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Algae

Algae. Reproduction of ulva. Alternation of Generations. Plants reproduce by switching back and forth between haploid and diploid generations. This is called alternation of generations . Alternation of Generations. Diploid plants ( sporophytes ):

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Algae

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  1. Algae Reproduction of ulva

  2. Alternation of Generations • Plants reproduce by switching back and forth between haploid and diploid generations. • This is called alternation of generations.

  3. Alternation of Generations • Diploid plants (sporophytes): • They always have a complete set of chromosomes; one from each parent.

  4. Alternation of Generations • Haploid plants (gametophytes): • These plants only have one set of chromosomes from one parent only. • In ulva, the sporophyte and gametophyte generations look the same!

  5. Reproduction of the Ulva • Note: • Isogamy: • Iso = same, gamy = gametes, so gametes of the same size and appearance. • Heterogamy: • Hetero = different, so gametes that are of different sizes. • Syngamy: • The fusion of gametes.

  6. Reproduction of the Ulva • Step 1: • The sporophyte develops into a diploid (2N) plant that is identical to the haploid plant. • Step 2: • Specialized cells in the sporophyte undergo meiosis to produce haploid zoospores. • This is asexual.

  7. Reproduction of the Ulva • Step 3: • The zoospores do not fuse, instead they divide by mitosis and form different (male /female ) gametophytes. • Step 4: • Gametophytes grow into haploid gametophyte plants.

  8. Reproduction of the Ulva • Step 5: • The gametophyte plants produce haploid female and male gametes. • The gametes are not the same size (heterogamy) • Step 6: • The gametes fuse (syngamy) and fertilization occurs. • This is the sexual stage.

  9. Reproduction of the Ulva • Step 7: • A diploid (2N) zygote is formed. • Step 8: • The zygote develops into a sporophyte.

  10. Reproduction of the Ulva • Asexual stage: • This allows for quick population growth when the conditions are good. • Sexual stage: • This might help algae survive sudden changes in the environment.

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