Roots, Stems, and Leaves

Roots, Stems, and LeavesBiology 11

Organs SystemsPlants have 4 organ system• 3 are vegetative organs•Leaf, stem root• 1 is reproductive•Flower

Roots•Absorb water and dissolved nutrients from soil•Anchor plants to ground•Hold plant upright

Stems•Can be thin and herbaceous or massive and woody•Provide structural support•Water and nutrient transport•Some stems for storage (ex. Potato is a tuber)

LeavesFunction:• Large surface area for receiving sunlight•photosynthesis takes place in mesophyll

• Covered in waxy cuticle

Stomata• Small openings in leaf that open or close•Opening and closing is regulated by guard cells

•Mainly found on the underside of leaves (for land plants)

• Functions:•Open to take in carbon dioxide and release oxygen and water•Close to decrease water loss

Vascular TissueXylem•Carries water and dissolved nutrients from roots to stems and leaves•Provides strength •Made of tracheid Cells•Functioning cells are dead

Phloem• Carry products of

photosynthesis from one part to another

• Main cells are sieve tube elements and companion cells

• Functioning cells are alive

How Water Moves Up to the Leaves• Root Pressure•Roots absorb water that must move up

• Capillary Action•Water movement opposes gravity in small tubes•adhesion (stick to side of tube) and cohesion (stick to each other) of water molecules

• Transpiration from Leaves • evaporation of water causes the pulling of the

next water molecule up to take place