Biology 2 Midterm Review: Biodiversity, Evolution, and Plant Form

Comprehensive vocabulary flashcards covering microscopy, prokaryotic groups, evolutionary concepts, protistan supergroups, and nonvascular and seedless vascular plants based on the Bio 2 midterm lecture notes.

Compound Microscope

A microscope that magnifies specimens using ocular and objective lenses; includes a revolving nosepiece to change objectives, a stage and clips to hold slides, a diaphragm to control light, a light source, coarse and fine adjustments for focusing, and an arm and base for support.

Dissecting Microscope

A microscope used for viewing larger specimens and observing objects in 3D.

Total Magnification

The overall magnification calculated by multiplying the magnification of the ocular lens by that of the objective lens (for example, $10\times$ ocular $\times 40\times$ objective $= 400\times$).

Prokaryotes

Abundant cellular organisms encompassing Bacteria and Archaea that lack a nucleus and membrane-bound organelles and are generally smaller and simpler in structure.

Eukaryotes

Organisms characterized by having a membrane-bound nucleus and membrane-bound organelles; includes protists, plants, fungi, and animals.

Peptidoglycan

A polymer composed of sugars and amino acids that forms an essential component found in all bacterial cell walls.

Cyanobacteria

Photosynthetic prokaryotic organisms that lack a nucleus and membrane-bound organelles; they produce oxygen, fix carbon dioxide and nitrogen, cycle nutrients, and can form toxic blooms under high-nutrient conditions.

Nitrogen Fixation

The biochemical process performed by certain cyanobacteria in which atmospheric $N_2$ is converted into usable nitrogen compounds.

Heterocysts

Specialized cyanobacterial cells dedicated specifically to performing nitrogen fixation.

Anabaena

A genus of filamentous cyanobacteria capable of developing heterocysts for nitrogen fixation and akinetes for survival during difficult conditions.

Oscillatoria

A genus of filamentous cyanobacteria known for its oscillating movement and ability to orient toward light.

Merismopedia

An aquatic cyanobacterium whose cells divide in two directions and are held together by a mucilaginous sheath, forming flat, grid-like sheets.

Gram Staining

A differential staining technique that distinguishes bacteria based on cell wall composition, following the sequence: crystal violet, iodine, decolorizer, and safranin.

Gram-Positive Bacteria

Bacteria with a thick peptidoglycan layer that traps crystal violet during staining, resulting in a purple final appearance.

Gram-Negative Bacteria

Bacteria with a thin peptidoglycan layer that fails to retain crystal violet after decolorization and takes up safranin, resulting in a pink final appearance.

Phylogenetic Tree

A branching diagram illustrating evolutionary relationships, in which nodes represent common ancestors and branches represent evolutionary lineages.

Monophyletic Group

A phylogenetic group consisting of a common ancestor and all of its descendants.

Paraphyletic Group

A phylogenetic group consisting of a common ancestor and some, but not all, of its descendants.

Polyphyletic Group

A phylogenetic grouping comprising organisms from different evolutionary branches without their most recent common ancestor.

Natural Selection

A non-random evolutionary mechanism wherein individuals with traits that favor survival and reproduction are more likely to pass those traits to the next generation, altering population allele frequencies.

Genetic Drift

Random fluctuations in allele frequencies from generation to generation, having an especially pronounced effect in small populations.

Bottleneck Effect

A form of genetic drift that occurs when the size of a population is suddenly and drastically reduced.

Founder Effect

A form of genetic drift that occurs when a small group of individuals separates from a larger population to establish a new population.

Convergent Evolution

The evolutionary process wherein distinct, unrelated lineages independently evolve similar traits due to facing similar environmental pressures.

Divergent Evolution

The evolutionary process wherein related organisms sharing a common ancestor become increasingly distinct as they adapt to different environments.

Protists

A diverse, non-monophyletic assemblage of eukaryotic organisms that are not classified as plants, animals, or fungi.

Excavata

A eukaryotic supergroup characterized by a specialized feeding groove, containing autotrophic, heterotrophic, photosynthetic, and parasitic members.

Euglena

A genus of Excavata that is both autotrophic and heterotrophic, propels itself using a flagellum, and possesses a pigmented stigma (eyespot) near the flagellar base.

