Arborist exam 2023/24 with complete solutions

cambium thin sheath of dividing cells that produces the cells which become the vascular system of the tree, xylem and phloem xylem conduct water, support weight, store carbohydrates, defense against spread of disease Phloem moves carbohydrates from leaves throughout tree for storage cork cambium second lateral meristem which produces the bark; periderm. symplasm living cells inside xylem apoplasm non-living cells inside xylem tracheids elongated non-living cells which conduct water and provide mechanical support fibers provide mechanical strength parenchyma cells living cells in outer layer of xylem, store carbohydrates and help defend against decay, structural component vessels primary conducting elements in hardwoods, dead hollow cells ring porus trees which vessls early in growing season and narrower later in season, Ulmus, Quercus, Fraxinus diffuse porous Uniform size throughout growing season, Acer, Populus growth rings result of xylem and cambium seasonal growth sapwood living cells within xylem that conducts water heartwood non-living cells farther within tree xylem which do not conduct water sieve cells living cells in phloem of conifers sieve tube elements, companion cells living cells in phloem of hardwoods Rays parenchyma cells that transport carbohydrates into sapwood radially lenticels small openings in bark for gas exchange epicormic dormant buds elongate and produce shoots transpiratoin loss of water through leaves abscission zone area at base of leaf which provides two functions, allow leaf to drop and protect area against desiccation and pathogens anthocyanis red and purple pigments carotenoids yellow, orange, and red pigments Respiration carbohydrates generated by photosynthesis stored as starch auxin produce shoot tips, root development. Associated with tropism cytokins produce in root and instrumental in shoot initiaion and growth tropism, geotropism, phototropism direction of growth in response to natural environment. Response to gravity-geotropism. Phototropism-response to light