Plants

1. Plants Autotrophs

2. Plants all share some characteristics: • All are photosynthetic. • All are multicellular. • All are eukaryotic organisms. • All can reproduce sexually.

3. Some evidence suggests that plants evolved from green algae: • Both use chlorophyll a, chlorophyll b, and carotenoid pigments during photosynthesis. • Primary food reserve of both is starch. • Both develop cell plate during cell division. • Both have cellulose cell walls.

4. Plants Have specialized cells. Have leaves, stems, roots. Most do not require water for fertilization. Adapted to life on land. Algae Few specialized cells. No special structures. Need water for fertilization. Adapted to life in water. Some important differences

5. Alternation of Generations 2-phase life cycle named for type of reproductive cells produced. Zygote divides by mitosis. Divide by mitosis. Form gametes by mitosis.

7. Lack vascular tissue (no true roots, stems, leaves) for transporting water and nutrients (restricts size). Rhizoids (root-like structures). Generally restricted to moist areas because flagellated sperm require film of water to swim to egg. Sporophyte dependent on gametophyte, which is dominant phase. Nonvascular Plantsmosses (Bryophytes)/liverworts (Hepatophyta)/hornworts (Anthocerophyta)

9. Vascular Plants • Contain specialized conducting tissue that transport water and dissolved substances from one part of the plant to another.  • Can grow larger, taller, and live in more environments than nonvascular plants. • Sporophyte is dominant phase.

10. Seedless vascular plantsFerns/whisk ferns/club mosses/horsetails • Have true roots, stems, and leaves. • Reproduce by windblown spores. • Flagellated sperm requiring water for fertilization. • Gametophyte usually separate small organism, quite different from independent sporophyte.

11. Phylum Pterophytaferns, whisk ferns, horsetails 1st vascular plant w/leaves & vascular tissue. Sporophyte dominant. Gametophyte independent. underground stems store starch

15. Vascular Seed Plants • Gametophyte very small sporophyte parasite. • Seed plants have 2 different spore sizes: megaspores and microspores.

16. Naked seeds produced in cones. • Microspores: • Produced in male cones. • Give rise to male gametophyte. • Develop into pollen grains. • Pollen grains carried by wind. Gymnosperms • Megaspores: • Produced in female cone. • Give rise to female gametophyte. • Each contained in an ovule. • Produce archegonia with egg cells.

17. Phylum Coniferophyta-conifers-largest, most familiar • Pine/firs/spruces/sequoias/junipers/cypresses • Tallest living redwood-360 feet tall. • Most massive tree-giant sequoia-6,200 tons. • Oldest-bristlecone pine-4,900 years old. • Evergreen adapted to cold: • Needles have thick cuticle and sunken stomata-lose water slower than broad leaves, don’t fall off. • Bark reduces water loss through stem. • Branches and needles flexible so snow and ice slide off tree (conical shape) and don’t break. • Antifreeze in sap-keeps leaves all year.

18. Cycads Cone-bearing palmlike–plants, mainly tropical/subtropical regions today. Ginkgo Only one species left. Chinese saved by planting them along roadsides. Gnetophytes Wood vessels like angiosperms. Other types of gymnosperms

19. Phylum Anthophyta-angiospermsflowering plants • Several factors led to success of angiosperms: • Seeds germinate, produce mature plants, and seeds in 1 growing season. • Gymnosperms->10 years to reach maturity. • Fruits of flowering plants protect seeds and aid in dispersal. • Mostly animal pollination-better than less efficient wind pollination. • More efficient vascular system.

20. Homework: Do Worksheets, pp. 93-96 http://www.glencoe.com/sec/science/biology/bio2000/pdfs/bdol21-1.pdf http://www.glencoe.com/sec/science/biology/bio2000/pdfs/bdol21-2.pdf

21. Roots/stems store food during drought, cold, limited sun. Underground modified buds of stem or fleshy scale leaves-rounder in shape. Short, thickened, underground stem-flatter in shape. Swollen root or stem with buds that sprout new plants (potato)-no scales or covering.

22. Life span of Anthophytes • Annuals-live for one year or less: • Germinate from seeds, grow, reproduce and die in single growing season. • Most are herbaceous-green stems with no woody tissue. • Form drought-resistant seeds that survive winter.

23. Biennials-life span of two years: 1st year-germinate, grow leaves, develop root system. Over winter, above ground portion dies 2nd year-new shoots produce flowers and seeds. Many develop large storage roots.

24. Perennials-live for several years: Produce flowers/seeds usually every year. Woody stems and underground storage organs remain intact and dormant each winter. Include deciduous trees, herbaceous grasses, wildflowers.

