Plant Cells, Tissues and Organs

Cell Specialization & Cell Differentiation

http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookplantanat.htmlhttp://www.emc.maricopa.edu/faculty/farabee/biobk/

biobookplantanat.html

http://earthsky.org/human-world/nate-lewis-on-artificial-photosynthesis http://www-plb.ucdavis.edu/labs/rost/tomato/Roots/rootcell.html

Specialized Cells & Tissues in PlantsTissue: group of specialized

cellsOrgan: Group of several types

of tissues working towards a specific function

Meristem: unspecialized cell that can form specialized cells in plants

Tissues in Plants

Repairing & Replacing Specialized Cells

Buds: Swelling of the stem◦ Terminal Bud –

most active growth, produce Auxin

◦ Lateral Bud – dormant regions, inhibited by Auxin

Plant OrgansLeafStemRootFlower

The LeafDermal tissuePalisade

tissueMesophyll

tissueVascular

bundles

The Leaf – TissuesDermal tissue

◦ Waxy cuticle – limits water loss◦ Protects the leaf

Palisade tissue◦ Prime site of photosynthesis – palisade cells and

chloroplastMesophyll tissue

◦ Loosely packed cells◦ Spaces contain gases such as H2O, CO2 and O2

Vascular tissue◦ Xylem – transports water to the photosynthesizing cells◦ Phloem – transports sugar throughout the plant◦ Small vein branches – every cell gets water and

nutrients

The Leaf – Lower epidermisExchange of gasesGuard cells

◦ Control opening and closing of stomataStomata

◦ Connected to spongy mesophyll◦ CO2 enters, O2 and H2O exits through them

Transpiration – evaporation of water from leaves

Chloroplast

The StemProvides physical

support and transports sap

Composed mainly of xylem tissue◦ Dead tubular hollow

cells fortified with lignin

Vascular bundle◦ Phloem (living porous

cells) exchanges materials with neighbouring cells

The RootsAnchor a plant to

the ground

Allow water and minerals uptake from the soil

Some also act as plant’s storage area

The RootsDermal tissue

◦ Root hair – increase surface area for absorption

Ground tissue ◦ Cortex – provide

support◦ Pericycle –

vascular tissue

Types of Roots

Fibrous root• Large surface

area to absorb water

• Stabilize soil• Prevent erosion

& landslides

Tap root• Allows plant

to reach far underground for water

• Anchors the plant

Plants Under Attack

The FlowerReproduction - pollen

and eggsPollination: transfer of

pollen to female parts of flower

Seeds are produced and embedded in fruits

Hormone called ethylene stimulates ripening of fruits

Homework P. 69 # 1, 3, 5 - 7