Biology Lecture Notes: Microbes, Fungi, and Plants (Vocabulary Flashcards)

A collection of vocabulary flashcards covering key concepts from microbes, endosymbiosis, fungi, and plant biology in the lecture notes.

Heterocyst

Specialized nitrogen-fixing cell in filamentous cyanobacteria; creates an anaerobic environment to enable nitrogen fixation separate from oxygenic photosynthesis.

Quorum sensing

Cell–cell communication where cells secrete autoinducers to sense population density and coordinate gene expression.

Three domains of life

The highest taxonomic rank: Eukarya, Archaea, and Bacteria.

Eukaryote

Organism with membrane-bound organelles and a nucleus; linear DNA; mitochondria; often capable of sexual reproduction.

Prokaryote

Organism lacking a true nucleus and membrane-bound organelles; DNA is circular; often includes plasmids.

Autotroph

An organism that makes its own organic molecules from inorganic carbon sources.

Heterotroph

An organism that obtains energy and carbon from organic molecules produced by others.

Chemotroph

An organism that derives energy from chemical reactions.

Phototroph

An organism that derives energy from light, typically via photosynthesis.

Binary fission

Asexual reproduction in prokaryotes where a cell divides into two genetically identical daughter cells.

Biofilm

A structured community of microorganisms attached to a surface and embedded in extracellular matrix; often more resistant to antibiotics.

Microbiome

All microorganisms in a well-defined habitat, including their genetic material.

Horizontal transmission

Spread of microbes through the environment or between individuals, not from parent to offspring.

Vertical transmission

Transmission of microbes from parent to offspring during reproduction.

Arbuscular mycorrhizal (AM)

Fungi that penetrate plant root cells to form arbuscules, aiding nutrient uptake.

Ectomycorrhizal (ECM)

Fungi that form a network around root surfaces and between cells without entering root cells.

Stromatolite

Layered sedimentary structures formed by ancient microbial mats, especially cyanobacteria, contributing to early oxygen production.

Endosymbiotic theory

Idea that eukaryotic organelles (mitochondria, chloroplasts) originated from free-living prokaryotes engulfed by a host cell.

Primary endosymbiosis

Engulfment of a cyanobacterium by a proto-eukaryote, leading to plastids/chloroplasts in descendants.

Secondary endosymbiosis

A eukaryote engulfs a primary endosymbiont, resulting in chloroplasts with additional membranes.

Tertiary endosymbiosis

A third-level endosymbiotic event where a eukaryote engulfs a secondary endosymbiont; chloroplasts with multiple membranes.

Plastid

An organelle derived from endosymbiotic bacteria; includes chloroplasts and related structures.

Mitochondrion

Organelle responsible for aerobic respiration; contains its own circular DNA and ribosomes.

Chloroplast

Plastid specialized for photosynthesis in plants and algae; derived from cyanobacteria.

Cyanobacteria

Photosynthetic bacteria that contributed to the accumulation of O2 in Earth’s atmosphere.

Mycelium

Network of fungal hyphae forming the vegetative body of a fungus.

Hypha

Filamentous thread that composes the body of a fungus.

Chitin

Structural polysaccharide forming fungal cell walls.

Lignin

Complex polymer in plant cell walls; resistant to degradation; fungi can decompose lignin.

Basidiomycete

Fungus in the phylum Basidiomycota; forms basidia and basidiospores.

Basidium

Club-shaped structure on which basidiospores are formed in Basidiomycota.

Basidiospore

Fungal spore produced on a basidium.

Plasmogamy

Fusion of cytoplasm between two mating-compatible hyphae; heterokaryotic stage.

Dikaryotic

Cell or mycelium containing two genetically distinct, haploid nuclei.

Karyogamy

Fusion of two nuclei to form a diploid zygote.

Meiosis

Nuclear division that halves the chromosome number to produce haploid spores or gametes.

Basidiocarp

The fruiting body of Basidiomycota (e.g., a mushroom).

Zygote

Diploid cell formed by the fertilization of gametes; develops into a new organism.

Endosymbiont

Organism living inside another in a mutualistic relationship.

Serial endosymbiosis

Sequential endosymbiotic events leading from primitive plastids to diverse chloroplast-containing lineages.

Sorus

Cluster of sporangia on the undersides of fern fronds.

Megasporangium

Structure that produces megaspores (female spores) in heterosporous plants.

Microsporangium

Structure that produces microspores (male spores) in plants.

Megaspore

Female spore that develops into the female gametophyte in heterosporous plants.

Microspore

Male spore that develops into the male gametophyte (pollen) in seed plants.

Pollen

Male gametophyte produced in the anthers of flowers or cones.

Pollen grain

A compact male gametophyte carried by pollen; germinates to form a pollen tube.

Ovule

Structure containing the female gametophyte; develops into a seed after fertilization.

Integument

Outer layer of the ovule that develops into the seed coat (testa) after fertilization.

Carpel

Structural unit of the pistil; the ovary, style, and stigma; contains ovules.

Pistil

The female reproductive part of a flower, often composed of one or more carpels.

Stamen

Male reproductive part of a flower, consisting of a filament and anther.

Anther

Pollen-producing sac at the tip of a stamen; contains microsporangia.

Filament

Stalk that supports the anther in the stamen.

Stigma

Sticky surface at the top of the style that captures pollen.

Style

Plow-like stalk through which a pollen tube grows to reach ovules.

Ovary

Structure within the pistil that contains ovules and develops into fruit after fertilization.