Transcript 2. Plants (also called autotrophs or producers)

Ab botany
A. Overview of Plants:
1. All plants are multicellular, eukaryotic &
contain chlorophyll inside of chloroplasts.
2. Plants (also called autotrophs or producers)
trap energy from the sun by photosynthesis
& store it in organic compounds. (remember)
3. Heterotrophs or consumers get their energy
directly or indirectly from plants. Plants
also release oxygen needed by consumers.
4. Plants are very diverse & may be terrestrial
or aquatic. Kingdom Plantae is divided into
12 phyla or Divisions. More than 270,000
plant species have been identified.
B. Plant evolution
1.Plants evolved from green algae
2. Both algae & plants have chlorophyll a & b,
have cell walls made of cellulose, and
store energy as starch.
3. The First land plants had to develop
adaptations to scarcity of water & climate
changes (air temperature changes more
rapidly than water temperature).
4. The origin of vascular tissue (specialized
tissue for carrying food , water, & minerals)
was an evolutionary breakthrough in the
colonization of land.
5. plants have a two-generation life cycle
known as alternation of generations.
-This means that a plant exists in 2 forms: the
haploid generation is the gametophyte that
produces gametes; and the diploid generation
is the sporophyte that produces spores by
meiosis.
6. Most plants have vascular tissue (conducts
water and other nutrients). Nonvascular
plants are usually small and transfer
materials by osmosis and diffusion. Examples
include mosses and hornworts.
7. The earliest vascular plants reproduce
with spores instead of seeds. An example is
the fern.
8. Vascular plants with seeds can be divided
into two major groups:
a. Gymnosperms= plants with naked seeds.
-seeds do not develop in a fruit. Most
develop in a cone.
-examples – confiers (pines, spruces,
junipers) and ginkgos.
-gymnosperms are wind pollinated. Conifers
produce two cones: female (seed) cone and
male (pollen) cone.
b. Angiosperms – flowering plants.
-seeds are enclosed in fruit.
-flowers attract pollinators, ensure the
transfer of pollen to egg, and aid in
protecting seeps, pollen and egg.
-examples: roses, mustards, legumes, etc
9. Angiosperms are divided into two major
categories:
a. monocots- have a single cotyledon.
examples include grasses, lilies, corn
d. Dicots – have two cotyledons. Examples
include many shrubs, trees
10. Parts of a seed:
-seed coat - protection
-radicle – embryonic root
-plumule – immature leaf
-endosperm – fleshy inner tissue – for
nutrients (in beans, peanuts, etc. the
endosperm nutrients end up in the
cotyledons.
11. Parts of a typical flowering plant
12. The three basic parts of a plant are the
roots, shoots and leaves.
a. Roots function to anchor plants, absorb
water and minerals and some store
nutrients (carrots, sweet potatoes)
-roots grow at the tips. A great source
for cells undergoing mitosis.
b. Shoots (stems) – connect roots to leaves
and have vascular tissue for the transport
of nutrients, minerals and water. Shoots
also provide structural support for a
plant.
-vascular tissue 1. xylem- carries water and minerals up
a plant. Water is cohesive and adhesive
allowing it to “climb” the xylem. Also
transpiration of water out the leaves
and absorption by roots provides a
constant movement of water.
2. Phloem – sugars and other organic
molecules move down through the phloem.
3. Other tissues (cork, bark, cambium)
provide strength and protection.
c. Leaves – the site for photosynthesis.
-a typical leaf has a petiole (stem) and a
leaf blade. The vascular system of the
shoot passes through the petiole into
the midrib (central vein)
-the upper epidermis of a leaf is coated with
awaxy layer of cutin. This helps keep
water in.
-within the leaf are layers of
photosynthesizing cells
-the lower epidermis has stomata (stomate =
singular). These are openings that allow
carbon dioxide in and allow water vapor
out.