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G.O.2: As species reproduce. Characteristics are passed from parents to offspring. 2.2 Asexual and Sexual Reproduction. Reproduction. Reproduction produces new individuals of a species. The way a species reproduces determines how much variation the new individuals will have.
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G.O.2: As species reproduce. Characteristics are passed from parents to offspring. 2.2 Asexual and Sexual Reproduction
Reproduction • Reproduction produces new individuals of a species. • The way a species reproduces determines how much variation the new individuals will have. • Reproduction can produce new individuals that are identical to or very different from one another • Asexual Reproduction – involves one individual, all of the offspring are identical to that parent • Sexual Reproduction – usually involves two individuals, the offspring will have a mix of characteristics from both parents
Asexual Reproduction • Type of reproduction with only one parent. Each offspring is identical to the parent (how is this different than sexual reproduction?) • Types of asexual reproduction: • Budding • Binary Fission • Spore reproduction • Vegetative reproduction
Asexual Reproduction • There are 4 ways that organism reproduce asexually: • Binary Fission • Budding • Spore Production • Vegetative Reproduction
Asexual Reproduction • Binary Fission: Cell splits in two and produces two identical organisms.http://www.youtube.com/watch?v=3cD3U2pgb5w • Budding: parent organism produces a smaller version of itself (known as a bud). The bud eventually detaches from the parent and becomes an independent organism which is exactly the same as the parent.http://www.youtube.com/watch?v=489CSop00sY
Budding barrel sponge Budding sea sponges Budding tube sponge
Asexual reproduction • Spore production – Spores are like seeds but are produced by one parent (seeds require two parents). The spore is identical to the parent. Mould Spores
Spores forming on lichen Spores forming on a fern Spore forming bacteria
Types of Asexual Reproduction: 4) Vegetative Reproduction – reproduction that does not involve the formation of a seed • Many plants reproduce this way, but there is more than one method of vegetative reproduction • Each method involves taking a cutting of the parent plant, which will eventually grow identical to the parent
Vegetative Reproduction Pg. 31 Runners Aspen suckers Grafting
Sexual Reproduction • Reproduction with two individuals. Most plants and animals reproduce sexually. The offspring has a mix of characteristics of both parents.
Sexual Reproduction in Animals • Sexual reproduction in animals: • http://www.youtube.com/watch?v=POJAQX760VY&feature=fvsr
Sexual Reproduction in Animals • General process of animal reproduction is similar (from fungi to protists to dragonflies to bears; small details vary) • Involves gametes (sex cells) • Male gametes = Sperm Cell • Female gametes = egg Cell (Ova) • Union of the two gametes during mating is called fertilization • The fertilized cell created is known as the Zygote • The zygote undergoes continuous divisions (cleavage) to create a multicellular life form called the embryo
Sexual Reproduction in Animals • The cell division will take place inside the female (most mammals) or outisdein an egg (most other animals) • Remember: The embryo is not identical to either parent; it will have a mix of characteristics from both parents
Sexual Reproduction in Animals • Only one of the many sperm cells surrounding the egg will fertilize the egg. • InfoBit: Hermaphrodites • Common garden worms and slugs are hermaphrodites. They can produce both math and female gametes. • Although most slugs and worms usually prefer to mate with other individuals of their species, in times of environmental stress, they can fertilize themselves.
Sexual Reproduction in Plants • Sexual reproduction in plants: • http://www.youtube.com/watch?v=FsBQQDg5GIw
Sexual Reproduction in Plants • As in animals, sexual reproduction requires the joining of a male and female gametes to create a zygote, and with continued division, an embryo • Most plants produce both male and female gametes; some only produce one or the other • Pollen contains the male gametes (found in the stamen) • Ovules contain the female gametes (found in the pistil)
Sexual Reproduction in Plants Pistil • You will need to know all of the structures involved in plant reproduction. • Stamen • Filament • Anther • Pistil • Stigma • Style • Ovary • Ovule • Sepal • Petal • Receptacle
Sexual Reproduction in Plants • Pollination occurs when pollen is transferred from the anther of the stamen to the stigma of the pistil. • Fertilization occurs when the male and female gametes unite • Cross-Pollination occurs when the pollen of one plant is carried to the stigma of another by wind, water, or animals, such as bees or butterflies • Cross-fertilization occurs when a grain of this pollen produces a long tube that eventually grows down the style into the ovary that contains the ovules
Asexual Reproduction Sexual Reproduction Advantages • Provides lots of variation which helps the species survive environmental change Disadvantages • Takes a lot of energy and time; means limited offspring can be produced Advantages • Does not require specialized cells or a way of uniting gametes • Can produce lots of offspring very quickly Bacteria: 1 10 million in 12 hr Disadvantages • If conditions become unfavorable, the entire population may be wiped out (because they are identical) • So all 10 million bacteria could be wiped out by the same antibiotic
Asexual or Sexual • Some species have the ability to reproduce both sexually and asexually. • In plants, seeds can often be produced sexually and asexually. If the seeds don’t have a contribution from a sperm cell they will be genetically identical to the parent (i.e. _____________, sunflowers, roses) • In animals, aphids, sponges, __________ and moss can alternate between asexual and sexual reproduction