6. Describe the range of variation in the nervous systems of invertebrates. 7. Distinguish among asymmetry, radial symmetry, and bilateral symmetry.

Punnett squares are used to show possible combinations of alleles or to predict the probability of a trait occurring in offspring. a parakeet that is heterozygous for blue feathers (dominant) is crossed with a parakeet that is homozygous for white feathers (recessive). according to the punnett square for this cross, what percentage of offspring is predicted to have blue feathers? 25 percent 50 percent 75 percent 100 percent