Download Plant Cells, Tissues, and Organs

Plant Cells, Tissues, and Organs
Section 2.1
Homework
Pg. 62 #1-4
Chapter 2
Plants: From Cells to Systems
In this chapter you will investigate:
• how plant cells specialize to form different tissues
• the link between cells, tissues, organs, and systems in plants
• the function of plant tissues and organs
• how organs work together to meet the needs of a plant
• diseases that threaten plant tissues and organs
Organization in a multi-cellular organism
Hierarchical levels of organization:
Organism
Most complex
Organ
systems
Organs
Tissues
Cells
Least complex
Specialized plant cells
Heart
muscle cell
Heart muscle
tissue
Heart
Circulatory
system
Zebra
Maple tree
Epidermal cell
simplest
level of
organization
Dermal tissue
Leaf
Shoot system
a collection of
a structure
consists of one
made up of
similar cells composed of two or more organs many different
that perform
or more tissues
and other
organ systems
a particular
working together structures that
working
function
to perform a
work together to
together
complex body
perform a vital
function
body function
• Plant stem cells are
called meristematic
cells.
• Meristematic cells
have the potential to
constantly divide
and differentiate.
▫
▫
▫
▫
photosynthesis
gas exchange
material transport
support
Meristematic cells allow plants to
constantly replace old organs.
All growth in the plant is due to
the division of meristem.
▫ Most occurs at
the terminal bud.
Buds
Regions containing
meristematic cells
Apical meristems
▫ Found in buds at
tips of roots and
shoots.
▫ Responsible for
increase in
height.
Lateral meristems
▫ Responsible for
increase in
width.
Growth is controlled by chemicals called auxins.
▫ Produced by actively dividing cells.
▫ Signal neighbouring cells not to divide.
Plant tissue types
Meristematic tissue
Differentiates into...
Dermal tissue
Vascular tissue
Ground tissue
covers outer surface
moves substances
through plant
supportive tissue
Every plant organ contains
tissue from all three systems.
Dermal tissue
• Plant’s outermost
layer
• Two types:
▫ Epidermal tissue
 thin layer of cells;
covers non-woody
surfaces of plant
▫ Periderm tissue
 covering that forms the
woody surface on
stems/large roots
Adaptations of dermal tissue
Adaptation
Function
Root hairs
Maximize water uptake
Leaf hairs
Contain chemical irritants
Waxy cuticle
Makes surface waterproof
Vascular tissue
• system of tubes
• distributes absorbed water, minerals
and nutrients
Xylem
Phloem
Dead, hollow tissue
Living tissue
Transports water
and minerals
upwards from roots
Transports sugars
produced by leaves,
to the rest of the plant
Non-woody plant
Woody plant
Vascular tissue
arranged in bundles
Vascular tissue forms a ring
along trunk diameter
Ground tissue
• “Filler” tissue between dermal and vascular
• Variety of functions:
▫ photosynthesis, in the green parts of plants
▫ storage of carbohydrates in the roots
▫ storage and support in the stems
Plants have two organ systems
SHOOT SYSTEM
Stem, leaves,
flowers, fruit
(if present)
ROOT SYSTEM
One or more
separate roots
The Root System
Functions:
• anchor the plant
• absorb water and minerals from
soil
• store food
Structure:
•
•
•
•
no leaves
usually grows below ground
composed of dermal tissue
root hairs maximize surface
area
Spaces between cortex cells allow water
to move from soil to the endodermis.
Endodermis controls
transport of water
and minerals between
cortex and xylem.
Types of roots:
Taproots vs. Fibrous roots
The Shoot System
Functions:
•
•
•
•
carry out photosynthesis (leaves)
structural support
transport substances throughout plant
produce flowers for sexual reproduction
Structure:
• usually above
ground
• components:
▫ leaves
▫ stem
▫ flowers/fruit
Leaves
Main site of photosynthesis:
CO2+ H2O + light energy ___________+ O2
• chloroplasts contain chlorophyll; absorb
sunlight’s energy
• glucose is used for
cellular respiration,
plant growth, and
energy storage
Layers of the Leaf
Epidermis
Transparent outer layer, made of dermal
tissue.
▫ The upper epidermis secretes waxy cuticle.
▫ The lower epidermis contains stomata (holes)
for exchange of gases ((H2O, O2, CO2).
 opening/closing of stomata is controlled
by guard cells
Mesophyll
Middle layers, sandwiched between upper and
lower epidermis
▫ Palisade cells – Perform most of the
photosynthesis in the leaf
 contain many chloroplasts
 tightly-packed together
▫ Spongy parenchyma cells – Loosely-packed
 to allow the movement of gases within the leaf
Vascular bundles
Composed of vascular tissue (xylem and phloem)
▫ arranged in bundles
▫ visible on the leaf as veins
Chloroplasts
• membranebound organelle
• contains more
membranebound sacs
(thylakoids)
• thylakoids are
arranged in
stacks (grana)
Leaves have structures that help the plant obtain
and keep the reactants for photosynthesis:
CO2+ H2O + light energy  glucose + O2
Spongy
parenchyma is
loosely-packed to
allow gases to
circulate to all
photosynthesizing
cells.
Guard cells
close the
stomata on hot
days to prevent
evaporation of
water.
Cuticle is transparent
to let light through.
Palisade cells are
tightly-packed to
maximize the area
exposed to the Sun.
The Stem
• Functions:
▫ Support for shoot system
▫ Transport of nutrients and water to leaves
• Specialized stems: Food storage, protection,
photosynthesis, reproduction
• Uses: sugar cane, medicines, cork, wood and
paper
Flowers
• Contain reproductive structures (male/female/both)
Organ
Gamete
Male
Female
Stamen
Carpel/Pistil
Pollen grains
Eggs
• Fertilization occurs by pollination,
and produces seeds.
▫ contained in the fruit
• Pollination can be assisted
by wind, animals, or insects.
Flowers: Adaptations
To attract pollinators,
plants will have attractive
flowers or nectar.