1. Unit 2 Multicellular Organisms Cells, Tissues and Organs
National 5 Biology
Key Area 1:
Cells, Tissues and Organs
National 4 Biology
Key Area 5:
Growth and development of different organisms

2. By the end of the lesson you will be able to …..
National
4 & 5 outcomes
By the end of the lesson you will be able to …..
Describe the different levels of organisation found in a multi-cellular organism.
State that multi-cellular organisms have more than one cell type and are made up of tissues and organs.
Give examples of specialised cells in animals and plants.

3. Cells, tissues and organs
Living things are made up of organized systems too.
Each specific cell is grouped with other cells similar in structure and function to form tissues and ultimately organs.
Cells are the basic units of life.
Groups of cells work together to form tissues.
Groups of tissues work together to form organs.
cell
tissue
organ

4. Levels of Organisation
Cells are the simplest ___ of life.
______ -> ______ -> ______ -> ______ -> ______
Multicellular organisms are made of _____ cells.
___________ cells are cells that perform a specific function in the organism, e.g. a red blood cell transports oxygen.
unit
Organ
Systems
Cell
Tissue
Organ
Organism
many
Specialised
The difference between cells, tissues and organs

5. Function
To transport oxygen
Specialisation
· Large surface area for oxygen transport
· Biconcave shape
· Chemical (Haemoglobin) which binds with oxygen

6. Connections at each end Can carry electrical signals
Function
To carry nerve impulses to different parts of the body
Specialisation
  Long
Connections at each end
Can carry electrical signals

7. Function
To provide nourishment for the embryo before implantation in the womb
Specialisation
  Large
Cytoplasm contains nutrient and energy rich yolk which will nourish the embryo before implantation

8. · Head contains chemicals to help penetrate the female egg
Function
To reach the female egg and fertilise it
Specialisation
· Long tail for swimming
· Head contains chemicals to help penetrate the female egg

9. · Large surface area for absorption
Function
Absorbing water and minerals from the soil
Specialisation
· Large surface area for absorption
· Thin cell wall for minerals to pass through

10. Many chloroplasts (containing chlorophyll, for photosynthesis)
Function
To absorb sunlight (needed for photosynthesis)
Specialisation
Large surface area
Many chloroplasts (containing chlorophyll, for photosynthesis)

11. Phloem Tissue (made up of sieve tubes and companion cells)
Function
Transports sugar around a plant
Specialisation
End walls have holes to allow sugar to be transported to next cell
Companion cell with large nucleus to control the cell.
end walls perforated/ with holes to allow sugar to be transported to next cell
companion cell with large nucleus to control both types of phloem cells
Companion cell
Sieve tube
End wall of sieve tube perforated

12. Xylem Vessel Hollow tube Wall strengthen by lignin
Function
Support
Water transport up the plant
Specialisation
Hollow tube
 Wall strengthen by lignin
 Lignin deposited as rings or spirals allowing expansion and contraction
Hollow tube
Wall strengthen by lignin
Lignin deposited as rings or spirals allowing expansion and contraction
Lignin deposits