Topic 13 Plant Science

A.S. Obj. 13.1 Plant Structure (2h)
13.1.1 2
Outline the wide diversity in the plant kingdom as exemplified by the structural differences between bryophytes, filicinophytes, coniferophytes and angiospermophytes.
No details of internal structures of life cycles are expected.
13.1.2 1
Draw a diagram to show the external parts of a named dicotyledonous plant.
Include the root, stem, leaf, axillary and terminal buds.
13.1.3 1
Draw plan diagrams to show the distribution of tissues in the stem, root and leaf of a generalized dicotyledonous plant.
Either one species could be selected for the whole study or different species could be used for the stem, root and leaf, depending on the availability of material and/or local interest. Note that plan diagrams show distribution of tissues (eg xylem, phloem) and do not show individual cells. They are sometimes called "low power" diagrams.
13.1.4 3
Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues.
The functions should include absorption of light, gas exhange, support, water conservation, transport of water and products of photosynthesis.
13.1.5 2
Outline four adaptations of xerophytes.
These could include: CAM and C4 physiology, reduced leaves, rolled leaves, spines, deep roots, thickened waxy cuticle, reduced number of stomata, stomata in pits surrounded by "hairs", water storage tissue, low growth form and annual plants with short life cycles.
13.1.6 2
Outline two structural adaptations of hydrophytes.
These could include air spaces, flotation, ploiable parts with little strengthening tissue, "breathing" roots, reduced roots and finely divided submerged leaves.
    13.2 Transport in Angiospermophytes (4h)
13.2.1 3 Explain how the root system provides a large surface area for mineral ion and water uptake by means of branching, root hairs and cortex cell walls.
13.2.2 2 Describe the process of mineral ion uptake into roots by active transport.
13.2.3 3
Explain the process of water uptake by root epidermis cells and its movement by the symplastic and apoplastic pathways across the root to the xylem.
Water potential terminology is not expected. Water movement should be explained in terms of differences in solute concentration and pressure.
13.2.4 1 State that terrestrial plants support themselves by means of thickend cellulose, cell turgor and xylem.
13.2.5 1
Define transpiration.
Transpiration -- the loss of water vapour from the leaves and stems of plants.
13.2.6 3
Explain how water is carried by the transpiration stream, including the structure of xylem vessels, transpiration pull, cohesion and evaporation.
Limit the structure of xylem vessels to one type of primary xylem.
13.2.7 1 State that guard cells can open and close stomata to regulate transpiration.
13.2.8 3 Explain how the abiotic factors, light, temperature, wind and humidity, affect the rate of transpiration in a typical terrestrial mesophytic plant.
13.2.9 2 Outline the role of phloem in active translocation of biochemicals.
13.2.10 2 Describe an example of food storage in a plant.
    13.3. Reproduction in Flowering Plants (2h)
13.3.1 1
Draw the structure of a dicotyledonous animal-pollinated flower, as seen with the naked eye and hand lens.
Limit the diagram to sepal, petal, anther, filament, stigma, style and ovary.
13.3.2 1 Define pollination.
13.3.3 2 Distinguish between pollination, fertilization and seed dispersal.
13.3.4 1
Draw the external and internal structure of a named dicotyledonous seed.
The named seed should be non-endospermic. The structure in the diagram should be limited to testa, micropyle, embryo root, embryo shoot and cotyledons.
13.3.5 2
Describe the metabolic events of germination in a typical starchy seed.
Absorption of water precedes the formation of gibberellin in the coyledon. This stimulates the production of amylase which catalyses the breakdown of starch to maltose. This subsequently diffuses to the embryo for energy production and growth. No further details are expected.
13.3.6 3
Explain the conditions needed for the germination of a typical seed.
Seeds vary in their light requirements and therefore this factor need not be included.