2006-2007

KingdomBacteria

KingdomArchaeabacteria

DomaineEukaryote

Common ancestor

Kingdom: Plants

Photosynthetic Eukaryotes

Plants

• General characteristics• eukaryotes• autotrophs, photosynthetic• cell wall

• cellulose• not mobile

Transition from water to land

Challenges to overcome

Water conservation

Reproduction without water

InternalTransport

Support

Preventing water loss• Cuticle - waxy layer

• Lipids do not dissolve in water

• the cuticle creates a barrier that helps prevent the water in the plant’s tissues from evaporating into the atmosphere

Plant Diversity

Mossesno watertransportsystem(pipes)

Fernswater

transport,no seeds

Coniferspollen &

seeds

Flowering plantsflowers & fruit

seed plants

water transport system

colonization of land

Overcoming challenges = Adaptations• Symbiosis

• Tissues

• Roots/stems/leaves

• Reproduction

• Horomones

Seeds!

Symbiosis• Mutualistic associations played a key role in the

initial occupation of organisms on land• Mycorrihzae (fungi + plant)

• First plants = no roots• Fungi absorbed minerals from rocks• Plants now have access to minerals• Fungi get free food

• Commensalism• Parasitic

Plant Tissue

• All vascular plants have tissues• 3 types• Dermal tissue: covers plant’s entire body; serves to protect• Ground tissue: performs photosynthesis, stores water and carbohydrates,

surrounds and supports the transport tissues• Vascular tissue: conducts water, minerals, nutrients and carbohydrates made

by photosynthesis

Vascular Tissue (vascular bundles)

• Function – transport• Composed of xylem and phloem

• Xylem: made of dead cells; transports water and minerals from the roots up to the leaves

• Phloem: transports nutrients and carbohydrates to other parts of the plant

Roots• Anchor plant in place• Absorb water/dissolved minerals from

environment• Store excess food• Root hairs• Increase absorptive surface area

Leaves• Composed of mesophyll tissue and

veins (vascular tissue in bundles)

• Leaves vary greatly in size and shape

• Function of leaves• Photosythesis/energy production• Gas exchange• transpiration

Leaf – external anatomy

Leaf – internal anatomy

• Main organs of photosynthesis in plants

Vein

Mesophyll

Stoma

Guard Cells

Xylem &

Phloem

Cuticle

Epidermis

Epidermis

Leaf Structures• Cuticle – waxy covering;

prevents water loss through evaporation

• Mesophyll – majority of leaf; contains vascular tissue; photosynthesis • Palisade• Spongy

• Stomata (stoma) – tiny openings on underside of leaf; gas exchange

• Guard cells – control opening and closing of stomata

Leaves and Transpiration

• Transpiration – water loss through evaporation

Stems (shoots)• Function – support & house vascular tissue• Above ground• Main axis of plant• Structural adaptation allow plants to overcome

obstacle of gravity• Connection between roots and leaves

XIII. Reproduction• Seedless

• Spores• Dependent on water for reproduction

• Seed bearing• Seeds• Not dependent on water for

reproduction

Interdependence within plants

• Plant systems are dependent on each other• If one fails, the rest will fail• Roots depend on sugars synthesized by photosynthetic leaves • Stems depend on water/minerals absorbed from soil by roots & sugars

synthesized by leaves• Leaves depend on water/minerals absorbed by roots & support/transport of

stem