25. Monocots Dicots

28. reproductive structure of angiosperms large, colorful, ,attract pollinators sticky top protect developing bud • Flower-modified stems with specialized leaves and other structures for reproduction. • Have 3 basic components-male (stamen), female (pistil or carpel) and sterile parts (sepals, petals). • Perfect flower-has both male and female parts. • Imperfect flower-contains only male or female part. May or may not contain sepals or petals. • Complete flower-contains all four organs-male, female, petals or sepals. • Incomplete flower-missing one or more of four main organs.

32. Self-pollination: Pollen to stigma on same flower, no pollinator. Beneficial for plants isolated from own kind.  Usually undesirable (reduces new gene combinations). Hybridizing or Cross-pollination: More desirable (new gene combinations). Increasing chances by: Separate♀/♂ flowers. Separate♀/♂ plants. Pollen matures at different time from eggs. Location of flowers or flower parts. Chemical factors preventing self-fertilization. Pollinationpollen carried by wind, water, animals

33. 2 haploid sperm cells and 1 haploid tube cell Pollen growth and fertilization formed from tube cell grows down style tiny opening where 2 sperm cells enter ovule 2nd sperm nucleus fertilizes two polar nuclei to form which divides many times to form food-storing endosperm. Sperm nucleus fuses w/egg to form only in angiosperms

35. Seeds • Food supply used by embryo before photosynthesis begins. • Protected by tough seed coat. • Adapted for dispersal. • Do not need water for fertilization. • Pollen containing sperm cells carried by wind rather than water. • Ovule contains megaspore cell (egg). • Presence of a flower and fruit. • Fruit-ripened ovary that surrounds seeds of angiosperms. • Ovary-female reproductive part that encloses eggs.

36. Part of angiosperm seed 1. Cotyledon 2. Micropyle 3. Hilium-scar that marks where seed was attached to ovary wall. 4. Seed coat-protects embryo/ food supply (endosperm-carbohydrate in most, protein/ lipids in others). 3 embryo parts named by relationship w/cotyledons between cotyledon and radicle • Part above cotyledons • Become stem/leaves becomes embryonic roots leaflike structure (not true foliage leaves)

39. Seed Germinationwhen exposed to certain environmental conditions • Seeds absorb water (softens seed coat) to germinate: • Activates enzymes that convert starch in cotyledons or endosperm into simple sugars. • Provides energy for embryo to grow. • Seed coat cracks open, allowing oxygen (cellular respiration) to reach embryo. • Temperature range is 25-30oC. • At T < OoC or > 45oC, most won’t germinate. • Many need light-too deep, won’t germinate. • Some only after being exposed to extreme conditions: • After freezing. • Passing thru digestive system-breaks down seed coat.

40. Radicle • Straightens when breaks through soil. • Embryonic leaves unfold, make chlorophyll, begin photosynthesis.  • After stored nutrients used up, shrunken cotyledons fall off. Hypocotyl curves, hook-shaped. 

41. In monocot, cotyledon remains underground and transfers nutrients from endosperm to growing embryo. • Hypocotyl does not hook or elongate. • Plumule protected by sheath as it passes through soil. • Shoot breaks thru soil surface, leaves of plumule unfold.

42. Homework: Do Worksheet, pg. 107 http://www.glencoe.com/sec/science/biology/bio2000/pdfs/bdol24-2.pdf

43. Positive Gravitropism movement or growth toward stimulus. Tropisms-growth curves in response to stimuli of unequal intensity on different sides of plant organ

44. Negative Gravitropism movement or growth away from stimulus.

45. Thigmotropism

46. Phototropism

47. Tropistic Growth • Believed to be triggered by presence of plant hormones (auxin) that promote cell growth. • Moves to darker side of plant, causing cells there to grow larger than corresponding cells on lighter side of plant. • Produces curving of plant stem tip toward light. • Cells on underside of root elongate more slowly than those on upper side • Resulting in the root's downward growth.

48. Gibberellins Promote stem elongation. Increase rate of seed germination and bud development. Stimulate formation of flowers and fruits in some plants. Cytokinins Promote cell division. Produced in growing areas-meristems at tip of shoot.

49. Ethylene Gas produced on plasma membrane of ripe fruits. Used to ripen crops at the same time. Causes withering of flower parts after fertilization. Promotes dropping of leaves in fall. Inhibitors-AbscisicAcid Promotes seed and bud dormancy by inhibiting cell growth during unfavorable environmental conditions. Involved in opening and closing of stomata as leaves wilt (during water shortages).

50. Nastic movements (nasties)-generalized plant responses to a stimulus. Opening of bud scales/flower petals Growth movements that occur in response to stimuli (light/heat) without regard for direction of the stimulus. Some spring flowers exhibit thermonasties-flowers open in response to warmth and not amount of light.