Reproduction: Asexual vs. Sexual

Reproduction is important for the survival of all living species.

Without a way to reproduce, life would come to an end.

Two types of reproduction:

Asexual reproduction involves only one parent & results in an exact duplicate of an organism.

There are many types of asexual reproduction There are many types of asexual reproduction. (budding, binary fission, fragmentation, regeneration, spores, cloning, etc…)

Sexual reproduction involves the joining of male & female sex cells, called gametes.

The male’s sperm & female’s egg are joined in a process called fertilization & results in the production of a zygote.

Advantages & disadvantages of each type of reproduction:

Asexual Reproduction

1. Asexual reproduction is common among plants, single-celled organisms & simple animals.

2. Asexual reproduction requires only one parent.

3. Asexual reproduction has the advantage of producing large numbers of offspring very quickly.

4. The offspring produced by asexual reproduction, from the same parent, are identical to one another & they are identical to the parent (clones) which prevents adaptations from occurring.

5. If a species of organism shows no variation & cannot adapt it may become extinct.

Sexual reproduction

1. Sexual reproduction is common among higher animals & flowering plants.

2. Sexual reproduction requires sex cells produced by two parents 2. Sexual reproduction requires sex cells produced by two parents. (sperm from males & eggs from females)

3. Sexual reproduction is more complex & slower than asexual reproduction.

4. The offspring produced by sexual reproduction have genetic variation. They may look like their parents, but they are not identical.

5. Amongst populations of wild animals & plants, individuals show variation as a result of sexual reproduction. This variation allows them to adapt to the environment.

Sexual Asexual Definition Sexual reproduction always requires fertilization so it requires the sex cells of two parents. Asexual reproduction does not require fertilization so only one parent is involved.

Less complex and more reliable. Sexual Asexual Advantages The offspring will be different from its parents. This variation allows the species to adapt to its surroundings. “Good” traits are passed on and strengthen the species which increases their survival rate. The fertilized egg (zygote) can sometimes survive in adverse conditions (drought). Asexual reproduction is usually faster and easier, so a new plant or animal can colonize an area more quickly. A mate does not have to be found so no travel is involved which saves energy. Less complex and more reliable.

Organisms with no variation that cannot adapt it may become extinct. Sexual Asexual Dis-advan-tages Often slower than asexual reproduction, more complex, and less reliable. The new organisms are genetically identical to their parents. (they will all look exactly the same as each other). Organisms with no variation that cannot adapt it may become extinct.

Sexual Asexual Plants that make spores (moss, ferns). Examples Most animals reproduce sexually (fly, human, snake, frog). All flowering plants and those that make seeds reproduce sexually. (daffodil, grass, rose, oak tree). Plants that make spores (moss, ferns). Fungi make spores (mold, mushrooms). Single cells, which reproduce by binary fission or splitting in two (amoeba, bacteria). Budding (spider plant, hydra). Runners (grass, strawberries). Fragmentation (planarians). Regeneration (starfish).

Examples of Asexual Reproduction:

Spores: Ferns, mosses molds & mushrooms produce spores which are dispersed, then under favorable conditions a single spore develops into a new individual.

Spores

Binary fission: Amoebas, bacteria and other single-celled organisms divide to form two identical cells that become the same size.

Binary fission

Budding: Some bacteria, plants, fungi, yeast, sponges, corals and hydras form new organisms when part of the parent breaks off to form a daughter cell that grows into a new individual that is identical to the parent.

Budding

Runners: Potatoes, strawberries, some grasses and other plants can form horizontal stems that grow on top of or just below the ground which can produce new plants horizontally at nodes or tips along the stem.

Runners

Fragmentation: Some plants, planarian and other worms can be split into many fragments that each grow into new identical individuals.

Fragmentation

Regeneration: Type of fragmentation in which starfish, lizards & sponges can grow back body parts that are damaged or lost.