Unit 2 Lesson 1 - Paleo-Botany, Global Nutrient Cycles, GMOs, Plant Uses, Competition, and Succession

Sources: Stern’s Introductory Plant Biology (Bidlack & Jansky), the official Science Olympiad 2026 Botany rules, Biology LibreTexts Plant Evolution and Biogeochemical Cycles modules, and Britannica’s peer-reviewed botany entries.

paleo-botany

The scientific study of ancient plants through fossils, spores, pollen, and preserved tissues that reveals the evolutionary history and timing of major plant adaptations on land.

embryophytes

True land plants that produce a multicellular embryo protected within female reproductive structures, marking the transition from aquatic algae to terrestrial life around 470 million years ago.

cuticle

Waxy protective layer on early land plant surfaces that reduced water loss and enabled survival in drier terrestrial environments.

rhyniophytes

Early extinct vascular plants from the Silurian period with simple branching stems, terminal sporangia, and no true leaves or roots, representing one of the first land colonizers.

carboniferous forests

Vast swampy ecosystems dominated by pteridophytes during the Carboniferous period that produced massive coal deposits through burial and compression of plant remains.

megaphylls

Large leaves with complex venation that evolved in pteridophytes and seed plants, increasing photosynthetic surface area compared to earlier microphylls.

pollen

Male gametophyte structure in seed plants that allows fertilization without free water by delivering sperm through a pollen tube.

cretaceous explosion

Rapid diversification and dominance of angiosperms during the Cretaceous period driven by the evolution of flowers and fruits for efficient pollination and seed dispersal.

archaeefructus

Early fossil angiosperm from the Cretaceous showing primitive flower structures that document the rapid rise of flowering plants.

carbon fixation

Process in which plants incorporate atmospheric CO₂ into organic molecules during photosynthesis, serving as the primary biological entry point for carbon into the biosphere.

biological carbon sink

Role of plants and ecosystems in removing and storing atmospheric CO₂ in biomass and soils through photosynthesis and long-term burial.

nitrogen fixation

Conversion of atmospheric N₂ gas into biologically usable forms like ammonia by specialized bacteria, either free-living in soil or symbiotic in legume root nodules.

rhizobium

Symbiotic nitrogen-fixing bacteria that live in root nodules of legumes, providing the plant with usable nitrogen in exchange for sugars.

nitrification

Bacterial process that oxidizes ammonium to nitrites and then to nitrates, making nitrogen available for plant uptake from the soil.

ammonification

Decomposition of organic nitrogen compounds from dead organisms or waste into ammonium by soil bacteria and fungi.

denitrification

Anaerobic bacterial process that converts nitrates back into atmospheric N₂ gas, completing the nitrogen cycle in waterlogged or oxygen-poor soils.

assimilation

Incorporation of nitrates or ammonium by plant roots into amino acids, proteins, nucleic acids, and chlorophyll within plant tissues.

transgenic plants

Plants whose genome has been altered by the insertion of foreign genes using genetic engineering techniques such as Agrobacterium Ti-plasmid or gene gun methods.

bt crops

Genetically modified plants engineered with a bacterial gene that produces a toxin lethal to specific insect pests while remaining safe for humans and non-target organisms.

roundup-ready crops

Genetically modified plants containing a modified EPSPS gene that confers resistance to the herbicide glyphosate, allowing weed control without damaging the crop.

ti-plasmid

Tumor-inducing plasmid from Agrobacterium that is modified in the laboratory to insert desired genes into plant chromosomes during genetic engineering.

gene gun

Biolistic device that shoots DNA-coated gold or tungsten particles into plant cells to achieve genetic transformation without using bacterial vectors.

pioneer species

Hardy early colonizers in primary succession, such as lichens and mosses, that break down bare rock into initial soil and begin ecosystem development.

primary succession

Gradual colonization and community development on newly exposed bare rock or lava with no previous soil, starting with pioneer species and progressing to climax community.

secondary succession

Faster recovery of a plant community on existing soil after a disturbance like fire or farming, beginning with grasses and herbs and leading to a climax community.

climax community

Stable, mature ecosystem stage in succession dominated by long-lived species such as oak-hickory forests that maintain themselves under local climate conditions.

intraspecific competition

Competition among individuals of the same plant species for limited resources like light, water, or nutrients, often leading to self-thinning in dense stands.

interspecific competition

Competition between individuals of different plant species for shared resources, driving natural selection and niche differentiation over time.