● After their formation, male and female gametes must be `color{Violet}"physically brought together"` to facilitate fusion (`color{Violet}"fertilisation"`).
● In a majority of organisms, male gamete is `color{Violet}"motile"` and the female gamete is `color{Violet}"stationary"`.
● Exceptions are a `color{Violet}"few fungi and algae"` in which both types of gametes are motile.
● There is a `color{Violet}"need for a medium"` through which the male gametes move.
● In several simple plants like algae, bryophytes and pteridophytes, `color{Violet}"water is the medium"` through which this gamete transfer takes place.
● A large number of the male gametes, however, `color{Violet}"fail to reach"` the female gametes.
● To `color{Violet}"compensate this loss"` of male gametes during transport, the number of male gametes produced is `color{Violet}"several thousand times"` the number of female gametes produced.
● In seed plants, pollen grains are the `color{Violet}"carriers of male gametes"` and `color{Violet}"ovule have the egg"`.
● Pollen grains produced in `color{Violet}"anthers"` therefore, have to be `color{Violet}"transferred to the stigma"` before it can lead to fertilisation .
● In bisexual, `color{Violet}"self-fertilizing/ self-pollinating plants"`, e.g., peas, transfer of pollen grains to the stigma is `color{Violet}"relatively easy"` as anthers and stigma are located `color{Violet}"close to each other"`; pollen grains soon after they are shed, come in contact with the stigma.
● But in `color{Violet}"cross pollinating plants"` (including dioecious plants), a specialised event called `color{Violet}"pollination"` facilitates transfer of pollen grains to the stigma.
● Pollen grains `color{Violet}"germinate"` on the stigma and the `color{Violet}"pollen tubes"` carrying the male gametes reach the `color{Violet}"ovule"` and discharge male gametes near the egg.
● In `color{Violet}"dioecious"` animals, since male and female gametes are formed in `color{Violet}"different individuals"`, the organism must evolve a `color{Violet}"special mechanism"` for gamete transfer.
● `color{Violet}"Successful transfer"` and `color{Violet}"coming together"` of gametes is essential for the most critical event in sexual reproduction, the `color{Violet}"fertilisation"`.
● After their formation, male and female gametes must be `color{Violet}"physically brought together"` to facilitate fusion (`color{Violet}"fertilisation"`).
● In a majority of organisms, male gamete is `color{Violet}"motile"` and the female gamete is `color{Violet}"stationary"`.
● Exceptions are a `color{Violet}"few fungi and algae"` in which both types of gametes are motile.
● There is a `color{Violet}"need for a medium"` through which the male gametes move.
● In several simple plants like algae, bryophytes and pteridophytes, `color{Violet}"water is the medium"` through which this gamete transfer takes place.
● A large number of the male gametes, however, `color{Violet}"fail to reach"` the female gametes.
● To `color{Violet}"compensate this loss"` of male gametes during transport, the number of male gametes produced is `color{Violet}"several thousand times"` the number of female gametes produced.
● In seed plants, pollen grains are the `color{Violet}"carriers of male gametes"` and `color{Violet}"ovule have the egg"`.
● Pollen grains produced in `color{Violet}"anthers"` therefore, have to be `color{Violet}"transferred to the stigma"` before it can lead to fertilisation .
● In bisexual, `color{Violet}"self-fertilizing/ self-pollinating plants"`, e.g., peas, transfer of pollen grains to the stigma is `color{Violet}"relatively easy"` as anthers and stigma are located `color{Violet}"close to each other"`; pollen grains soon after they are shed, come in contact with the stigma.
● But in `color{Violet}"cross pollinating plants"` (including dioecious plants), a specialised event called `color{Violet}"pollination"` facilitates transfer of pollen grains to the stigma.
● Pollen grains `color{Violet}"germinate"` on the stigma and the `color{Violet}"pollen tubes"` carrying the male gametes reach the `color{Violet}"ovule"` and discharge male gametes near the egg.
● In `color{Violet}"dioecious"` animals, since male and female gametes are formed in `color{Violet}"different individuals"`, the organism must evolve a `color{Violet}"special mechanism"` for gamete transfer.
● `color{Violet}"Successful transfer"` and `color{Violet}"coming together"` of gametes is essential for the most critical event in sexual reproduction, the `color{Violet}"fertilisation"`.