Transcript Introduction to Plants

Introduction to Plants
Table of Contents
The Plant Kingdom
Photosynthesis and Light
Mosses, Liverworts, and
Hornworts
Ferns, Club Mosses, and
Horsetails
•
Introduction to Plants - The Plant Kingdom
What Is a Plant?
• Multicellular
organisms with tissues
and organs.
• Contain chlorophyll
inside chloroplasts and
can make food.
• Can not move from
place to place.
• Made of eukaryotic
cells with cell walls.
Introduction to Plants - The Plant Kingdom
Plant Cell Structure Activity
• Click the Active Art button to open a
browser window and access Active Art
about plant cell structure.
Introduction to Plants
Adaptations to Land
• To move to land, plants had to develop
adaptations to solve the following problems:
– Prevent water loss – cell walls made of
cellulose help prevent water loss. Most land
plants also have a waxy covering called a
cuticle on their stems and leaves that also aids
in preventing water loss.
– Obtain water and nutrients from soil – plants
evolved roots.
Introduction to Plants
Adaptations to Land
– Transport Materials —water moves up and
food moves down through tube-like vascular
tissue.
– *Support their own weight—cell walls and
vascular tissue provide structure and support.
Stems and roots then evolved.
– *Reproduction—the most successful land
plants evolved ways to reproduce without
water (seeds).
Introduction to Plants - The Plant Kingdom
Water Loss in Plants
• The graph shows
how much water a
certain plant loses
during the hours
shown.
Introduction to Plants - The Plant Kingdom
Water Loss in Plants
• Reading Graphs:
–What variable is
plotted along each
axis?
–Horizontal axis–time
of day; vertical axis–
water loss.
Introduction to Plants - The Plant Kingdom
Water Loss in Plants
• Interpreting Data:
–According to the
graph, during what
part of the day did the
plant lose the most
water? The least
water?
–Most–midday; least–
in the evening.
Introduction to Plants - The Plant Kingdom
Water Loss in Plants
• Drawing Conclusions:
• What could account
for the pattern of
water loss shown?
–The plant seemed to
lose the most water
during the sunniest or
warmest parts of the
day.
Introduction to Plants - The Plant Kingdom
Water Loss in Plants
• Predicting:
–How would you expect
the graph to look from 10
p.m. to 8 a.m.? Explain
your reasoning.
–The line graph would
descend during the night
and rise again in the
morning hours; water loss
is less during the night
when there is no sun.
Introduction to Plants
Origin of Plants
• Evolved from one-celled,
plant-like protists in the
ocean (Green Algae)
– Fossil record is sketchy
because most plants decay
before they form fossils.
– Oldest plant fossils are about
400 million years old. They
had no leaves and their stems
grew underground.
Introduction to Plants
Photosynthesis
• All plants make food through the process of
photosynthesis.
• During photosynthesis, plants use energy from
sunlight to change carbon dioxide and water
into sugar and oxygen.
– 1. Sunlight or “white light” is made of all of the
colors of the rainbow (the visible spectrum).
– 2. Plants absorb most of these colors except
green. Green light is reflected by the pigment
known as chlorophyll.
– 3. Other plant pigments reflect other colors and are
called accessory pigments. We see them mostly
in the fall, when plants stop making chlorophyll.
Introduction to Plants - Photosynthesis and Light
The Photosynthesis Process
• In photosynthesis,
the energy in
sunlight is used to
make sugar and
oxygen from
carbon dioxide
and water.
Introduction to Plants
The Big Picture of Photosynthesis
• Water enters through the roots of the plant.
• Carbon dioxide enters through tiny openings in
the leaves of the plant called stomata.
• They travel to the chloroplasts where they are
changed into a special sugar, called glucose,
and oxygen.
• Glucose is the plant’s food. It is broken down,
just like our food, to give the plant energy to
grow, develop, respond and reproduce.
• Most of the oxygen is released also through the
stomata of the leaves and used by other
organisms.
Introduction to Plants - Photosynthesis and Light
The Photosynthesis Process Activity
• Click the Active Art button to open a
browser window and access Active Art
about the photosynthesis process.
Introduction to Plants
The Photosynthesis Equation
• The many chemical reactions of
photosynthesis can be summarized by this
equation:
light energy
carbon dioxide + water
(6CO2)
(6H2O)
sugar + oxygen
(C6H12O6)
(6O2)
Introduction to Plants - Photosynthesis and Light
Photosynthesis
• Click the Video button to watch a movie
about photosynthesis.
Introduction to Plants
Classification of Plants
• The Plant Kingdom is divided into nine
divisions (not phyla).
• The first division includes nonvascular plants.
– Nonvascular plants have no vessels
(vascular tissue) for transporting food and
water. Therefore, they are all very small
and grow in damp shady places. They
include:
– 1. Division Bryophyta —mosses,
liverworts and hornworts
Introduction to Plants
Classification of Plants
• The remaining eight divisions are all vascular
plants.
