Education Journalist | Study Abroad Strategy Lead
Sporophyte and Gametophytes are multicellular structures formed, when the plants go through alternation of generations. The gametophytes produce both male and female gametes from the plant body through the process of mitosis. However, the sporophyte uses meiosis to produce haploid cells. Bryophytes and Algae have a gametophytic process that is dominant in nature. The sporophyte is found to be dominant in gymnosperms, pteridophytes, and angiosperms. The gametophyte and sporophyte represent the sexual and asexual phases of the plant life cycle respectively. Gametophyte and sporophyte are mainly distinguished on the fact that gametophyte is a haploid and hence is made with the help of meiosis while sporophyte is a diploid and is made with the help of mitosis.
| Table of Contents |
Key Terms: Sporophyte, Gametophyte, Plants, Haploid Cells, Diploid Cells, Spores, Gametes, Reproduction, Mitosis, Meiosis
What are Gametophytes?
[Click Here for Sample Questions]
The meaning of Gameto and Phyte means gametes and plants respectively. Plants use their sex organs to produce gametes. The gametophyte is when the plant reaches a stage in its life-cycle where they own the Haploid cells. These cells have a set (n) of chromosomes that help to carry genetic information.
Gametes tend to fuse together and participate in Fertilisation, which produces a diploid zygote. Further development of this diploid zygote produces the next stage known as the Sporophyte, having diploid (2n) chromosomes. Gametophytes tend to undergo mitosis.
All plants such as angiosperms, bryophyte, algae, gymnosperms, etc. have this process running in them.
As an example, plants like algae produce non-motile and simple gametes inside their body, while plants like Spirogyra produce their gametes inside their own bodies but transfer them through conjugation to another spirogyra. Plants like Bryophyta have sex organs to make gametes, these sex organs are called antheridia and archegonia. Similarly, plants like gymnosperms and pteridophytes also have archegonia in them, and different ways are employed for their development. The development of pollen grains causes Angiosperms to make gametes. So, most of these plants experience gametophyte generation.
Life Cycle of Gametophytes
What are Sporophytes?
[Click Here for Sample Questions]
Sporo and Phyte mean spores and plants respectively. Bryophytes, Algae, gymnosperms and angiosperms all make spores. Their diploid cells have two sets of chromosomes (2n), one set being the male parent’s, and the other set of chromosomes being that of the female parent’s. A tiny structure that germinates and leads to a new plant is called a spore. Spores are basically of two kinds, namely meiotic spore and mitotic spore. Meiosis and Mitosis are the two kinds of cell divisions that help in the formation of spores.
Chlamydomonas can also produce asexual spores, while Bryophytes produce sexual or meiotic spores, homosporous pteridophytes produce spores of the same size from their spore mother cell, whereas heterosporous pteridophytes produce two different varieties of spores, them being megaspore from the megaspore mother cell and microspore from the microspore mother cell. Heterosporous angiosperms and gymnosperms produce their own spores.
Difference between Gametophytes and Sporophytes
Read More:
Difference between Sporophytes and Gametophytes
[Click Here for Sample Questions]
The various differences between Gametophytes and Sporophytes have been mentioned in a tabular form below:
| Sporophyte | Gametophyte |
|---|---|
| Sporophytes reproduce with the help of meiosis. | Gametophytes reproduce with the help of mitosis. |
| Sporophytes help form spores. | Gametophytes help form gametes. |
| They are diploid plants. | They are haploid plants. |
| The sets of chromosomes are two in number. | The set of chromosomes is single. |
| They reproduce asexually. | They reproduce Sexually. |
| Diploid spore mother cell goes through meiosis and forms haploid (n) meiospores. | The gametes fertilise or fuse and produce diploid (2n) zygotes. |
| They are dependent on gametophytes. | They are an independent and dominant body of the plant. |
| They form megaspores and microspores. | They produce female and male gametes. |
Things to Remember
- Gamete forming plants, and their whole generation is called Gametophyte. Plants use their sex organs to produce gametes.
- The haploid cells have a set (n) of chromosomes that help to carry genetic information.
- Gametes tend to fuse together and participate in Fertilisation, which produces a diploid zygote.
- Further development of this Diploid zygote produces the next stage known as the Sporophyte, having diploid (2n) chromosomes.
- Gametophytes tend to undergo Mitosis.
- Spores producing plants and their generation is called the sporophyte.
- Spores are basically of two kinds, namely meiotic spore and mitotic spore.
- Meiosis and Mitosis are the two kinds of cell divisions that help in the formation of spores.
- Mitotic spores and meisotic are asexual and sexual spores respectively.
