Download Plant Cells, Tissues, and Systems

Plant Cells,
Tissues, and
Systems
Sec C3.1
Unit C
Objectives
• describe the specialized structures and
functions of cells in the leaf system
• explain the transport system in plants
• relate a multi-cellular level of organization with
cell, tissue, and system specialization
Multicellular vs
Unicellular
• What are the advantages to having a large
structure with lots of cells?
• Division of Labour
• When a cell is specialized (performs a
particular function), it is more effective and
efficient.
• A single-celled organism must multi-task (do
many jobs).
Multicellular vs
Unicellular
• Size
• The surface area to volume ratio and related
rate of diffusion restricts growth in
unicellular organisms.
• Efficient transport systems within
multicellular organisms allow for growth.
Multicellular vs
Unicellular
• Interdependence of Cells
• A single-celled organism is dependent on
that one cell.
• If a multicellular organism loses a cell, the
entire organism will not die. However, a cell
not functioning properly (ex. cancerous) can
cause problems for the rest of the organism.
Plant Structure
• Plants are multicellular: made of many parts, each
with its own function – organized in increasing
complex levels of organization
• Tissues= group of cells performing same function
together
• Organs= tissues contributing to same function
• System= group of interconnected organs (two in
plants)
• Shoot system  everything above ground
• Root system  everything below ground and aerial roots
What about animals?
• What are some examples of tissues, organs
and systems in humans?
• Ex. Heart/cardiac tissue  heart  circulatory
system
Do now
• Find the definition/function associated with
each of the following terms (workbook - chart)
Meristem
Dermal tissue/epidermis
Cuticle
Ground tissue
Vascular tissue
Xylem tissue
Phloem tissue
Sieve tube cells
Companion cells
How did you do?
• Meristem- growth areas
• Dermal tissue/epidermis- outer layer of cells;
responsible for exchange of matter and gases and
protection
• Cuticle- waxy substance; resists attack and
prevents water loss
• Ground tissue- majority of plant; strength and
support (stem); food and water storage (roots);
site of photosynthesis (leaves)
How did you do?
• Vascular tissue- transport of materials; xylem and
phloem
• Xylem- moves water and minerals from roots to
leaves; thick, non-living, perforated cells
• Phloem- transports sucrose and other sugars from
leaves to other parts; made of sieve cells
• Sieve tube cells- form continuous ducts;
perforated
• Companion cells- direct activity of sieve tube cells
Plant Growth
• Cells divide to grow and repair damage. This
cell division is called mitosis.
• In plants, increase in size results from the cell
division in growth areas called meristems
Rapidly dividing
cells - Cell walls
thin, nuclei are
large, vacuoles,
small or absent
Meristems
• Onion root tip – note different stages of
mitosis (cell division)
Specialization of Cells
• Once cells are no longer in the meristem,
they will specialize
• Produce products only for their function
• The root and shoot systems are made up
of 3 types of tissues:
• Dermal Tissue (epidermis)
• Ground Tissue
• Vascular Tissue
Types of Tissue
• Dermal Tissue
• Outer layer of cells that covers all
herbaceous (non-woody) plants.
• Responsible for exchange of matter and
gases into and out of the plant.
• Also protects the plant from disease. This is
done by the cuticle (waxy substance), which
resists attacks from micro-organisms and
helps reduce water loss.
Types of Tissue
• Ground Tissue
• Found underneath epidermis, it makes up
majority of plant.
• Provides strength and support to the plant
(stem).
• Involved in food and water storage (roots).
• Location of photosynthesis (leaves).
Types of Tissue
• Vascular Tissue
• Responsible for transport of material, which
occurs in xylem tissue and phloem tissue
Vascular Tissue - xylem
• Cells in xylem tissue allow transport of water
• Die when differentiate leaving empty tubes
Long fibres in
celery are
vascular tissue
(both xylem and
phloem)
Vascular Tissue - phloem
• Phloem Tissue
• Formed from long sieve tube cells (no
nuclei), which are connected with
companion cells (nucleated) that direct
activity.
• Transports carbohydrates and water from
the leaves to other parts of the plant.
Leaf Cross section
http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf
Vascular Tissue
Vascular tissue
From: http://www.youtube.com/watch?v=4V0VcNCRKTo&feature=related at 4:14
Vascular Bundles
Sieve tubes
More specialization:
Roots
• Cells in root system will produce tiny
hair-like projections called root hairs
• Why is this beneficial for the plant?
• Increases the surface area for
absorption of water
Root hairs
Root hairs
More …
• Dermal cells in shoot system produce a cuticle
• Why is this beneficial?
• Prevents water loss
And last…
• Lower epidermis in leaves have guard cells
• Form tiny pores called stomata for gas
exchange
• Only cells with chloroplasts
• Why is this important?
• Photosynthesis!
Leaf Cross section
http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf
Leaf Cross section
• Can you indentify some of the structures?
How does water move
up the plant?
• Gravity should pull water down – how does it move up
from the roots to the leaves? How do all these
specializations allow for this? Shall be investigating
this in this section.
• http://www.youtube.com/watch?v=U4rzLhz4HHk&fea
ture=related