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Ch. 8 Cell Diversity
cell – tissue – organ - system
Defn: A cell is the smallest basic unit of living things
Defn: A tissue is a group of similar cells that are
modified (or adapted) to carry out the same
functions
Simple Tissue = 1 cell type
Complex Tissue =
> 1 cell type
Plant Tissue (need to know 2)
Main types
1.Dermal 2. Vascular 3. Ground 4. Meristematic
(1) Dermal Tissue
A single layer of cells that surrounds
different parts of a plant.
E.g. The Epidermis
E.g. The Epidermis
Location
- An outer covering on leaves, stems & roots
Description
- Living, rectangular shaped cells
- Slightly thickened cell wall
- Can have a waterproof layer called the Cuticle on outer
surface
Function
- Protection
- Waterproofing if Cuticle is present
(2) Vascular Tissue
- Transportation of minerals around plant
- A complex tissue – 2 types of cells i.e. xylem &
phloem
Xylem
Description
Hollow tubes running from root,
through stem & into leaves
Function
- Transport water & dissolved minerals
- Support in woody plants
Phloem
Description
- Tube like structures
- Found in leaves, stems & roots
Function
- Transport food from leaves to other parts of
plant
Animal Tissue
4 main types:
Epithelial,
Connective,
Muscular (can contract)
& Nervous Tissue
**need to know 2 in detail
Connective Tissue
- connects/binds other tissues together
E.g.'s Adipose tissue (stores fat),
Cartilage,
Bone
Blood
Blood Tissue
Consists of:
- red cells (carry oxygen),
- white cells (defence)
- platelets (clot blood)
All suspended in a liquid
called plasma
Nervous tissue
Description
Compound of nerve cells
called Neurons
Function
Neurons carry electrical
impulses to & from
brain & spinal cord
Learning Check
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Can you name 3 types of cell?
What is a tissue?
Can you recall 2 types of animal tissue?
Can you recall 2 types of plant tissue?
Tissue culture
Defn: Tissue culture is the growth of cells in
or on a sterile nutrient medium outside an
organism
How it works?
A tissue sample is removed from a plant or
animal & grown in glassware (in vitro – outside
the body) in a bath of sterile nutritive fluid
which often contains hormones and growth
substances
- Growth is by mitosis and produces a
cluster of identical offspring - a clone
Main conditions necessary for Tissue
culture
- Absence of contaminating microorganisms
- Food, vitamins & minerals
- Substances to stimulate growth (e.g
hormones)
- Oxygen
- Correct pH
Q. Suggest a reason why sterile
conditions are needed in tissue culture?
A. to prevent bacterial growth or
contamination
Stages in Tissue Culture
Example of tissue culture is Organ transplants
• Skin cells obtained
• Enzymes added
• Individual Cells isolated
• Controlled culture medium
• Sheets of cells grown
Applications of Tissue Culture
1. Plant breeding = Micropropagation
2. Cancer research
3. Skin grafts
**need to know 2
Applications of tissue cultures
• Virus reproduction
• Hela cells used to grow and investigate viruses
• **Micropropagation of plants
• Produces exact copies
• Quickly produces mature plants
• Doesn’t need pollinators or seeds
• Producing plants that are disease resistant and
virus free
Applications of tissue cultures
• **Growing human tissue for organ transplants
• Skin cells
• Liver cell
• Pancreas cells
• Producing biotechnology products
• Insulin
• Interferon
• Pregnancy testing kits
• Drug testing kits
• Cancer testing kits
(2) Skin Grafts
New skin can be grown from cells (usually
stem cells)
Learning Check
• What is Tissue Culture?
• What kind of conditions do cells in tissue
culture need?
• What are the stages of tissue culture?
• Can you name two uses for tissue culture?
Organs
Defn: An organ is a structure composed of a
number of tissues that work together to carry
out one or more functions
Examples of Plant Organs: root, stem, leaves,
flowers, stems & fruit
Examples of Animal Organs: stomach, brain,
liver, kidney & heart
Need to know 1 E.g. of a Plant Organ
Organ: Leaf
Tissues it contains:
- Dermal (found in Epidermis)
- Vascular ( found in Vascular bundle as Xylem
& Phloem tissue)
- Ground ( found as Palisade & Mesophyll Cells)
Highlight Tissue types in the diagram in your book
E.g. of An Animal Organ
Organ: Heart
Tissues it Contains:
- Muscle tissue called Cardiac Muscle
- Enclosed in Pericardium (a membrane contains epithelial tissue)
- Connective Tissue ( blood & vessels)
- Controlled by Nervous Tissue
An Organ System: consists of a number of
organs working together to carry out one or
more functions
All organ systems combine to make the
organism
Numerous organ systems in human
The Circulatory System: heart, blood vessels,
blood & lymph
Function: transport materials & fight
infection
The Digestive System: mouth, oesophagus,
stomach, small intestine, large intestine & Anus
Function: Take in food, break it down, &
transfer it to the circulatory system.
Learning Check
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What is an organ?
Can you name 2 plant organs?
Can you name 2 animal organs?
What is an organ system?
Can you recall 2 animal organ systems?