- Both types of spores can be made by sporophytes, for example, algae form asexual or mitotic spores, even though it is a simplified organism.
Sample Questions
Ques. What does it mean that gametophytes are dominant? (2 marks)
Ans. Gametophytes of the plant can produce their personal food and don't have to rely upon sporophytes for any kind of nutrient. Alternatively, sporophytes depend on gametophytes for food and nutrition as they are weaker than the gametophytic phase. Gametophyte being the dominant form can help the sporophyte to develop from the female sex organ and also be protected and nurtured by the gametophyte.
Ques. Explain the event in the life cycle of a flowering plant. (4 marks)
Ans. The events that take place in the life cycle of a flowering plant are as follows:
- Germination: The stage where the plant begins to germinate or grow from seed and its roots start appearing below the soil while the stem and leaves appear above the soil.
- Pollination: The process where the pollen grains are transported to another flower with the help of wind or insects.
- Fertilisation: When the pollen reaches another flower’s ovary, and the male and female gametes fuse together, the process is called fertilisation.
- Dispersal: The scattering of seeds with the help of wind or animals is called dispersal. Some of The dispersed seeds may grow into a new plant.
Ques. What are the different stages in the alternation of generations? (3 marks)
Ans. Alternation of generations between sporophyte and gametophyte takes within the following ways:
- Sporangium found in diploid sporophytes undergoes meiosis to shape haploid spores.
- The spore develops into a gametophyte that's haploid in nature.
- The gametophyte inclusive of reproductive organs goes through mitosis to form haploid gametes.
- These gametes fertilised to produce a haploid zygote which matures right into a mature sporophyte.
- Thus, the cycle continues repeating and the generations keep expanding, this is called alternation of generations.
Ques. What are some examples of a sporophyte dominant plant? (2 marks)
Ans. A sporophyte is a multicellular diploid that is in algae and flowers that go through the alternation of generations. It produces haploid spores that eventually get transformed into a gametophyte. The gametophyte then makes gametes that fuse and grow right into a sporophyte. In many plant life, the sporophyte generation is the dominant generation. These kinds of plants are the sporophyte dominant plant.
Ques. Why is the sporophyte of moss semi-dependent on gametophyte? (2 marks)
Ans. In the bryophyte plant life cycle, the diploid (2n) sporophyte generation is a brief structure that grows without delay from the dominant haploid (n) gametophyte plant. The sporophyte structure is dependent on the food collected and produced by the gametophyte plant.
Ques. Trees are vascular plants and, thus, their dominant generation is the sporophyte generation. If so, why do apples, which are produced by a sporophyte apple tree, contain seeds and not spores? (2 marks)
Ans. In seed plant life, the gametophyte generation is decreased and depends on the sporophyte. The female gametophytes develop from megaspores in ovules in the reproductive systems of the female flower referred to as the carpel, where their ovum is produced for fertilisation. The male gametophytes develop from microspores inside the pollen grain for dispersal from the male reproductive structures of the flower known as the stamen. Upon pollination with the female structures inside the flower, the male gametophyte inside the pollen grain produces sperm for fertilisation. The result is a sporophyte embryo inside the apple fruit’s seeds.
Ques. Why is a pine tree called a sporophyte? (2 marks)
Ans. Pine trees contain cones and thus are allied conifers. They carry both female and male sporophylls which are found on the same mature sporophyte. They are classified as monoecious plants. Pines are heterosporous like all other gymnosperms and generate two varieties of spores, namely female megaspores and male microspores.
While Sporophytes is the stage in the Plant life cycle that is a diploid stage, which means its egg and sperm fuse together. It has two sets of chromosomes that are taken as one from each parent. Hence, it can be said that the Pine trees have both of the sporophylls on the same sporophyte.
Ques. What is the difference between meiosis and mitosis? (5 marks)
Ans. Tabulated below are the major differences between meiosis and mitosis:
| Meiosis | Mitosis |
|---|---|
| Meiosis occurs when two successive cell divisions take place. | Mitosis occurs when only one cell division takes place. |
| Meiosis results in the formation of four daughter cells. | Meiosis results in the formation of two daughter cells. |
| The chromosome number in formed daughter cells is halved as compared to the parent cell. | The chromosome number in formed daughter cells is doubled as compared to the parent cell. |
| Results in the formation of haploid cells. | Results in the formation of diploid cells. |
| Formed daughter cells are different genetically to each other. | Formed daughter cells are identical genetically to each other. |
| Creates only germ cells, i.e, egg and sperm. | Creates somatic cells. |
| Prophase is usually longer than mitosis. | Prophase in mitosis is much shorter. |
Read More:
Comments