- A Two separate pollen tubes are sometimes mistakenly thought to fuse together within the micropyle; found in all seed plants
- B One sperm fertilizes the egg AND another fuses with polar nuclei to form triploid endosperm; found exclusively in angiosperms
- C Two distinct egg cells are sometimes mistakenly thought to be fertilized simultaneously within a single ovule; found in gymnosperms
- D Two male sperm cells are sometimes mistakenly thought to fuse directly with each other before fertilization; found in bryophytes
Correct answer: B. One sperm fertilizes the egg AND another fuses with polar nuclei to form triploid endosperm; found exclusively in angiosperms
Explanation: Double fertilization: one sperm (n) + egg (n) = zygote (2n); second sperm (n) + two polar nuclei (n+n) = triploid endosperm (3n). This is unique to angiosperms and was discovered by Nawaschin and Guignard.
Concept context
Classification of plants from algae to angiosperms. Understanding plant diversity is essential for NEET.