Exploring Life Science
Chapter 8
Plants
Chapter 8 – Plants
Engage:
What are some seeds you eat?
Objectives:
1. Identify the characteristics that seed plants share.
2. Explain how seeds become new plants.
3. Describe the function of roots, stems, and leaves.
8-3 : The Characteristics of Seed Plants
A. What is a Seed Plant?
1. Out number seedless plants 10 to 1
2. Vascular Tisses
 Phloem – carry food.
 Xylem – carry water & minerals.
3. Pollen & Seeds
 Pollen – becomes sperm cells.
 Seed – Contains young plant inside a
protective covering.
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Exploring Life Science
Chapter 8
Plants
B. How Seeds Become New Plants
1. Inside a seed is a partially developed plant. If a
seed lands in an area where conditions are
favorable, the plant sprouts out of the seed &
begins to grow.
2. Seed Structure – 3 Parts
 Embryo – Young plant that develops from the
Zygote. Embryo has roots, stems & leaves.
 Stored food – Used by embryo until plant can
make there own food.
Cotyledons – “Seed Leaves” – can be stored
food.
 Seed Coat – Outer covering of a seed. Acts
like plastic wrap- protecting the embryo &
keeps food from drying out.
Eg. “Skin” of lima beans & peanuts
3. Seed Dispersal - Scattering of seeds.
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Wind -- (i.e., dandelion, maples)
Animals – Burdock, Hitch- hikers
Animals – Eat fruits – cherries or grapes.
Water -- Coconut
Explosion -- Impatiens
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Exploring Life Science
Chapter 8
Plants
4. Germination – Seed begin to grow.
 Begin by absorbing water.
 Seedling – What plants are called once you
see their leaves.
C. Roots
1. Function
a. Anchor in ground
b. Absorb minerals
c. Store food
2. Root Systems
a. Fibrous Roots -- Several main roots branch
repeatedly to form a tangled mass of thin
roots. (i.e., grass, corn, trees).
b. Taproot -- Long, thick main root and thin
branching roots.
(i.e., carrots, cacti & dandelions)
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Exploring Life Science
Chapter 8
Plants
3. Structure
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Exploring Life Science
Chapter 8
Plants
a. Epidermis
(epi = upon dermis = skin)
Outermost layer of the root.
b. Root hairs -- Hair-like extensions on
epidermis.
c. Cortex -- Store food, carry water and
dissolved minerals into the center of the
root.
d. Root Cap -- Protects the tip of the root.
e. Growth Tissue -- Where new cells are
formed.
4. Uses
a. Food -- Carrots, beets, yams & turnips.
Tapioca -- From root of cassava - starchy
lumps in certain puddings & baby food.
Marshmallows -- Root of Marsh Mallow
plant.
Roasted Chicory and Dandelion
Roots -- Sub. for coffee.
Licorice, horseradish & sassafras for
spices.
b. Medicines
c. Dyes
d. Insecticides
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Exploring Life Science
Chapter 8
Plants
D. Stems
1. Function
a. Transportation between roots and leaves –
(xylem & phloem).
b. Support -- Hold in air enabling leaves to
receive sunlight & make food.
2. Two Groups
a. Herbaceous -- Stems green & soft.
(i.e., sunflowers, peas, grass, tomatoes).
b. Woody -- Wood – hard substances. Made
of layers of xylem (i.e., roses, maples &
firs).
3. Structure
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Exploring Life Science
Chapter 8
Plants
a. Outer bark -- Protects.
b. Inner bark -- Phloem – transports food.
c. Vascular Cambium -- growth region
produces xylem & phloem.
d. Sapwood -- Active xylem -- transport
water & mineral.
e. Heartwood -- Clogged xylem -- support.
f. Pith -- Store food & water (center)
g. Rings -- Layer of xylem.
1 dark ring -- summer growth
1 light ring -- spring growth
1 year of growth
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Exploring Life Science
Chapter 8
Plants
4. Use
a. Wood
b. Food -- Potatoes, onions, ginger &
sugar cane.
c. Dyes
d. Medicine
e. Wicker Furniture
E. Leaves
1. Types
a. Simple -- blade is 1 piece.
(i.e., maple, oak & apple)
b. Compound -- blade divided into a
number of separate, leaf-like parts.
(i.e., rose, clover & palm).
2. Function
a. Photosynthesis -- food-making process
photo = light
synthesis = put together
Chlorophyll -- captured sun’s light
energy.
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Exploring Life Science
Chapter 8
Plants
sunlight
Carbon dioxide + water
glucose + oxygen
chlorophyll
sunlight
6CO + 6H2O
C6H12O6 + 6O2
chlorophyll
4. Structure
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Exploring Life Science
Chapter 8
Plants
 Epidermis -- Outermost layer - waterproof
coating.
 Mesophyll -- Inner cells
meso = Middle
phyll = Leaf
Where photosynthesis occurs
 Stomata -- Microscopic opening in the epidermis.
CO2 enters here
O2 & H2O exits
stoma = mouth
guard cells -- open & close stomata.
Control transpiration - loss of H2O.
4. Uses
a. Food
b. Drugs – Digitalis, atropine & cocaine.
c. Poisons -- Strychnine & nicotine.
d. Dyes -- Indigo & henna.
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