Reproduction is a process by which one organism produces offsprings. It is one of the basic processes in all known life forms. Every organism we see around us is a direct result of reproduction.
Reproduction can be of two types-
- Sexual reproduction
- Asexual reproduction
These two modes of reproduction have given birth to all life forms.
It is the mode of reproduction in which sex cells from two organisms, one male and one female, combine to form a singular zygote. This zygote shares half of its genetic information with the father and the other half with the mother. Though the basics of it remains the same, there are many different modes of reproduction sexually, in both plants and animals.
Sexual Reproduction in Plants
Plants that reproduce sexually have sex parts which we know as flowers. The process of reproduction involves the fusion of male gametes, namely, pollen with the female gamete, also known as ovules. This fusion results in the formation of a zygote and an endosperm nucleus, which grow into seeds and fruits respectively.
Sexual Reproduction in Animals
Among the different modes of reproduction in animals, sexual reproduction is the most common one. Most animals reproduce sexually, though in a variety of different ways.
Sexual reproduction in animals involves the union of a haploid sperm and a haploid egg to form a diploid zygote, which shares its DNA with both the parent cells.
Certain invertebrates, such as tapeworms and certain other parasites, reproduce through the process of self-fertilization in which they fertilize their egg with their own sperm.
Sexual reproduction in animals may happen through internal fertilization (humans, dogs) or external fertilization(certain reptiles and birds).
It is the mode of reproduction which involves only one organism. The offspring that is produced is genetically identical to the mother and almost always has the same number of chromosomes.
Modes of asexual reproduction in plants
Some plants have the ability to reproduce asexually, that is, without the help of flowers or pollens. There are different modes of asexual reproduction in plants, both natural and human induced.
In the natural mode, a plant can give rise to an offspring with the help of roots. Certain plants also use budding and cutting to reproduce asexually.
Human induced asexual reproduction in plants include grafting, layering, cutting and micropropagation.
Modes of asexual reproduction in animals
Some simple animals, many of whom are single celled, reproduce asexually.
The different modes of asexual reproduction in animals include gemmules (sponges), fragmentation (planarians), regeneration (echinoderms) and parthenogenesis (ants, wasps).