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Recent 5 years
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Topic 8.1
8.1 Xylem and phloem
Objectives in this topic
8.1.1—Functions of xylem and phloem: (a)
State the functions of xylem and phloem: (a) xylem – transport of water and mineral ions, and support (b) phloem – transport of sucrose and amino acids
8.1.2—Xylem and phloem positions
Identify in diagrams and images the position of xylem and phloem as seen in sections of roots, stems and leaves of non-woody dicotyledonous plants
8.1.3—Relate the structure of xylem vessels
Relate the structure of xylem vessels to their function, limited to: (a) thick walls with lignin (details of lignification are not required) (b) no cell contents (c) cells joined end to end with no cross walls to form a long continuous tube
Topic 8.2
8.2 Water uptake
Objectives in this topic
8.2.1—Root hair cells and state their
Identify in diagrams and images root hair cells and state their functions
8.2.2—Large surface area of root hairs
State that the large surface area of root hairs increases the uptake of water and mineral ions
8.2.3—Pathway taken by water through
Outline the pathway taken by water through the root, stem and leaf as: root hair cells, root cortex cells, xylem, mesophyll cells
8.2.4—Investigate, using a suitable stain
Investigate, using a suitable stain, the pathway of water through the above-ground parts of a plant
Topic 8.3
8.3 Transpiration
Objectives in this topic
8.3.1—Transpiration as the loss of water
Describe transpiration as the loss of water vapour from leaves
8.3.2—Water evaporates from the surfaces
State that water evaporates from the surfaces of the mesophyll cells into the air spaces and then diffuses out of the leaves through the stomata as water vapour
8.3.3—Effects of variation of temperature
Investigate and describe the effects of variation of temperature and wind speed on transpiration rate
8.3.4—Water vapour loss is related
Explain how water vapour loss is related to: the large internal surface area provided by the interconnecting air spaces between mesophyll cells and the size and number of stomata
8.3.5—Mechanism by which water moves upwards
Explain the mechanism by which water moves upwards in the xylem in terms of a transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules
8.3.6—Effects on the rate of transpiration
Explain the effects on the rate of transpiration of varying the following factors: temperature, wind speed and humidity
8.3.7—Why wilting occurs
Explain how and why wilting occurs
Topic 8.4
8.4 Translocation
Objectives in this topic
8.4.1—Translocation as the movement
Describe translocation as the movement of sucrose and amino acids in phloem from sources to sinks
8.4.2—Describe: (a) sources as the parts
Describe: (a) sources as the parts of plants that release sucrose or amino acids (b) sinks as the parts of plants that use or store sucrose or amino acids
8.4.3—Some parts of a plant may act
Explain why some parts of a plant may act as a source and a sink at different times