BIOL 371: Final PLANTS

apoplastic pathway

water moves across cortex to endodermis via cell walls & intercellular spaces (passive trans.)

symplastic pathway

water flows from cytoplasm of one cell to the next via plasmodesmata (active trans.)

Casparian strip

forces apoplastic water & nutrients into symplast (into the cell cytoplasm)

cohesion-tension mechanism

intermollecular attractrion that explains the process of water flowing upwards (against gravity) through xylem driven by transpiration

transpiration

water movement through plant and is lost as it evaporates out of the stomata

guttation

when root pressure is strong enough to force water out of leaf openings (stomata)

source

any region of plant where organic substances are loaded into phloem (ie. mature leaves) through stomata or photosynthesis

sink

any region of plant where organic substances are unloaded from phloem (ie. growing leaves, damaged leaves, storage regions)

tonoplast

membrane enclosing the central vacuole

plasmolysis

Collapse of a walled cell's cytoplasm due to a lack of water

Methods for Asexual Reproduction in Eukaryotes

- budding
- fragmentation
- parthenogenesis

budding

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism

fragmentation

A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals

parthenogenesis

a form of asexual reproduction in which the egg develops in the absence of sperm

yolk

provides nutrients for developing embryo

amnion

membrane surrounding fluid-filled cavity that allows the embryo to develop in a watery environment

allantois

a space for metabolic wastes to be collected

chorion

surrounds entire embryo, including yolk & allantoic sac

placenta

fusion of chorion & allantois

polyspermy

fertilization with more than one sperm

cleavage

single large cell divides into many smaller cells (kinda like differentiation - but not really)

blastula

cell division results in a fluid-filled hollow ball of cells (marks beginning of pregnancy)

organogenesis

transformation of germ layers into the organs of the body

Gibberellins

stimulates growth & elongation of stems & fruit/flower opening

Auxins

indoleacetic acid - promotes growth & elongation of cells (synthesized mainly in shoot apical meristems, young stems & leaves)

Cytokinins

promotes cell division in roots & shoots (making new plant organs) - produced in root apical meristems

Ethylene

suppresses elongation (plant growth) & ripens fruit, stimulates opening of flowers and leaves falling off

Abscisic acid

suppresses growth and influences responses to environmental stress (ie. closing stomata)

Brassinosteroids

regulate plant growth responses

Jasmonates

regulate growth & have roles in defence (ie. slows down growth to use energy to repair plant tissue wounds)

Florigen

hormone that triggers flowers to grow at meristems

hypersensitive response

a plant's localized defense response to a pathogen, involving the death of cells around the site of infection

apical dominance

The preferential growth of a plant upward (toward the sun), rather than laterally; concentration of growth at the tip of a plant shoot, where a terminal bud partially inhibits axillary bud growth.

perfect flower

have both carpel and stamen

imperfect flower

has only carpel or stamen, not both