Answer: One sperm fertilizes the egg AND another fuses with polar nuclei to form triploid endosperm; found exclusively in angiosperms.
- 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.
Plants evolved from water-dependent algae through increasingly land-adapted groups, gaining vascular tissue (Pteridophyta), then seeds (Gymnosperms), and finally fruit-enclosed seeds (Angiosperms) - each step reducing dependence on water for reproduction.
Concept context
Classification of plants from algae to angiosperms. Understanding plant diversity is essential for NEET.