Plant Biology Lecture Review

Flashcards covering the evolution of plants, various plant types (algae, non-vascular, vascular, seed plants), plant features, defense mechanisms, and growth regulation based on lecture notes.

Glaucophytes

Unicellular freshwater algae with chloroplasts containing traces of peptidoglycan and characteristic cell wall material of bacteria. Sister group to the rest of the Plantae.

Red algae

Multicellular organisms whose red color is due to phycoerythrin, an accessory photosynthetic pigment.

Green plants

Organisms with chlorophylls a and b, cellulose in cell walls, starch to store carbohydrates, and chloroplasts surrounded by 2 membranes.

Chlorophytes

Most abundant and diverse group of green algae, using chlorophylls a and c.

Streptophytes

A group of green plants that includes all organisms except chlorophytes, making them a sister group to land plants.

Coleochaetophytes

Multicellular green algae with flattened, thin-walled cells. They retain the egg in the parent organism and are a sister group to stoneworts and land plants.

Stoneworts

Multicellular green algae exhibiting branching, apical growth, and plasmodesmata. They retain the egg in the parent and are the closest relatives of land plants.

Land plants (embryophytes)

Plants that develop an embryo, with multicellular sporophyte and gametophyte stages, and possess a cuticle.

Non-vascular plants

Plants that lack vascular tissue and do not form a clade.

Liverworts

Non-vascular plants without stomata; they have flat or leafy gametophytes that lie close to the ground, and sporophytes remain attached to the gametophyte.

Mosses

Non-vascular plants with a filamentous stage and leafy gametophytes, where the sporophyte grows apically. They move water solely by diffusion and may contain hydroids.

Hornworts

Non-vascular plants characterized by embedded archegonia and cells containing a single chloroplast. Their sporophyte has no growth limit, restricted only by the lack of a transport system.

Vascular plants (tracheophytes)

Plants that possess xylem and phloem (vascular tissue) and form a clade, characterized by the presence of tracheids.

Tracheids

Vascular cells found in the xylem of vascular plants.

Lycophytes

Vascular plants characterized by microphylls in spirals, sporangia in leaf axils, and apical cell division growth. Their sporangia are often arranged in cone-like strobili.

Euphyllophytes

A clade of vascular plants that is a sister group to lycophytes, includes plants with megaphylls, and constitutes seed plants and monilophytes, utilizing overtopping growth.

Monilophyta

A group within Euphyllophytes including horsetails and ferns, characterized by simple leaves in whorls or frondlike compound leaves, and a difference between main stem and side branches.

Sori

Clusters of sporangia found on the undersurfaces of fern leaves.

Rhyniophytes

An extinct group of early vascular plants anchored by rhizomes and rhizoids, with dichotomously branching stems bearing terminal sporangia but no true leaves or roots.

Gymnosperms

A group of seed plants that lack vessel elements for water conduction and support (except gnetophytes).

Cycads

Gymnosperms with compound leaves, swimming sperm, and seeds modified on leaves; they are the earliest clade and have highly toxic tissues.

Ginkgo

A deciduous gymnosperm with fan-shaped leaves and swimming sperm, represented today only by the species Ginkgo biloba, possessing distinct X and Y sex chromosomes.

Gnetophytes

Gymnosperms characterized by vessels in their vascular tissue and opposite, simple leaves, sharing characteristics analogous to those found in angiosperms.

Conifers

The most abundant gymnosperms, characterized by seeds in cones and needle or scale-like leaves.

Angiosperms

Flowering plants characterized by endosperm, carpels, reduced gametophytes, and seeds enclosed within fruits.

Cuticle

A coating of waxy lipids on plants that helps retain water.

Stomata

Openings on plant surfaces used to regulate gas exchange and water loss.

Gametangia

Multicellular organs in plants that enclose gametes and prevent them from drying out.

Embryo

A protective structure of a young plant.

Pigment

Substances in plants that provide protection against UV radiation.

Spore walls (polymer)

Protective structures that prevent spores from decaying.

Alternation of Generations

A life cycle that contains multicellular haploid and diploid stages, where gametes are produced by mitosis and meiosis produces spores that develop into multicellular haploids.

Sporophyte

The mature diploid plant stage in the alternation of generations, which develops from a multicellular embryo and produces spores by meiosis.

Gametophyte

The haploid plant stage in the alternation of generations, which develops from a spore by mitosis and cytokinesis, and produces haploid gametes by mitosis.

Archegonium

A multicellular, flask-shaped female sex organ in plants that produces a single egg.

Antheridium

A male sex organ in plants, each bearing two flagella, produced in large numbers.

Vascular tissue

Specialized tissue in plants, consisting of xylem and phloem, for the transport of water, minerals, and sugars.

Branching independent sporophyte

Sporophytes that can branch, allowing them to produce more spores and develop in complex ways, independent of the gametophyte.

Homospory

A condition in plants where a single type of spore is produced, and the gametophyte bears both female and male reproductive organs.

Heterospory

A condition in plants where megaspores develop into female gametophytes and microspores develop into male gametophytes, facilitating easier transportation and nutrition for the embryo.

