Exam III Review - Plant Biology PDF

EXAM III REVIEW  Categories of Plants Annual plants - Cycle completed in single season. Cycle = from seed germination to mature plant producing seeds Biennial plants - Cycle completed in two growing seasons. Perennial plants - Cycle takes several to many growing seasons or pl...

EXAM III REVIEW  Categories of Plants Annual plants - Cycle completed in single season. Cycle = from seed germination to mature plant producing seeds Biennial plants - Cycle completed in two growing seasons. Perennial plants - Cycle takes several to many growing seasons or plant produces flowers on new growth, while other plant parts persist indefinitely There are two major classes of flowering plants: Magnoliopsida (dicots) Liliopsida (monocots) © McGraw Hill 2  Monocots and Dicots Leaf venation Dicots: network of veins Monocots: parallel primary veins Vascular cambium and cork cambium Dicots: present Monocots: absent Vascular bundle of stem Dicots: bundles are in a ring Monocots: bundles are scattered Pollen grains Dicots: grains have three apertures Monocots: grains have one aperture © McGraw Hill 3  Sepals and Petals Sepals - Outermost whorl Collectively referred to as calyx Protects flower while in bud Petals - Next whorl inside sepals Collectively referred to as corolla Showy corollas attract pollinators. Inconspicuous or missing corollas in many trees, weeds, grasses, and wind-pollinated plants Calyx and corolla form perianth Access the text alternative for slide images. © McGraw Hill (Top Right) © Kingsley Stern 4  Ovaries Ovaries evolved from carpels with margins rolled inward. Carpel - Leaf with ovules on margins Carpels may be fused together into compound ovary. Pistil can consist of one to several carpels. Superior Ovary - Calyx and corolla attached to receptacle at base of ovary. Inferior Ovary - Receptacle grows up and around the ovary. Calyx and corolla appear attached at top of ovary. Ovary contains ovules. Ovules develop into seeds after fertilization. © McGraw Hill 5  Inflorescence Flowers can be produced singly or in inflorescences. Inflorescence - Group of flowers Access the text alternative for slide images. © McGraw Hill 6  Exocarp, Endocarp, and Mesocarp Exocarp - Skin Endocarp - Inner boundary around seed(s) Mesocarp - Tissue between exocarp and endocarp Three regions collectively called pericarp. Peach fruit Access the text alternative for slide images. © McGraw Hill 7  Berries From compound ovary, with more than one seed, and with fleshy pericarp True berry - With thin skin and relatively soft pericarp Tomatoes, grapes, peppers, blueberries, bananas Pepo - Relatively thick rind Pumpkins, cucumbers Hesperidium – berry with a leathery skin that contains oils Members of the citrus family Grape berries © McGraw Hill © Kingsley Stern 8  Pomes Pome - Flesh comes from enlarged floral tube or receptacle that grows up around ovary. Endocarp papery or leathery Apples, pears - Core and a little of adjacent tissue is from ovary; remainder is from floral tube and receptacle Apple pomes Access the text alternative for slide images. © McGraw Hill © Kingsley Stern 9  Aggregate Fruits Aggregate Fruits Derived from single flower with several to many pistils Individual pistils mature as clustered unit on single receptacle. Raspberries, blackberries, strawberries Blackberry aggregate fruits © McGraw Hill (a) © Kingsley Stern; (b) © Pixtal/age fotostock 10  Fruit and Seed Dispersal Dispersal by Wind Fruits: Samaras, plumes or hairs on fruit Seeds: Small and lightweight, or with wings Access the text alternative for slide images. © McGraw Hill 11  Seeds Structure Ovules develop into seeds. Cotyledons - Food storage organs that function as “seed leaves” Embryo = cotyledons and plantlet Plumule - Embryo shoot Epicotyl - Stem above cotyledon attachment Hypocotyl - Stem below cotyledon Bean seed attachment Radicle - Tip of embryo that develops into root Access the text alternative for slide images. © McGraw Hill 12  Germination Germination is beginning or resumption of seed growth. Some require period of dormancy. Brought about by mechanical or physiological factors, including growth-inhibiting substances present in seed coat or fruit Break dormancy by mechanical abrasion, thawing and freezing, bacterial action, or soaking rains. Scarification - Artificially breaking dormancy After ripening - Embryo composed of only of few cells when fruit ripens; seeds will not germinate until embryo develops. © McGraw Hill 13  Epigeous and Hypogeous Germination Epigeous germination Hypocotyl lengthens, bends and becomes hook-shaped. Top of hook emerges from ground, pulling cotyledons above ground. Hypogeous germination Hypocotyl remains short and cotyledons do not Epigeous germination