Transcript Notes Chapter 28

Plant Evolution and
Classification
Adapting to Land
More exposure to sunlight
Increased CO2 levels
Greater supply of inorganic nutrients
Susceptible to drying out
cuticle (waxy coating to prevent water
loss) with stomata (for gas exchange)
Reproduction
Developed structure to protect
reproductive cells from drying out
Spore - haploid reproductive cell
surrounded by a hard outer wall
Seed - embryo surrounded by a
protective coat
Absorbing and Transporting
Nutrients
Some plants have vascular tissue to
transport food (phloem) and water
(xylem), and help support the plant
Classifying Plants
12 phyla (formerly divisions), include
more than 270,000 species.
Three phyla of nonvascular plants
Have neither true vascular tissue not
true roots, stems, or leaves.
Classifying Plants Cont.
Nine phyla of vascular plants (have vascular
tissue and true roots, stems, and leaves)
Vascular plants can be divided into two groups
Seedless plants - ferns and fern-like plants
Seed plants - plants that produce seeds
Classifying Plants Cont.
Seed plants can be divided into two
groups
Gymnosperms - produce seeds not
enclosed in fruits (pine trees)
Angiosperms - produce seeds enclosed
in fruits
Alternating Life Cycles
All plants have life cycles consisting of
two phases, which are named for the
type of reproductive cells they produce
Alternation of generations
Sporophyte (2n) - produces spores
Gametophyte (1n) - produces gametes
Alternating Life Cycles Cont.
In the nonvascular plant life cycle, the
gametophyte is the dominant phase.
Alternating Life Cycles Cont.
In the vascular plant life cycle, the
sporophyte is the dominant plant.