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Botany Study of Plants I Are all plants the same? A. All plants share some common characteristics. 1. 2. 3. All plants are photosynthetic autotrophs. In order to photosynthesize, plants use special cell structures called chloroplasts. Chloroplasts are filled with a pigment called chlorophyll that transfers light energy into chemical energy. The plant then uses the energy to make sugars, which store the energy for later use in respiration. All plants are multicellular. Plants are made of eukaryotic cells with cell walls surrounding the cell membrane for protection against cell lysis, large vacuoles near the center of the cell to store water, and chloroplasts in specialized cells within the plant body. Plants are common producers in ecosystems, forming the base of all terrestrial food webs. I Are all plants the same? B. Plants are divided into groups based on differing characteristics. 1. The first main division of plants is based on the presence of vascular tissue. Vascular tissue consists of specialized cells joined into tubes that aid the plant in moving water and nutrients throughout the plant body. a. b. Nonvascular plants lack vascular tissue. Vascular plants have two basic types of vascular tissue: xylem (which carries water) and phloem (which carries nutrients). I Are all plants the same? 2. Vascular plants can be further divided based on the means of reproduction: a. b. c. Paw-Paw cashew Seedless vascular plants reproduce using spores (ex. fern). Gymnosperms are vascular plants which store seeds in cones (ex. spruce). Angiosperms are vascular plants which store seeds in fruits which develop from flowers (ex. daisy). Review Questions 1. Name three characteristics shared by all plants. Multicellular, autotrophs(photosynthetic) eukaryotic cells with cholorplasts. 2. What are the two main divisions of plants? Vascular plants and Nonvascular plants 3. How are vascular plants further sub-divided? Angiosperms and Gymnosperms 4. What is an angiosperm? A vascular plant that stores seeds in fruits that develop from flowers. II Are plants alive? A. Transport describes how plants get what they need to the cells and remove wastes from the cells. 1. 2. Non-vascular plants depend on osmosis to take in water and diffusion to move other important substances (sugars) to the cells. Therefore, the plant must be small and grow in mats which have a spongy quality which help to absorb and retain water. Vascular plants have a system of tubes and vessels which allow them to transport water and nutrients throughout the plant body. Therefore, the plant can grow much taller. a. b. Xylem is the vascular tissue that transports water from the roots to the rest of the plant body. Phloem is the vascular tissue that transports nutrients (sugars produced through photosynthesis) from the photosynthetic structures (ex. leaves) to the rest of the plant body. II Are plants alive? B. Respiration describes the process by which plants (and all other cells) transform the stored energy of sugars into the quick energy of ATP. In order to respire plants need to obtain oxygen (from environment and/or photosynthesis) and sugars (from photosynthesis). II Are plants alive? diffusion/osmosis animation C. Excretion describes how the plant rids itself of wastes. 1. Non-vascular and vascular plants get rid of excess gases produced by photosynthesis and cellular respiration by diffusion. Vascular plants, however, have special microscopic openings on the surface of the leaves through which the diffusion takes place. These openings are called stomata and are formed by two adjacent guard cells. 2. Plants can also store waste in the vacuole or in organs which are destined to fall off or die (ex. leaves in the autumn). Some plants excrete waste products into the soil, occasionally using the wastes as chemical weapons against other competing plants Black Walnut Toxicity to Plants , Humans and Horses Review Questions 1. How do non-vascular plants transport water? osmosis 2. What vascular tissue transports water? xylem 3. What do plants need in order to respire? oxygen and glucose 4. From where do plants get oxygen for cellular respiration? photosynthesis 5. What are stomata? Openings on the underside of the leaf where gases are exchanged and water evaporates from the plant. II Are plants alive? D. E. Synthesis describes how organisms build necessary molecules. Plants produce sugars through photosynthesis which requires gas exchange through the stomata. Plant cells must also produce essential cell molecules such as phospholipids for membranes and proteins for enzymes. Nutrition describes how organisms break down food. The sugar produced in photosynthesis may be stored or moved throughout the plant to be broken down and used during cellular respiration. Apical Meristems II Are plants alive? F. Regulation describes how organisms control body processes. 1. Plants produce hormones which regulate their growth and development and may control responses to stimuli. a. b. c. Auxins are hormones that allow for elongation of the cell. This increased flexibility allows the plant to bend Cytokinens are hormones that promote rapid cell division. These hormones are found in rapidly growing regions of the plant such as the apical meristems (plant tissue in root tips and buds of shoots that supply cells for the plant to grow in length). Ethylene is a hormone that promotes fruit ripening. Because ethylene is a gas, it can affect nearby fruit. II Are plants alive? 2. • Plant tropisms are plant growth responses to external stimuli. These responses are made possible by hormones such as auxin. a. Phototropism describes a plant’s response to light. Ex. Leaves and stems grow toward the light to help with photosynthesis. b. Gravitropism/Geotropism describes a plant’s response to gravity. Ex. Roots grow toward the force of gravity but stems grow against the force of gravity. c. Thigmotropism is a response to constant contact. Ex. Vines wrap around an object, such as a mailbox. Plant Movement Animations Review Questions 1. Give two examples of important substances plants need to synthesize. proteins, sugars, phospholipids 2. How does a plant use the sugar produced in photosynthesis? To make ATP through respiration 3. What regulates the growth and development of plants? Hormones 4. What term describes a plant’s response to constant contact? Thigmotropism Plant Life Cycle Animation