Biology- Plant Biology

What is the external structure of a plant

shoots and roots

Shoots

• located above ground

• stems/ leaves/ flowers/ fruit

Roots

• located below ground

• anchor plants to the soil

• hairs absorb water and minerals

• store food

Zones in the longitudinal section of a plant

• zone of protection

• meristematic zone

• zone of elongation

• zone of differentiation

Zone of protection

root cap protects the root as it pushes through the ground

Meristematic zone

• plant grows rapidly with mitosis, creating new root tissue

• located at root and shoot tips

Zone of elongation

• small stems formed by meristem elongate

• stimulated by plant growth regulators

Zone of differentiation

• identical elongated cells develop into different tissues

• dermal, vascular or ground

• water absorbed through root hairs

Tissues in the transverse section

• dermal

• vascular

• ground

Dermal tissue

protective covering around plant epidermis and root hair

Vascular tissue

used for transport

• xylem transports water and minerals UP

• phloem transports food UP and DOWN

Ground tissue

• fills empty space between other tissue

• storage and chemical reactions eg. photosynthesis takes place

Structure of stems

• herbaceous plants have no wood/ligin

• woody plants have ligin

• cell walls contain cellulose

Functions of stems

• supports aerial parts (leaves, flowers)

• transports materials between leaves and roots

• stores food eg. potato

Parts of the stem

• internode

• terminal/ apical bud

• meristem

• auxilary/ lateral bud

• lenticels

• leaf scars

What is the internode

the part of the stem between two nodes

Where is the terminal/apical bud

at the tip of the stem

Where is the meristem

on the apical bud

Function of the meristem

allows upward growth

Function of auxilary bud

makes new growth, eg. flowers

What are lenticels

pores in the stem for gas exchange, eqivalent of leaf stomata