30. Overview of Animals

Which of the listed characteristics is shared by plants, fungi, and animals?

Animals probably evolved from colonial protists. How do animals differ from these protist ancestors?

Many young animals are __________, a sexually immature form that is morphologically distinct from the adult stage. These young animals undergo __________ to become __________, which resemble adults but are not yet sexually mature.

Which of the following groups does not exhibit bilateral symmetry?

Which of the following is a characteristic of cnidarians?

In the embryo of a shark, ectoderm gives rise to __________; mesoderm gives rise to __________; endoderm gives rise to __________.

Which of the following is the defining characteristic of the clade Ecdysozoa for which this group is named?

Unlike other animals, sponges __________.

Which of the following is characteristic of protostomes?

All animals with bilateral symmetry have __________ germ layer(s).

A true coelom is __________.

One of the primary developmental/anatomical characteristics distinguishing the major animal phyla is the condition of the body cavity. A pseudocoelomate animal is one in which the body cavity is __________.

The presence of a coelom is advantageous because __________.

Indeterminate cleavage produces embryonic cells that __________.

The zygotes of many protostomes undergo __________ cleavage and __________ cleavage.

An animal with a true coelom that has __________ cleavage must be a(n) __________.

Which of the following is a trait shared by protostomes and deuterostomes?

Name two phyla of animals that are radially symmetric and two that are bilaterally symmetric. How do the general lifestyles of radial and bilateral animals differ?

One of the characteristics unique to animals is a. gastrulation. b. multicellularity. c. sexual reproduction. d. flagellated sperm.

The table below lists the common names of the nine animal phyla surveyed in this chapter. For each phylum, list the key characteristics and some representatives.

Which synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates? a. multicellularity b. coloniality c. heterotrophy d. movement

The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of a. a body cavity. b. a complete digestive tract. c. mesoderm. d. tissues.

Identify the pattern of embryonic development shown in each drawing below and name the phylum (or phyla) that exhibit this pattern.

In a tube-within-a-tube body plan, what is the interior tube derived from? a. ectoderm b. mesoderm c. the coelom d. endoderm

Which of the following was probably an important factor in bringing about the Cambrian explosion? (A) the movement of animals onto land (B) an increase in the concentration of atmospheric nitrogen (C) the emergence of predator-prey relationships (D) the origin of bilaterian animals

Which of the following was probably the least important factor in bringing about the Cambrian explosion? a. the emergence of predator-prey relationships b. an increase in the concentration of atmospheric oxygen c. the movement of animals onto land d. the origin of Hox genes

Bilateral symmetry in animals is best correlated with a. an ability to see equally in all directions. b. the presence of a skeleton. c. motility and active predation and escape. d. adaptation to terrestrial environments.

True or false? New major animal body plans have continued to evolve since the Cambrian about 550 million years ago.

Which of the following combinations of phylum and description is correct? (A) Echinodermata—radial symmetry as a larva, coelom (B) Nematoda—roundworms, internal skeleton (C) Platyhelminthes—flatworms, gastrovascular cavity, no body cavity (D) Porifera—gastrovascular cavity, coelom

Based on the tree in Figure 32.11, which statement is false? a. The animal kingdom is monophyletic. b. Acoelomate flatworms are more closely related to echinoderms than to annelids. c. Sponges are basal animals. d. Bilaterians form a clade

Select True or False for each statement. T/F Sister chromatids are homologous chromosomes. T/F Non-sister chromatids are found on two different homologs. T/F Crossing over occurs between sister chromatids. T/F A chiasma forms between two of the four molecules of double-stranded DNA on duplicated homologous chromosomes.

Why is it ecologically significant that animals are heterotrophic and multicellular?

Which of the following animal groups does not have tissues derived from mesoderm? a. annelids b. echinoderms c. cnidarians d. flatworms

If you followed a woman's cells through meiosis, at what stage of meiosis would the amount of DNA in one of these cells be equal to the amount of DNA in one of her G1 phase (before DNA replication) kidney cells?

Evaluate this statement: Animals evolved from simple to complex.

Triploid (3n) watermelons, which are seedless, are produced by crossing a tetraploid (4n) strain with a diploid (2n) plant. Explain why this mating produces a triploid individual.

A species of rotifer, a small freshwater invertebrate, lost the ability to reproduce sexually millions of years ago. A remarkable feature of its life cycle is the ability to withstand dry conditions. When the rotifer's environment dries out, so does the rotifer, and it can be blown to a new area. Rotifers that land in water will rehydrate and resume an active life. A major pathogen of these rotifers is a species of fungus that cannot survive drying. Some scientists hypothesize that drying rids the rotifers of this pathogen. (a) Design an experimental study to test this hypothesis.

A species of rotifer, a small freshwater invertebrate, lost the ability to reproduce sexually millions of years ago. A remarkable feature of its life cycle is the ability to withstand dry conditions. When the rotifer's environment dries out, so does the rotifer, and it can be blown to a new area. Rotifers that land in water will rehydrate and resume an active life. A major pathogen of these rotifers is a species of fungus that cannot survive drying. Some scientists hypothesize that drying rids the rotifers of this pathogen. (b) Why might the ability to withstand drying reduce any potential advantage of sexual reproduction in this rotifer species?