Transcript The Characteristics of Seed Plants Chapter 8 Section 3 What is a

CHAPTER 8 SECTION 3
THE CHARACTERISTICS OF SEED PLANTS
WHAT IS A SEED PLANT?
• Seed plants outnumber seedless plants
• Produce much of the oxygen we breathe
• All seed plants have roots, stems, and leaves
• The plants that you see are the sporophytes, the
gametophytes are microscopic
• 2 important characteristics
• Vascular tissue
• Use pollen and seeds to reproduce
VASCULAR TISSUE
• Helps support plants
• Food, water, and nutrients are transported through
the plant
• Two types of vascular tissue
• Phloem: tissue through which food moves
• Xylem: tissue through which water and minerals move
POLLEN AND SEEDS
• Do not need water for sperm to swim to eggs
• Instead, seed plants produce POLLEN
• Tiny structures that contain cells that will later become
sperm cells
• Pollen delivers sperm cells directly near
eggs…fertilization occurs…seeds then develop
• Seed
• A structure that contains a young plant inside a protective
covering
HOW SEEDS BECOME NEW PLANTS
• Inside a seed is a partially developed plant
• Seed lands in favorable area, the plant sprouts out
of the seed and begins to grow
• Seeds need light, water, and nutrients to grow
SEED STRUCTURE
• Three main parts
• Embryo
• Young plant that develops from the fertilized egg (zygote)
• Cotyledon
• A seed leaf that sometimes stores food
• Seed coat
• Keeps the seed from drying out
• Acts like plastic wrap
• In many plants, the seeds are surrounded by a
structure called a fruit
SEED DISPERSAL
• Animals
• Seeds pass through animal’s digestive
system and are deposited in new
areas
• Barblike structures hook onto an
animal’s fur
• Water
• Seeds that fall into oceans and rivers
• Wind
• Disperse light weight seeds
(dandelions and maple trees)
• Shooting out of a plant
GERMINATION
• Occurs when the embryo begins to grow again and
pushes out of the seed
• Seed absorbs water from environment
• Seedling
• When you are able to see a plants leaves
• Better chance of living when seedling is far away from parent
ROOTS
• Anchor a plant into the ground
• Absorb water and minerals from the soil
• Sometimes store food
TYPES OF ROOTS
• Fibrous root system
• Similarly sized roots that form a dense, tangled mass
• Take much soil with them when pulled out of ground
• Lawn grass, corn, onions
• Taproot system
• One long, thick main root
• Carrots, dandelions, cacti
THE STRUCTURE OF A ROOT
• Root cap
• Protects the root from injury during growth
• Root hairs
• Increase the amount of water and minerals absorbed by
the root
• Water and nutrients are absorbed from the soil and
move quickly to the xylem
• Phloem transports food manufactured in the leaves
to the root
STEMS
• Carries substances between the plant’s roots and
leaves
• Support the plant and holds up the leaves so they
are exposed to the sun
THE STRUCTURE OF A STEM
• Two types
• Herbaceous
• Woody
HERBACEOUS
• Contain no wood and are soft
• Coneflowers and pepper plants
WOODY
• Hard and rigid
• Outermost layer is bark
• Cambium
• Produces new cells which divide to produce new phloem
and xylem
• Sapwood
• Active xylem that transports water and minerals
• Heartwood
• Old, inactive, xylem that provides support to
• Maple trees and roses
ANNUAL RINGS
• One year’s growth of a tree is represented by one
pair of light and dark rings in the tree’s stem
• Page 269
LEAVES
• Capture the sun’s energy and carry out the foodmaking process of photosynthesis
THE STRUCTURE OF A LEAF
THE LEAF AND PHOTOSYNTHESIS
• Cells that contain the most chloroplasts are located
near the leaf’s upper surface
• Chlorophyll in the chloroplasts traps the sun’s
energy
CONTROLLING WATER LOSS
• Transpiration
• Process by which water evaporates from a plant’s leaves
• Plants retain the water by closing the stomata