• Vascular plants have vessels (vascular tissue) to
transport water and materials and help support the
plant. Therefore they can grow very tall and are
better suited to all land habitats. Some reproduce
using spores and some use seeds. This chapter
will look at the three divisions of seedless vascular
plants.
1. Division Lycophyta —club mosses
2. Division Sphenophyta —horsetails
3. Division Pterophyta —ferns
Introduction to Plants
Division Bryophyta
• Mosses are the most
common type of bryophyte.
– 10,000 different species
• All are simple, rootless plants
with leaf-like growths in a spiral
around a stalk.
• Root-like threads called
rhizoids replace true roots and
hold the moss in place.
• Most range in size from 2-5cm
in height.
Introduction to Plants
Division Bryophyta
Liverworts—simple,
rootless plants that have
a flattened, leaf-like body.
Their name means, “liver
herb” and in the Middle
Ages, people believed
this plant looked like
one’s liver.
Introduction to Plants
Division Bryophyta
Hornworts—small
plants with flat,
round, leaf-like
structures. It’s
sporophyte looks
like an animal’s
horn. They live
near lakes and
rivers.
Introduction to Plants
Importance of Bryophytes
• Bryophytes such as mosses and
liverworts are often called pioneer
plants because they are the first to
grow in new or disturbed areas.
• Nonvascular plants like them were
also probably the first land plants to
evolve millions of years ago.
• Many people use peat moss from
bogs in agriculture and gardening.
Introduction to Plants - The Plant Kingdom
Complex Life Cycles
• Simple plants like
mosses and other
bryophytes have
complex life
cycles that
include two
different stages:
the sporophyte
stage and the
gametophyte
stage.
Introduction to Plants - Mosses, Liverworts, and Hornworts
Mosses
• A moss gametophyte is
the green leafy part of
the plant and the rootlike rhizoids. There are
separate male and
female gametophytes.
• The moss sporophyte is
made of a stalk and a
capsule. It grows from
the zygote cell and will
produce new spores that
will grow into new
gametophytes.
Introduction to Plants
Another look at the
moss reproduction
process.
Introduction to Plants - Mosses, Liverworts, and Hornworts
Links on Nonvascular Plants
• Click the SciLinks button for links on
• nonvascular plants.
Introduction to Plants - Ferns, Club Mosses, and Horsetails
Charact. of Seedless Vascular Plants
• Ferns, club mosses, and horsetails
also reproduce using spores not seeds.
However, they have vascular tissue
which means they can grow much
taller. There are three divisions of
seedless vascular plants.
Introduction to Plants
Division Lycophyta
Division Lycophyta—
also known as club
moss. Produce spores
in structures that look
like tiny pinecones.
Sometimes called
ground pine.
Introduction to Plants
Division Sphenophyta
Division Sphenophyta—
also known as horsetails.
Stems are jointed with a
hollow center. They
contain silica (a gritty
substance found in sand).
They were used by
pioneers to scour their pots
and pans.
Introduction to Plants
Division Pterophyta
Division Pterophyta—
includes all species of
ferns. Largest group of
seedless vascular plants.
Ancient species were
huge (25 meters). Today,
the largest species are
3-5 meters. These
ancient fern forests
formed today’s coal
deposits.
Introduction to Plants - Ferns, Club Mosses, and Horsetails
Characteristics of Ferns
• Most ferns have underground stems in
addition to roots. The leaves, or fronds,
grow above ground.
Introduction to Plants
Fern Reproduction
Ferns and other seedless vascular plants also
reproduce using a sporophyte and a
gametophyte generation.
Fern sporophyte with
spore cases called sori
Fern gametophyte with young
sporophyte beginning to grow
Introduction to Plants
Fern Life Cycle
The sporophyte is the fern leaf
or “frond”. On the underside of
the frond are spore cases
called sori. These release
thousands of spores. A spore
grows into a heart-shaped
gametophyte called a
prothallium. It is held in place
by root-like structures called
rhizoids and has both sperm
and egg cells on it. They unite
and a new sporophyte begins to
grow.
Introduction to Plants
Wrap-up
• Both mosses and ferns rely on water for
reproduction because the sperm cells must
swim to egg cells. Therefore, these plants
live only in fairly moist areas. It wasn’t until
plants evolved seeds for reproduction that
they truly became successful in all land
habitats.
• Seed producing vascular plants include all
other plants not discussed in this chapter.
We will be studying them next.
Introduction to Plants
Graphic Organizer
Characteristic
Moss
Fern
Size
Small and low
Can be tall
Environment
Moist
Moist
Body parts
Rootlike, stemlike,
leaflike structures
True roots,
stems, and leaves
Familiar generation
Gametophyte
Sporophyte
Is true vascular
tissue present?
No
Yes