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

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 _______.
The main photosynthetic organs of a plant are
the __________.

4.


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



Introduction to Plants
Kingdom: Plantae
 Cell wall
 Autotroph (photosynthesis)
 Multicellular
 Angiosperms (flowering plants)
 ~90% plants
 Produce seeds within a fruit
 Key adaptations: flowers & fruits


Plant Organization

I. Plant Organs
Shoot
system

•Above ground
•Stems, leaves

Root
system

•Underground (usually)
•Roots


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 Roots





Mat of thin roots spread
just below surface
Shallow
Increased surface area

Fibrous Root
(scallion)

Taproots





One thick, vertical root
Many lateral (branch) roots
Firmly anchors
Stores food

Taproot
(carrot)


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


Modified stems


Runner or stolin
◦ Aspen, strawberries, grass
◦ Grow on surface
◦ For asexual reproduction



Rhizome
◦
◦
◦
◦



Iris, ginger, potato, onion
Grow underground
Store food & DNA for new plant
Tuber: end of rhizome

Bulb – underground shoot
◦ Onion
◦ storage leaves


C. Leaves


Function: Photosynthetic organ

blade
petiole


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


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
A.

A.

Xylem
 Conducts H2O and minerals up from root
 Dead, tubular, elongated cells
Phloem
 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
Hairs

Zone of Maturation: primary growth
becomes functionally mature
Zone of Elongation : cells elongate; push
root tip ahead
Zone of Cell Division : apical meristem;
new cells produced (mitosis)
Root cap: protects meristem as it pushes
through soil


Leaf Anatomy
◦ Epidermis of underside interrupted by stomata (pores),
flanked by guard cells (open/close stomata)
◦ Mesophyll: ground tissue between upper/lower epidermis
◦ Parenchyma: sites of photosynthesis