1. B5: Transportation
Transport in Plants

2. State the functions of xylem and phloem
Flowering plants have two separate transport systems: xylem and phloem.
These tissues are found throughout the plant body in roots, stems and leaves,
Xylem vessels transport water and mineral ions from the roots up the stem to the leaves.
Roots absorb water and mineral ions from the soil.
These travel in the xylem upwards in the stem to the leaves, flowers and fruits.
This is one-directional movement: from roots, via the stem, to the leaves.
Water transport
Water movement in plants

3. State the functions of xylem and phloem
Phloem vessels transport sucrose, amino acids and hormones to other parts of the plant.
Sucrose is a soluble complex sugar
Sucrose is made from the sugars made in photosynthesis and from the starch stored in roots and stems.
Substances are moved in two directions in the phloem:
downwards from leaves to roots
upwards from leaves to flowers, fruits and buds
Upwards from storage organs to new stems and leaves.
Phloem loading video

4. Plant tissue animation
Water movement animation

5. Inside a root

6. Inside a stem
Sink and source

7. Up the stem

8. Identify root hair cells and state their functions
Roots have 2 functions:
Anchor the plant in the soil
Take up water and mineral salts
Root hairs are microscopic
Water passes into the root hair from the soil via osmosis.
This process continues through all the cells until the water reaches the xylem.
The xylem transports the water up the stem.
Structure of root hairs:
Long and thin with a large surface area.

9. Absorption by roots

10. Transpiration
The evaporation of water from the leaves and the loss of water vapour to the atmosphere.
Water only diffuses out of the leaf when the stomata are open.
The flow of water up the stem relies on:
Cohesion of water molecules to each other
Adhesion of water molecules to the xylem

11. Factors affecting transpiration
Use your textbook p93 to summarise the factors that will affect the rate of transpiration in a plant (draw graphs if appropriate)
Light
Humidity
Temperature
Wind
Page 98 – 99 complete the exam-style questions: 1 - 7