Bio 1B Organismal (Midterm 3) Vocabulary - Lecture Study Guide - Fall '25

Prokaryote

Small cells without a nucleus or specialized organelles

Eukaryotes

Larger cells with DNA packed into a membrane-enclosed nucleus andmembrane- enclosed organelles to compartmentalize cellular processes

Difference between Eukaryotes and Prokaryotes

Eukaryotes are larger, have membrane-bound organelles, their DNA is stored in nucleus, reproduce asexually and sexually, and have multiple linear chromosomes in the nucleus.

Prokaryotes are typically smaller, lack membrane-bound organelles, don't have DNA enclosed in a nucleus, reproduce asexually, and have single circular chromosomes.

Binary Fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

Cyanobacteria

Bacteria that can carry out photosynthesis

Human microbiome

the complete collection of microorganisms in the human body's ecosystem

An example of the human microbiome is the gut bacterium Bacteroides thetaiotaomicron, which helps break down complex carbohydrates we cannot digest ourselves. Another example is Staphylococcus epidermidis on the skin, which helps protect against harmful microbes.

Pathogen

An organism that causes disease

Symbiosis

A close relationship between two species that benefits at least one of the species.

Photosynthesis

Conversion of light energy from the sun into chemical energy.

Chemoautotroph

energy comes directly from chemical reactions

Photoautotroph

energy comes from light

Aerobic Respiration

process that requires oxygen, oxygen breaks down glucose and produces ATP. occurs in the mitochondria.

Hyphae

The branching, threadlike tubes that make up the bodies of multicellular fungi

Mycelium

mass of hyphae

Saprotroph

an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion

Mycorrhizae

Ecological relationship between the mycelium of a fungus and the roots of certain plants

Chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Spore

A reproductive cell with a hard, protective coating

Decomposer

An organism that breaks down wastes and dead organisms

External digestion

the process in which enzymes are secreted to digest food outside the organism

Fermentation

Process by which cells release energy in the absence of oxygen

Algae

Plantlike protists (a single-celled or simple multicellular eukaryotic organism)

Primary Endosymbiosis

The engulfment of a cyanobacterium by a larger eukaryotic cell that gave rise to the first photosynthetic eukaryotes with chloroplasts.

Secondary Endosymbiosis

A process in eukaryotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic eukaryotic cell which survived in a symbiotic relationship inside the heterotrophic cell

Red Algae

Primarily marine, photosynthetic eukaryotes that use chlorophyll a and the accessory pigment phycoerythrin, allowing them to live in deeper waters; they store carbon as Floridean starch and include the source of agar and carrageenan.

Green Algae

A diverse group of primarily freshwater photosynthetic eukaryotes that use chlorophylls a and b and store starch in their chloroplasts; they are the closest relatives of land plants.

Brown algae

Marine multicellular algae, including kelps, that use chlorophylls a and c plus the pigment fucoxanthin; they have complex life cycles and form large coastal habitats such as kelp forests.

Diatoms

Unicellular photosynthetic protists characterized by their silica cell walls (frustules), which form intricate, species-specific patterns; they use chlorophylls a and c and are major primary producers in marine and freshwater environments. Drives a large share of global oxygen production, form the base of aquatic food webs, and are key indicators of environmental change.

Dinoflagellates

Unicellular, photosynthetic or mixotrophic protists distinguished by their two perpendicular flagella, cellulose plates (theca), and often bioluminescent capabilities; many form symbioses with corals (zooxanthellae) or cause harmful algal blooms. Understanding marine productivity, coral reef ecology, and the dynamics of toxic algal blooms that influence ecosystem and human health.

Lichen

An organism made of a fungus and either algae or autotrophic bacteria that live together in a mutualistic relationship.

Desiccation

dehydration

Seed

plant embryo and a food supply encased in a protective covering

Seed Dispersal

scattering of seeds; can be done by animals, insects, air, or water

Fruit

A mature ovary of a flower that protects dormant seeds and aids in their dispersal.

Carpel

The female reproductive organ of a flower, consisting of the stigma, style, and ovary.

Monocot

An angiosperm that has only one seed leaf.

Self-pollination

the transfer of pollen grains from an anther to the stigma of the same flower or to the stigma of another flower on the same plant

Phytochrome

A type of light receptor in plants that mostly absorbs red light and regulates many plant responses, such as seed germination and shade avoidance.

Primary Growth

Growth produced by apical meristems, which lengthen stems and roots.

Secondary Growth

Growth produced by lateral meristems, which thickens the roots and shoots of woody plants.

Vascular Tissue System

carries out long-distance transport of materials between roots and shoots

Endodermis

The innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder.

Vascular bundles

strands of vascular tissue that run the length of the stem

Vascular cambium

adds layers of vascular tissue called secondary xylem (wood) and secondary phloem

Nitrogen-fixing bacteria

bacteria that convert atmospheric nitrogen into ammonia

Terrestrialization

the series of processes (adaptation) that makes an aquatic organism capable of living and sustaining itself on land. It is usually considered as one of the most important events in the evolutionary history of life on Earth.

Algal bloom

an immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient

Phytoplankton

Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems

Biofuels

Fuels, such as ethanol or methanol, that are created from the fermentation of plants or plant products.

