31. Invertebrates

Which phylum is characterized by animals that have a segmented body? a. Cnidaria b. Platyhelminthes c. Arthropoda d. Mollusca

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.

Which protostome phyla successfully made the transition from water to land? Select True or False for each phylum. T/F Mollusca T/F Arthropoda T/F Annelida T/F Nematoda

A plant with orange, spotted flowers was grown in the greenhouse from a seed collected in the wild. The plant was self-pollinated and gave rise to the following progeny: 88 orange with spots, 34 yellow with spots, 32 orange with no spots, and 8 yellow with no spots. What can you conclude about the dominance relationships of the alleles responsible for the spotted and unspotted phenotypes? What can you conclude about the genotype of the original plant that had orange, spotted flowers?

Propose an explanation for why annelids and arthropods were thought to be closely related, before phylogenetic analyses in the late 1990s.

In peas, purple flowers are dominant to white. If a purple-flowered, heterozygous plant were crossed with a white-flowered plant, what is the expected ratio of genotypes and phenotypes among the F1 offspring? If two of the purple-flowered F1 offspring were randomly selected and crossed, what is the expected ratio of genotypes and phenotypes among the F2 offspring?

Use your understanding of insect evolution to predict two adaptations for terrestrial living that occurred in spiders.

Pose a hypothesis to explain why the evolution of the wing was such an important event in the evolution of insects.

Suppose that a gene originally identified in nematodes (roundworms) is found to be homologous with a gene that can cause developmental abnormalities in humans. Would it be possible to use fruit flies as a model organism to study this gene? Explain.

Imagine repeating the experiment on epigenetic inheritance that is shown in Figure 19.6. You measure the amount of radioactive uridine (U) incorporated into Hnf4a mRNA in counts per minute (cpm) to determine the level of Hnf4a gene transcription in rats born to mothers fed either a normal diet or a low-protein diet. The results are 11,478 cpm for the normal diet and 7368 cpm for the low-protein diet. For this problem, your task is to prepare a graph similar to the one at the bottom of Figure 19.6 that shows the normalized results for the low-protein diet relative to the normal diet. Normalizing values means that the value obtained from one condition is expressed as 1.0 (the norm; the normal diet in this case) and the values obtained from any other conditions (low-protein diet in this case) are expressed as decimal values relative to the norm.

A team of 102 scientists spent a year surveying a small area of the San Lorenzo rain forest in Panama to count the number of species of arthropods living there. After collecting 129,494 specimens—using nets, traps, shovels, tree-climbing harnesses, helium balloons, and other creative gear—it took the team eight years to sort and identify the arthropods. Which of the following nested groups best describes the taxonomic context for the San Lorenzo project? a. Animalia > Bilateria > Arthropoda > Ecdysozoa b. Protostomia > Lophotrochozoa > Ecdysozoa7 Arthropoda c. Arthropoda > Protostomia > Ecdysozoa > Bilateria d. Bilateria > Protostomia > Ecdysozoa > Arthropoda

You have crossed two Drosophila melanogaster individuals that have long wings and red eyes—the wild-type phenotype. In the progeny, curved wings and lozenge eyes mutant phenotypes appear as follows According to these data, is the curved-wing allele autosomal recessive, autosomal dominant, sex-linked recessive, or sex-linked dominant?

You have crossed two Drosophila melanogaster individuals that have long wings and red eyes—the wild-type phenotype. In the progeny, curved wings and lozenge eyes mutant phenotypes appear as follows. Is the lozenge-eyed allele autosomal recessive, autosomal dominant, sex-linked recessive, or sex-linked dominant?

Rank the three most diverse phyla of protostome animals.

a. Arthropoda > Mollusca > Nematoda

b. Mollusca > Arthropoda > Nematoda

c. Arthropoda > Nematoda > Mollusca

The pygmy zebra octopus is a potential new model organism for understanding brain function in humans despite the independent evolution of high intelligence in both groups. Describe (or draw a phylogenetic tree to show) the relationships among humans (H. sapiens), the pygmy zebra octopus (O. chierchiae) and two other protostome model organisms in medicine: the fruitfly (D. melanogaster) and roundworm (C. elegans).