Lesson 12

Guard cells

Specialized cells that form the border of the plant stoma

Cuticle

Protective barrier, keeps plants from drying out

Stomata

Small pores, crucial for gas exchange (allowing CO2 to enter and O2 to exit)

Vascular tissue

Crucial for water and nutrient transport

Lignin

Strong polymer built from six-carbon rings, abundant in woody plants

Tracheids

In vascular plants, they have pits that allow water movement between adjacent cells

Primary cell wall

Outermost layer, made of cellulose and polysaccharides, defines the shape of the cell

Secondary cell wall

Inner layer that provides support or protection

Embryophytes

Plants that nourish their embryo inside their own body. All land plants are embryophytes.

Alternation of generations

Life cycle that occurs in plants and some protists

Gametophyte

Multicellular haploid stage

Sporophyte

Multicellular diploid stage

Heterospory

Production of two types of spores

Homospory

Production of a single type of spore. (All nonvascular and seedless vascular plants are homosporous)

Microsporagania

Produces microspores that develop into male gametophytes (produces sperm by mitosis)

Megasporangia

Produces megaspores that develop into female gametophytes (produces eggs by mitosis)

Pollen Grain

Male gametophyte enclosed within a protective coat of sporopollenin

Ovule

Contains a megasporangium with eggs

Endosperm

Triploid (3n) tissue in a seed of an angiosperm, serves as food for the plant embryo

Stamen

Male reproductive structure in a flower, has an anther which pollen grains are produced

Carpel

Female reproductive organ in a flower, has a stigma

Pollination

Transfer of pollen from a plant's stamen to another plant's carpel

Coevolution

Evolution pattern where two species reciprocally influence each other's adaptations over time

Adaptive radiation

Single lineage produces a lot of descendant species that are adapted to a wide variety of habitats

Monocots

Angiosperms that have a cotyledon upon germination

Dicots

Angiosperms that have two cotyledons upon germination

Cotyledon

Stores nutrients and supplies them to a developing embryonic plant

Eudicots

True dicots

Lichens

Stable association between cyanobacteria or green algae and fungi

Rhizoids

Hairlike structure that anchors a nonvascular plant to the substrate