Bio Exam #3

Which of the following statements is correct?

All animals share a common ancestor. It is thought to have been a protist similar to a choanoflagellate.

The ancestors of amniotes laid eggs in water. It could be argued that embryos of amniotes still develop in water for which of the following reasons?

the amnion encases each embryo in water

Animal tissues develop from embryonic germ layers. Triploblastic animals have three germ layers (ectoderm, mesoderm, and endoderm) and three basic body plans related to body cavities (acoelomate, pseudocoelomate, and coelomate). Select the three statements that are true.

--> A pseudocoelom has the same functions as a true coelom. --> In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity. --> A diploblast has no mesoderm. Triploblasts have tissues derived from three embryonic germ layers: endoderm inside, ectoderm outside, and mesoderm in the middle. The three basic body plans of triploblasts relate to the presence or absence of a body cavity. No body cavity: acoelomate Body cavity lined on the inner side by endoderm-derived tissue and on the outer side by mesoderm-derived tissue: pseudocoelomate Body cavity lined entirely by mesoderm-derived tissue: coelomate

Which of the following chordate groups include(s) humans?

--> Amniotes --> Gnathostomes --> Hominins

The phylogenetic tree shown here displays the major clades of chordates. Which statements about the phylogenetic tree are true?

--> Rays and frogs have vertebrae. --> Birds and ray-finned fishes have a notochord and jaws. --> Descendants of organism (d) have limbs with digits. --> Mammals and turtles are more closely related than are lungfishes and sharks. --> Organism (a) is a common ancestor of all chordates. The phylogenetic tree shown above represents the evolutionary relationships between the major clades of chordates. The hatch marks on the tree indicate derived characters shared by all the groups to the right of each mark. For example, all chordates have a notochord, and all mammals produce milk. The phylogenetic tree also shows the degree of relatedness of particular groups of chordates. For example, mammals are more closely related to hagfishes than to lancelets.

Brown et al. and Morwood et al. reported in 2004 that they had found skeletal remains of a previously unknown type of hominin, now dubbed Homo floresiensis, on the Indonesian island of Flores. These hominins were small (approximately 1 m tall) with small braincases (approximately 380 cm3) as compared with other hominins. The remains of H. floresiensis were found alongside handmade stone tools and the remains of dwarf elephants that also inhabited the island, suggesting that H. floresiensis was able both to make tools and to coordinate the hunting of animals much larger than itself. H. floresiensis is estimated to have lived at the site where the remains were found from 700,000 years ago to 60,000 years ago. The table is a comparison of several characteristics of H. floresiensis to those of nine other hominin species (arranged roughly from oldest to most recent). What do these data suggest?

A large brain is not necessarily required for toolmaking.

Which of the following statements is most consistent with the data in the graph? (BMR with different species plot)

A smaller animal would consume more food per gram of tissue.

The graph shows mortality and brain size data for 14 species of birds. Deviation from expected brain size is shown on the x-axis, and mortality rate is shown on the y-axis. Deviation values < 0 indicate brain sizes smaller than expected; values > 0 indicate sizes larger than expected. What can you conclude about the relationship between deviation from expected brain size and mortality rate?

Adult mortality tends to be lower in birds with unusually large brains for their body size, suggesting that these unusually large brains confer an advantage in survival. The slope of the best-fit line indicates that adult mortality is lower in birds with brains that are larger than expected for their body size. This suggests that these unusually large brains confer an advantage in survival.

Which of the following statements about deuterostomes is false?

All deuterostomes exhibit radial symmetry in their bodies. This statement is false; in the deuterostome lineage, only adult echinoderms exhibit radial symmetry.

Select the correct statement describing feedback control in animals.

An animal may be a regulator for one environmental variable but a conformer for another. An animal may be a regulator if it uses internal control mechanisms to regulate internal change when experiencing external fluctuations. An animal may be a conformer if it allows its internal condition to conform to external changes.

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

Animals have more specialized cells.

