Matthew Boggs Aaron Seigler Victor Makali Gordon Gulledge A seed is a fertilized, ripened ovule of a gymnosperm or angiosperm. • Ovule- In plants, a structure that contains a gametophyte and, within the gametophyte, an egg; when it matures, an ovule becomes a seed. • Angiosperm- Plants with ovules, enclosed in an ovary. • Gymnosperm- a vascular plant whose seeds are not in an ovary. A fruit is a ripened and mature ovary containing seeds. • Ovary- Any female organ, that produces an egg. (Source- Life: The Science of Biology) Angiosperms: Examples- tomatoes, roses, walnuts, oranges Gymnosperms: Examples- shrubs, some wild flowers, giant Sequoia’s (Source- Dictionary.com) Seed Coat Cotyledon- an embryonic organ that stores and digests reserve materials. Shoot Apex Root Apex Endosperm- contains stored nutrients for the developing embryo. • Is a triploid or has three sets of DNA 3n. (Source- Life: The Science of Biology) Exocarp Mesocarp Endocarp The “Pericarp” is the collective term for the above components of a fruit. (Source- Life: The Science of Biology) Since some plants do not produce seeds, they must reproduce asexually. The two types of plants that reproduce asexually are sporophytes and gametophytes. Sporophytes – The spore-producing phase in the life cycle of a plant that exhibits alternation of generations. Example: Mosses Gametophytes – The gamete-producing phase in a plant characterized by alternation of generations. Example: Willows (Source- Life: The Science of Biology) The “above ground” part of the plant, known as the shoot system starts to grow once the root system as established secure anchoring. The growth of the shoot system occurs at the shoot meristem. This is where mitosis cell division occurs. These cells can be omnipotent, totipotent, or pluripotent. • • • • • Mitosis- Division leading to the formation of two daughter cells. Meristem- Plant tissue made up of undifferentiated actively dividing cells. Omnipotent- Can virtually change into any type of cell. Totipotent- Can give rise to every type of cell. Pluripotent- Can differentiate into a limited number of cell types. (Source- Life: The Science of Biology) Stems Leaves Nodes and Internodes - a node is the point on a stem where a leaf is or was attached. - an internode is the region between two nodes. (Source- Life: The Science of Biology) A Plant is able to determine which way is up through the use of photoreceptors. These photoreceptors direct the plants grow towards a stimulus; stimuli include light. Photoreceptors- a sensory receptor cell that senses and responds to light energy. Once direction has been determined, the growth of the plant is regulated by hormones; similar to how hormones regulate growth in animals. Animals – example of a hormone: Testosterone Plants hormones– Auxins and Gibberellins (Source- Life: The Science of Biology) The upper parts of the plant depend on the roots to provide water and dissolved minerals collected from the soil. (Source- Life: The Science of Biology) The root depends on the upper part of the plant to produce sugars and other organic substances through photosynthesis. (Source- Life: The Science of Biology) The Shoot System and Root System are connected through two sets of vascular tissues(Xylem and Phloem) that transport resources back and forth. Xylem- the vascular tissue that conducts/transports water and dissolved minerals in plants upward. Phloem- the vascular tissue that conducts/transports dissolved sugars and other organic compounds in plants up and down. (Source- Life: The Science of Biology) Dictionary.com Sadava, David, David Hillis, William K. Purves, H. C. Heller, and Gordon H. Orians. Life : The Science of Biology. 8th ed. Boston: W. H. Freeman & Company, 2006. “Plants Know the Way to Grow.”Fast Plants. 1995. http://www.fastplants.org/pdf/activities/ know_the_way.pdf