31. Invertebrates

The arthropods superficially resemble earthworms in that both groups __________, yet the two are distinctly different because arthropods, but not earthworms, __________.

A major characteristic of arthropods is __________.

In most insects, gas exchange is accomplished by __________.

In arthropods, molting is necessary because __________.

Which phylum is characterized by animals that have a segmented body?a. Cnidariab. Platyhelminthesc. Arthropodad. Mollusca

What is the function of the arthropod exoskeleton?a. The presence of an exoskeleton has given arthropods a good fossil record, because hard parts fossilize more readily than do soft tissues.b. It has no well-established function. (Trilobites had an exoskeleton, and they went extinct.)c. It provides protection and functions in locomotion.d. It makes growth by molting possible.

Why is the pea wrinkle-seed allele a recessive allele?a. It 'recedes' in the F2 generation when homozygous parents are crossed.b. The trait associated with the allele is not exhibited in heterozygotes.c. Individuals with the allele have lower fitness than that of individuals with the dominant allele.d. The allele is less common than the dominant allele. (The wrinkled allele is a rare mutant.)

The alleles found in haploid organisms cannot be dominant or recessive. Why?a. Dominance and recessiveness describe which of two possible phenotypes are exhibited when two different alleles occur in the same individual.b. Because only one allele is present, alleles in haploid organisms are always dominant.Ac. lleles in haploid individuals are transmitted like mitochondrial DNA or chloroplast DNA.d. Most haploid individuals are bacteria, and bacterial genetics is completely different from eukaryotic genetics.