1. Topic 9: Plant Science 9.2 Transport in Angiosperms
Modified from S. Taylor, S. Frander and L. Ferguson

2. 9.2 Transport in Angiosperms
2.Water and minerals are transported upward in xylem
3. Transpiration pulls water from the leaves’ stomata
4. Gases are exchanged through the stomata
5. Sugar is produced in the leaves and transported in phloem
6. Roots exchange gases with the air spaces in the soil
1. Roots absorb water and mineral ions from the soil.
These mineral ions are dissolved in water in the soil.
Needed mineral ions include:
Nitrate NO3-
Sulfate SO42-
Di-hydrogen phosphate H2PO4-
Potassium K+
Calcium Ca2+
Magnesium Mg 2+
Iron Fe3+
Zinc Zn2+
Copper Cu 2+

3. Outline how the root system provides a large surface area for mineral ion and water uptake by means of branching and root hairs.
The root system continually branches out to increase its surface area.
Many roots also develop root hairs, extensions of the epidermis that increase the epidermis surface area for faster water absorption. Some plants will increase the number of root hairs in drier soil
Some plant can develop a mutualistic relationship with a fungus. The thread-like hyphae of the fungus grows on the roots, into the root cells, and out into the soil. They absorb water and mineral ions for the plant.

4. Mycorrhiza: a mutualistic association between a fungus and a plant root
Hyphae cover a small eucalyptus root
Lab Idea—
growing one plant in pot with fungicide
(left pot)
Ectomycorrhizae/ endomycorrhizae

5. 9.2.2 List ways in which mineral ions in the soil move to the root
1. Active transport of mineral ions into the root by membrane proteins
2. Fungal hyphae
Mycorrhizae
3. Mass flow of water in the soil carrying ions
Diffusion (often slow because mineral ions bond to soil particles)

6. Highly selective process since protein pumps pick up specific ions
9.2.3 Explain the process of mineral ion absorption from the soil into roots by active transport
Active Transport
Occurs against concentration gradient to bring in ions into plant cells
Highly selective process since protein pumps pick up specific ions
Process requires ATP

7. State that terrestrial plants support themselves by means of thickened cellulose, cell turgor and lignified xylem
Flaccid cell—hypertonic or isotonic solution
Cell Turgor --When a cell is placed in a hypotonic solution, it gains water. The increased water pressure inside the cell presses outward, keeping the cell turgid (rigid)
Turgid cell –hypotonic solution

8. Osmotic Pressure
Pressure created by osmosis also provides support for plant cells
Water enters the cell by osmosis from the higher osmotic potential to the lower osmotic potential.
The volume of the cell cytoplasm increases forcing the plasma membrane outwards against the cell wall. Pressure potential develops.
Think Newton’s 3rd law…

9. Arrangement of Tissues in Stem
Stems are cylindrically shaped
Vascular bundles allow flexing of stem
Thickening of sclerenchyma tissues allows for reduced cytoplasmic content, allowing rigidity

10. During primary growth, stems have fiber cells that contain thickened cellulose to support the plant

11. Development of lignified xylem—secondary growth from the vascular cambium

12. 9.2.5 Define transpiration (the loss of water vapor from leaves and stems of plants) Explain how water is carried by the transpiration stream, including the structure of xylem vessels, transpiration pull, cohesion, adhesion, and evaporation

13. ….the structure of xylem vessels, transpiration pull, cohesion, adhesion, and evaporation
Xylem vessels are long continuous tubes, with lignified walls form strength.
The tubes are formed from linear cells connected at each end
Water is attracted to the cellulose in the xylem cells (adhesion)
Water molecules are attracted to each other (cohesion)
Evaporation from the leaves causes transpiration
When water is evaporated from one cell, adhesion and cohesion cause more water to replace it (transpiration pull)

14. 9.2.7 State that the guard cells can regulate transpiration by opening and closing stomata State that the plant hormone abscisic acid causes the closing of stomata.
Stomata are openings on the leaf epidermis for gas exchange and water evaporation. Each stoma is flanked by 2 guard cells
Abscisic acid is a plant hormone that closes stomata during dry weather. When a plant begins to wilt, abscisic acid accumulates in the leaves, causing water loss from the guard cell, which become flaccid.

15. 9.2.9 Explain how abiotic factors light, temperature, wind and humidity affect the rate of transpiration in a typical terrestrial plant.
Light—increases evaporation from leaves, increases transpiration
Temperature—heat increases evaporation from leaves, increases transpiration
Wind —more wind increases evaporation from leaves, increases transpiration
Humidity—more humidity decreases evaporation from leaves, decreases transpiration

16. Thickened, waxy cuticle Reduced number of stomata Water storage tissue
Outline four adaptations of xerophytes that help reduce transpiration
Reduced leaves
Rolled leaves
Spines
Deep roots
Thickened, waxy cuticle
Reduced number of stomata
Water storage tissue
Low growth rate
CAM photosynthesis
Closing stomata in the daytime to conserve water
Xerophyte Leaf (oleander), has a thick waxy cuticle, and recessed stomata. The trichromes (hairs) reduce wind speed.

17. Outline the role of phloem in active translocation of sugars (sucrose) and amino acids from source (photosynthetic tissue and storage organs) to sink (fruits, roots, seeds)
Source-where sugar is made by photosynthesis, or released from starch breakdown in a storage organ.
Sink-where sugar is stored or consumed.
Phloem transports sap, consumed here by an aphid.

18. Overview of Transport
Sugars move down into other plant parts from leaves through phloem tissues
Oxygen leaves the plant through leaves

19. Translocation
The movement of photosynthetic products from leaves to other parts of the plant via phloem tissues