Exam 2: Plants and the Conquest of Land

Charopycean

protist ancestor with a relatively complex body

• filament of cells with side branches

cellulose

constituent of plant cell walls

plasmodesmata

channel through the cell wall allows substances to move between cells (can allow communication and specialization of different tissues)

apical meristem

localized regions of cell division

embryo

a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination

matrotrophy

zygotes remain sheltered and fed within gametophyte tissue (embryophytes)

sporopollenin walled spores

tough material that composes much of the walls of plant spores (dry, air-resistant reproductive cells) and helps to prevent cellular damage during transport through the air

spores

what is produced by sporangia is a dry, air-resistant reproductive cell

gametangia

specialized structures that protect developing gametes (sperm, egg) from drying out and microbial attack

gametes

sperm and egg

antheridia

round or elongate gametangia producing sperm

archegonia

flask shaped gametangia enclosing egg

sporangia

structure where spores are produced (bigger diploid sporophyte stage means more spores produced, so we see the evolution of larger diploid generations

alternation of generations (sporic life cycle)

two types of multicellular “bodies” that alternate in time

• multicellular diploid sporophyte makes haploid spores through meiosis

• haploid spores are dispersed and undergo mitosis to make multicellular haploid gametophyte

• haploid gametophyte makes gametes through mitosis

• haploid sperm cells fuse with haploid egg cells to make the diploid zygote

• diploid zygote undergoes mitosis to make embryo and ultimately sporophyte

zygotic life cycle

Asexual reproduction by mitosis when conditions are favorable, but switch to sexual when conditions become unfavorable.

• The diploid zygote undergoes meiosis to make 4 haploid spores

• Disadvantage: only a few haploid spores produced per zygote

gametophyte

haploid gametophytes make gametes through mitosis

sporophyte

a multicellular diploid sporophyte that makes haploid spores through meiosis

placental tissue transfer

• often in gametophyte tissues closest to embryos and in the embryos themselves

• cells are specialized to promote the movement of solutes from gametophyte to embryo

• finer-like ingrowths of cell wall increase surface area of plasma membrane for transport

embryophytes

has embryos

tracheophytes

lycophytes, ferns are seed-producing plants are vascular plants

thracheid

tracheids possess these. elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts.

lignin

waterproofing material found in cell walls of tracheids

vascular tissue

for structural support and condition of water, minerals, and nutrients found in other plants (vascular plants)

• occur in the major plant organs: stems, roots, and leaves

xylem

conducts water and dissolved nutrients

phloem

conducts sugars and metabolic products

stems

• contain vascular tissue and produce leaves and sporangia

• contain phloem and xylem (contains tracheids and lignin)

roots

specialized for uptake of water and minerals from the environment

leaves

photosynthetic function

rhizomes

a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes

waxy cuticle

present on most surfaces of vascular plant sporophytes

• wax prevents dessication

cutin

found in cuticle that helps prevent pathogen attack

stomata

pores that open and close to allow gas exchange while minimizing water loss

microphyll

only a single unbranched strand of vascular tissue (lycophytes)

euphylls

leaves that have multiple veins, usually branching one or more time in leaf (fern and rest of land plants)

K/T event

• marking the end of the Cretaceous and the beginning of the Tertiary

• huge amounts of ash, smoke and haze dimmed sunlight long enough to kill many of the world’s plants

• in the aftermath, surviving flowering plants diversified

• new types of animals also appeared