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Published byBrayan Granger Modified over 9 years ago
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Plants
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Asexual reproduction: one living organism involved. Offspring identical to parent. Sexual reproduction: requires one male and one female parent. Offspring looks like parents but is genetically different.
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Conifers and flowering plants: produce cones, flowers and seeds. Algae, mosses and ferns: produce spores.
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Does not involve meiosis or fertilization. One parent. Used by single-celled organisms such as Archaea, bacteria, and protists. Plants use roots, stems or leaves to reproduce asexually.
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An advantage of asexual reproduction is that an organism can reproduce by itself and it can occur rapidly. Asexual reproduction can lead to rapid population growth of a species. A disadvantage of asexual reproduction is that only clones are reproduced – there is no genetic variation. An organism would not be able to adapt and evolve to a changing environment.
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One forest = one individual
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Binary fission: one cell divides to form two identical cells. It duplicates its genetic material and then divides. Each new cell has its own complete copy of the parent’s genetic information. Budding: part of the parent develops into a new organism. The new organism then pinches off from the parent and lives independently. The new organism is genetically identical to its parent. Fragmentation: the body of the parent breaks into two distinct pieces, each can produce an offspring.
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Increased genetic diversity of the offspring. Characterized by two processes: Meiosis Fertilization: combination of two gametes (sex cells) During meiosis, chromosomes usually cross over = genetic recombination. Primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants. Plants reproduce sexually: through flowers, cones or seeds.
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Sexual reproduction has the advantage of providing lots of variation within a species, helping it to survive when the environment changes. The main disadvantage is that this process takes a lot of energy and time. This means that they can only produce small populations.
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A seed contains all the requirements needed to produce a new plant: The embryo: small immature plant The cotyledon: food reserves The seed coat: protective cover
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Gymnosperm (conifer): “naked seed” The seed only has the seed coat to protect it. Angiosperm (flowering plant): “enclosed seed” The seed has the seed coat as well as a second cover (pod, shell or pulp). Pod (beans) Shell (nuts) Pulp (fruits)
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Reproduction in spore-producing plants: No production of seeds! Spores: cells that contain complete genetic material – can become an immature plant without fertilization. Males spores become plants that produce spermatozoa and female spores become plants that produce ovules. Then comes fertilization. Reproduction in conifers: Male cones contain male gametes Female cones contain female gametes Seeds develop in female cones once the ovules are fertilized. Reproduction in flowering plants: Pollination and Fertilization Seed development Seed dispersal
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Flowers can either have male reproductive organs (stamens), female reproduction organs (pistils or carpels) and often a flower has both.
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Anther: where pollen is produced and stored Filament: supports the anther Pollen: contain male gametes (spermatozoa)
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Stigma: sticky surface that captures the pollen. Style: supports the stigma Ovary: contains female gametes (ovules) Ovules: female gametes
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Pollination leads to fertilization (zygote or fertilized egg). Fertilization: male and female gametes combine. Pollen must land on the stigma in order to fertilize the flower = pollination. Self-pollination: pollen transferred to the pistil of the same flower. Cross-pollination: pollen transferred to the pistil of a different flower through wind or insects.
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1 st stage of development: spermatozoon (singular of spermatozoa) enters the ovule = fertilization. 2 nd stage of development: Cell divides into many cells that specialize themselves into different structures for different functions.
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Seed dispersal: main mode or style of dispersing seeds is through fruits. 5 main agents of seed dispersal: Animals, water, wind, the plant itself and humans (sowing seeds).
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Seed, seedling (young plant), adult plant, flower, fruit and back to seed.
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