State the primary functions of the root - anchorage, water and mineral uptake.
Anchorage – holds the plant in the ground. Water and mineral uptake.
Monocots only have a fibrous root system (adventitious arising from nodes on the stem), they do not branch or produce secondary thickening. Dicots have a tap root system (developing from the radicle) they branch and produce secondary thickening.
Describe root types - ‘tap’, ‘lateral’, ‘fibrous’ and ‘adventitious’, to include the origin of each type e.g. tap root from radicle, adventitious roots from stem.
Primary root – first root, origin from the radicle (tap root of tree/or biennial, e.g., carrot).
Secondary/lateral – roots coming off the primary root producing the mass of the root system for anchorage, water absorption and mineral uptake.
The root system of monocotyledonous plant arising from the central apex of the plant. Straight growing, not normally able to branch.
Roots coming off any other part of the plant other than the primary root system. Origin – off stems/stolen/aerial/from cuttings.
Some plants produce adventitious roots off their stems which cling onto rough surfaces, allowing the plant to grow up the surface as a climbing plant, e.g., Hedera helix.
First part to emerge from the seed, forming the main root. embryonic root
Describe the difference between monocotyledon and dicotyledon roots.
Describe the structure of the root and state the function of its components - internal and external structures to include drawings of transverse and longitudinal sections through a young dicotyledon root to show the following components: root cap, apical meristem, zone of elongation, zone of differentiation, root hairs, epidermis, cortex, endodermis, pericycle, phloem, xylem and cambium.
Protection and lubricates the root. May inhibit the roots of other plants. Influences ion uptake. Attracts beneficial soil micro-organisms. Glues soil particles to the root so improving the soil/plant contact. Protects the root cells from drying out. Physically protects the root meristem.
Root hairs – produce a vast surface area for water and mineral uptake.
See Root Cortex & STEM CORTEX
Packing and connective cells.
Stores starch and produces energy (respiration).
Protection of inner vascular bundle.
Controls water and mineral uptake.
Gives rise to lateral roots.
Describe how the root is adapted to perform other functions - storage/perennation, tap root (Daucus) and root tuber (Dahlia), climbing (Hedera) and support/prop (Zea).
Tap root stores food, mostly as sugars and takes the plant over the winter. In spring the plant produces a flowering shoot, Daucus carota subsp. sativus.
Root tuber plant stores food in swollen root tubers, e.g., Dahlia variabilis. Plant regrows from buds on the base of the stem. Tubers have no buds.
Prop roots – some plants produce adventitious roots off their stems which grow down into the soil so supporting tall plant, e.g., Zea mays.
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