Chapter 9Chapter 9

PlantsPlants

Ch 9.1Ch 9.1 – Overview of Plants – Overview of Plants

A. Plant CellsA. Plant Cells

1. Unlike animal cells, plant cells have 1. Unlike animal cells, plant cells have

cell wallscell walls which provide structure and which provide structure and

supportsupport

2. Plant cells contain the green pigment 2. Plant cells contain the green pigment chlorophyllchlorophyll which is found in which is found in chloroplastschloroplasts used in photosynthesisused in photosynthesis

3. Most of the space inside a plant cell is taken 3. Most of the space inside a plant cell is taken up by a large up by a large central vacuolecentral vacuole that stores water that stores water

B. Scientists think that plants probably evolved from B. Scientists think that plants probably evolved from green algae in the sea because fossils are similar and green algae in the sea because fossils are similar and both contain chlorophyllboth 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 3. Developed cellulosecellulose – the chemical in cell – the chemical in cell walls which give extra support allowing them walls which give extra support allowing them to stand uprightto stand upright

D. Plant ClassificationD. Plant Classification

1. 1. VascularVascular – have tube-like structures to – have tube-like structures to carry food and watercarry food and water

2. 2. NonvascularNonvascular – lack tube-like structures – lack tube-like structures

3. 3. SeedSeed – reproduce by producing seeds – reproduce by producing seeds

4. 4. SeedlessSeedless – reproduce without the use of seeds – reproduce without the use of seeds

Ch 9.2Ch 9.2 – Seedless Plants – Seedless Plants

A. A. Seedless NonvascularSeedless Nonvascular – very small plants – very small plants that have rhizoids rather than roots; water that have rhizoids rather than roots; water absorbed directly through cell wallsabsorbed directly through cell walls

1. grow in damp environments1. grow in damp environments

2. reproduce by spores not seeds2. reproduce by spores not seeds

3. Examples:3. Examples:

a) Mossesa) Mosses

b) Liverwortsb) Liverworts

c) Hornwortsc) Hornworts

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

B. B. Seedless VascularSeedless Vascular – reproduce by spores but – reproduce by spores but dodo have vascular tissue to carry water and have vascular tissue to carry water and nutrients in the plantnutrients in the plant

1. Can grow bigger than nonvascular plants1. Can grow bigger than nonvascular plants

2. Examples:2. Examples:

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

b) b) Club MossesClub Mosses – have needlelike leaves – have needlelike leaves

c) c) HorsetailsHorsetails – have jointed, hollow stems – have jointed, hollow stems

C. Importance of seedless plantsC. Importance of seedless plants

1. 1. FuelFuel – become compressed into peat then – become compressed into peat then coalcoal

2. 2. Soil ConditionersSoil Conditioners – as they die nutrients – as they die nutrients from their bodies return to the soil to provide from their bodies return to the soil to provide nourishment for next generation of plantsnourishment for next generation of plants

Ch 9.3Ch 9.3 – Seed Plants – Seed Plants

A. CharacteristicsA. Characteristics

1. Have leaves, stems and roots that contain 1. Have leaves, stems and roots that contain vascular tissuevascular tissue

2. Reproduce by 2. Reproduce by seedsseeds that contain an embryo that contain an embryo and stored foodand stored food

B. B. LeavesLeaves – trap light to make food through – trap light to make food through photosynthesisphotosynthesis

1. 1. EpidermisEpidermis – thin layer of cells on top and bottom – thin layer of cells on top and bottom

a) upper layer covered by cuticlea) upper layer covered by cuticle

Upper Epidermis

Lower Epidermis

Cuticle

b) b) StomataStomata – small openings in the lower – small openings in the lower epidermis that allow for gas exchange epidermis that allow for gas exchange

(CO2 & O2) and water(CO2 & O2) and water

Stomata

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

2. 2. Palisade LayerPalisade Layer – contains chloroplasts to – contains chloroplasts to make foodmake food

Palisade Layer

3. 3. Spongy LayerSpongy Layer – loosely arranged cells with – loosely arranged cells with lots of air spaces; contains tubes of vascular lots of air spaces; contains tubes of vascular tissuetissue

Spongy Layer

*Diagram p.252

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

1. Two kinds:1. Two kinds:

a) Herbaceous – soft & greena) Herbaceous – soft & green

b) Woody – hard, rigid, woodb) Woody – hard, rigid, wood

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

E. Vascular TissueE. Vascular Tissue

1. Xylem – transports water1. Xylem – transports water

2. Phloem – transports food2. Phloem – transports food

3. Cambium – makes new xylem & phloem3. Cambium – makes new xylem & phloem

2 Types of Seed Plants:2 Types of Seed Plants:

F. F. GymnospermsGymnosperms – produce seeds in cones – produce seeds in cones

1. Oldest trees alive1. Oldest trees alive

2. Have no flowers2. Have no flowers

3. Leaves are needlelike – called “evergreens”3. Leaves are needlelike – called “evergreens”

4. AKA “conifers” b/c they reproduce with 4. AKA “conifers” b/c they reproduce with conescones

G. G. AngiospermsAngiosperms – produce seeds in fruit – produce seeds in fruit

1. Fruit develops from flowers1. Fruit develops from flowers

2. Two groups:2. Two groups:

a) a) MonocotsMonocots – one cotyledon (food storage – one cotyledon (food storage space); long leaves with parallel veins; space); long leaves with parallel veins; scattered vascular tissue; flower parts in 3’sscattered vascular tissue; flower parts in 3’s

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

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