Presentation on theme: "Plant life cycles alternate between producing spores and gametes."— Presentation transcript:
1 KEY CONCEPT All plants alternate between two phases in their life cycles.
2 Plant life cycles alternate between producing spores and gametes. A two-phase life cycle is called alternation of generations.haploid phasediploid phasealternates between the twofertilizationmeiosisSPOROPHYTEPHASEGAMETOPHYTE
3 The spore-producing plant is the mature sporophyte. sporophyte phase is diploidbegins with fertilized eggspores produced through meiosisThe gamete-producing plant is the mature gametophyte.gametophyte phase is haploidbegins with sporegametes produced through mitosisfertilizationmeiosisSPOROPHYTEPHASEGAMETOPHYTE
4 Life cycle phases look different among various plant groups. Nonvascular plants have a dominant gametophyte phase.moss gametophytes look like green carpetmoss sporophytes shoot up as stalklike structuressporophyte (2n)gametophyte (1n)capsulespores (1n)
5 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 zygote3) Diploid sporophyte will grow from the gametophyte where the zygote is located4) Sporophyte will create and release haploid spores.....sporophytegametophyte
6 5) Spores land and grow into new gametophytes 6) The process repeats .....groundgametophyte
7 The sporophyte is the dominant phase for seedless vascular plants. Fern spores form in sacs, sori, on underside of mature sporophytes (fronds).sporophyte (2n)sori
8 A fern gametophyte, or prothallus, produces sperm and eggs. gametophyte (1n))rhizoidA zygote forms on the prothallus, growing into the sporophyte.
11 3) From the haploid spores, a prothallus (haploid gametophyte) grows in the soil -- Rhizoids anchorLet’s zoom inground
12 4) Sperm swim through water from the antheridium to the archegonia Let’s zoom back out
13 5) Diploid sporophyte (fiddlehead) grows from the prothallus -- prothallus eventually diesground
14 6) Fiddlehead uncurls into fronds of ferns. 7) Cycle repeats-- Sporangia creates spores to be released....ground
15 The sporophyte is the dominant phase for seed plants. pine trees are typical seed plant sporophytesfemale spores produced in female conesmale spores produced in male conesmale spores develop into pollen grains, the male gametophytesfemale spores develop into female gametophytes that produce eggssperm from pollen travel down pollen tube toward eggfertilized egg develops into embryoovule develops into protective pine seed
16 The sporophyte is the dominant phase for seed plants.
17 1) Male and female seed cones grow in adult sporophytes
18 2) Pollen grains released from the male seed cones 2) Pollen grains released from the male seed cones -- Pollen is the male gametophyteLet’s zoom into the female seed cone
19 3) Pollen grain sticks to the female ovule 4) Pollen tube grows from the male spore5) Two nuclei transfer into female spore - one fertilizes the egg6) Diploid embryo develops (sporophyte stage restarts)
20 7) After seeds harden, the cone reopens and the seeds are released