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Plants . Overview, Reproduction, PRocesses. Characteristics of Plants. Cell wall – protective and structure to cell Chlorophyll – green pigment that aids in photosynthesis Central Vacoule – stores water
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Plants Overview, Reproduction, PRocesses
Characteristics of Plants • Cell wall – protective and structure to cell • Chlorophyll – green pigment that aids in photosynthesis • Central Vacoule– stores water • Cuticle – waxy, protective layer on the surface of plants (controls evaporation – retains water) • Cellulose – chemical plants make out of sugar (help with cell wall creation) • Roots/root like structures – hold them in the ground and absorb nutrients from soil or water
Plant Classification • Vasucular – tube-like structures that carry water, nutrients and other substances throughout the plant Or * Nonvascular – do not have the tube-like structures. Use other ways to transport.
Seedless Nonvascular Plants • Usually only a few cells thick • Do not have roots, but RHIZOIDS that anchor them into the ground (thread-like structure) • Do Not have flowers • Most grow in damp areas • Reproduce by spores – carried by the wind • Usually the first species in a new area (after a fire for example) • Examples: Moss, Liverworts, Hornworts
Seedless Vascular Plants • Reproduce by spores NOT seeds • Have tube-like structures to transport water and nutrients throughout the plant • Can grow bigger and thicker then nonvascular. • A lot of fossils: most grew 360-286 million years ago • ex.: fern, horsetail
Importance of seedless plants • Turns into coal over millions of years • Peat – forms from remains of moss, - low cost fuel in Ireland and Russia • House plants • Weaving material – baskets • Ground into flour • Folk medicine – used to treat stings, burns, fevers and dandruff.
Seed Plant Characteristics • They have leaves, stems, roots and vascular tissue • Produce seeds • Classified as either gymnosperms or angiosperms • Leaves are the organ of the plant – food making happens • Stems – transfer nutrients from roots to leaves • Roots – large or larger then the actual plant above. Support the plant, store food, absorb nutrients and water.
Gymnosperm characteristics • They are the oldest trees alive • Produce seeds that are not protected by fruit • They do not have flowers • The leaves are needle-like or scale-like • Examples: Conifers, Ginkgoes, pine, firs, spruce, redwoods
Angiosperm Characteristics • Has flowers and produces fruit with one or more seeds • More then half of the known plant species belongs to angiosperms • The flower and fruit are the reproductive part of the plant • Divided into monocot and dicot • Life cycle: if done in one year (annual) within two years (biennials)take more then two years (perennials)
Importance of seed plants • Paper, books, desks, chairs, tables • Clothing • Food (bread, fruit, potato chips) • Wood for building (construction)
Plant reproduction • Plants can reproduce either sexually or asexually • Sexually – needs a male and female part • Needs fertilization to take place • This happens by the transport of water, wind, animals (insects) • Asexually – making new plants without sex cells (identical to parent)
Seed plant reproduction • Angiosperms • Use flowers – have both male and female parts • Flowers and scent are used to attract animals/bees • Small flowers use wind or water • Gymnosperms • Both male and female parts are in the cone • Pollen is carried by the wind • Reproduction of a seed might take 2-3 years
Photosynthesis • When chlorophyll traps light energy and sugars are produced. • Only cells with chloroplasts complete photosynthesis • Importance • Produces food • Use carbon dioxide and realease oxygen • 90 percent of the oxygen entering the atmosphere is from photosynthesis
Respiration • Breaks down food molecules and releases energy • Occurs in cells of most organisms (us!) • If it uses oxygen – aerobic • Doesn’t use oxygen – anaerbic • Importance • Changes food energy into something we can use • Releases carbon dioxide – so plants can use it.
Tropisms • A plants reaction to stimuli (change) • Can be positive or negative • Due to touch, light or gravity.
Plant Hormones • Ethylene – speeds up the ripening in fruit • Auxin – response to light , help in development of flowers, roots and fruit • Gibberllins and Cytokinins – causes stems to grow tall and seeds to germinate • Abscisic Acid – keeps seeds from sprouting in the winter.
Photoperiods • The amount of dark and light a plant receives each day. • Some plants are either long-day plants, short-day plants or day-neutral plants