emerge above surface. Access the text alternative for slide images. © McGraw Hill 14  Longevity Seed viability varies, depending on species and storage conditions. Viability extended: At low temperatures When kept dry Vivipary - No period of dormancy; embryo continues to grow while fruit is still on parent. Vivipary in red mangrove © McGraw Hill © Kingsley Stern 15  Diffusion Diffusion Movement of molecules from a region of higher concentration to a region of lower concentration State of equilibrium - Molecules distributed throughout available space Rate of diffusion depends on pressure, temperature and density of medium. © McGraw Hill 16  Osmosis Solvent - Liquid in which substances dissolve Semipermeable membranes - Membranes in which different substances diffuse at different rates All plant cell membranes Osmosis - Diffusion of a solvent (usually water) through a semipermeable membrane from a region where water is more concentrated to a region where it is less concentrated Osmosis can be measure using an osmometer. © McGraw Hill 17  Osmotic Pressure and Osmotic Potential Osmotic pressure - Pressure required to prevent osmosis Osmotic potential balanced by resistance of cell wall. Pressure potential (Turgor Pressure) - Pressure that develops against walls as result of water entering cell Turgid cell - Firm cell due to water gained by osmosis Water potential of cell = osmotic pressure + pressure Turgid cell potential © McGraw Hill 18  Pathway of Water Through a Plant Osmosis is the primary means by which water enters plant cells. Water moves in via the cell walls, intercellular spaces of the epidermis and root hairs until it reaches the endodermis. across the endodermal cells to reach the xylem. throughout the plant via the xylem and diffuses out through stomata © McGraw Hill 19  Plasmolysis Plasmolysis - Loss of water through osmosis Accompanied by shrinkage of protoplasm away from the cell wall Normal cells versus plasmolyzed cells © McGraw Hill (a-b) © Kingsley Stern 20  Imbibition Large molecules, such as cellulose and starch, develop electrical charges when wet, and thus attract water molecules. Water molecules adhere to large molecules. Results in swelling of tissues Imbibition is first step in germination of seed. Seeds before and after imbibition © McGraw Hill © Kingsley Stern 21  Active Transport Process used to absorb and retain solutes against a diffusion, or electrical, gradient by expenditure of energy Involves proton pump - Enzyme complex in plasma membrane energized by ATP molecules Transport proteins - Facilitate transfer of solutes to outside and to inside of cell Some plants are able to survive in salty environments by accumulating large amounts of organic solutes, which drive osmosis. © McGraw Hill © Kingsley Stern 22  The Cohesion-Tension Theory The Cohesion-Tension Theory - Transpiration generates tension to pull water columns through plants from roots to leaves. Water columns created when water molecules adhere to tracheids and vessels of xylem and cohere to each other. © McGraw Hill 23  When Stomata Open When photosynthesis occurs, stomata open. Guard cells expend energy to acquire potassium ions from adjacent epidermal cells. Causes lower water potential in guard cells Water enters guard cells via osmosis. Guard cells become turgid and stomata opens. © McGraw Hill (b) © Jeremy Burgess/SPL/Photo Researchers, Inc. 24  When Stomata Close When photosynthesis does not occur, stomata close. Potassium ions leave guard cells. Thus, water leaves. Guard cells become less turgid and stomata close. © McGraw Hill (b) © Jeremy Burgess/SPL/Photo Researchers, Inc. 25  Guttation Guttation - Loss of liquid water If cool night follows warm, humid day, water droplets are produced through hydathodes at tips of veins. In absence of transpiration at night, pressure in xylem elements forces water out of hydathodes. Guttation in barley plants © McGraw Hill © Kingsley Stern 26  Transport of Food (Organic Solutes) in Solution Important function of water is translocation of food substances in solution by phloem. Pressure-Flow Hypothesis - Organic solutes flow from source, where water enters by osmosis, to sinks, where food is utilized and water exits. Organic solutes move along concentration gradients between sources and sinks. © McGraw Hill (a) © P. Dayanandan/Science Source; (b) © Steven P. Lynch 27  Macronutrients and Micronutrients Macronutrients - Used by plants in greater amounts Nitrogen, potassium, calcium, phosphorus, magnesium and sulfur Micronutrients - Needed by the plants in very small amounts Iron, sodium, chlorine, copper, manganese, cobalt, zinc, molybdenum and boron When any required element is deficient in soil, plants exhibit characteristic symptoms. © McGraw Hill 28