Notes, Exercises, Videos, Tests and Things to Remember on Sexual Reproduction
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The reproduction that takes place with the fusion of male gamete and the female gamete is called sexual reproduction. Such reproduction usually occurs in animals and higher plant. Two parents male and female are involved in this process of sexual reproduction. In most of the animals, male and female are separate. Such animals are called uni-sexual. Man, birds, etc. in animals and papaya, pumpkin, etc. in plants are the examples of unisexual. In some animals, male reproductive organ and female reproductive organ are present in one animal. Such animals are called bisexual organisms. These organisms are also called hermaphrodite. Hydra, Earthworm. The mustard plant, etc. are the examples of bisexual organisms.
Reproduction takes place in the flowers of the plant. The male organ of flower is androecium and female organ of flower is gynoecium. Androecium produces pollen grains whereas gynoecium produces ova. Fusion of pollen grains and ova leads to fertilization. The zygote starts to form after fertilization.
There is no asexual reproduction in animals. After the sexual intercourse between male and female, the female is able to conceive the baby. After meiosis, the male reproductive system produces sperm (male gamete) and the female reproductive system produces an egg (female gamete). Then male releases its gamete that fuses with female gamete. The fusion may be internal (in higher organisms) or external (in lower organisms). If it is external then a medium, that carries male gamete, is required and mostly it is water. After fertilization, the egg becomes zygote and undergoes mitosis to become an embryo. Embryo again with the help of mitosis becomes a new individual.
In animals, there are two types of fertilization. They are:
The reproduction that takes place with the fusion of male gamete and the female gamete is called sexual reproduction. The types of reproduction are:
The fusion of male gamete and female gamete during the sexual reproduction of organism is called fertilization.
i. The fusion of male and female gametes takes place outside the female's body.
ii. The embryo is not protected from external injuries as it develops outside.
i. The fusion of male and female gametes takes place inside the female's body.
ii. The embryo is protected from external injuries as it develops inside the female's body.
i. It is produced by females through the meiosis cell division of reproductive cells.
ii. It is haploid (n) in nature, i.e. it has half the number of chromosomes as that of the parent cell.
iii. It does not have an independent existence.
i. It is formed as a result of the fusion of male and female gametes.
ii. It is diploid (2n) in nature, i.e. the chromosomes exist in pair.
iii. It has an independent existence.
1. It is the transfer of pollen grains from stamen to stigma.
2. It takes place outside the ovary.
1. It is the fusion of male gamete with the female gamete.
2. It takes place inthe ovary.
The reproduction in which male and female gametes fuse to form a zygote is called sexual reproduction. Sexual reproduction brings variation among the offspring of the same parents. So, sexual reproduction is necessary for the evolution and origin of new species.
The organism that has both male and female reproductive parts in the body is called hermaphrodite. As earthworm has both male and female reproductive parts in itself, it is a hermaphrodite.
The two significances of sexual reproduction are:
1. It is smaller in size.
2. It is highly active.
1. It is bigger in size.
2. It is inactive.
1. It is formed due to the fusion of male gamete and two polar nuclei.
2. It is triploid (3n) in nature.
1. It is formed due to the fusion of male gamete and an ovum.
2. It is diploid (2n) in nature.
Somatic cells reproduce by ______, while sex cells reproduce by ______.
Ocytes are ______.
ova that have not yet completed the oogenesis process
formed after ovulation
the locations on chromosomes where ova are produced
the male equivalent of ova
Process of reproduction where formation of isogametes takes place is called ______.
Fusion of pollen grains and ova leads to ______.