Download LS Ch. 8 Sec. 3 Notes

Ch. 8 Sec. 3-The Characteristics of Seed Plants
What is a Seed Plant?
*3 main characteristics:
1. Vascular Tissue
2. Use pollen and seeds to reproduce
3. Have true body plans (roots, stem, leaves)
*Like seedless plants, seed plants have sporophyte and gametophyte stages.
Vascular Tissue
*Most seed plants live on land so they need vascular tissue to:
-Support plant
-Transport food and water
*There are 2 types of vascular tissue:
1. Phloem: tissue that transports food
2. Xylem: tissue that transports water and other nutrients.
Pollen and Seeds
*Pollen: tiny structures that contain the cells that will later become sperm cells
*After sperm cells fertilize the eggs, seeds develop.
*Seed: structure that contains a young plant inside a protective covering
How Seeds Become New Plants
**Inside a seed is a partially developed plant.
**If a seed lands in an area where conditions are good, then the plant sprouts out
of the seed and begins to grow.
Seed Structure
*A seed has 3 main parts:
1. Embryo: young plant that develops from zygote
2. Stored food: young plants use this food to help them grow before they
become autotrophs
3. Seed coat: protects embryo and its food from drying out.
*Seeds are surrounded by a fruit structure.
Seed Dispersal
*Scattering of seeds from its original location.
*3 methods:
1. Dispersal by Other Organisms
-Animals eat fruits, digest the seeds, and deposit them in new areas
through their waste.
-Barb-like structures attach themselves to animals and humans and get
scattered elsewhere.
2. Dispersal by Water
-Seeds get scattered around from falling into oceans or rivers.
3. Dispersal by Wind
-Wind blows seeds away.
Germination
*Embryo begins to grow and pushes out of the seed.
Step 1: seed absorbs water from environment
Step 2: embryo uses stored food to grow
Step 3: Roots grow first, downward
Step 4: stem and leaves grow outward
*When you can see a plant's leaves, its called seedling.
Roots
**Roots anchor a plant in the ground, absorb water and minerals from soil, and
sometimes store food.**
Types of Roots
*2 types of root systems:
1. Fibrous Root System
-consists of many regular sized roots that form a dense, tangled mass
-easy to pull out the ground
ex: grass, corn, onion roots
2. Taproot System
-has 1 long, thick main root with small root-like branches
-hard to pull out of the ground
ex: carrots, dandelions, and cacti
The Structure of a Root
*Root cap: protects root from injury
*Root hair: absorbs water and
minerals; anchors plant in soil
Stems
*The stem carries substances between the roots and leaves
*The stem provides support for the plant
*The stem holds up the leaves so they are exposed to sun
Stem Structure
*2 types of stems:
1. Herbaceous: contain no wood and are soft
ex: Coneflowers and pepper plants
2. Woody: hard and rigid
ex: Maple trees and roses
Annual Rings
*Represent a tree's yearly growth
*Made from the vascular tissue, xylem
*Light, thick rings are made in the summer
*Dark, thin rings are made in the winter
-A pair of dark and light rings = 1 year of growth
*More rain = thicker rings
*Less rain = thinner rings
Leaves
*Leaves capture the sun's energy and carry out the food-making process of
photosynthesis
The Structure of the Leaf
*Look at Figure 16 on page 270
The Leaf and Photosynthesis
*Chloroplast cells are located near surface of leaf to gain most sunlight
Controlling Water Loss
*When water evaporates from a plant's leaves is called transpiration
*Plants have cuticles and stomata to help control water loss