7. Watermelons are exposed to a mutagen to produce a variety that has four sets of
chromosomes. The new variety is then crossed
with a normal watermelon to produce seedless
watermelons. What type of mutation is involved in
the growing of seedless watermelon?
a. point mutation
b. gene duplication
c. frameshift mutation
d. trisomy 21

The standard number of chromosomes in watermelon is 22. This is called the diploid number (di meaning two, as in dissect – cut in two). With this even number, cell division is highly regular and produces pollen and egg cells with 11 chromosomes that recombine to produce seed with the usual 22 chromosomes. Through a chemical process, the chromosome number can be doubled from 22 to 44 (tetraploid, tetra meaning four). Cell division in plants with 44 chromosomes is, again, highly regular and will produce pollen and egg cells with 22 chromosomes that recombine to produce seed having 44 chromosomes. However, if pollen from a plant with 22 chromosomes is placed on a female flower of a plant with 44 chromosomes, the resulting seed will have 33 chromosomes (triploid – three sets of the base number of 11 chromosomes). This odd number does not produce (or rarely produces) viable pollen and eggs in the resulting seedlings.            -Michigan State UN                                                 Explanation:

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

maybe because its impossible for balloons to lift a whole entire house.