Download “The Root of the Problem” or “Stem the Tide” or “Leaf Me Alone”

“The Root of the Problem” or “Stem the Tide” or “Leaf Me Alone”
Roots
 Anchor plant to soil.
 Absorb water (by diffusion) and nutrients (N, P, K) (by active
transport) from soil.
Root Adaptations for function
 Taproot—a long main root to reach deep for water. Also
stores nutrients for dormant periods. Example: trees,
dandelion, carrot.
 Fibrous roots—shallow spreading roots. Gather water
quickly in dry areas. Examples: grass, corn
 Epidermis—has root hairs (increase surface area) and is
hypertonic compared to soil to draw in water (root pressure.)
Stems
 Hold leaves up for sunlight.
 Transport food and water.
Tissues of “woody” stems (from outside to in)
 Cork cambium (bark)—protect stem and prevent drying out.
 Food transport—occurs in the phloem. Phloem cells have
partially broken end walls and are also called sieve tubes.
 Water transport—occurs in the xylem. Xylem cells grow end
to end, but the connecting cell walls die, leaving hollow tubes.
Capillary action helps draw water up to leaves.
 Dead xylem and “pith” make heartwood (strong center of
stem)
Leaves
 Absorb sunlight for photosynthesis.
 Control transpiration (movement of water from roots to
leaves drawn by evaporation).
Tissues of leaves (from outside to in)
 Cuticle—waxy covering to keep water in.
 Epidermis—contains stomata, which are openings to
allow air into the leaf. Stomata can be closed by guard
cells when the leaf is drying out.
 Mesophyll—contains chloroplasts and veins. Veins are
xylem and phloem tissue. Mesophyll must remain moist
for gas exchange and photosynthesis to occur.