ryan1992hk asked in 科學及數學生物學 · 1 decade ago

F.6 Biology Plant Reproduction

Bacteria can undergo asexual or sexual reproduction to produce offsprings.

(1)However, how do algae/prototists reproduce?(By spores? Asexually or sexually?)

(2) Fungi, Moss and fern reproduce by producing spores, is it an asexual or sexual reproduction?(Are spores diploid or haploid?)

(3) Gymnosperms have seeds on their cones, does it mean that gymnosperms undergo sexual reproduction?(Those seeds are only found on the female cones but not the male cones?Gymnosperms can also produce ovum and sperms?Why does it mean the line stated on the textbook'Male and female cones are found in the same or separate tress':can have self-pollination or cross-pollination?)

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  • 1 decade ago
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    (1)How do algae/prototists reproduce?(By spores? Asexually or sexually?)

    Both. At good times, asexual reproduction is quick and effective. It can be fragmentation, budding, etc.

    At bad times, they produce sex cells, so that the zygote is protected under a tough case to live through the hard times. Also, sexual reproduction means a shuffling of genes, which will produce a better genotype by random. So with natural selection, these better genotypes persisted and the whole population is improved.

    (2)

    Fungi, Moss and fern reproduce by producing spores, is it an asexual or

    sexual reproduction?(Are spores diploid or haploid?)

    Fungi, moss and fern have two stages, 1N is called gametophyte, 2N is called sporophyte. This type of lifecycle is called [alternation of generations]. See it here:

    http://en.wikipedia.org/wiki/Alternation_of_genera...

    Ferns:

    圖片參考:http://upload.wikimedia.org/wikipedia/commons/thum...

    Gametes, gametophyte, actually the pink part of the diagram, is haploid. Spores and sporophytes are diploid. The part we usually call fern is the sporophyte part of the cycle.

    Moss and liverwort:

    It is the other way around. What we see as moss is the gametophyte. The sporophyte is very small for us to notice. But it works the same as fern, it has alternation of generation.

    Fungi:

    Fungi is a very large group. Yeasts works similar with bacteria. But mushrooms and slime works very differently. It's too complicated to discuss here. Please go to:

    http://en.wikipedia.org/wiki/Fungi#Reproduction

    2009-12-30 19:44:35 補充:

    (3) Gymnosperms have seeds on their cones, does it mean that gymnosperms undergo sexual reproduction?

    Yes!

    Those seeds are only found on the female cones but not the male cones?

    Of course. Just like the fruit and seed is only formed in the ovary of flowering plants, and not in the anthers!

    2009-12-30 19:45:04 補充:

    Gymnosperms can also produce ovum and sperms?

    Yes. Gymnosperms have sex cells: megaspore (female) and microspore (male), which is somehow equivalent to ovule and pollen of the flowering plants.

    2009-12-30 19:45:18 補充:

    Why does it mean the line stated on the textbook 'Male and female cones are found in the same or separate tress':can have self-pollination or cross-pollination?

    If a plant only produce one type of sex cells, it cannot mate with itself. So self pollination is impossible.

    2009-12-30 19:45:24 補充:

    For flowering plants, cross pollination means A's pollen got onto B's stigma and B's pollen got onto A's stigma. So both A and B should have both male and female parts, right? If a plant only produce one sex, how can they cross pollinate?

    2009-12-30 19:50:24 補充:

    If male and female cones are found on the same tree, so it is possible for self pollination and cross-pollination.

    Source(s): wikipedia
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