Megaspore

A spore that develops specifically into the female gametophyte (megagametophyte).

Microspore

A spore that develops into the male gametophyte (microgametophyte).

Microsporangium

A structure where meiotic products are microspores, which are then shed.

Pollen grain

A multicellular male gametophyte formed by mitotic division of a microspore, distributed by wind or animal pollinators.

Sporopollenin

A protective polymer that defends the pollen grain against dehydration and chemical damage.

Megagametophytes

Female gametophytes that are dependent on the sporophyte for food and water.

Integument

Sporophytic structures that surround and protect the megasporangium.

Ovule

The megasporangium combined with its integument.

Pollen tube

A structure that develops from a pollen grain landing on an appropriate surface, elongates to the megagametophyte, and releases sperm at its tip.

Embryonic sporophyte

A young plant formed when a diploid zygote divides repeatedly.

Seed

The end product of seed plant reproduction, a multicellular structure containing an embryonic sporophyte.

Megastrobilus

A tight cluster of woody scales that protect seeds in conifers.

Seed coat

A protective layer that develops from the integument and protects the embryo.

Micropyle

A small opening in the integument through which the pollen grain enters.

Microstrobilus

A structure in conifers, typically herbaceous, composed of modified leaves beneath which are pollen-bearing microsporangia.

Flower

The sexual structure of angiosperms.

Inflorescence

A group of flowers.

Petals

Inner flower parts, often brightly colored to attract insects, collectively called the corolla.

Corolla

The collective term for all petals of a flower.

Sepals

Outer flower parts, usually protective, collectively called the calyx.

Calyx

The collective term for all sepals of a flower.

Perfect flowers

Flowers that possess both functioning megasporangia (carpels) and microsporangia (stamens).

Imperfect flowers

Flowers that lack either functional stamens or carpels.

Fruits

A mature ovary that contains seeds.

Carpel

A modified leaf that forms the female part of a flower, protecting ovules and seeds, and often preventing self-fertilization.

Ovary

The swollen base of the carpel containing one or more ovules.

Style

The stalk at the top of the carpel.

Stigma

The terminal surface of the carpel that receives pollen grains.

Pistil

Refers to two or more fused carpels, or a single carpel if only one is present.

Vessel elements

Tracheary elements with perforated end walls found only in angiosperms, aiding in water conduction.

Fiber

An elongated cell with a thick cell wall that serves as support in the xylem.

Stamens

The male parts of a flower, consisting of a filament and an anther, bearing microsporangia.

Filament

The part of the stamen that supports the anther.

Anther

The pollen-bearing portion of the stamen that contains microsporangia.

Monoecious

A condition where female and male parts (or flowers) are present on the same plant.

Dioecious

A condition where a plant bears either flowers with stamens or flowers with carpels, but never both on the same individual.

Simple fruit

A fruit that develops from a single carpel or several fused carpels (e.g., plum or peach).

Aggregate fruit

A fruit that develops from several separate carpels of a single flower (e.g., raspberry).

Multiple fruits

Fruits formed from a cluster of flowers (e.g., pineapples and figs).

Accessory fruits

Fruits derived from parts in addition to the carpel and seeds (e.g., apples, pears, and strawberries).

Climacteric fruit

Fruits that continue to ripen after being harvested (e.g., apple, banana).

Monocots

One of the two large clades of angiosperms, characterized by a single cotyledon, parallel leafy veins, a fibrous root system, and pollen grains with a single opening.

Eudicots

One of the two large clades of angiosperms, characterized by pollen grains with three openings, net-veined leaves, taproots, and multiple cotyledons.

Constitutive defenses

Plant defenses that are always present in the plant.

Trichomes

Hair-like outgrowths on plants that serve as physical and chemical defenses.

Thorn

A modified stem that serves as a plant defense.

Prickles

Epidermis outgrowths that serve as a plant defense.

Spines

Modified leaves that serve as a plant defense.

Laticifers

Elongated plant cells that store latex, used to defend against herbivores by gumming up their mouths or acting as a poison.

Indirect defense

A plant defense strategy that involves attracting or housing natural enemies of predators and parasites.

Secondary metabolites

Substances not essential to the plant's primary metabolism, such as toxins, used for defense.

Alkaloids

Nitrogen-containing secondary metabolites in plants that can induce stimulants or narcotics.

Terpenoids

Diverse group of secondary metabolites derived from isoprene units.

Phenolics

A group of secondary metabolites including flavonoids, anthocyanins, and related compounds.

Induced defenses

Plant defenses that are produced in reaction to the presence of a pathogen, herbivore, or other threat.

Avr (avirulence) genes

Genes in pathogens that code for elicitors, triggering plant defenses.

Elicitors

Distinctive molecules in pathogens that trigger specific defense responses in plants.

R (resistance genes)

Plant genes that recognize specific elicitors using a 'lock and key' mechanism, conferring resistance to specific pathogens.

Phytoalexins

Antibiotics produced by plants as a local defense response, toxic to bacteria and fungi.

Pathogenesis-related (PR) proteins

Enzymes produced by plants as a local defense response that break down cell walls of pathogens.