Brown et al. and Morwood et al. reported in 2004 that they had found skeletal remains of a previously unknown type of hominin, now dubbed Homo floresiensis, on the Indonesian island of Flores. These hominins were small (approximately 1 m tall) with small braincases (approximately 380 cm3) as compared with other hominins. The remains of H. floresiensis were found alongside handmade stone tools and the remains of dwarf elephants that also inhabited the island, suggesting that H. floresiensis was able both to make tools and to coordinate the hunting of animals much larger than itself. H. floresiensis is estimated to have lived at the site where the remains were found from 700,000 years ago to 60,000 years ago. Which would be the most feasible method of figuring out to which other hominin species H. floresiensis was most closely related?

Compare the skeletal morphology of H. floresiensis to that of each of the other hominin species.

Which feature of deuterostome development explains the formation of identical human twins?

Deuterostomes have indeterminate development. Most deuterostomes have indeterminate cleavage, meaning that each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo. For example, if the cells of a sea urchin embryo are isolated at the four-cell stage, each can form a complete larva. It is the indeterminate cleavage of the human zygote that makes identical twins possible.

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups-Lophotrochozoa and Ecdysozoa. What does this finding suggest?

Division of these two groups occurred after the protostome developmental sequence appeared.

Which statement about endotherms and ectotherms is correct?

Ectotherms are more abundant and diverse than endotherms. There are far more ectotherms than endotherms on Earth. Remember that birds and mammals are the only large taxa of endotherms; other vertebrates, and virtually all invertebrates, are ectotherms.

How do endotherms and ectotherms differ?

Endotherms and ectotherms differ in the means by which they regulate their body temperature. Endotherms regulate body temperature through metabolically generated heat. Many ectotherms regulate their body temperatures by behavioral means.

Which structure is not an innovation that occurred during vertebrate diversification?

Exoskeleton Exoskeletons are present in groups other than the vertebrates, including some in the protostome lineage.

True or false? An organism that is radially symmetric has many well-developed head regions.

False An organism that is radially symmetric does not have a well-developed head region.

Which of the following claims about human evolution is most consistent with current scientific understanding?

Humans and other apes represent divergent lines of evolution from a common ancestor.

Lancelets and tunicates are two groups of chordates. Classify each statement as applying to lancelets, tunicates, both lancelets and tunicates, or neither.

Lancelets: --> all chordate characters present in adults --> adults bury themselves into the sediment of the seafloor --> adults swim by the contraction of a series of muscles along the notochord Tunicates: --> most chordate characters not present in adults --> larvae swim using the notochord, but adults may be sessile --> in adults, water enters through one siphon and leaves through another Both: --> adults feed with the aid of pharyngeal slits Neither: --> adults swim using the vertebral column Tunicates and lancelets are two groups of chordates. Both possess the four derived characters of chordates during their development. However, whereas adult lancelets retain all four of these characters, adult tunicates retain only one (pharyngeal slits). Lancelets swim by contracting a series of muscles located along the side of the notochord, which results in a motion similar to the swimming motion of fishes. Larval tunicates are mobile, using their tail muscles and notochord to propel themselves through the water; adult tunicates are sessile or float with the current. Adult lancelets and tunicates use their pharyngeal slits to filter suspended food particles from the water.

Why might natural selection have favored the evolution of large brains despite their high maintenance costs?

Large brains may make individuals more likely to survive and reproduce. As long as the benefits of brains that are large relative to body size are greater than the costs, large brains can evolve. Natural selection might favor the evolution of brains that are large relative to body size because such brains confer an advantage in obtaining mates and/or an advantage in survival.

A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus?

Look for cell walls under a microscope --> Fungal cells have cell walls, and animal cells do not.

The fossil record documents trends in which brains that are large relative to body size evolved in certain lineages, including hominins. In such lineages, what can you infer about the costs and benefits of large brains?

Natural selection favored the evolution of larger brains, suggesting that the benefits of large brains outweighed the costs. Because brain size tends to increase consistently in these lineages, we can conclude that natural selection favored the evolution of larger brains and hence that the benefits outweighed the costs.

Select the correct statement about osmolarity.

