Mastering Biology Exam 4 Flashcards
Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition by
ingesting it
What do animals as diverse as corals and monkeys have in common?
presence of Hox genes
The last common ancestor of all animals was probably a
flagellated protist.
Gastrulation is the process that directly forms the _____.
primary germ layers
Which of the following is NOT a characteristic of all animals?
They have tissues, organs, and organ systems.
Which of the following animals does NOT have a body cavity?
flatworm
During embryological development, the anus forms before the mouth in _____.
humans
At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?
gastrulation
At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo?
cleavage
What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates
have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.
You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?
Muscular activity of its digestive system distorts the body wall.
The blastopore denotes the presence of an endoderm-lined cavity in the developing embryo, a cavity that is known as the
archenteron.
Protostome characteristics generally include which of the following?
determinate cleavage
With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive
3 4 2 1
What does recent evidence from molecular systematics reveal about the relationship between grades and clades?
Some, but not all, grades reflect evolutionary relatedness
The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of β-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that
the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait.
The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
true tissues
Acoelomates are characterized by
a solid body without a cavity surrounding internal organs
Which of these is a point of conflict between the phylogenetic analyses presented in Figures 32.10 and 32.11 in your textbook?
the relationship of taxa of segmented animals to taxa of nonsegmented animals
What is the key difference between a coelom and a pseudocoelom?
Only a coelom is fully lined with mesoderm tissue.
Which feature of deuterostome development explains the formation of identical human twins?
Deuterostomes have indeterminate development.
Basal group of animals
Porifera (sponges)
Basal group of bilaterates
Acoela
