10: Transpiration, Transport and Support in Plants Flashcards
What is transpiration?
Transpiration is the evaporation of water stored in plants from plant surfaces, which is lost in the form of water vapour.
Where does transpiration occur?
Stomata (90-95%), cuticle (5-10%), lenticels in woody plants (0.1%)
What are 5 examples of parts of plants containing stomata?
Leaves, sepals, petals, fruits, seeds
What is the layer covering the leaf epidermis of terrestrial plants?
Cuticle
State the function of guard cells.
To control the opening and closing of the stomata.
State three adaptations of different xerophytes to reduce water loss.
Reduced leaves, rolled leaves, sunken stomata
State the difference in stomatal density for upper and lower epidermis of most terrestrial dicotyledonous plants.
The stomatal density of the lower epidermis is higher than that of the upper epidermis.
State the difference in stomatal density for upper and lower epidermis of most terrestrial monocotyledonous plants.
The stomatal density of the lower epidermis is similar to that of the upper epidermis.
State the difference in stomatal density for upper and lower epidermis of submerged aquatic plants.
There are no stomata in the epidermis.
State the difference in stomatal density for upper and lower epidermis of floating plants.
There are no stomata in the lower epidermis, but there are stomata on the upper epidermis.
Describe the change in rate of transpiration as light intensity increases.
As light intensity increases, the rate of transpiration increases and levels off at high light intensities.
Describe the change in rate of transpiration as temperature increases.
As temperature increases, the rate of transpiration increases and levels off at high temperatures.
Describe the change in rate of transpiration as wind speed increases.
As wind speed increases, the rate of transpiration increases initially. After the rate of transpiration reaches a maximum value, as wind speed increases further, the rate of transpiration decreases.
Describe the change in rate of transpiration as relatively humidity of the surrounding air increases.
As the relatively humidity of the surrounding air increases, the rate of transpiration decreases.
State 3 factors, other than environmental factors, that affect the rate of transpiration of a plant.
Total surface area of leaves, thickness of cuticle, abundance of stomata.
State the difference between the net amount of water lost and the net amount of water absorbed by a healthy plant in 24 hours.
The net amount of water absorbed should be more than the net amount of water lost, indicating the plant has a net uptake of water.
Are roots of dicotyledonous plants covered by cuticle?
No
In which form is food mainly stored in the cortex of roots of dicotyledonous plants?
Starch
Which vascular tissue is located in the centre of the roots of dicotyledonous plants?
xylem
State the significance of growing root hairs on roots of dicotyledonous plants.
This provides a page surface area for absorption of water and minerals from the soil.
State the major way in which water in the soil enters root hair soils of roots of dicotyledonous plants.
Osmosis
State the major way in which minerals in the soil enters root hair soils of roots of dicotyledonous plants.
Active transport
State a possible way in which minerals in the soil enters root hair soils of roots of dicotyledonous plants other than active transport.
Diffusion
State 4 adaptive features of roots of dicotyledonous plants for absorption of water and minerals.
- Highly branched root with numerous root hairs
- Root hairs are long and fine
- Epidermis of root is not covered by cuticle
- Root hair cells contain many mitochondria
Explain the significance for dicotyledonous plants to have highly branched roots with numerous root hairs on the root.
This provides a large surface area for absorption of water and minerals.
Explain the significance for dicotyledonous plants to have long and fine root hairs.
The root hairs can easily grow between soil particles to absorb water and minerals; it can also provide good anchorage and support to the plant.
Explain the significance for dicotyledonous plants to have epidermis not covered by cuticle.
This allows water to and minerals to pass through the epidermis into the root easily.
Explain the significance for root hair cells of dicotyledonous plants to have many mitochondria.
This ensures that enough energy is supplied to absorb minerals from the soil by active transport.
State the functions of xylem in flowering plants.
It transports water and minerals, and provides support for plants.
State the adaptive features of xylem.
It mainly consists of xylem vessels, which are hollow. The walls of the xylem vessels are thick and lignified.
Explain the significance for xylem vessels to be hollow in terms of transport.
It allows the passage of water with little resistance.
Explain the significance for xylem vessels to have thick and lignified walls in terms of transport.
It prevents the vessels from collapsing under the great tension of transpiration pull.
State whether the cells making up xylem vessels are living.
Immature xylem vessels consist of living cells, but mature xylem vessels consist of dead cells only.
State the functions of phloem in flowering plants.
It transports organic nutrients, mostly sucrose.
State two types of cells which the phloem consists of.
Sieve tubes and companion cells.
State the
