Lecture AP Biology Chapter 35 Plant structure, growth, and development

Lecture AP Biology Chapter 35: Plant structure, growth, and development. After completing this chapter, students will be able to: The function of xylem and phloem tissue, the anatomy of a leaf, the anatomy of a root.

Ch 35 Warm-Up

1 Draw and label the 3 main organs of a

plant.

2 What are 3 ways that plant cells differ

from animal cells?

3 Most H2O and minerals taken up from the

soil by a plant are absorbed by _.

4 The main photosynthetic organs of a plant

are the .

Ch 35 Warm-Up

1. List the 3 types of plant tissues What

is the function of each type?

2. What are meristems? Where are they

located in a plant?

3. What effect does “pinching back” a

house plant have on the plant?

Chapter 35

Plant Structure, Growth, and Development

What you must know

The function of xylem and phloem tissue.

The anatomy of a leaf

The anatomy of a root

Produce seeds within a fruit

Key adaptations: flowers & fruits

Plant Organization

•Above ground

•Stems, leaves

•Underground (usually)

A Roots

 Anchors plant, absorbs H2O &

minerals, stores sugars/starches

 Root hairs – tiny extensions of

epidermal cells, increase surface

area for H2O and mineral absorption

 Mycorrhizae: fungus + plant root

symbiotic relationship

Root hairs

Fibrous Root

(scallion)

Taproot (carrot)

Fibrous Roots

 Mat of thin roots spread

just below surface

 Shallow

 Increased surface area

Taproots

 One thick, vertical root

 Many lateral (branch) roots

 Firmly anchors

 Stores food

Modified Roots

Mangrove Forest in Florida

B Stems

Function: display leaves

 Terminal bud: growth concentrated at top end of stem

 Secretes hormone to prevent growth of axillary buds; growth directed

upward, toward light

 Axillary buds – located in V between leaf and stem; forms branches (lateral shoots)

 Pinching/pruning – removing terminal bud

◦ Store food & DNA for new plant

◦ Tuber: end of rhizome

Bulb – underground shoot

◦ Onion

◦ storage leaves

C Leaves

organ

petioleblade

Modified leaves

II Plant Tissues

A Dermal Tissue

Single layer, closely packed cells that cover entire plant

Protect against water loss & invasion

by pathogens (viruses, bacteria)

Cuticle: waxy layer

B Vascular Tissue

Continuous throughout plant

Transports materials between roots & shoots

◦ Xylem & Phloem Phloem

C Ground Tissue

Anything that isn’t dermal or vascular

Function: storage, photosynthesis,

support

Pith: inside vascular tissue

Cortex: outside vascular tissue

III Cell Types

 Conducts sugar & organic compounds

from leaves to other parts of plant

 Living cells aid movement of sugar

 2 Cell Types: sieve tubes,

companion cells

Xylem Phloem

Plant Growth

Types of Flowering Plants:

 Annuals – 1 year life cycle

 Biennials – 2 years

 Perennials – continuous life cycle for many

years

Meristem: perpetually embryonic tissues

◦ Cells divide for plant growth

 Apical meristem: growth at tips of roots & buds of shoots; cause primary growth

(increase length)

 Lateral meristem: growth thickens shoots and roots; secondary growth

Primary and Secondary

Growth

Root Anatomy

Root cap: protects meristem as it

pushes through soil

Zone of Cell Division: apical

meristem; new cells produced (mitosis)

Zone of Elongation: cells elongate;

push root tip ahead

Zone of Maturation: primary

growth becomes functionally mature

Root Hairs

Leaf Anatomy

◦ Epidermis of underside interrupted by stomata

(pores), flanked by guard cells (open/close

Secondary Growth = increase

diameter

Involves lateral meristems

◦ Vascular cambium: produces

secondary xylem (wood)

◦ Cork cambium: produces tough

covering that replaces epidermis

Bark = all tissues outside vascular

cambium

Primary and secondary growth

Vascular cambium Primary phloem

Pith Primary xylem

Vascular cambium Primary phloem

Primary xylem Secondary phloem Secondary xylem First cork cambium Cork

Grow th

0.5 mm

Vascular cambium Secondary phloem

Secondary xylem

Transverse section

of a old Tilia (linden) stem (LM)

three-year-Late wood Early wood

0.5 mm

Cork cambium Cork

Secondary xylem (two years of production)

Cork

Bark Layers of periderm

Most recent cork cambium

Primary and Secondary Growth of a

Stem