Biology: Chapter 7 - Stems Outline

Discrete vascular bundles arranged in a cylinder

Between primary xylem and primary phloem

Secondary xylem and secondary phloem

<p>Annual ring</p> Signup and view all the answers

<p>Age of a tree and climate during tree's lifetime</p> Signup and view all the answers

<p>Produces cork cells with suberin, reduces water loss, and protects stem against injury</p> Signup and view all the answers

<p>Node</p> Signup and view all the answers

<p>Axil</p> Signup and view all the answers

<p>Bundle scars</p> Signup and view all the answers

<p>All leaves</p> Signup and view all the answers

<p>Age of twig</p> Signup and view all the answers

<p>Stipules</p> Signup and view all the answers

<p>To contribute to the increase in stem length.</p> Signup and view all the answers

<p>Protoderm, procambium, and ground meristem.</p> Signup and view all the answers

<p>Mature leaves and buds, respectively.</p> Signup and view all the answers

<p>A trace is a strand of xylem and phloem that branches off from the main vascular cylinder and enters a leaf or bud.</p> Signup and view all the answers

<p>Bud scales and leaf primordia.</p> Signup and view all the answers

<p>The vascular cambium produces secondary xylem (wood) and secondary phloem.</p> Signup and view all the answers

<p>In spring, the secondary xylem contains relatively large vessel elements (spring wood), while later in the season, it has fewer and smaller vessel elements, with more tracheids and fibers (summer wood).</p> Signup and view all the answers

<p>The bark consists primarily of tissues outside the vascular cambium, including secondary phloem and cork.</p> Signup and view all the answers

<p>Conifers lack vessel elements and fibers; their wood consists primarily of tracheids.</p> Signup and view all the answers

<p>The cork cambium produces cork, which is part of the protective bark layer.</p> Signup and view all the answers

<p>Laticifers are ducts found mostly in the phloem that secrete latex.</p> Signup and view all the answers

<p>Softwood is the wood of conifers and lacks fibers or vessel elements, while hardwood is the wood of dicot trees.</p> Signup and view all the answers

<p>Resin canals are tube-like structures lined with cells that secrete resin, found scattered throughout the xylem and other tissues of some plants.</p> Signup and view all the answers

<p>Tyloses are protrusions of adjacent parenchyma cells into the conducting cells of xylem that prevent conduction of water.</p> Signup and view all the answers

<p>Radially cut (quartersawed) boards show annual rings in side view, while tangentially cut (plainsawed or slab cut) boards are cut perpendicular to rays and show annual rings as irregular bands.</p> Signup and view all the answers

<p>Dry wood is composed of about 60-75% cellulose and 15-25% lignin. Density is the weight per unit volume, and durability (ability to withstand decay) is affected by the presence of tannins and oils.</p> Signup and view all the answers

<p>The three primary meristems formed from the apical meristem cells are: protoderm (which gives rise to the epidermis), procambium (which gives rise to primary xylem and phloem), and ground meristem (which gives rise to the pith and cortex).</p> Signup and view all the answers

<p>The leaf primordia develop into mature leaves, and the bud primordia develop into mature buds.</p> Signup and view all the answers

<p>A trace is a strand of xylem and phloem that branches off from the main vascular cylinder. It leads into a leaf or bud.</p> Signup and view all the answers

<p>The apical meristem is protected by bud scales and leaf primordia before the growing season begins.</p> Signup and view all the answers

<p>The leaf gap or bud gap is formed when a trace branches off from the vascular cylinder, leaving a gap filled with parenchyma cells.</p> Signup and view all the answers

<p>Vascular cambium and cork cambium</p> Signup and view all the answers

<p>Ungrained, uniform wood or spring wood and summer wood</p> Signup and view all the answers

<p>Bark</p> Signup and view all the answers

<p>Alternating layers of crushed phloem and cork</p> Signup and view all the answers

<p>Fewer, smaller vessel elements in proportion to tracheids and fibers</p> Signup and view all the answers

<p>The central cylinder is called the stele.</p> Signup and view all the answers

<p>Dicotyledons (dicots) have two cotyledons, while monocotyledons (monocots) have a single cotyledon.</p> Signup and view all the answers

<p>Monocot stems have discrete vascular bundles scattered throughout the stem, with xylem closer to the center and phloem closer to the surface, while dicot stems have a vascular cambium that produces secondary vascular tissues in discrete bundles.</p> Signup and view all the answers

<p>A monocot vascular bundle contains two large xylem vessels, several small xylem vessels, phloem consisting of sieve tubes and companion cells, and a sheath of sclerenchyma cells.</p> Signup and view all the answers

<p>The first formed xylem cells in monocot stems stretch and collapse, leaving irregularly shaped air spaces.</p> Signup and view all the answers

<p>The primary function of the vascular cambium in woody dicotyledonous stems is to add secondary vascular tissues, including secondary xylem (wood) and secondary phloem.</p> Signup and view all the answers

<p>The vascular rays, consisting of parenchyma cells, function in the lateral conduction of nutrients and water.</p> Signup and view all the answers

<p>One year's growth of xylem forms an annual ring.</p> Signup and view all the answers

<p>The annual rings of wood indicate the age of a tree and the climate conditions during the tree's lifetime.</p> Signup and view all the answers

<p>The primary function of the cork cambium is to produce cork cells with suberin and phelloderm cells, which reduce water loss and protect the stem against injury.</p> Signup and view all the answers

<p>Herbaceous dicotyledonous stems have discrete vascular bundles arranged in a cylinder.</p> Signup and view all the answers

<p>The vascular cambium adds secondary xylem and secondary phloem to herbaceous dicotyledonous stems.</p> Signup and view all the answers

<p>The dry part of wood is composed of about 60-75% cellulose and about 15-25% lignin. The density, or weight per unit volume, and the durability, or ability to withstand decay, of wood are affected by these primary components. Tannins and oils in the wood also help repel decay organisms and contribute to the durability of the wood.</p> Signup and view all the answers

<p>Resin canals are tubelike canals scattered throughout the xylem and other tissues of the stem. They are lined with specialized cells that secrete resin. Resin canals are common in conifers and some tropical flowering plants like those that produce frankincense and myrrh.</p> Signup and view all the answers

<p>Tyloses are protrusions of adjacent parenchyma cells into the conducting cells of the xylem. Their function is to prevent the conduction of water, as they accumulate resins, gums, and tannins that darken the wood, forming heartwood.</p> Signup and view all the answers

<p>The wood of conifers, or softwood, lacks fibers or vessel elements, whereas the wood of dicot trees, or hardwood, contains these structures. Additionally, softwood does not have the resin canals that are found scattered throughout the xylem and other tissues of hardwood.</p> Signup and view all the answers

<p>The two main types of sawing patterns for wood are radial (quartersawed) and tangential (plainsawed or slab cut). Radially cut boards show the annual rings in side view, while tangentially cut boards are cut perpendicular to the rays and show the annual rings as irregular bands of light and dark streaks.</p> Signup and view all the answers

<p>Laticifers are ducts found mostly in the phloem that have latex-secreting cells. They secrete substances like rubber, chicle (chewing gum), and morphine.</p> Signup and view all the answers