Cuticle

A waxy covering on the surface of stems and leaves that acts as an adaptation to prevent water loss in terrestrial plants.

Stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

Xylem

vascular tissue that carries water upward from the roots to every part of a plant

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant

Symbiosis (Mycorrhizae)

Fungus

- supplies water and minerals

Plant

- Supplies sugar

Carbon Sequestration

an approach to stabilizing greenhouse gases by removing CO2 from the atmosphere

Bryophytes

Nonvascular land plants that include mosses, liverworts, and hornworts; they lack true xylem and phloem, require water for fertilization, and have a life cycle dominated by the gametophyte generation. They typically occupy moist habitats, reproduce via spores, and serve as early colonizers on bare substrates. Essential for understanding the early evolution of land plants, water-nutrient cycling in ecosystems, and the transition from aquatic to terrestrial life.

Ferns

Any of numerous flowerless, seedless vascular plants having roots, stems, and fronds and reproducing by spores.

Lycophytes

Ancient lineage of vascular plants that include club mosses, spike mosses, and quillworts; they possess true xylem and phloem, reproduce with spores, and are characterized by microphylls (simple leaves with a single vein). They were once dominant forest-forming plants in the Carboniferous but today are primarily small, ground-dwelling species. Illustrates early vascular plant evolution, the origins of leaf structure, and the ecological transitions that shaped Earth's first extensive terrestrial forests.

Gametophyte Reduction

Evolutionary trend in land plants in which the multicellular gametophyte generation becomes progressively smaller, shorter-lived, and more dependent on the sporophyte. In bryophytes the gametophyte is dominant, in seedless vascular plants it is small and independent, and in seed plants it is microscopic and completely reliant on the sporophyte. Shows how plants adapted to life on land by protecting reproductive structures and enabling reproduction in drier, more variable environments.

Heterospory

produces both microspores (male gametophytes) & megaspores (female gametophytes)

Pollen

A fine dust that contains the sperm of seed-producing plants

Pine Seed

Composed of a seed coat (2N from the mother), then megagametophyte tissue (from the mother N), and the embryo (2N from both parents)

Gymnosperm

group of seed plants that bear their seeds directly on the scales of cones

Conifer

a cone-bearing tree

Cycad

a division of gymnosperms that grow in tropical climates and resemble palm trees

Gnetophyte

a division of gymnosperms with varied morphological features that produce vessel elements in their woody tissues

Ovule

A structure that develops within the ovary of a seed plant and contains the female gametophyte.

Gametophyte

The stage in the life cycle of a plant in which the plant produces gametes, or sex cells.

Sporophyte

The stage in the life cycle of a plant in which the plant produces spores.

Pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants

Angiosperm

A flowering plant which forms seeds inside a protective chamber called an ovary.

Endosperm

food-rich tissue that nourishes a seedling as it grows

Stamen

the male reproductive organ of a flower

Sporophyll

A modified leaf that bears sporangia and hence is specialized for reproduction.

Sporangia

a sac-like structure found in plants, fungi, and algae that produces and stores spores

Vascular Tissue

Plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body.

Eudicot

Member of a clade consisting of the vast majority of flowering plants that have two embryonic seed leaves, or cotyledons.

Cotyledons

first leaf or first pair of leaves produced by the embryo of a seed plant

Germination

the process whereby seeds or spores sprout and begin to grow

Pollination syndrome

a set of flower characteristics associated with a particular type of pollinator

Cross-pollination

a reproductive process in which pollen from one plant is transferred to the stigma of another plant

Double fertilization

A mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the embryo sac to form the zygote and endosperm.

Fruit morphology

the make up of ovary tissue

Fruit types

Simple fruits develop from a single ovary of one flower (example: cherry).

Aggregate fruits form from multiple separate ovaries within a single flower (example: raspberry).

Multiple fruits arise from the fused ovaries of many flowers in an inflorescence (example: pineapple).

Accessory fruits incorporate non-ovary tissues, such as the receptacle, into the edible portion (example: strawberry).

Biotic dispersal

Seed dispersal involving living organisms.

Abiotic dispersal

gravity, wind, water

Diaspore

Any plant dispersal unit containing seeds or spores along with any attached structures, such as wings, fruits, or hairs, that aid in movement away from the parent plant. It represents the functional package that enables dispersal by wind, water, or animals.

Red Light/Far-red light

red light - signals adequate sun to start growing/germination and flowering

far red light - indicates shade, turns phytochrome off, signals plant to grow taller to avoid shade

Photoperiodism

A plant's response to seasonal changes in length of night and day

Vernalization

the cooling of seed during germination in order to accelerate flowering when it is planted.

Apical Meristem

Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length.

Lateral Meristem

Growth region of a plant that provides secondary growth, increase in girth

Dermal Tissue System

plant's outer protective covering

Ground Tissue System

Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support.

Parenchyma

Fundamental tissue composed of thin-walled living cells that function in photosynthesis and storage.

Collenchyma

A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth

Sclerenchyma

type of ground-tissue cell with an extremely thick, rigid cell wall that makes ground tissue tough and strong

Monocots and Dicots

The 2 classes of angiosperms

Taproot

primary root found in some plants that grows longer and thicker than other roots

Fibrous root system

A root system common to monocots consisting of a mat of thin roots spreading out below the soil surface.