Apical bud

Node

Node

Leaves

Internode

Axillary bud

Branch

Stem

Sh

oo

t s

ys

tem

Ro

ot

syst

em

Lateralroots

Sunlight

CO2

Water

Taproot

Nutrients(such as N, P, K)

Plants:

photosyntheticmulticellularautotrophswith cellulosic cell walls

Growing points Meristems

Plant traits:

longitudinal section of stem apex

longitudinal section of root tip

Cross sections:

Dermal tissuesystem (brown)

Ground tissuesystem (gray)

Vascular tissuesystem (red)

Dermal tissuesystem (brown)

Ground tissuesystem (gray)

Vascular tissuesystem (red)

Meristematictissue

Leaf

Stem

Root

Meristematictissue

Ro

ot

syst

emS

ho

ot

syst

em

(a) Plant cells have unique organelles:cell walls, vacuoles, and chloroplasts;and other organelles in common withanimal cells:

Cell wall

Plasmamembrane

Vacuole

Chloroplast

MitochondrionGolgi apparatus

Plasma membrane

Smooth endoplasmic reticulum

Rough endoplasmic reticulum

Cell wall

Cell wall

Smooth ER

Plasmodesma

Plasma membrane

Cell 2

Cell 1

(b) Adjacent plant cells are connectedby plasmodesmata.

Primarycell wall

Plasmamembrane

Side view

50 nm

Cellulosemicrofibrils

Top view

Cross-links

Pectin

1 m

Plant cells are bounded by a cellulosic cell wall.

Most cells have only primary (1st) walls: Woody cells have secondary walls:cellulose, hemicellulose, pectin, proteins including lignin, and many layers of

cellulose microfibrils

Functions of cell walls: