Reproduction
From CreationWiki, the encyclopedia of creation science
A reproduction is something that has been copied. In biology, reproduction refers to the production of a new member of a population from existing members. This can refer to individual cells or an entire organism, and it does not necessarily mean that an exact copy of the original member has been made. The process fundamentally consists of segregation of a portion of the parental body, and its subsequent growth and differentiation into a new individual. Biological reproduction can be either sexual or asexual.
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Sexual Reproduction
- Main Article: Sexual reproduction
Sexual reproduction is a biological process by which organisms create descendants by combining their genetic material. These organisms have two different adult sexes (male and female). New individuals are produced by the fusion of haploid gametes (sperm, ovum, pollen), formed through a unique form of cell division called meiosis. Fertilization occurs when the two gametes fuse to form a diploid zygote. The zygote is a single cell which contains all the information required to build the adult organism. The growth from zygote to adult is achieved through somatic cell division called mitosis.
Asexual Reproduction
- Main Article: Asexual reproduction
Asexual reproduction is a mode of having offspring that does not involve sex. Offspring resulting from this method come from a single parent and inherit the genes from that parent only. In genetics terms, it is a method of reproduction where a 1N cell produces two to four cells with the same chromosome number. It does not involve meiosis or the the union of gametes such as ovum, sperm, or pollen. Therefore, offspring are identical to the parent, unlike those produced through sexual reproduction. This form of reproduction (also known as agamogenesis) is common among plants and single-celled organisms such as amoeba.
Binary Fission
- Main Article: Binary Fission
Binary fission is a form of asexual reproduction during which a single cell divides to form two new cells called daughter cells. This can be by a motile stage or a nonmotile stage. Both daughter cells contain an exact copy of the genetic information contained in the parent cell.
Vegetative Reproduction
- Main Article: Vegetative Reproduction
Although sexual reproduction is common in plants, most also reproduce asexually through what is commonly called vegetative propagation. There are a number of plant tissues capable of this process, for example rhizomes (potato), runners (strawberry), stem pieces (willow), and seed (dandelion).
Budding
Budding is a form of asexual reproduction where a copy of the parental body forms as a protrusion. The bud stays attached to the primary organism for a while, before becoming free. Like all forms of asexual reprodution, the new organism is genetically identical to the parent. Budding is very common in plants, but is also found in some animals, such as the hydra, sponge, and corals.
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