Heterogametes – Class 12 | Chapter – 1 | Short Notes Series PDF

Heterogametes: The conjugating gametes that are exclusive of their form, length, shape or sexes, etc. are known as heterogametes. The gametes of an organism are the reproductive or intercourse cells. The gametes that are just like every other are known as homogametic. Heterogametes vary from every different in form and length. Ex. The Spermatozoa which is known as a male gamete is spiral, small in length, and motile. The Ovum which is known as a female gamete is oval, huge in length, and immovable. Hence, they’re known as heterogametes. In such types of organisms, the male gamete is called the antherozoid or sperm and the female gamete is called the egg or ovum.



Heterogamy is a term that refers to a wide range of phenomena in various scientific fields. “Hetero” usually refers to a difference, while “gamy” refers to reproduction. In reproductive biology, heterogamy refers to the alternation of generations, such as parthenogenetic and sexual generations. Some aphids, for example, exhibit heterogamy. Alternatively, heterogamy or heterogamous is sometimes used as a synonym for heterogametic, which refers to the presence of two chromosomes that are not identical in sex. The heterogamous sex, for example, consists of XY males and ZW females.

Key Points on Heterogametes:

  • These gametes are dissimilar in appearance.
  • They are also called Anisogametes.
  • They have different morphology or behavior.
  • The two gametes differ in shape and size and thus can be easily distinguished. The larger gamete is called the Macrogamete, and the smaller gamete is called the Microgamete. Generally, the female gametes are larger and non-motile. And the male gametes are smaller and motile.
  • In animals, the female gamete is called the ova or egg, and the male gamete is called the sperm.
  • In plants, the male gamete is called the pollen grain, and the female gamete is called the ovule.
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