1. AP Biology 2005-2006 Chapter 38. Plant Reproduction

2. AP Biology 2005-2006 Animal vs. Plant life cycle multicellular 2n multicellular sporophyte 2n multicellular gametophyte 1n unicellular gametes 1n spores 2n gametes 1n AnimalPlant alternation of generations

3. AP Biology 2005-2006 diploid Alternation of generations haploid

4. AP Biology 2005-2006 Alternation of generations

5. AP Biology 2005-2006 Alternation of generations  Fern sporophyte  leafy plant you are familiar with  Fern spores  haploid cells that will sprout into gametophyte

6. AP Biology 2005-2006 Alternation of generations  Fern gametophyte  small diploid plant which produces gametes

7. AP Biology 2005-2006

8. AP Biology 2005-2006 Alternation of generations  Archegonium  female gamete-producing structure  produces a single egg cell in a vase-shaped organ

9. AP Biology 2005-2006 Alternation of generations  Antheridia  male gamete-producing structure  produces many sperm cells that are released to the environment flagella = swimming sperm

10. AP Biology 2005-2006 Evolutionary trends  Alternation of generations  dominant haploid plant  bryophytes - mosses  dominant diploid plant  pteridophytes - ferns  gymnosperm - conifers  angiosperm - flowering plants  Evolutionary advantage?  reduction of gametophyte protects delicate egg & embryo in protective sporophyte

11. AP Biology 2005-2006 Moss sporophytes

12. AP Biology 2005-2006 Reduction of gametophyte

13. AP Biology 2005-2006 Gametophytes of seed plants  male gametophyte  pollen in male cone  female gametophyte  develops in female cone  seed  naked in cone  male gametophyte  pollen in anthers of flower  female gametophyte  develops in ovaries of flower  seed  protected in ovary  ovary wall can develop into fruit GymnospermAngiosperm

14. AP Biology 2005-2006 Gymnosperm life cycle female gametophyte in cone male gametophyte in pollen sporophyte in seed

15. AP Biology 2005-2006 Angiosperm life cycle female gametophyte in ovary male gametophyte in pollen sporophyte in seed

16. AP Biology 2005-2006 Flowers

17. AP Biology 2005-2006 Flower  Modified shoot with 4 rings of modified leaves  sepals  petals  stamens  male  carpals  female

18. AP Biology 2005-2006 pistil

19. AP Biology 2005-2006 Male & female parts of flower

20. AP Biology 2005-2006 Parts of flower  Male  stamens = male reproductive organs  stamens have stalks (filament) & terminal anthers which carry pollen sacs  pollen sacs produce pollen  pollen grain = gametophyte  sperm-producing structure

21. AP Biology 2005-2006 Parts of flower  Female  carpels = female reproductive organs  ovary at the base  slender neck = style  within the ovary are 1 or more ovules  within ovules are embryo sacs  female gametophyte = embryo sac  egg-producing structure

22. AP Biology 2005-2006

23. AP Biology 2005-2006

24. AP Biology 2005-2006 Fertilization  Pollination  pollen released from anthers is carried by wind or animals to land on stigma  pollen grain produces a pollen tube  pollen tube grows down style into ovary & discharges 2 sperm into the embryo sac  1 sperm fertilizes egg = zygote  zygote develops into embryo  ovule develops into a seed  ovary develops into a fruit containing 1 or more seeds

25. AP Biology 2005-2006 Preventing self-pollination  Various mechanisms  stamens & carpels may mature at different times  arranged so that animal pollinator won’t transfer pollen from anthers to stigma of same flower  biochemical self-incompatibility = block pollen tube growth

26. AP Biology 2005-2006 Preventing self-fertilization  This model involves the “S” allele  Pollen (male) with same allele cannot germinate on stigma (female)  Matching alleles interact & inhibit RNA production

27. AP Biology 2005-2006 Biochemical mechanism  Preventing self-fertilization  pollen produces signal → receptor → kinase → signal transduction path → effector protein produced → block pollen tube growth

28. AP Biology 2005-2006 Fertilization in flowering plants  Double fertilization  2 sperm from pollen  1 sperm fertilizes egg = diploid zygote  1 sperm fuses with 2 polar nuclei to form 3n endosperm  endosperm = food tissue in seed  coconut milk  grains

29. AP Biology 2005-2006 Pollen tube growth  grow down style to ovule  path for sperm nuclei

30. AP Biology 2005-2006 Fertilization in flowering plants  Development of the new sporophyte

31. AP Biology 2005-2006 Plant embryo endosperm cotyledons embryo seed coat ovary wall

32. AP Biology 2005-2006 Seed Anatomy  Sporophyte in seed  Sets stage for structure of plant  Roots  Shoots  Leaves

33. AP Biology 2005-2006 Germination  How does the dicot differ from the monocot?

34. AP Biology 2005-2006 Mobilization of nutrients  Seed germination  1. seed imbibes water  2. gibberellin release signals aleurone layer  3. amylase is released which hydrolyzes starch  4. sugar is absorbed by embryo

35. AP Biology 2005-2006 Fruit  Fruit is a mature ovary  seeds develop from ovules  wall of ovary thickens to form fruit  fruits protect dormant seeds & aid in their dispersal

36. AP Biology 2005-2006 Fruit development  Pea (legume)

37. AP Biology 2005-2006 Fruit development  Peach (stone fruit or drupe)  1 flower : 1 carpel : 1 ovary : 1 seed

38. AP Biology 2005-2006 Fruit development  Apple (pome fruit)  1 flower : 5 carpels : many ovaries : many seeds

39. AP Biology 2005-2006 Fruit development  Citrus fruit (berry)  1 flower : many carpels : many ovaries : many seeds

40. AP Biology 2005-2006 Fruit development  Raspberry (aggregate fruit)  1 flower : many ovaries : many seeds

41. AP Biology 2005-2006 Reproduction in angiosperm  Sporophyte plant produces unique reproductive structure = the flower  male gametophyte = pollen grain  develop within anthers of flower  female gametophyte = embryo sac  develop within ovaries of flower  pollination by wind or animals brings pollen grain to female gametophyte  fertilization takes place within ovary  double fertilization = embryo & endosperm  seeds contain sporophyte embryo  development of seeds in ovary  ovary develops into fruit around the seed

42. AP Biology 2005-2006 Coevolution of plants & animals  Angiosperms & animals have shaped one another’s evolution  Natural selection reinforced the interactions because they improved the reproductive success of both partners

43. AP Biology 2005-2006 Seed dispersal  Plants produce enormous numbers of seeds to compensate for low survival rate  a lot of genetic variation for natural selection to screen