Answer: Formation of any floral organs (in sep1 sep2 sep3 triple mutants, all organs become leaf-like despite functional ABC genes).
- A Root system development through specific control over the formation of lateral root primordia along the main root structure
- B Formation of any floral organs (in sep1 sep2 sep3 triple mutants, all organs become leaf-like despite functional ABC genes)
- C Pollen tube guidance alone, specifically directing tube growth toward the micropyle opening of the developing ovule
- D Seed dormancy mechanisms that are regulated largely independently of any floral organ identity gene activity present
Correct answer: B. Formation of any floral organs (in sep1 sep2 sep3 triple mutants, all organs become leaf-like despite functional ABC genes)
Explanation: SEP genes (SEP1-4): essential cofactors for floral homeotic MADS proteins. Without SEP, ABC proteins cannot form active tetrameric complexes. All organs revert to leaf-like structures in sep triple mutants.
Double fertilisation in angiosperms: one male gamete fuses with the egg to form the diploid zygote (syngamy), while the second fuses with the two polar nuclei to form the triploid primary endosperm nucleus (triple fusion). Image: Triploid, CC BY 3.0, via Wikimedia Commons.
Concept context
Flower structure, pollination, double fertilization, and seed/fruit development - the highest-scoring Class 12 biology chapter in NEET.
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