54. Bananas we routinely eat are seedless because
A) They are naturally parthenogenetic
B) They are triploid
C) They are haploid
D) Their fruits develop faster than the seeds
Correct Answer
Bananas we routinely eat are seedless primarily because they are triploid (3n), leading to meiotic irregularities that prevent viable seed formation. This condition disrupts balanced chromosome segregation during gamete production, resulting in sterile pollen and ovules. Commercial Cavendish bananas exemplify this trait, propagated vegetatively to maintain seedlessness.
Option Analysis
A) Naturally parthenogenetic
Parthenogenesis involves embryo development from an unfertilized egg, but bananas produce seedless fruits via parthenocarpy, where fruit forms without fertilization, not true parthenogenesis. While some sources link it loosely, triploidy is the core genetic cause, not parthenogenetic reproduction alone.
B) Triploid (Correct)
Triploid bananas have three chromosome sets, causing uneven meiosis and non-viable gametes, halting seed development despite pollination. This sterility ensures seedless fruits, a key domestication trait from Musa acuminata hybrids.
C) Haploid
Haploid plants (n) occur in gametophytes but lack the genomic stability for diploid-like fruiting bodies; bananas are typically triploid or diploid cultivars, not haploid. Haploidy would not explain commercial seedlessness.
D) Fruits develop faster than seeds
Fruit development timing does not inhibit seed formation; seedlessness stems from genetic sterility in triploids, not developmental speed. Wild seeded bananas develop both simultaneously.
Biological Mechanism
Edible bananas arose from selective breeding of diploid progenitors, yielding sterile triploids with parthenocarpic fruits that grow without seeds. Propagation via suckers bypasses sexual reproduction, preserving this trait for global cultivation. This explains why bananas we routinely eat remain consistently seedless.