Osmolarity measures the moles of solute per liter of solution.

Which structure can be used for feeding and gas exchange?

Pharyngeal gill slit A pharyngeal gill slit is an opening into the throat that can be used for feeding and gas exchange.

Which of the following best summarizes the results shown in the graph?

Southern populations of flat periwinkles have accumulated traits that make them less vulnerable than northern populations to predation by European green crabs.

Placing sponges as the basal metazoans on the basis of lack of tissues implies which of the following?

Sponge ancestors never had tissues.

What is believed to be the most significant result of the evolution of the amniotic egg?

Tetrapods are no longer tied to the water for reproduction.

You just received a freshwater aquarium as a gift and decide to add more fish. When you get to the pet store, you find that the most beautiful fish are saltwater animals, but you decide to buy them anyway. What will happen when you put your saltwater fish in your freshwater aquarium?

The cells of the fish will take up too much water and the fish will die. The osmoregulatory problems of freshwater animals are opposite to those of marine animals. Freshwater fish are adapted to life in a hypotonic environment and have mechanisms to get rid of excess water absorbed into the body. Saltwater fish are adapted to the marine environment and have extracellular fluids that have a composition similar to seawater. Placing them in fresh water will upset their osmotic balance, and they may not have regulatory mechanisms that can compensate.

Soft-shell crab is a prized dish in many ocean-side resorts. Which of the following statements provides the best explanation for the soft shell of the crabs?

The crab has just molted and the new exoskeleton has not yet hardened.

Which of the following statements about vertebrates is true?

The development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water. Reptiles and their descendants reproduce on land via an amniotic egg, which prevents the embryo from drying out.

Select the correct statement about the evolution of animals.

The oldest generally accepted fossils of large animals range in age from 565 to 550 million years old. The Ediacaran biota was a group of early animals. Some are sponges, whereas others may be related to living cnidarians. Still others of these fossil organisms have proven difficult to classify.

Which characteristics define a chordate?

The presence of four specific morphological traits Chordates are defined by the presence of four morphological traits: a notochord, a dorsal nerve cord, pharyngeal gill slits, and a tail behind the anus.

Which characteristic distinguishes echinoderms from the other two deuterostome lineages?

Their body plan Echinoderms exhibit a unique body plan characterized by an endoskeleton and a water vascular system.

Which of the following statements correctly describes a characteristic of the phylum Platyhelminthes?

They are dorsoventrally flattened. This is why they are also known as flatworms.

Which of these statements accurately describes a similarity between sharks and ray-finned fishes?

They have a lateral line that is sensitive to vibrations.

Which of the following statements is true of annelids?

They perform gas exchange across their skin. Cutaneous respiration occurs across their skins. Some annelids, such as the errantians, have lateral extensions (parapodia) which provide additional surface area for cutaneous respiration.

Which of the following is a hypothesis the researchers were testing in this study?

Through evolution, periwinkle populations with a history of predation by crabs have become less vulnerable to crab predation. The researchers' hypothesis was that southern periwinkle populations with a history of predation by crabs have become less vulnerable to crab predation through evolution.

You are studying a large tropical reptile that has a high and relatively stable body temperature. How do you determine whether this animal is an endotherm or an ectotherm?

You subject this reptile to various temperatures in the lab and find that its body temperature and metabolic rate change with the ambient temperature. You conclude that it is an ectotherm.

Which of the following animals most likely uses the largest percentage of its energy budget for homeostatic regulation?

a bird living year-round in a desert

dorsal, hollow nerve cord

a bundle of nervous tissue running the length of the body --> may develop into the brain and spinal cord

Which of the following characteristics is shared by both cnidarians and flatworms?

a digestive system with a single opening

notochord

a flexible rod that runs along the anterior-posterior axis --> may be associated with a jointed skeleton

A land snail, a clam, and an octopus all share

a mantle

The increase in plant species diversity is correlated with which of the following events?

a massive increase in species diversity of insects

Which of these structures would most likely have been observed in the common ancestor of chondrichthyans and osteichthyans?

