Download Plant Structure

Plant Structure
and Function
Biotechnology II
Essential Question(s)
 Why
are plants important to our
Biosphere?
 What role do key plant structures play in
the growth and development of the
plant?
 How is Biotechnology contributing to
agriculture industry and development of
economically viable plants?
Plants are vital to the Planet’s
Well-Being




Source of food for
animals directly or
indirectly
Provide shelter and
breeding areas for
animals
Roots prevent soil
erosion
Photosynthesis helps
reduce CO2 and raise
O2 in the atmosphere

minimize the effect of
burning fossil fuels causing
rise in atmospheric CO2
Significance to Biotechnology


Biotechnology is
interested in producing
a variety of
economically
important crops with
desirable traits
Accomplished by


Manipulating their
DNA
Putting those desirable
traits into different
plant varieties through
plant breeding, also
known as artificial
selection
Examples of Plant Engineering

Make their own
insecticides
•

Improve nutritional traits
•

High lysine seeds; bcarotene in rice
Improve environmental
adaptation of plants
•

Combat leaf feeding
caterpillars
More drought tolerant,
salt tolerant
Using plants as
bioreactors
•
Plastics, oils, drugs
produced in plants
Plant Body
 Shoots
–divided in
stems and leaves

Conduct
photosynthesis


provide sugar and
other organic nutrients
to roots and nonphotosynthetic tissue
Contain flowers

through sexual
reproduction produce
seeds –lead to next
generation of plants
 Roots

Provides water and
minerals to shoot
 Plants
require both
Roots
 Found
below ground
 Function:


Anchors the plant
Absorbs water and various ion
 Critical


for plant’s nutrition
Stores Food
Produce Hormones
 Chemical
signals that control
plant growth and development
Roots
 Two

Fibrous Root
types
Fibrous
 Highly
branched
 Found close to surface of
soil

Taproot
 One
main root
 Grows deep into soil
 Lateral roots


Branch off main root
Smaller in diameter and
length
Taproot
Root Structure
 Root
Tip –divided
into Four Zones




Root Cap
Region of Cell
Division
Region of Cell
Elongation
Region of
Maturation
Shoot system


Made of leaves,
stem and organs for
reproduction (e.g.
flowers)
Stem- above ground
and supports leaves
and flowers


Nodes – points
where petiole
attach
Internodes- region
between nodes
Function of Stem
 Support
for leaves
 Transports water
and minerals from
roots to leaves
 Transports
carbohydrates
from leaves to nonphotosynthetic
tissue
 Production of
hormones
Buds on Stem

Terminal bud- at top of
stem



Where apical
meristem located
Function of apical
meristem-produce
new stems that
elongate and
causing plant to grow
in height
Axillary bud – present
between petiole and
stem

Develop into lateral
branches or flowers
Apical Dominance
 Terminal
bud synthesizes hormones that
inhibit growth of axillary bud
 Evolutionary adaptation- concentrate
resources on stem growing taller and
increasing plant’s exposure to light
 Remove terminal buds – stimulate growth
of axillary buds
Specialized Stems

Stolons-stems which
grow horizontally at
the soil surface or just
below ground



At nodes form
adventitious roots
At buds form new
plants
Examples
strawberries
 Grasses
 Potato tubers –
modified stolonused for storing
carbohydrates

Specialized Stems

Rhizomes- stem that
is found
underground

Main stem from
plant



Unlike stolons, that
sprout from existing
stem
Roots and shoots
sprout from its nodes
Example

Ginger
Specialized Stems
 Bulbs



Short stems with
fleshy leaves
Function as food
storage organs
Ex. onions
Leaves

Most prominent of
shoot organ




Major light capturing
organ of most plants
Can you think of an
exception?
Where bulk of
photosynthesis takes
place
Attached to a slender
stalk known as the
petiole

Petiole attaches the
leaf to the stem
Leaves Come in Variety of
Forms


Simple leaf- single,
undivided blade
attached to petiole
Compound Leaf –
blade divided into
leaflets


Pinnately compound
– leaflets occurs in
pairs along a central
axis
Palmately
compound – leaflets
radiate from a
common point
Leaves contain Stomata

Stomata are pores in the
leaf


Pores surrounded by
guard cells that causes
the pores to open and
close
Function of stomata

Control water loss from
the plant



Conserve water –stomata
close
Lower plant temperature
– stomata open
Control the uptake of
CO2 for photosynthesis


Need CO2 – stomata
open
CO2 within plant plentiful –
stomata close
Plant Tissues
 Specialized
tissue
and cells found in
plant organs
 Tissues work together
to allow the plant to
complete basic life
functions



Storage of
food/water
Protection
Transport of water,
minerals, and food
Example of Plant Tissues
Tissue
Function
Location
Epidermis
Covering,
protection
Surface of plant
organs
Meristem
Cell division
In shoot / leaf
buds, root tips
Cortex
Water, food
storage
Filling
stems/roots
Xylem
Water/mineral
transport
Roots, stems,
leaf/flower veins
Phloem
Food and sap
transport
Roots, stems,
leaf/flower veins
Parenchyma
Water, food
storage
Filling
stems/roots
Collenchyma
Support
Thick-walled
cells of plant
organs
Meristematic Tissue

To biotechnologists,
particularly
interested in
meristematic tissue –
region where cell
division occurs


Cells divide by
mitosis
From this tissue,
create new shoots
and roots via tissue
culture
Answer the following questions:
1. Why would biotechnology be interested in plants?
2. What is the function of roots, of stems?
3. What role do each of the following parts of the root tip play
in root growth?
 Root cap
 Zone of cell division
 Zone of cell elongation
 Zone of maturation
4. Explain the role of terminal bud, axillary bud found on the
stem.
5. You want to make a plant more bushy rather than tall and
skinny. How would you alter the plant to make that happen?
6. Explain the difference between a compound leaf and
simple leaf?
7. What is the function of stomata?
8. Why is meristematic tissue of significance to
biotechnologists?