Transcript Plants… - lperleybiology112

• Why plants are important • http://www.enviroexplorers.com/wildflowers/importance_of_plants
_and_plant_c.htm
• Cool plant Facts:
• http://hubpages.com/hub/plantfacts
• http://www.youtube.com/watch?v=igkjcuw_n_U
• http://www.youtube.com/watch?v=fc50QniIzVM
• Pretest
• The World of Plants (15 minutes)
Plant Diversity
Chapter 22
Miller & Levine Text
Biology 112
Introduction to Plants
(Chapter 22)
Plants…
• Provide the base for food chain on land
• Provide shade, shelter and oxygen for all
animals
• Oldest fossil evidence of plants dates
from about 470 million years ago!
What is the name of the science of
studying plants??
Botany
Kingdom Plantae
• Multicellular
• Eukaryotic
• Carry out photosynthesis using
green pigments called chlorophyll
• Include trees, shrubs, grasses,
mosses and ferns
• Most are autotrophs
• Cell Walls made of cellulose
What do Plants Need?
1.
2.
3.
4.
Sunlight
Water & Minerals
Gas Exchange
Movement of Water and Nutrients
Plant Life Cycle
• Two alternating phases, a diploid
(2N) phase called the sporophyte
generation and a haploid (N)
known as gametophyte generation
• These alternating phases are known
as “alternation of generations”
Early Plants
• For most of Earth’s history plants
did not exist. Life was concentrated
in oceans, lakes and
streams…Oxygen came from algae
and cyanobacteria
• The first plants evolved from an
organism much like the multicellular
green algae living today.
Overview of the Plant
Kingdom
Botanists divide the plant kingdom
into 4 groups based on three
important features:
1. Water-conducting tissues
2. Seeds
3. Flowers
Water-Conducting Tissues
• Evolved as an adaptation to land
• Absence – no xylem or phloem
• Presence of tissue:
– Xylem
• Carries water and nutrients that enter
the plant in the roots up through the
stem and out to all parts of the leaves
– Phloem
• Parallel to the xylem
• Carries sugar (energy) produced in
leaves (site of photosynthesis) to all
parts of the plant
Types of Plants
Cone-bearing plants
760 species
(gymnosperms)
Ferns & Relatives
11,000 species
Mosses & Relatives
15,600 species
235,000 Flowering
Plants (Angiosperms)
Bryophytes (Non-Vascular)
No Xylem or Phloem
• Confined to moist habitats b/c they
need water for sexual reproduction
– Do not flower so no seeds
– They produce spores
• Commonly found in wetlands, rain
forests, and roadside ditches
• Generally less than 20cm tall
• 3 classes: mosses, liverworts, and
hornworts
Liverwort
Mosses
Hornwort
Bryophytes
• Have leaflike, stemlike and rootlike
organs
• Have rhizoids (fine-like roots) that anchor
the plant
• Water and nutrients move from cell to cell
by osmosis / diffusion
• Mosses are the most common and they
hold a lot of water – this sponge like
feature makes them useful in oil spills,
and potting soils
Seedless Vascular Plants
(Ferns & Relatives)
• Dominant land plant 300 million
years ago
• Most are now extinct
Seed Plants (Vascular)
• Divided into two groups
– Gymnosperms (naked seed)
– Angiosperms (covered seed)
• What makes them different?
– Seed type is the main criterion for distinguishing the two
major seed-bearing groups; gymnosperms and angiosperms
– Greek: sperma “seed”, gymnos “naked”, and angeion “vessel”
• Why are they successful?
– Reproductive Adaptations and an improved vascular
system largely account for the success of seed plants
– The most widely distributed and complex group of
plants on Earth
– 270 000 known seed plants
– Have separate male and female gametophytes, as well
as roots, stems and leaves.
Seed Plants - Gymnosperms
• The most ancient surviving seed
plants are the gymnosperms
• Seeds are often found in a cone
• Represent all seed plants that DO
NOT form flowers (therefore do not
have seeds enclosed within a fruit)
• The most numerous and
widespread are the conifers
Gymnosperms: Conifers
• Cone bearing woody trees and shrubs
• Leaves are usually needlelike
• Most are evergreen (don’t drop their
leaves in the Autumn)
• Conifers DO shed their needles, just not
all at once – usually 2 to 4 years
• Grow in many different environments
• 600 species (pine, fir, spruce, cedar,
hemlock, sequoias)
• Produce useful products, ie.
lumber/paper
Seed Plants – Angiosperms
(Flowering Plants)
• There are thousands of different kinds of
flowering plants
• They range from tiny pond-surface plants, which
are less than 1 mm long to trees 100 m tall.
• Angiosperms ALL produce seeds in
reproductive structures called flowers. Then, as
the seeds mature, the flower changes into a
fruit.
• Angiosperms produce seeds that are enclosed
and protected inside the fruit, which is formed by
the flower.
• Mature seeds are scattered, or dispersed, along
with the fruit