list different kinds of syngamy or fertilization among living organisms and explain any five only
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Answer:
Types of syngamy
Syngamy is of two kinds on the basis of the source of fusion gametes, which are
Self-fertilization or Endogamy: The includes the fusion of two forms of gametes originating from the same parent for example, Taenia. It is a process is very uncommon.
Cross-fertilization or Exogamy: When two fusing gametes for example in human, frog, cockroach, etc. are derived from separate parents. It is more general.
There are three types of syngamy and they are:
Isogamy: This occurs when the gametes that fuse are similar. An advanced system of recognition is used so as to avoid self-fertilization. Surface proteins such as cells of immune system help in recognizing the different types of genotypes.
Heterogamy: This happens when the gametes are of two different sizes. Based on the division of labor, the difference between the two gametes are done. Usually the female is larger while the male is smaller. Also, the number of male gametes is more so that there is an increase in the competition and makes fertilization likely.
Oogamy: This takes place when the mobility of the gametes are different. Oocyte is the non-motile female and spermatozoon is the flagellate male. In most of the cases, spermatozoon is the only mobile gamete. Spermatozoa and spermatia are known as sperms.