Which of the following animal groups does not have tissues derived from mesoderm?
a. Annelids
b. Echinoderms
c. Cnidarians
d. Flatworms

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?

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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.

Sister chromatids are homologous chromosomes.

Non-sister chromatids are found on two different homologs.

Crossing over occurs between sister chromatids.

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?

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.

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. 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. Why might the ability to withstand drying reduce any potential advantage of sexual reproduction in this rotifer species?