Download Thursday, February 23rd

Thursday, February 23rd
Plant Growth and Structure
The Plant Body
• The plant body is divided into two main parts
• 1. Roots: Anchors plants in the ground and
absorbs water and minerals
• 2. Shoots: above ground framework for leaves,
flowers, and fruits
Two form of Root Systems
• Taproot
• Fibrous Root System
Taproot
• Large central root (primary root) off which
smaller roots (lateral roots) grow
• Taproots have small surface area so they are
not as effective at absorbing water and
nutrients
• However, the large root can store nutrients
and water – Think of a CARROT
• Advantage to plants that grow in regions of
minimal water
Taproot
Fibrous Root System
• Composed of a diffuse system of roots, no
single main root
• Greater surface area and extends further
absorbing more water and nutrients
• Ex: ferns and grass
Fibrous Root System
Root System Parts & Functions
• Primary Root - Central root of plant,
extending from the stem
• Lateral roots - Roots growing directly
off the primary root
• Root Hairs - Hairs that extend from
the root and greatly increase surface
area
Apical Root Meristem
• Apical Root Meristem Cell growth at the tip of
the primary root, required
for growth of the plant
body
• Root Cap – protects the
root, these cells are
sloughed off and replaced
as the root moves through
the soil
• Meristem Cells
are not
differentiated
yet – they are
like stem cells
for plants
• When they
divide, they
produce
another
meristem cell
and a
differentiated
cell
Types of Growth
• Primary growth – results in
increase of length (height in
shoots, depth in roots)
• Secondary Growth – result in
increase of diameter
Vascular Tissue (in roots and shoots)
• Cells arranged to form tubes through which
water and nutrients can flow through the
plant
• Two Types:
– Xylem conveys water and minerals up the
root
– Phloem conveys the product of
photosynthesis down from the leaves
Structures in the Stem
• The stem provides structural support
for the plants leaves, flowers, and
fruits
• Nodes - the point where the leaves are
connected to the stem
• Internodes – stretches of stem
between the nodes
Structures in the Stem
• Terminal Buds - Underdeveloped
shoot at the tip of a stem
• Auxiliary buds - Underdeveloped
shoot where petiole (joins stem to
leaf) meets the stem
• Apical Shoot Meristem - Cell growth
at the tip of the stem
Leaf Structure
• Leaf - primary site of photosynthesis.
Includes petiole
• Cuticle -waxy coating on plants that
prevent water loss and also protects
the plant from bacteria & viruses
• Stomata - tiny pores in the leaves
surface that allows substances (water,
oxygen, carbon dioxide) to pass
through the plant
Stoma (singular
for Stomata)
Guard
Cell
Guard Cell
• Guard Cell – sausage-shaped cells that look
like a mouth. They control whether the
stomata is open or closed
Page 730 In Your Book
• There is a diagram of a plant body I want
you to sketch in your journal.
• You should label the following structures:
• “Shoot Apex” and “Root Apex” where
Apical Meristem cells are located
• Node, Internode, Leaf, Petiole, Primary
Root, Lateral root, Root System, Shoot
System
Pg 730
Auxin promotes elongation
Gravitropism
Gravitropism
Gibberellin
Ethylene
• Bananas are picked when they’re green so
they are easier to ship.
• Once they reach a storage location close to
where they’re going to be sold, they are
artificially ripened using Ethylene
Pg 730