Question

3. Polyploids are characterised by gigantism.
Justify your answer.​

Answer 1

Quantum speciation

Tetraploidy

Polyploidy is common among plants and has been, in fact, a major source of speciation in the angiosperms. Particularly important is allopolyploidy, which involves the doubling of chromosomes in a hybrid plant. Normally a hybrid is sterile because it does not have the required homologous pairs of chromosomes for successful gamete formation during meiosis. If through polyploidy, however, the plant duplicates the chromosome set inherited from each parent, meiosis can occur, because each chromosome will have a homologue derived from its duplicate set. Thus, polyploidy confers fertility on the formerly sterile hybrid, which thereby attains the status of a full species distinct from either of its parents. It has been estimated that up to half of the known angiosperm species arose through polyploidy, including some of the species most prized by man. Plant breeders utilize this process, treating desirable hybrids with chemicals, such as colchicine, that are known to induce polyploidy.