Plant Life Cycles

1. Plant Life Cycles Plant life cycles alternate between two cycles: Producing spores and producing gametes

2. Alternation of Generations • Sporophyte (diploid) • Begins when sperm fertilizes egg (zygote) • Diploid zygote divides by mitosis to create a mature sporophyte • Meiosis produces haploid cells called spores • Haploid spores released

3. Alternation of Generations • Gametophyte (haploid) • Begins with spores created by meiosis • Spore grows into gametophyte • Male gametophyte creates sperms • Female gametophyte creates eggs • Sperm & egg create diploid zygote (process repeats)

4. Capsule Spores sporophyte (2n) gametophyte (1n) Group OneSeedless, nonvascular plants (ex: moss) • Characteristics: • Live in moist environments • Lack true leaves (only one cell thick) • Rhizoids anchor into soil • Early inhabitant of new ecosystems (succession) • Moss gametophytes look like green carpet • Moss sporophytes shoot up as stalk-like structures

5. Moss Life Cycle Snapshot • Gametophyte phase • Dominant stage • Carpet of moss growing near ground • Archegonium: produces female egg • Antheridium: produces male sperm • Sperm swims through water to fertilize egg • Sporophyte phase • Stalk grows up from the gametophyte (zygote) • Sporangia (capsule)houses haploid spores • Spores land, and new gametophyte grows See appendix B in your text book for more info

6. 1) Moss gametophytes grow near the ground (haploid stage) 2) Through water, sperm from the male gametophyte will swim to the female gametophyte to create a diploid zygote 3) Diploid sporophyte will grow from zygote 4) Sporophyte will create and release haploid spores . . . . . XY - Antheridium Sporophyte XX - Archegonium egg zygote zygote egg egg zygote zygote egg male male Gametophyte Phase female female female male female male

7. 5) Haploid spores land and grow into new gametophytes 6) The process repeats . . . . . ground Gametophyte Phase

8. Plant Life Cycle Comparisons

9. Group TwoSeedless, vascular plants (ex: ferns) • Characteristics: • Vascular system allows nutrient transport to greater heights • Rhizoids: Underground stems draw nutrients, like roots • Fiddleheads are uncurled leaves (fronds) • Fern sporophytes are the typical leaf like plant • Fern gametophytes (prothallus) look like a heart

10. Fern Life Cycle Snapshot • Sporophyte phase • Dominant stage • Sporangia (spore producing structure) creates haploid spores • Sori are clusters of sporangia • Spores released and land • Gametophyte phase • Spore grows into prothallus • Archegonium: produces female egg • Antheridium: produces male sperm • Sperm swims to egg • Zygote begins sporophyte stage See appendix B in your text book

11. 1) Sporophyte creates and releases haploid spores . . . . Adult Sporophyte (diploid) Ground

12. 2) Haploid spores land in the soil . . . . Ground

13. 3) From the haploid spores, gametophyte grows in the soil Let’s zoom in… Ground

14. 4) Sperm swim through water from the male parts (antheridium) to the female parts (archegonia) Let’s zoom back out… egg zygote egg zygote egg zygote

15. 5) Diploid sporophyte grows from the zygote sporophyte Ground

16. 6) Fronds uncurls into leaves. 7) Cycle repeats -- Haploid spores created and released . . . . Ground

17. Plant Life Cycle Comparisons

18. Group ThreeSeeded, vascular plants (ex: gymnosperms) Cycad Ginkgo • Characteristics: • Vascular system allows nutrient transport to greater heights • Seeds not enclosed in fruit (angiosperms); produced inside cones • Advantages of seed plants • Seeds allow for reproduction without free-standing water = Pollen • Seeds nourish and protect the growing plant embryo = Endosperm , seed coat, dormancy • Seeds allow plants to disperse to new places = Wind, water, animals • Conifer sporophyte is the typical tree like structure • Conifer gametophytes are inside the male/female cones Conifer What are the other types of gymnosperms?

19. Conifer Life Cycle Snapshot • Sporophyte phase • Dominant stage • Cones grow on tree • Female cones produce egg & seed • Male cones produce pollen • Pollen reaches end of female scale and sticks to ovule • Pollen tube grows from pollen • Sperm travels down pollen tube (zygote/seed created) • Sporophytestage restarts See appendix B in your text book

20. The sporophyte is the dominant phase for seed plants

21. 1) Male and female seed cones grow on adult sporophytes

22. 2) Pollen grains released from the male seed cones -- Pollen is the male gametophyte Let’s zoom into the female seed cone…

23. 3) Pollen grain sticks to the female ovule 4) Pollen tube grows from the male spore 5) Two nuclei transfer into female spore - one fertilizes the egg 6) Diploid embryo develops (sporophyte stage restarts)

24. 7) After seeds harden, the cone reopens and the seeds are released

25. 8) Seed will land Ground

26. 9) Seedling grows into (sporophyte)…the cycle repeats Ground

27. 9) Seedling grows into (sporophyte)…the cycle repeats Ground

28. Plant Life Cycle Comparisons

29. Group FourSeeded, vascular plants (ex: angiosperm)

30. stamen filament anther stigma style carpel ovary sepal petal Flowers contain reproductive organs protected by specialized leaves • Sepals and petals are modified leaves. • Sepals are outermost layer that protectsdeveloping flower • Petals can help to attract animal pollinators • A stamen is the male structure of the flower • anther produces pollen grains • filament supports the anther • The innermost layer of a flower is the female carpel. • stigma is sticky tip • style is tube leading from stigma to ovary • ovary produces female gametophyte

31. Flowering plants can be pollinated by wind or animals • Wind pollinated flowers have small flowers and large amounts of pollen. • Animal pollinated flowers have larger flowers and less pollen. many flowering plants pollinated by animal pollinators • Pollination occurs as animal feeds from flower to flower • Animal pollination more efficient than wind pollination

32. Fertilization takes place within the flower • Male gametophytes, or pollen grains, are produced in the anthers. • Male spores produced inanthers by meiosis • Each spore divides bymitosis to form twohaploid cells • Two cells form asingle pollen grain Pollen grain Stamen Anther Filament

33. One female gametophyte can form in each ovule of a flower’s ovary • Many cells can be made in the ovule • One cell becomes the egg • One cell becomes 2 polar nuclei • The rest die Polar nuclei (2n)

34. 1. Pollen stick to animal or released into wind.

36. 2. Animal finds a new flower to feed on and pollen grains land on the stigma (pollination) 3. Pollen tube grows and 2 nuclei transfer into the ovule . . Let’s zoom in…

37. female gametophyte egg sperm polar nuclei ovule 4. Flowering plants go through the process of double fertilization. Double Fertilization 1 sperm fuse with the polar nuclei = triploid (3n) endosperm 1 sperm fuse with the egg = zygote

38. endosperm seed coat embryo 5. Each ovule becomes a seed. • Endosperm provides food supply for embryo The surrounding ovary grows into a fruit.

39. 6. Seeds get dispersed 7. Seed germinates, and the cycle starts over Ground

40. Plant Life Cycle Comparisons