a mineralized, bony skeleton

During the development of most animals, cleavage leads to __________.

a multicelled blastula It is incorrect to say that cleavage leads to fertilization, metamorphosis, the formation of a zygote, or the formation of a gastrula. Fertilization occurs before cleavage. Metamorphosis is a resurgence of development that transforms an animal from a larva into an adult. There are many developmental stages between cleavage and metamorphosis. A zygote is formed during fertilization, and the zygote undergoes cleavage. Cleavage leads to the blastula stage, which leads to gastrulation and the formation of a gastrula.

muscular, post-anal tail

a structure that contains muscles and extends past the anus --> may be used to propel some species in water

Which of the following could be considered the most recent common ancestor of living tetrapods?

a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates

Which of the following organisms is considered the most recent common ancestor of living tetrapods?

a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates

Which of the following characteristics is shared by a hagfish and a lamprey?

a well-developed notochord

Which of the following chordates is most likely to look the least like other chordates?

adult tunicate An adult tunicate does not have a notochord (or vertebrae), a nerve cord, or a post-anal tail. The only chordate feature it retains is pharyngeal slits.

Listed below are four adaptations of terrestrial vertebrates. Which choice is a characteristic only of truly terrestrial animals with no need to return to water at any stage of the life cycle? --> tetrapod locomotion --> amniotic eggs --> hearts with more than two chambers --> lungs

amniotic eggs In contrast to the shell-less eggs of amphibians, amniotic eggs (of most reptiles and a few mammals) have shells that retain water and can be laid in a dry place.

Most members of which of the following groups are most closely associated with a wet (or moist) environment?

amphibians Amphibians typically have water-permeable skin that does not easily-resist drying. Thus, amphibians tend to be found in moist environments.

A terrestrial animal species is discovered with the following larval characteristics: exoskeleton, system of tubes for gas exchange, and modified segmentation. What other characteristic is most likely present in this organism?

an open circulatory system

Which of the following groups includes members that all have fully opposable thumbs?

anthropoids

Members of the phylum Mollusca __________.

are soft-bodied and often covered by a shell Members of the phylum Mollusca are soft-bodied and are often covered by a shell.

Which type of symmetry does each of the following animals display?

asymmetry: sponge radial symmetry: jelly fish, hydra bilateral symmetry: bobcat, turtle, octopus, snake

In what respect do hominins differ from all other anthropoids?

bipedal posture

Which of the following are the only extant animals that descended directly from dinosaurs?

birds

Which one of these mollusk groups is classified as suspension feeders?

bivalves

Jaws evolved __________.

by modification of the skeletal rods that previously supported the anterior pharyngeal slits According to a leading hypothesis, this marked a reduction in the number of pharyngeal slits and a change in the function of gills from feeding to respiration.

At one time, Chondrichthyes were thought to have diverged from other vertebrates before the evolution of bone. Now we have concluded that the Chondrichthyes diverged after the evolution of bone had started. What does this change demonstrate about the evolution of fishes?

characteristics can be lost in evolution

The evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of which of the following evolutionary processes?

convergent evolution

Mammals and birds eat more often than reptiles. Which of the following traits shared by mammals and birds best explains this habit?

endothermy

Which of the following characteristics evolved independently in mammals and birds?

endothermy

Negative feedback is a method of homeostatic control that __________.

ensures conditions in an organism do not vary too much above or below their set points

The panting responses observed in overheated birds and mammals dissipate heat loss by what process?

evaporation

Which of the following processes must freshwater fish undertake to maintain homeostasis?

excrete large quantities of water

In vertebrates, the earliest known mineralized structures were associated with body parts involved in which of the following processes?

feeding

Which of the following was a trend first observed in the evolution of the earliest tetrapods?

feet with digits

Ancient fossils that seem to be an intermediate stage in the evolution from fish to tetrapods had which of the following characteristics?

fins and scales like a fish but ribs to support the body and a bone structure in the front limb like tetrapods

Choose the list that correctly describes metabolic rates, corrected for body mass, from lowest to highest.

fish, dog, mouse Fish are ectotherms, typically having lower metabolic rates than endothermic mammals and birds; furthermore, a mouse is much smaller than a dog, so the mouse's cells have higher rates than those of the dog.

