<<

This activity was used as a jigsaw. Students were split into 6 groups and each group had to read the paragraph they were assigned and then draw a picture to explain it underneath the reading. They also drew their picture on an overhead transparency. After each group was finished and had been checked they presented their type of asexual using the overhead. Each group had to give a brief overview of the method, tell how many parents were involved, and how the offspring compared to the parents. The students sitting at their seats (from the other groups) had to draw the picture that the group put on the overhead. At the end we discussed similarities between the methods as a class.

Asexual Reproduction Binary : Pera 0405: Binary fission is the asexual reproduction method for most one-celled organisms. The parent cell simply divides by copying all of its and going through . The one celled organism has now become two. Each of these will grow and eventually divide to produce more cells. After binary fission the offspring produced are genetically identical to the parents. This type of reproduction is used in ameba and .

Budding Here, offspring develop as growth on the body of the parent. Cells of the parent go through mitosis creating a small or growth that will eventually develop into a new organism. In some , e.g., , the break away and take up an independent existence. In others, e.g., , the buds remain attached to the parent and the process results in colonies of . is also common among parasitic animals, e.g., tapeworms. Budding can also be used in single celled animals such as . In budding the offspring are genetically identical to the parent.

Fragmentation As certain tiny worms grow to full size, they spontaneously break up into 8 or 9 pieces. Each of these fragments develops into a mature worm and the process is repeated. This allows one worm to reproduce or make many worms. In fragmentation the offspring are genetically identical to the parent.

Pera 0405: Asexual reproduction In parthenogenesis ("virgin "), the produce , but these develop into young without ever being fertilized. Parthenogenesis occurs in some , several kinds of , and a few species of . In a few species it is the only method of reproduction, but more commonly animals turn to parthenogenesis only at certain times. For example, use parthenogenesis in the spring when they find themselves with ample food. Reproduction by parthenogenesis is more rapid that and the use of this mode of asexual reproduction permits the animals to quickly exploit the available resources. Parthenogenesis also occurs in some types of wasps.

Regeneration is a specialized form of asexual reproduction. Through regeneration some organisms (e.g., the and the ) can replace an injured or lost part. For example if a starfish loses an arm the starfish will re-grow the arm and the arm will also regenerate the parts it is missing. This will create two starfish. Many are capable of total regeneration—the formation of a whole individual from a single fragment such as a stem, root, or . This means you can cut a root of a carrot and given the right nutrients an entire new plant will grow from the root. Among animals, the lower the form, the more capable it is of total regeneration; no have this power.

Sporulation : Sporualtion is the type of reproduction used in mushrooms, bread mold, and ferns. The organism creates thousands of small and encloses them in little cases. Each is then released and is able to grow into an entire new organism without ever being fertilized. After spores are released they will begin to grow if they have found the right type of area. If they have not they can live for a long time because of the case surrounding them. Often times spores will remain through fires and very harsh winters.

Pera 0405: Asexual reproduction