27 The Plant Body.docx

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University of Toronto Scarborough
Biological Sciences
Jamie Donaldson

27 The Plant Body: Evolutionary adaptations:  A shoot system: helps support leaves and other body parts in air  A root system: anchors the plant in soil and provides access to soil nutrients and water  Tissue for internal transport of water and nutrients and  Specialization for preventing water loss 27.1 Plant Structure and Growth:  Plants are photosynthetic ”self-feeders” and require nutrients that are usually available in the soil  They capture these nutrients over large surface areas, above and below ground-(spread out like a tree-dendritic)  Life on land has resulted in a body consisting of two linked components: shoot system that extend upward into the air and a non-photosynthetic root system that extends downwards into the soil. (Look at picture to the left) 27.1a Cells of All Plant Tissue Share Some General Features  The root and shoot system consists of many organs: body structures that contain two or more types of tissues and have a definite form and function (leaves stems)  Tissue: a group of cells and intercellular substances that function together in one or more specialized task.  they have a vacuole (maintance of rigid tissue and cell elongation) and chloroplast for photosynthesis  Plant tissue have primary cell wall: surrounding the plasma membrane and cell content- skeleton  The cell wall is composed of cellulose-polymer of glucose.  Plasmodesmata: a cytoplasmic connection between adjacent walls allowing solutes to move from one cell to another  The second cell wall contains lignin: a complex water insoluble polymer that makes the plant strong and rigid.  Totipotency: the ability to develop into any type of cell. For example cutting a shoot and placing into water. Any plant cell that has become specialized can become dedifferentiate and produce an entirely new plant. 27.1b: Shoot and Root stems Perform But Integrated Functions Chapter 24 terms  Root: anchoring structures that also absorb water and nutrients  Root systems (in vascular plants): consist of underground, cylindrical absorptive structure with a large surface area that favours the rapid uptake of water and minerals-above and below the ground.  Shoot systems (in vascular plants): they have stems and that arise from apical meristems (regions of onstantly diving ell near the tips of roots and shoots that produce all tissues of the plant body) and that unction in the absorption of light energy from the sun and carbon dioxide from the air.  A flowering plant’s shoot system contains leaves, stems and buds. Stem attached to the leaves and buds is a vegetative (non-productive) shot and a bud usually extends form the shoot into a branching shoot. A reproductive shoot produces flowers  Leaves increase a plant surface area and the exposure to light.  Stems are framework for upright growth-which favours pollination and light exposure  The root system grows below ground and anchors the plan and supports its upright plants. It also helps with the absorption of water and dissolved minerals. 27.1c Meristems Produce New Tissues throughout a Plant’s Life:  Determinate growth: grow to a certain size and then the growth slowly or dramatically stops (animals)  Indeterminate growth: In plants they can grow throughout their live times.  Plant parts such a s leaves, flowers and fruits exhibit determinate growth but every plant has continuing embryonic tissue called meristems, that grow at the tips of shoots and roots  Under plant hormones meristems produce new tissue more or less continuously while the plant is alive  Plants have indeterminate growth because it allows plants to have a great deal of flexibility (plasticity). They are able to adapt in response to changes in the environment.  Indeterminate growth allows a root system to extend and grow out of regions in which nutrients have been depleted for.  Plants grow by two mechanisms:  By the increase number of ells by mitotic cell division in meristems  And by an increase in the size of individual cells  In the tips of roots and shoots the daughter cells are increasing in size and in length. 27.1d Meristems are Responsible for Growth in Both Height and Grith:  All plants have apical meristems: clusters of continuing tissue at the tip of buds, stems and rots  The tissue that develop from apical meristems are called primary tissues and they make up the primary plant body (leads to primary growth)  Herbaceous plants have primary growth.  Secondary grow originate at the cylinders of tissue called lateral meristems and increase the diameter of the older roots stems (develop from secondary tissue)  Woody plants have secondary tissue. Secondary and primary plant growth can occur simultaneously. 27.1e Monocots and Eudiots are the Two General Structural Forms of Flowering Plants:  Two major categories of flowering plants are monocot and eudicot lineages  Eudicot: one of the two major classes of angiosperms. The embryos have two seeded leaves and their pollens grain have three grooves.  Monocot: one of the two major classes of angiosperms. The embryo has a single seeded leaf and pollen grains with a single groove. 27.1f: Flowering Plants can be Grouped According to Type of Growth and Lifespan  Annuals are herbaceous plants (life cycle completed in one growing season). They have minimum secondary growth  Biennales complete their life cycle in two growing seasons and limited secondary growth. First season, roots stems and leaves form and in the second year of growth- plant flowers, forms seeds and then dies  Perennials: vegetative growth and production continue year after year, some have secondary tissue. 27.2 The Three Plant Tissue Systems:  The ground tissue system: makes up most of the plant body, functions in the metabolism, storage and support  The vascular system consists of xylem and phloem; they transport water and nutrients throughout the plant.  The dermal tissue system: is the skin like protective covering for the plant body. 27.2a Ground Tissues are all Structurally Simple But Exhibit Important Differences:  There are three types of tissue systems: parenchyma, collenchyma and schlenchyma. Each system is very simple and is composed of one type of cells.  The ells in ground tissue carry out photosynthesis, store carbohydrates, and provide support. Tissue system Name of tissue Cell types in tissue Tissue function Ground tissue Parenchyma Parenchyma Photosynthesis, Cells respiration, storage and secretion Collenchyma Collenchyma Flexible strength for Cells growing plant parts Schleronchyma Fibers or scleroids Rigid support, deterring herbivores Vacular tissue Xylem Conducting cells Transport water and (tracheid, vessels dissolved minerals members), parenchyma ells, scheloerenchyma cells Phloem Conducting cells (sieve Sugar transport tube members, vessels members), parenchyma ells, scheloerenchyma cells Dermal tissue Epidermis Undifferentiated cells, Control of gas exchange, guard cells, other water loss protection specialized ells Periderm Cork, cork cambium, protection phelloderm Parenchyma: soft tissue primary tissues.  parenchyma makes up the bulk of the primary growth of roots, stems, leaves, flowers and fruits  parenchyma cells are have only a thin primary wall and so are pliable and preamble to water  they have air spaces between them especially in leaves  stems and leaves in aquatic plants tend to have large spaces between parenchyma cells went oxygen is submerged into parts of plants  They have specialized task for storage, secretion and photosynthesis  In some species, modified parenchyma cells are used for short-distance transport of solutes. These cells are common in where tissue and solutes are rapidly moved.  Parenchyma cells are usually alive and active when matured. Collenchyma: Flexible Support:  Help strengthen plant parts that are still elongating  Collenchyma cells are typically elongated and often form strands under dermal tissue of growing shoot regions and leaf stalk  Primary walls of collenchyma cells are built rom cellulose and pectin. These walls are suitable for flexible support.  Mature collenchyma cells are alive and metabolically active Schlereenchyma: Rigid Support and Protection:  Mature plant parts gain
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