4.3 Transportation in Vascular Plants

Question 1

What 5 things need to be transported in plants?

Answer 1

• Respiratory gases
• Energy (sugars)
• Nutrients (including water)
• Wastes
• Hormones

Question 2

What are the 2 requirements plants have for transport systems?

Answer 2

1. Transportation of water and inorganic nutrients from the roots to all the other areas of the plant
2. Transportation of sugars produced in the leaves to other sections of the plant

Question 3

What are the 2 specialised plant transport systems?

Answer 3

• Xylem: Transport water and inorganic nutrients from the roots to all areas of the plant
• Phloem: Transport sugars produced in the leaves of other parts of the plant

Question 4

Describe the structure of xylem:

Answer 4

• Consists of xylem vessels
• Ends are perforated or completely open (water flows through like a pipeline)
• Walls are impregnated with lignin providing strength and support
• Have pits (thinner areas) in the side walls that enable the movement of substance into and out of the adjacent companion cells.

Question 5

What are xylem tracheids?

Answer 5

Are non-living and are not connected end to end (water is transferred horizontally through adjoin pits)

Question 6

Describe the process taking place in xylem?

Answer 6

Water and dissolved inorganic nutrients are transported from the roots to all the tissues and cells of the plant.

Question 7

What is transpiration?

Answer 7

Evaporation of water from the leaves of plants due to heat from the sun.

Question 8

Describe the process of transpiration:

Answer 8

• Roots have a higher water concentration as opposed to the air’s low water concentration
• This carries movement of water (and dissolved mineral salts) from the roots to the leaves, within the xylem vessels
• Driven by energy from the sun (heat evaporates the water) and does not require the plant to use energy
• Water moves up the xylem via capillary action (due to cohesion of water molecules)

Question 9

What are the 4 factors which speed up transpiration?

Answer 9

• Low CO2 concentrations (stomata are open)
• Bright light (more evaporation of water from leaves)
• Wind (Blows water away from the leaf)
• Heat (more evaporation of water from the leaves)

Question 10

Describe the structure of phloem:

Answer 10

• Composed of sieve tubes and companion cells
• Made up of living cells, but sieve cells have lost their nuclei
• Neighbouring companion cells control the movement of sugars in the sieve tubes
• Plant expends energy by moving material through the phloem

Question 11

Describe the process taking place in phloem:

Answer 11

The sugars produced in photosynthesis are moved upwards to new growing tissues and buds as well as downwards to the roots and storage organs

Question 12

What is translocation, what is it driven by and what does it require?

Answer 12

Transport of sugars in solution from leaves through sieve tubes to other parts of the cell.

• Driven by the pumping of sugars
• Requires energy