolved minerals upward from roots.

Phloem

Vascular tissue responsible for transporting sugars and photosynthetic products from sources to sinks.

Bryophytes

Nonvascular land plants, including mosses, liverworts, and hornworts, whose life cycles are dominated by the haploid gametophyte stage.

Alternation of Generations

A plant reproductive cycle that alternates between a multicellular diploid sporophyte and a multicellular haploid gametophyte.

Sporophyte

The multicellular diploid ($2n$) phase of a plant life cycle that produces haploid spores via meiosis.

Gametophyte

The multicellular haploid phase of a plant life cycle that produces gametes through mitosis.

Gymnosperms

Vascular seed plants, such as conifers, cycads, and ginkgoes, that produce seeds not enclosed within a fruit.

Angiosperms

Vascular seed plants characterized by flowers and seeds enclosed within protective fruit tissues.

Double Fertilization

A specialized angiosperm fertilization event where one sperm fertilizes the egg to form a zygote ($2n$) and a second sperm fertilizes central nuclei to form endosperm ($3n$).

Endosperm

A nutritive tissue, typically triploid ($3n$), formed during double fertilization that nourishes the developing angiosperm embryo.

Saprobe

A decomposer organism that secretes enzymes to break down and absorb nutrients from non-living or dead organic matter.

Chitin

A tough, nitrogenous polysaccharide that forms the structural cell walls of fungi and the exoskeletons of arthropods.

Hypha

A single filament or thread-like structure that serves as the basic vegetative unit of a fungus.

Mycelium

A densely interwoven network of fungal hyphae that constitutes the vegetative body of a fungus.

Septum

A cross-wall that divides fungal hyphae into distinct cellular compartments.

Plasmogamy

The fusion of cytoplasm from two parent fungal mycelia without immediate nuclear fusion.

Karyogamy

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

Dikaryotic Stage

A fungal mycelial state characterized by cells possessing two distinct haploid nuclei ($n+n$) per cell.

Lichen

A stable mutualistic association between a fungus and a photosynthetic partner, such as a green alga or cyanobacterium.

Blastula

An early animal embryonic stage consisting of a hollow sphere of cells formed following cleavage.

Gastrulation

A developmental process involving cell migration in the blastula that establishes the primary embryonic germ layers.

Diploblastic

Having an embryo developed from two primary germ layers: ectoderm and endoderm.

Triploblastic

Having an embryo developed from three primary germ layers: ectoderm, mesoderm, and endoderm.

Nematocyst

A specialized stinging sub-cellular organelle found within the cnidocytes of cnidarians used for prey capture and defense.

Bilateria

A major clade of animals characterized by ancestral bilateral symmetry and triploblastic germ layer development.

Lophotrochozoa

A major protostome clade including flatworms (Platyhelminthes), mollusks, and annelids.

Ecdysozoa

A major protostome clade containing nematodes and arthropods, characterized by the shedding of an external cuticle or exoskeleton.

Acoelomate

A triploblastic animal that completely lacks a fluid-filled body cavity between the digestive tract and outer body wall.

Pseudocoelomate

An animal whose body cavity is only partially lined with tissue derived from mesoderm.

Coelomate

An animal possessing a true body cavity (coelom) completely lined with mesoderm-derived tissue.

Radula

A specialized rasping, ribbon-like tongue structure used by many mollusks to scrape and feed on food.

Scolex

The anterior, specialized attachment head region of a parasitic tapeworm.

Proglottids

The repetitive, individual body segments of a tapeworm containing complete reproductive units.

Deuterostome

A bilaterian animal lineage characterized by embryonic development in which the blastopore becomes the anus, and the mouth forms second.

Notochord

A flexible, longitudinal rod of tissue providing primary skeletal support in all chordate embryos.

Amnion

An extraembryonic membrane that encloses the amniotic fluid to cushion and hydrate the developing embryo.

Monotremes

A basal lineage of mammals that reproduce by laying eggs rather than bearing live young.

Marsupials

Mammals characterized by a short gestation period followed by the continued development of altricial young inside a maternal pouch.

Placentals

Mammals whose developing embryos receive prolonged internal nourishment through a complex maternal-fetal placenta.

Entropy

A thermodynamic quantity related to energy dispersal and the number of microscopic arrangements accessible to a system.

Self-Assembly

The spontaneous thermodynamic organization of individual molecules into ordered structural complexes, such as phospholipid bilayers.

Autocatalysis

A chemical reaction or series of reactions where a product catalyzes and accelerates its own continued formation.