Chapter 9 Plants

Ch 9.1 – Overview of Plants A. Plant Cells 1. Unlike animal cells, plant cells have cell walls which provide structure and support

2. Plant cells contain the green pigment chlorophyll which is found in chloroplasts used in photosynthesis 3. Most of the space inside a plant cell is taken up by a large central vacuole that stores water

B. Scientists think that plants probably evolved from green algae in the sea because fossils are similar and both contain chlorophyll

C. Plants adapted to new conditions on land 1. More sunlight & CO2 were available 2. Developed cuticles – waxy, protective layer on the surface of a plant to hold in water

3. Developed cellulose – the chemical in cell walls which give extra support allowing them to stand upright

D. Plant Classification 1. Vascular – have tube-like structures to carry food and water 2. Nonvascular – lack tube-like structures

3. Seed – reproduce by producing seeds 4. Seedless – reproduce without the use of seeds

Ch 9.2 – Seedless Plants A. Seedless Nonvascular – very small plants that have rhizoids rather than roots; water absorbed directly through cell walls 1. grow in damp environments 2. reproduce by spores not seeds

3. Examples: a) Mosses

b) Liverworts

c) Hornworts

4. Frequently pioneer species – organisms that are first to grow in new environments

B. Seedless Vascular – reproduce by spores but do have vascular tissue to carry water and nutrients in the plant 1. Can grow bigger than nonvascular plants 2. Examples:

a) Ferns – have stems, leaves & roots’ leaves are called fronds; spores found under fronds

b) Club Mosses – have needlelike leaves

c) Horsetails – have jointed, hollow stems

C. Importance of seedless plants 1. Fuel – become compressed into peat then coal 2. Soil Conditioners – as they die nutrients from their bodies return to the soil to provide nourishment for next generation of plants

Ch 9.3 – Seed Plants A. Characteristics 1. Have leaves, stems and roots that contain vascular tissue 2. Reproduce by seeds that contain an embryo and stored food

B. Leaves – trap light to make food through photosynthesis 1. Epidermis – thin layer of cells on top and bottom a) upper layer covered by cuticle Cuticle Upper Epidermis Lower Epidermis

b) Stomata – small openings in the lower epidermis that allow for gas exchange (CO2 & O2) and water Stomata

c) Each stoma is surrounded by 2 guard cells that open and close it

2. Palisade Layer – contains chloroplasts to make food

3. Spongy Layer – loosely arranged cells with lots of air spaces; contains tubes of vascular tissue *Diagram p.252

C. Stems – move materials between leaves and roots; usually above ground; may store food; support branches and leaves

1. Two kinds: a) Herbaceous – soft & green b) Woody – hard, rigid, wood

D. Roots – collect water & nutrients from the ground; anchor plants so they don’t blow away; may store food and water

E. Vascular Tissue 1. Xylem – transports water 2. Phloem – transports food 3. Cambium – makes new xylem & phloem

2 Types of Seed Plants: F. Gymnosperms – produce seeds in cones 1. Oldest trees alive 2. Have no flowers 3. Leaves are needlelike – called “evergreens” 4. AKA “conifers” b/c they reproduce with cones

G. Angiosperms – produce seeds in fruit 1. Fruit develops from flowers

2. Two groups: a) Monocots – one cotyledon (food storage space); long leaves with parallel veins; scattered vascular tissue; flower parts in 3’s

b) Dicots – 2 cotyledons; large leaves with branching veins; vascular tissue arranged in a circular pattern; flower parts in 4’s or 5’s

H. Importance of seed plants – wood for construction; paper products; angiosperms provide basis of diets for most animals