Ch 12 Plants Ec

I. What is a plant? A. Plant Characteristics 1. Plants make their own food through photosynthesis a. Chloroplasts contain a pigment chlorophyll that captures suns energy b. Chlorophyll converts CO 2 & water into food (glucose) c. Producers= make their own food

2. Plants have a cuticle to protect them from drying out  Waxy layer that coats the surfaces of the plants 3. Plants have cell walls  Rigid for support & protection

4. Reproduction: 2 stages a. Sporophyte stage= plants make spores b. Gametophyte stage= female gametophytes make eggs and male gametophytes make sperm c. Sperm must fertilize the egg and the fertilized egg grows into a new sporophyte

B. Plant classification Nonvascular plants: plant that doesn’t have specialized tissues to move water and nutrients a. Hornworts, liverworts, mosses b. Depend on diffusion & osmosis to get particles/water from end to end c. Must stay small (short)

2. Vascular plants: has tissues that deliver water and nutrients from one part of the plant to another (xylem & phloem) a. Divided into 3 groups:  Seedless vascular plants= ferns, horsetails & club mosses  Nonflowering seed plant= gymnosperms  Flowering seed plants= angiosperms

Stop and think…What are the 4 main groups of plants?  Nonvascular plant  Seedless vascular plants  Gymnosperms (vascular seed)  Angiosperms (vascular seed)

C. Origin of plants 1. About 440 million years ago plants were thought to have originated from a species of blue-green algae 2. Both:  Contain a pigment (chlorophyll) for photosynthesis  both make their own food through photosynthesis  Store energy as starch  Have a two-stage life cycle

Stop & think  One difference between green algae and plants is that green algae do not have a cuticle. Why don’t they have a cuticle? (think about what the cuticle is need for in plants)  What are some characteristics that green algae and plants share?

II. Seedless plants A. Nonvascular 1. Mosses, liverworts and hornworts: live together in small groups covering soil & rocks a. Have rhizoids that are rootlike and help to keep them in place, get water, & to get nutrients b. They have to be very small b/c they do not have true roots or stems to move water & nutrients

2. Importance of nonvascular plants a. Usually the 1 st plants in the area and can live on exposed rock with little to no soil b. When they die they start to create a new soil and the new plant’s rhizoids hold that new soil in place for larger plants to be able to start growing c. Peat mosses can be used for nesting material, potting soil, and can burn as a fuel source d. Can be a food source

B. Seedless Vascular plants Ferns: a. found from the arctic to tropical forests b. Rhizome: an underground stem that new leaves and roots grow from c. As the new stems sprout they are call “fiddleheads” because of the fronds curl out as they grow

3. Horsetails a. Can grow as tall as 8m but many are smaller b. Early pioneers used them to clean pots & pans so they called them scouring rushes c. Grow in marshy places 4. Club mosses: a. Usually about 20 cm tall b. Grow in woodland places c. Are vascular so they are not “real” moss

5. Importance of seedless vascular plants a. Help form soil b. Prevent soil erosion c. Take over an area after lichens & mosses begin the initial soil d. Lived about 300 mill years ago and now the remains are mined as coal

Stop and think  Imagine a very damp area. Mosses cover the rocks and trees in this area. Liverworts and hornworts are also very abundant. What might happen if the area dries out?

III. Seed Plants A. Two Groups 1. Gymnosperms= tress and shrubs that do not have flowers or fruit 2. Angiosperms= have flowers and seed that are protected by fruit

B. Characteristics of Seed Plants- Why they are almost everywhere on Earth today ! 1. Produce seeds that nourish & protect the young sporophyte 2. Gametophyte of the seed plant are tiny and form within the sporophyte 3. Sperm (male gamete) of a seedless plant needs water to get to the eggs of the female gametophyte  In seed plants sperm is enclosed in pollen that can be transported by wind, animals &/or pollen)

Stop & think  Why are seed plants found almost everywhere on Earth?

C. The Structure of Seeds 1. A seed forms after fertilization when sperm and eggs are joined 2. 3 parts to the seed  Young plant (sporophyte)  Stored food in the cotyledon (seed leaves)  Seed coat= surrounds and protects

3. Advantages of seed plants over seedless plants:  As the seed plant begins to grow it has a stored food source in the seed- spores do not have food  Seeds can be spread by animals and spores are usually spread by the wind

D. Gymnosperms 1. Seeds are usually protected by cones 2. Four groups:  Conifers  Ginkgoes  Cycads  Gnetophytes 3. Wind will carry pollen (sperm) from the male to the female for pollination

E. Angiosperms 1. Flower will attract animals to visit and they may transfer pollen from plant to plant for pollination 2. Wind may also assist in pollination 3. When the animal eats the fruit it will transfer the seeds to different areas

F. 2 types of angiosperms 1. Monocot;  Leaves in groups of 3  One cotyledon (seed leaves)  Veins parallel in the leaves  Bundles of vascular tissues scattered

2. Dicots;  Two cotyledons  Veins usually netlike  Vascular bundles arranged in rings flowers usually in multiples of 4’s or 5’s

G. Importance of angiosperms 1. Food for animals (seeds & berries) 2. Crops corn, wheat, medicines