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Plants

Plants. What is a Plant?. Plant Types : Trees, shrubs, grasses, mosses, ferns, algae Characteristics: Kingdom plantae Eukaryotes Have cell walls (contains cellulose) Conduct photosynthesis Autotrophic (some are parasites ( mistletoe ) or saprobes). What do plants need to survive?.

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Plants

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  1. Plants

  2. What is a Plant? Plant Types: Trees, shrubs, grasses, mosses, ferns, algae Characteristics: Kingdom plantae Eukaryotes Have cell walls (contains cellulose) Conduct photosynthesis Autotrophic (some are parasites (mistletoe) or saprobes)

  3. What do plants need to survive? • Sunlight - use energy from the sun to carry on phogosynthesis • Gas exchange - oxygen is needed to support cellular respiration, and is released in an exchange with the atmosphere and soil. - carbon dioxide is needed for photosynthesis • Water - raw material if photosynthesis; they absorb water via roots • Minerals - absorb minerals and nutrients from the soil for growth via diffusion.

  4. Plant Life Cycle Two phases of land plant life cycle: Known as alternation of generations Diploid (2N) phase, and haploid (N) phase Diploid Phase: • Called sporophyte Haploid Phase: - called gametophyte The Cycle • Sporophyte produces haploid spores via meiosis • Spores grow into gametophytes • Each gametophyte produces gametes (sperm and egg) • Fertilization occurs producing a diploid zygote • Zygote develops into a new sporophyte (cycle restarts)

  5. Seedless Plants Algae • First plants to appear on earth • Aquatic (fresh, and salt water, as well moist areas on land) • Absorb nutrients and moisture from surroundings (do not have specialized tissue) Life Cycle • Haploid cells can reproduce asexually in the life cycle pending on environmental factors, or it can produce sexually • Zygote has a thick wall (help survive in freezing or dry conditions) • Zygote grows and produces four flagellated haploid cells (swim away, mature and reproduce asexually)

  6. Mosses • Short in length • Soft • Thin waxy coating (helps resist drying) • Thin filaments called rhizoids(anchor to grown and absorb water /minerals from soil) • Belong to a group called bryophytes • Byrophyteshave reproductive organs within a nonreproductive cell. • Hornworts and liverworts are other plants in the group byrophyte.

  7. Byrophytes • Found in damp places • Most plants carry water in specialized tissues called VASCULAR TISSUES, but not byrophytes • Vascular tissues contain tubes hardened with lignin • Byrophytes do NOT make lignin or have vascular tissue (explains the small size) Life Cycle • Gametophyte is the dominant stage (carries most of the photosynthesis) • Sporophyte depends on the gametophyte for supply of water and nutrients • Sperm must be released in the water and swim to the eggs (why they live in damp areas)

  8. Vascular Plants • Known as TRACHEOPHYTES (contain a water conducting cells called TRACHEIDS) • Tracheids - hollow tubelike cells; thick cell walls strengthened by lignin - Find in xylems (carries water upward from the roots to the plant) - Openings between the tracheids that allow water to pass is called PITS. Vascular plants have a second transport tissue called PHLOEM. Phloem transports nutrients and carbohydrates

  9. Seedless Vascular Plants Three types: Mosses, horsetails, and ferns Ferns are the most abodundant of seedless plants Life Cycle The sporophyte is the dominant stage

  10. Seed Plants All seed plants produce seeds Seeds are plant embryos and food supply The plant within a seed is diploid and is in early sporophyte phase of the plant life cycle. Overtime some plants evolved adaptations that allowed them to survive in different conditions on dry land. Some of these adaptations are: • Reproductive process in cones or flowers • Transfer of sperm by pollination • protection of embryos in seeds Unlike mosses and ferns, the seed plant’s gametes do no not need standing water for fertilization,

  11. Cones and Flowers In seed plants male and female gametophytes grow and mature within the sporophyte. Gametophytes develop in reproductive structures called cones or flowers There are two groups that represent seed bearing plants: Gymnosperms- have seeds on the scales of cones Angiosperms- have seeds in flowers that are within layers of tissue (protects the seed

  12. In seed plants the male gametophyte is contained within a tiny structure called pollen grain. Sperm within pollen grain to not swim up water to fertilize the egg, instead they are carried to the female reproductive structure by wind, or insects. The transfer of pollen from male to female is called pollination. After fertilization, the zygote within the seed grows into a tiny plant (sporophyte embryo). The seed develops a protective seed coat, that prevents it from drying out. Ovules- structures where the female gametophyte develop. Meiosis produces haploid cells that grow and divide to produce female gametophytes.

  13. Pollination and Fertilization Conifer life cycle (pines) takes two years to complete Begins in the spring (male cones release pollen grains) When caught in the female cones they are caught in a sticky secretion on the scales of the female cone and pulled towards the ovule. Pollen tube- contains two haploid sperm nuclei, where fertilization takes place.

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