9.1 The Plant Kingdom
Key Concepts
 What characteristics do all plants share?
 What do plants need to live successfully on land?
 How do nonvascular plants and vascular plants differ?
 What are the different stages of a plant’s life cycle?
Key Terms
photosynthesis
tissue
chloroplast
vacuole
cuticle
vascular tissue
fertilization
zygote
nonvascular plant
vascular plant
chlorophyll
sporophyte
gametophyte
What Is a Plant?
 Members of the plant kingdom share several
characteristics.
1.
2.
3.
Nearly all plants are autotrophs, organisms that
produce their own food.
All plants are eukaryotes that contain many cells.
All plant cells are surrounded by cell walls.
Plants are Autotrophs
The textbook refers to a typical plant as a sun-powered,
food-making factory. What provides the energy for
this food-making process?
photosynthesis
During photosynthesis, a plant uses carbon dioxide gas
and water to make food and oxygen. We will look at
this process more closely in section 2.
Plants Are Multicellular
 Eukaryotes are organisms that contain many cells.
 No matter how large or small a plant is, its cells are
organized into tissues-groups of similar cells that
perform a specific function in an organism.
 An example would be the vascular tissue that
transports materials throughout the plant’s body.
Plant Cells
 Unlike the cells of some other eukaryotes, a plant’s cells are
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enclosed by a cell wall.
The cell wall surrounds the cell membrane and separates
the cell from the environment.
Plant cell walls contain cellulose, a material that makes the
walls rigid. Cell walls are what make apples and carrots
crunchy.
Plant cells contain structures called chloroplast-where food
for the plant is made.
Plant cells also contain a vacuole or large storage sac that
stores many substances, including water, wastes, and food.
Reading Checkpoint
 What is the function of the vacuole in a plant cell?
The function of a vacuole in a plant cell is to store
substances including water, wastes, and food.
Adaptations for Living on land
 For plants to survive on land, they must:
1.
Have ways to obtain water and other nutrients from their
surroundings (obtaining water and nutrients from the soil
through roots)
2. Retain water (cuticle-waxy, water proof layer that helps a
plant reduce water loss)
3. Transport materials in their bodies (vascular tissue-system
of tubelike structures inside a plant through which water,
minerals, and food are transported)
4. Support their bodies (Rigid cell walls and vascular tissue
strengthen and support the bodies of large plants)
5. Reproduce (Fertilization, when a sperm cell unites with an
egg cell, occurs resulting in a zygote-the fertilized egg)
Reading Checkpoint
 Why do plants need adaptations to prevent water loss?
Plants must have ways of holding onto the water they
obtain, otherwise they could easily dry out due to
evaporation.
Classification of Plants
 Plants are grouped into two major groups-nonvascular
plants and vascular plants.
o Nonvascular plants are plants that lack a well-developed
system of tubes for transporting water and other
materials.
o Vascular plants are plants with true vascular tissue.
Nonvascular Plants
 Nonvascular plants do not have true vascular tissue for
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support or transport. They grow low to the ground.
They obtain water and materials directly from their
surroundings.
The materials then pass from one cell to the next.
This slow method of transport helps explain why most
nonvascular plants live in damp, shady places.
Most vascular plants have only thin cell walls to
provide support.
Three Major Groups of
Nonvascular Plants
 Mosses-Grow in damp, shady places
 Liverworts-Often found growing on moist soil and
rocks
 Hornworts-Usually grow on moist soil, often mixed
with grass plants
Vascular Plants
 Vascular plants are better suited to life in dry areas
than are nonvascular plants.
 Their well-developed vascular tissue solves the
problem of transport, moving materials quickly and
efficiently throughout the plant’s body.
 Vascular tissue also provides strength, stability, and
support to a plant.
 Vascular plants are able to grow quite tall.
Three Major Groups of Vascular
Plants
 Seedless Vascular Plants-Reproduce by making spores
 Gymnosperms-Reproduce by seeds but do not form
flowers or fruit
 Angiosperms-Flower and produce seeds that are
surrounded by fruit
Origin of Plants
 Scientist have posed the question, “Which organisms were
the ancestors of today’s plants?”
 In search of an answer, biologist have studied the fossils of
ancient plants.
 Biologist compared the chemicals in modern plants to
those in other organisms.
o In particular, biologist studied a green pigment called chlorophyll,
found in the chloroplasts of plants, algae, and some bacteria.
o It was found that land plants and green algae contain the same
forms of chlorophyll.
o This evidence led biologist to infer that ancient green algae were the
ancestors of today’s land plants.
Reading Checkpoint
 What is chlorophyll?
Chlorophyll is a green pigment found in the
chloroplast of plants, algae, and some bacteria.
Complex Life Cycle of a Plant
 Plants have complex life cycles that include two
different stages, the sporophyte stage and the
gametophyte stage.
 In the sporophyte stage, the plant produces spores,
tiny cells that can grow into new organisms. A spore
develops into the plant’s other stage, called the
gametophyte.
 In the gametophyte stage, the plant produces two
kinds of sex cells: sperm cells and egg cells.
Plant Life Cycle
Reading Checkpoint
 During which stage does a plant produce spores?
A plant produces spores during the sporophyte stage.
Questions???