1. Growth and Development of different organisms
National 5 Biology
Key Area 6:
The Need for Transport
(a) Plant Transport Systems
National 4 Biology
Key Area 4
Growth and Development of different organisms

2. Learning Outcomes for Topic 6 – Part A
Explain why plants need a transport system
Name the 2 transport systems in plants
Give the function of each of the 2 plant transport system
Be able to identify 7 structures in a leaf
State the function of each structure
State what is meant by ‘transpiration’
Describe the process of transpiration in a plant
Name 3 factors which can increase the rate of transpiration

3. Transpiration
Water is transported from the roots to all parts of a plant by the xylem.
Water is needed to transport materials and as a raw material for photosynthesis.

4. ORGAN LEVEL
Leaves
Stem
Roots

6. Water enters by osmosis
Cellular Level: Stage 1
Epidermis
Root hair
lignin
Water enters by osmosis
xylem

7. Lateral transport of water to stem cells.
Cellular Level: Stage 2
Epidermis
Lateral transport of water to stem cells.

8. Cellular Level: Stage 3 Leaf Tissue Upper epidermis Mesophyll cells
Lower epidermis
Stomata
Guard Cell

9. Stage 1 description
Water Absorption
Water moves from a region of high water concentration in the soil to a region of low water concentration in the root hair cells. This process is called osmosis.
Water then continues to move through the root hair cells into the xylem vessel by osmosis.

10. There is also lateral (sideways) movement of water to side branches.
Stage 2 description
Transport up the stem
Water and mineral salts are transported by the xylem up the stem to the top of the plant.
There is also lateral (sideways) movement of water to side branches.

11. Stage 3 description
Transpiration
Transpiration is the process by which water is lost by evaporation from the leaves of a plant.
Water evaporates from the surrounding cells into air spaces in the leaf.
The water is then lost through tiny openings in the leaf (pores) called stomata by transpiration.

12. Transpiration rate is the rate at which water is lost from a leaf
Leaf Tissue
Upper epidermis
Mesophyll cells
Lower epidermis
Stomata
Guard Cell
Remind them what transpiration is from last day
Transpiration rate is the rate at which water is lost from a leaf
It varies depending on environmental conditions.

13. What would happen to the rate of transpiration in each of these conditions?
windy
Hot and sunny
Cold and rainy

14. Environmental conditions that increase transpiration rate
High temperatures
Wind
Low humidity
(very little moisture in the air)
The days your washing would dry on the line!