Post-Fertilisation: Endosperm, Embryo, Seed and Fruit
Post-fertilisation events are the changes after double fertilisation in which the primary endosperm nucleus forms endosperm, the zygote forms embryo, ovule becomes seed, and ovary becomes fruit.
In one line: Zygote to embryo, ovule to seed, ovary to fruit.
Concept Practice Coming SoonUnderstand it
- After fertilisation, the primary endosperm nucleus usually divides before the zygote develops actively, so nourishment is available for the embryo.
- Endosperm may remain free-nuclear for a time or become cellular.
- The zygote develops into an embryo with embryonal axis and cotyledons.
- In dicots, two cotyledons are present; in monocots, one cotyledon is present.
- The ovule develops into a seed, integuments form seed coats, and the ovary wall forms the pericarp of the fruit.
- In true fruits, the ovary mainly forms the fruit, while in false fruits other floral parts also contribute.
Example
Rule to remember
Conversion rule: zygote forms embryo; primary endosperm nucleus forms endosperm; integuments form seed coat; ovule forms seed; ovary wall forms pericarp; ovary forms fruit.
See it worked out
Follow the example line by line, then use the same method on new questions.
Worked example
- 1If asked what happens to integuments after fertilisation, answer that they become seed coats.
- 2If asked what the ovary wall becomes, answer pericarp.
Method you can reuse
- 1Double fertilisation produces zygote and primary endosperm nucleus.
- 2Primary endosperm nucleus divides to form endosperm.
- 3Zygote develops into embryo.
- 4Embryo differentiates into embryonal axis and cotyledons.
- 5Integuments harden into seed coats.
- 6Ovule matures into seed.
- 7Ovary wall forms pericarp and ovary matures into fruit.
- 8Other floral parts may contribute in false fruits.
Sketch it in your answer
Label dicot embryo parts such as cotyledons, plumule, radicle, hypocotyl, epicotyl, and seed coat; for monocot embryo label scutellum, coleoptile, coleorhiza, plumule, radicle, and endosperm.
Check yourself
Answer the question in your head before opening the answer.
Try it yourself
What is the difference between seed formation and fruit formation after fertilisation?
Think first, then show answerHide answer
Common wrong answer
A frequent wrong answer is saying endosperm always disappears before seed maturity. In some seeds it is consumed, while in others it persists.
Don't mix this up
Exam tip
Write it in the exam
Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.
How CBSE asks it
Answer plan
- 1
Enough for 1 mark
Post-fertilisation events are the changes after double fertilisation in which the primary endosperm nucleus forms endosperm, the zygote forms embryo, ovule becomes seed, and ovary becomes fruit.
- 2
Add for 2 marks
Example: Coconut water represents free-nuclear endosperm, while the white kernel represents cellular endosperm. Apple is commonly cited as a false fruit because the thalamus contributes to the edible part.
- 3
Add for 3 marks
After fertilisation, the primary endosperm nucleus usually divides before the zygote develops actively, so nourishment is available for the embryo.
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