Trypanosoma

A genus of parasitic excavates, including T. brucei (transmitted by tsetse flies, causing sleeping sickness) and T. cruzi (transmitted by kissing/cone-nose bugs, causing Chagas disease).

Giardia

A parasitic excavate characterized by having two nuclei; found in contaminated water, food, or surfaces and responsible for causing giardiasis.

SAR Clade

A major eukaryotic supergroup named as an acronym for its three constituent clades: Stramenopila, Alveolata, and Rhizaria.

Diatoms

Photosynthetic stramenopiles that cycle approximately $25\%$ of Earth's carbon, generate atmospheric oxygen, and serve as key primary producers.

Brown Algae

Large marine photosynthetic organisms classified within Stramenopila, exemplified by Fucus.

Alveolata

A clade within the SAR supergroup distinguished by the presence of alveoli, which are membrane-bound, sac-like vesicles.

Dinoflagellates

Alveolates bearing two perpendicular flagella and cellulose wall plates; notable for causing toxic red tides and exhibiting bioluminescence.

Taxis

A behavioral directional movement or response exhibited by an organism toward or away from an external stimulus.

Stentor

A large, trumpet-shaped alveolate protist that moves via cilia and exhibits taxis.

Rhizaria

A clade of the SAR supergroup that includes foraminifera (organisms that typically possess shells or tests) and radiolarians (organisms with intricate mineral skeletons).

Archaeplastida

A eukaryotic supergroup containing plastids acquired via primary endosymbiosis of a cyanobacterium; includes red algae, green algae, and land plants.

Volvox

A genus of colonial green algae belonging to the supergroup Archaeplastida and domain Eukarya.

Unikonta

A eukaryotic supergroup that includes amoebozoans, other amoeba-like protists, fungi, and animals.

Amoebozoans

Unikont protists that feed via phagocytosis, move via cytoplasmic streaming, and extend pseudopods (false feet) to engulf prey.

Slime Molds

Protists previously classed as fungi that ingest food and digest it internally, lacking fungal hyphae, absorptive external digestion, and chitinous cell walls.

Rhizoids and Roots

Plant structures that anchor the plant body to the substrate and aid in absorbing water and dissolved minerals.

Vascular Tissue

Specialized conducting tissue in plants responsible for transporting water and nutrients throughout the plant body.

Gametangium

A specialized plant reproductive organ that encloses and prevents developing embryos from desiccation.

Cuticle

A waxy protective coating on the surface of terrestrial plants that prevents water loss in the adult plant.

Alternation of Generations

A plant life cycle that alternates between a multicellular haploid gametophyte ($n$) and a multicellular diploid sporophyte ($2n$).

Gametophyte

The haploid ($n$) multicellular generation in the plant life cycle that produces gametes by mitosis.

Sporophyte

The diploid ($2n$) multicellular generation in the plant life cycle that produces haploid spores by meiosis.

Bryophytes

Nonvascular land plants lacking true vascular tissue, roots, stems, and leaves, in which the haploid gametophyte ($n$) is the dominant life stage; encompasses Marchantiophyta, Bryophyta, and Anthocerotophyta.

Marchantiophyta

The phylum comprising liverworts, which reproduce asexually by gemmae cups and fragmentation, and sexually via archegonia and antheridia.

Archegonia

The female gametangia in plants that produce egg cells.

Antheridia

The male gametangia in plants that produce sperm cells.

Bryophyta

The phylum comprising mosses (such as Polytrichium), characterized by a dominant haploid gametophyte ($n$) and a small diploid sporophyte ($2n$) confined to capsules.

Anthocerotophyta

The phylum comprising hornworts, recognized by a green gametophyte bearing elongated, horn-like sporophytes.

Vascular Seedless Plants

Plants possessing true vascular tissue, roots, stems, and leaves, where the diploid sporophyte is dominant and reproduction occurs via spores rather than seeds; divided into Monilophyta and Lycophyta.

Frond

The large, leaf-like photosynthetic structure characteristic of ferns.

Fiddlehead

An immature, tightly coiled frond of a young fern.

Sori

Clusters of spore-producing sporangia found on the undersides of mature fern fronds.

Rhizome

A horizontal, subterranean plant stem typical of ferns that gives rise to roots and fronds.

Equisetum

The sole surviving genus of horsetails (also known as scouring rush), belonging to the vascular seedless plant phylum Monilophyta.