Which of the following is a characteristic of cnidarians?

gastrovascular cavity The gastrovascular cavity, characterized by a single opening, is the digestive compartment of cnidarians.

pharyngeal clefts

grooves that separate pouches along the side of the pharynx --> may develop into parts of the ear

Unlike eutherians, both monotremes and marsupials

have some embryonic development outside the uterus.

In a cool environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm ________.

invests little energy in temperature regulation

The body fluids of an osmoconformer would be ________ with its ________ environment.

isoosmotic; seawater

If an organism exhibits a head with sensory structures, which of the following characteristics would it likely also exhibit?

it is bilaterally symmetrical

Which extant chordates are most like the earliest chordates in appearance?

lancelets

Primate evolution and behavior, such as hunting skills, have been directed in part by the development of depth perception. What anatomical change made depth perception possible?

location of the eyes at the front of the head

Homeostasis is the __________.

maintenance of a relatively constant and optimal internal environment

There are three major groups of mammals, categorized on the basis of their _____.

method of reproduction Monotremes are egg-laying mammals, marsupials are pouched mammals, and eutherians are placental mammals.

pharyngeal slits

openings to the outside of the body along the side of the pharynx --> may develop into gill slits

During chordate evolution, which of the following structures arose first?

paired fins

Jaws first occurred in which of the following group of fishes?

placoderms

Arrange the following taxonomic terms in order from most inclusive to least inclusive.

primates, anthropoids, apes, hominins, Homo

Many animals can be categorized as either protostomes and deuterostomes based on certain features of their embryonic development. Determine whether each of the following terms applies to only protostomes, only deuterostomes, both protostomes and deuterostomes, or neither.

protostome: mouth from blastospore, coelom from solid masses of mesoderm, and spiral, determinate cleavage deuterostome: anus from blastospore, coelom from folds of the archenteron, and radial, indeterminate cleavage both: triploblast neither: diploblast

While observing seawater through a microscope, you spot the embryo of an unknown animal. Which of the following criteria could you use to determine whether the organism exhibits protostome or deuterostome development?

spiral cleavage or radial cleavage

Identify the dependent variable in this experiment.

the number of periwinkles killed by crabs The dependent variable was the number of northern and southern periwinkles killed by crabs.

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, though some have three Hox genes. On the basis of these observations, some scientists have proposed that the ancestral cnidarian's were originally bilateral and, in stages, lost Hox genes from their genomes. If true, what would this mean regarding the phylogeny of animals?

the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait

Which of these characteristics contributed the most to vertebrate success in relatively dry environments?

the shelled, amniotic egg

Identify an independent variable in this experiment.

the source of the periwinkles (northern or southern sites in the Gulf of Maine) One of the independent variables was the source of the periwinkle population--northern or southern sites in the Gulf of Maine. The source of the crab population was also an independent variable.

Which of the following characteristics do all insects exhibit?

they have an exoskeleton or cuticle

Which of the following statements describes sponges?

they have larvae that are motile and move via the motion of flagella

Which of the following is most likely a characteristic of the earliest tetrapod fossils?

they indicate limited adaptation to life on land

Why did the researchers present unshelled northern and southern periwinkles to northern and southern crabs in the second experiment?

to test if either population of periwinkles was unpalatable to either population of crabs The researchers wanted to rule out the possibility that northern crabs didn't like the taste of southern periwinkles or that southern crabs didn't like the taste of northern periwinkles. This experiment allowed researchers to conclude that differences in numbers of southern and northern periwinkles killed were due to differing vulnerability to crab predation, not due to crab preferences.

Why did the researchers set up four treatments?

to test whether the origin (northern site or southern site) of the crabs and periwinkles affected their interactions

Which of these groups of organisms are amniotes?

turtles

All of the following represent diagnostic features of chordates except for which one?

vertebrae Lancelets and tunicates are two subgroups of chordates that lack vertebrae.