Question
Question: The development of endosperm in gymnosperms differs from that of angiosperms. Explain....
The development of endosperm in gymnosperms differs from that of angiosperms. Explain.
Solution
The angiosperms show double fertilization where endosperm development precedes embryo development whereas gymnosperms lack double fertilization.
Complete answer:
Double fertilization occurs in Angiosperms. Double Fertilization occurs as-
- Two sperm nuclei and an egg and two polar bodies are present in the angiosperms.
- The sperm nucleus (n) fertilizes the egg (n) and forms an embryo (2n).
- The other sperm nucleus (n) fuses with the two polar nuclei (n each= n+n) in the large central cell of the female gametophyte resulting in a triploid cell known as primary endosperm cell (PEC) (3n).
- This triploid cell develops into an endosperm which is triploid in nature.
- This process is called triple fusion since it involves the fusion of three haploid cells.
On the other hand, Gymnosperms do not have double fertilization. There are two sperm nuclei as well, but one them degenerates during development. As a result of degeneracy, there is no real endosperm. However, a nutritive tissue is still present since it is necessary for the growth and germination of the embryo. Endosperm in gymnosperms is formed before fertilization and is always haploid.
Additional Information:
The difference between Angiosperms and Gymnosperms is as follows:
| Angiosperms | Gymnosperms |
|---|---|
| A seed is produced by flowering plants and is enclosed within an ovary | A seed is produced by non-flowering plants and is unenclosed or naked. |
| The lifecycle of these plants are seasonal | These plants are evergreen |
| Has triploid tissue | Has haploid tissue |
| Leaves are flat in shape | Leaves are scalelike and needle-like in shape |
| Hardwood type | Softwood type |
| Reproduction rely on animals | Reproduction rely on wind |
| Reproductive system present in flowers (unisexual or bisexual) | Reproductive system present in cones and are unisexual |
Note: The cells of endosperm are filled with reserve food material and are used for the nutrition of the developing embryo. Angiosperms are the advanced plants that form fruit while gymnosperms form only seed.