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Chapter 12 Notes- Plants
I.
What is a Plant?
A. Most plants share common characteristics
B. Photosynthesis
1. Plant cells contain a chemical pigment called chlorophyll
2. They may also contain other pigments called carotenes
(colors like orange, yellow and red)
3. Chlorophyll is found in chloroplasts- organelles in a plant
cell
4. Formula for photosynthesis- CO + H O + sunlight =
Sugar + O
5. Since plants make their own food, they are known as
producers
C. Cuticles
1. Most plants live on dry land and require water to survive.
2. Plants don’t dry out because of a waxy layer that coats
most of the surfaces of plants exposed to air.
D. Cell Walls
1. Since plants don’t have skeletons, they rely on cell walls
to keep them upright.
2. Cell walls are found outside the cell membrane
3. Cell walls support and protect the plant cell
E. Reproduction
1. Plants have a 2 stage life cycle
a. Gametophyte stage
i. Refers to the sperm and egg cells
ii. females produce eggs (Gamete)
iii. males produce sperm. (Gamete)
iv. sperm and egg join to produce a sporophyte
b. Sporophyte stage
i. Formed when 2 gametes come together
ii. Makes gametophytes
Gametophyte
Stage- Egg and
Sperm
Sporophyte
Stage- Plant
F. Classification
1. Plants are sorted into 2 main groups
2. Nonvascular Plants
a. Plants that do not have specialized tissue to move
water and nutrients through the plant
b. They depend on diffusion to move water from one area
to another.
c. Diffusion- the movement of a substance from an area
high concentration to an area of low concentration
d. These plants must be small
e. Lack true stems, leaves and roots
f. Ex. Mosses, liverworts and hornworts
3. Vascular Plants
a. Plants that have specialized tissues to deliver water and
nutrients through the plant
b. Since water and nutrients can be transported
throughout the plant, they can grow to be almost any
size.
c. divided into 3 groups
i. Seedless vascular plants
ii. Nonflowering seed plants called gymnosperms
iii. Flowering seed plants called angiosperms
II.
Seedless Plants
A. Nonvascular Plants
1. Examples- Mosses, liverworts and hornworts
2. Have no vascular tissue
3. Each cell must get water from the environment, so they
must remain small
4. Usually the first plants in a new environment
5. They form a new layer of soil when they die to support
other plants.
6. Require water for reproduction
B. Seedless Vascular Plants
1. Examples- Ferns, horsetails and club mosses
2. Usually fairly small, although they are larger than
nonvascular plants
3. Many release spores which grow into sporophytes
4. Require water for reproduction- sperm need water to
swim to the eggs.
C. Seed Plants
1. Characteristics
1. Produce seeds which nourish and protect young
plants
2. Gametophytes are formed inside the reproductive
structures of the sporophyte
3. Sperm is formed in structures called pollen and
does not need water to get to the egg
2. Most common plants on Earth today
3. Seeds
1. A seed forms after fertilization when sperm and
egg join
2. Made of 3 parts
a. Young plant (sporophyte)
b. Stored food (often found in the cotelyedons
which are the seed leaves of the yound plant
c. Seed Coat- surrounds and protects the young
plant
3. Seeds help plants
a. Seeds can be transported farther by animals
b. Young plants can use the stored food to
grow
4. Gymnosperms
1. Seed plants that do not have flowers or fruits
2. Seeds are usually protected by a cone
3. 4 Groups
a. Conifers
b. Cycads
c. Ginkoes
d. Gnetophytes
5. Gymnosperm Reproduction
1. There are two kinds of cones in gymnosperms,
male and female.
2. Male cones contain sperm
3. Female cones contain eggs
4. The transfer of pollen from the male reproductive
structures to the female reproductive structures is
called pollination
5. Once the egg is fertilized, a seed develops with the
young plant inside
6. Angiosperms
1. Vascular plants that produce flowers and fruits
2. Most abundant plant
3. Pollination
a. Angiosperms use wind, insects, animals, etc.
to help carry pollen from flower to flower
b. Fruits surround and protect seeds
4. 2 kinds
a. Monocots
i. Leaves with parallel veins
ii. Flower parts in 3’s
iii. One cotyledon in seeds
iv. Bundles of vascular tissue scattered in
the stem
b. Dicots
i. Leaves with branching veins
ii. Flower parts in 4’s or 5’s
iii. Two cotyledons in seeds
iv. Bundles of vascular tissue in rings
III.
Structures of Seed Plants
A. Seed plants have 2 kinds of vascular tissue
1. Xylem
1. Transports water and minerals from the roots to the
shoots (shoots refers to stem and leaves)
2. “Zip up the xylem”
2. Phloem
1. Transports food molecules to all parts of the plant
from the site of photosynthesis (leaves)
2. “Flow down the phloem”
B. Roots
1. Supply plants with water and dissolved minerals that are
absorbed from the soil
2. Roots hold plants securely in the soil
3. Store surplus food made during photosynthesis- stored as
sugar or starch
4. Structure
1. Epidermis- layer of cells that covers the surface of
the roots
2. Root hairs- increase surface area of the root to
enable it to absorb more water
3. Root cap- roots grow longer at the tip, so the root
cap protects the tip of the root and produces a
slimy substance that helps it slide through the soil.
5. Root systems
1. 2 kinds
a. Taproot
i. one main root, like a carrot
ii. Found in dicots and gymnosperms
b. Fiberous root
i. several roots that spread out from the
base of the plants stem- like a
dandelion
ii. Found in monocots
C. Stems
1. Usually found above ground
2. Support the plant body, hold up leaves and flowers
3. Transport materials between the root system and leaves
4. Some store materials
5. 2 Kinds
1. Herbaceous Stems
a. Soft, thin and flexible
b. Ex. Bean plants, tomato plants
2. Woody Stems
a. Rigid stems made of wood and bark
b. Ex. Trees
D. Leaves
1. Vary greatly in shape
2. Main function is to produce food for the plant
3. Structure
1. Outer surfaces are covered by a cuticle which
prevents water loss.
2. Epidermis- single layer of cells that lies beneath
the cuticle
3. Stomata- openings in the epidermis that can open
and close to let carbon dioxide in.
E. Flowers
1. Flowers are adaptations for sexual reproduction
2. Flowers purpose is to attract pollinators
3. Smell, shape, color and nectar attract pollinators and
carry pollen to other plants
4. Parts of a flower
1. Sepals- outermost leaves of a flower, protect the
flower bud
2. Petals- broad, flat, thin, leaflike parts of a flower
3. Male parts
a. Stamen- composed of
i. filament- thin stalk that holds up the
anther
ii. anther- sac-like structure that
produces pollen
4. Female parts
a. Pisil- composed of
i. Stigma- tip of the pistil, often sticky,
where pollen is collected
ii. Style- long, slender portion of the
pistil
iii. Ovary- rounded base of the pistil,
where eggs are contained in ovules