Plant Biology Lec 1

Plant benefits

• Form foundation of food webs

• Building materials

• Decoration

• Many drugs are derived from plants

• Energy

• Production of oxygen via photosynthesis

5 groupings of organisms

Eubacteria (Unicellular prokaryotes, lack chromosomes (DNA is in a ring))

Archaebacteria (Unicellular prokaryotes, lack chromosomes (DNA is in a ring))

Protista (Eukaryotic (has chromosomes), unicellular, and multicellular)

• Plants (multicellular, eukaryotic)

• Animals (multicellular, eukaryotic)

• Fungi (multicellular, eukaryotic)

Major types of living plants

Non-vascular plants (bryophytes)

Vascular plants

Non-flowering seed plants (gymnosperms)

Flowering plants (angiosperms)

Non-vascular plants (bryophytes)

-Most primitive

-Lack vessels to move water internally

-Small

-Mosses

-Liverworts

-Hornworts

-8000 species

-Some mosses not really mosses

Vascular Plants

-Bigger than Brophytes

-Lack seeds (reproduce with spores)

-Ferns

-Horsetails

-Club mosses

-20,000 species

Gymnosperms (naked seeds)

-Most primitive of seed plants

-Includes some of the largest plants in the world

-Lack flowers (Instead, reproduce via cones where seeds are bare/naked)

-Also called non-flowering plants

-Cornifers (pines, hemlock, junipers, spruce, firs, cedars, etc)

-1000 extant species

Angiosperms (enclosed seeds)

-Most advanced

-”Flowering plants”

-Reproduce via flowers

-Seeds are made inside fruits

-Have showy flowers, small flowers, or flowers without petals (like maples)

-Largest group of plants

-250,000 species

Evolutionary history of plants

-First major innovation was evolution of vascular tissue (allowed plants to be larger)

-Then plants evolved seeds (making reproduction more efficient)

-Last, plants evolved flowers (pollination more efficient)

Two kinds of Angiosperms (flowering plants)

Based on seed morphology

-Dicotyledons

-Monocotyledons

Dicotyledons

-Seeds that are divided into two equal halves

-Two cotyledons

-Most angiosperms are this type

Monocotyledons

-One cotyledon (cannot be divided in half)

-60,000 species

-Includes grasses

Characteristics of plants

-Nearly all plants have green leaves, but some parasitic plants lack chlorophyll (no green)

-Most have leaves, not all of them

-Not always rooted to the ground (duckweed)

-Flowers are a trait, but many primitive plants lack

-All have cell walls

-All have multicellular eikaryote

-All photosynthesis

-All Have embryo

-All have two adult forms (produces spores, other eggs)

-Many have indeterminate growth (can keep growing)

-Have modular growth (repeatable units, which come from buds)

Cell wall structure

-Outer layer is primary cell wall

-Inner is secondary cell wall

-Separated by middle lamella

-When cells are touching, there is always a double layer

-Plasmodesmata are small pores that connect adjoining cells

-Cellulose is a main component of plant cell walls

Chloroplasts

-Organelle suspended in cytoplasm of photosynthetic tissues

-All non-parasitic plants have chloroplasts

-Not in animal cell

-Causes plants to appear green

Vacuale

-Central structure found in almost all plant cells, but not in animal cells

How are embryos of flowering plants (angiosperms) protected

-Protected inside the ovary of female part

-Not true for algae