Topic 13 Plant Science

13.1.1 Compare the 4 main types of plants by External Plant Structures Bryophytes (mosses) No roots, but rhizoids Mosses = simple leaves & stem Liverworts = flattened thallus Max height = 0.5 meters Reproduction = spores in a capsule at end of stalk

Filicinophytes (ferns) True roots, leaves, short non-woody stem Leaves are pinnate = in pairs of leaflets Max height = 15 meters Reproduction = spores in sporangia under leaves

Coniferophytes (conifers) Shrubs or trees with roots, leaves, woody stems. Leaves are narrow with thick waxy cuticle Maximum height = 100 meters Reproduction = seeds in female cones. Male cones produce pollen

Angiospermophytes (flowering plants) Usually have roots, leaves and stems. Stems may be woody or not. Maximum height = 100 meters Reproduction = seeds from flowers. Seeds in fruits.

13.1.3 Plan diagram of stem

Plan diagram of root

Plan diagram of leaf

Palisade mesophyll - main photosynthetic tissue 13.1.4 Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues. Palisade mesophyll - main photosynthetic tissue Near surface where the light is most intense for photosynthesis Upper epidermis Upper surface protects internal structure of leaf from water loss.

Stoma - a pore/opening gas moves through In lower surface - the barrier between leaf and atmosphere Spongy mesophyll - main gas exchange surface Near stomata in lower surface for easy gas exchange Guard cells A pair cells located on sides of stoma to open or close them

Xylem - Carry water from roots to other parts of plant Phloem - Carry products of photosynthesis (glucose = food for plant) Both are a vein that runs through center of leaf so all cells are near for exchange of materials

13.1.5 Outline the adaptations of xerophytes CAM and C4 physiology (Crassulacean acid metabolism)(phosphoenol pyruvic acid (C3) to form Oxoloacetic acid (C4) Involves opening stomata during night, not day Reduced leaves Reduced surface area = reduced transpiration Rolled leaves Protected surface area = reduced transpiration Thickened waxy cuticle Keeps water in

reduced number of stomata stomata in pits surrounded by "hairs” Spines Fewer openings for water to escape stomata in pits surrounded by "hairs” Holds water in Spines Reduces transpiration deep roots Absorb water deep down in soil water storage tissue Usable water during dry times

13.1.6 Outline two structural adaptations of hydrophytes. air spaces Buoyancy = floating near surface Flotation Allows plant to be at surface = light pliable parts with little strengthening tissue Move with waves without breaking "breathing" roots Roots sent above surface of water

finely divided submerged leaves. reduced roots No need for roots = surrounded by water finely divided submerged leaves. Surface area for water absorption