1. What is transpiration?
The process of which water inside the plant is lost from the surface into the atmosphere.
2. Where does transpiration take place?
(1) Through the stomata (90% or more)
(2) cuticle
(3) lenticel
3. What are the two processes of transpiration?
(1) Water evaporates from mesophyll cells to the air space.
(2) Water vapour in the air space diffuses from the air space to the atmosphere.
4. How is transpiration pull created?
(1) Mesophyll cells near the air space lose water due to transpiration, their water potential drops.
(2) Water from neighbouring cells us drawn towards these mesophyll cells by osmosis.
(3) Eventually water is drawn out of the xylem vessels, causing transpiration pull.
(4) Transpiration pull pull water up the xylem vessels from the root.
5. What is the significance of transpiration?
(1) produce transpiration pull which transport water and minerals to various parts of the plant.
(2) produce transpiration pull which assist absorption of water from the root
(3) cools down the plant
6. What are the adaptive features of leaves to prevent excessive loss of water?
(1) have cuticle
(2) less stomata in the upper epidermis
(3) have guard cells which can control the opening and closing of the stomata. When the temperature is too hot, the guard cells will lose water causing the stomata to close.
(4) sunken stomata are found in some leaves.
7. What are the factors affecting the rate of transpiration?
(1) light intensity (the higher, the faster the transpiration)
(2) temperature (the higher, the faster the transpiration)
(3) relative humidity (the higher, the slower the transpiration)
(4) wind speed (the higher, the faster the transpiration)
8. List the structures of the roots
Epidermis, cortex, xylem, phloem
9. What are the adaptive features of the roots for absorption of water?
(1) the root is highly branched
(2) no cuticle on the epidermis
(3) A lot of root hairs on the root (root hair is one of the types of epidermal cells)
(4) root hairs are long and fine
10. What is root hair?
It is a part that is sticking out from a root hair cell.
11. Which three ways are water being moved along the root cells?
(1) along the cell wall (fastest)
(2) through the cytoplasm of root cells
(3) through both the cytoplasm and the vacuole of the root cells.
12. How can minerals be absorbed?
Almost most of the time by active transport.
13. What are the adaptive features of the xylem for water transport?
(1) the cells are dead, forming hollow tubes. This allow water to flow freely with little resistance
(2) there are no end walls between cells.
14. What are the adaptive features of the phloem for transport of nutrients?
(1) There are no nucleus in the sieve tubes, and there are pores on the walls to allow organic nutrients to pass through.
(2) Companion cells are present support the metabolism of the sieve tubes.
15. How are the vascular tissues distributed in dicotyledonous plants?
The outer layer is phloem
The inner layer is xylem
16. What are the functions of xylem?>
(1) transport water and minerals (from root upwards)
(2) support the plant
17. What are the directions of the transport of nutrients in plants?
It can be transported from the leaf to the roots.
It can also be transported from the root to the upper parts of the plants.
18. What support the plants?
(1) turgidity of thin walled cells (especially important for herbaceous plants)
(2) the rigidity of thick walled cells
19. Compare the distribution of xylem in the stem and the root of dicotyledonous plants.
Stem: at the periphery
Root: at the middle part
20. How can thin walled cells offer support to herbaceous plants?
(1) When water supply is enough, the water potential in the xylem vessels is higher than that of the cells at the cortex and the pith,
(2) Water will enter these cells from the xylem vessels to these cells by osmosis
(3) These cells become turgid and press against each other.
(4) This make the stem stand upright.
21. What are the major substances inside the cell wall of thick walled cells?
Cellulose (present in all plant cells)
lignin