The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following most directly favors the evolution of the latter, more radical, kind of metamorphosis?
A) natural selection of sexually immature forms of insects
B) changes in the homeobox genes governing early development
C) the evolution of meiosis
D) the development of an oxidizing atmosphere on Earth

Answer: B

Which tissue type, or organ, is NOT correctly matched with its germ layer tissue?
A) muscular -mesoderm
B) skin - ectoderm
C) nervous - mesoderm
D) stomach - endoderm

Answer: C

Among protostomes, which morphological trait has shown the most variation?
A) type of symmetry (bilateral vs. radial vs. none)
B) type of body cavity (coelom vs. pseudocoelom vs. no coelom)
C) type of development (protostome vs. deutersostome)
D) number of embryonic tissue types (diploblasty vs. triploblasty)

Answer: B

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups - Lophotrochozoa and Ecdysozoa. What does this finding suggest?
A) The protostomes are a polyphylectic group.
B) Division of these two groups occurred after the protostome developmental sequence appeared.
C) These two subgroups have a common ancestor that was a deuterostome.
D) The lophotrochozoans are monophylectic.

Answer: B

The Hox genes came to regulate each of the following in what sequence, from earliest to most recent?

1. identity and position of paired appendages in protostome embryos
2. anterior-posterior orientation of segments in protostome embryos
3. positioning of tentacles in cnidarians
4. anterior-posterior orientation in vertebrate embryos

A) 4 → 1 → 3 → 2
B) 4 → 2 → 3 → 1
C) 4 → 2 → 1 → 3
D) 3 → 2 → 1 → 4

Answer: D

The presence of a lophophore in a newly discovered species would suggest that the species ________.
A) grows by shedding its external covering
B) is a suspension feeder
C) is motile
D) has an exoskeleton

Answer: B

Arthropod exoskeletons and mollusk shells both ________.
A) are secreted by the mantle
B) completely replace the hydrostatic skeleton
C) help retain moisture in terrestrial habitats
D) are comprised of the polysaccharide chitin

Answer: C

Which of the following could be considered the most recent common ancestor of living tetrapods?
A) a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates
B) an armored, jawed placoderm with two pairs of appendages
C) an early ray-finned fish that developed bony skeletal supports in its paired fins
D) a salamander that had legs supported by a bony skeleton but moved with the side-to-side bending typical of fishes

Answer: A

Which characteristic is common to all the modern representatives of all major reptilian lineages (turtles, lepidosaurs, crocodilians, and birds)?
A) ectothermy
B) presence of a notochord
C) presence of four walking limbs
D) presence of teeth

Answer: B

What is believed to be the most significant result of the evolution of the amniotic egg?
A) Tetrapods were no longer tied to the water for reproduction.
B) Tetrapods can now function with just lungs.
C) Newborns are much less dependent on their parents.
D) Embryos are protected from predators.

Answer: A

(DIAGRAM) In the diagram below, point "A" is ________; point "B" is ________.
A) the most recent species to evolve on Earth; the last common ancestor of Archaea and Eukarya
B) the common ancestor of all life; the last common ancestor of Archaea and Eukarya
C) the most recent species to evolve on Earth; an ancestor of group "A"
D) the common ancestor of all life; the common ancestor of Bacteria and Archaea

Answer: B

The various taxonomic levels (for example, phyla, genera, classes) of the hierarchical classification system differ from each other on the basis of
A) how widely the organisms assigned to each are distributed throughout the environment.
B) their inclusiveness.
C) the relative genome sizes of the organisms assigned to each.
D) morphological characters that are applicable to all organisms.

Answer: B

Some beetles and flies have antler-like structures on their heads, much like male deer do. The existence of antlers in beetle, fly, and deer species with strong male-male competition is an example of ________.
A) parsimony
B) a synapomorphy
C) convergent evolution
D) homology

Answer: C

(DIAGRAM) Refer to the figure above. Which of the following forms a monophyletic group?
A) C and D
B) E, F, and G
C) D, E, and F
D) A, B, C, D

Answer: B

The duplication of homeotic (Hox) genes has been significant in the evolution of animals because it ________.
A) caused the extinction of major groups
B) reduced morphological diversity into simpler forms of life
C) allowed animals to survive on significantly fewer calories
D) permitted the evolution of novel forms

Answer: D

What is true of the Cambrian explosion?
A) There are fossils of animals in geological strata that are older than the Cambrian explosion.
B) Only the fossils of microorganisms are found in geological strata older than the Cambrian explosion.
C) The Cambrian explosion is evidence for the instantaneous creation of life on Earth.
D) The Cambrian explosion marks the appearance of filter-feeding animals in the fossil record.

Answer: A

Which of the following is (are) unique to animals?
A) flagellated gametes
B) the structural carbohydrate, chitin
C) nervous system signal conduction and muscular movement
D) heterotrophy

Answer: C

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition by
A) preying on animals.
B) ingesting it.
C) consuming living, rather than dead, prey.
D) using enzymes to digest their food.

Answer: B

The last common ancestor of all animals was probably a
A) flagellated protist.
B) unicellular yeast.
C) multicellular algae.
D) multicellular fungus.

Answer: A

As you are on the way to Tahiti for a vacation, your plane crash-lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms; and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select three organisms and observe them in detail, making the notations found int he figure above. Which organism would you classify as an animal?
A) organism A
B) organism B
C) organism C

Answer: C

The most ancient branch point in animal phylogeny is that between having
A) radial or bilateral symmetry.
B) a well-defined head or no head.
C) diploblastic or triploblastic embryos.
D) true tissues or no tissues.

Answer: D

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome
and not a deuterostome?
A) The animal is triploblastic.
B) You see a mouth, but not an anus.
C) The animal is clearly bilaterally symmetrical.
D) There is evidence of cephalization.

Answer: B

What is the probable sequence in which the following clades of animals originated, from earliest to most recent?

1. tetrapods
2. vertebrates
3. deuterostomes
4. amniotes
5. bilaterians

A) 5 → 3 → 2 → 4 → 1
B) 5 → 3 → 2 → 1 → 4
C) 5 → 3 → 4 → 2 → 1
D) 3 → 5 → 4 → 2 → 1

Answer: B

Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would
A) strengthen sponges' evolutionary ties to the Eumetazoa.
B) mean that sponges must no longer be classified as animals.
C) confirm the identity of sponges as "basal animals."
D) mean that extinct sponges must have been the last common ancestor of animals and fungi.

Answer: C

Which of the following is most likely to be aquatic?
A) suspension feeder
B) deposit feeder
C) mass feeder
D) fluid feeder

Answer: A

Why might researchers choose to use molecular data (such as ribosomal RNA sequences) rather than morphological data to study the evolutionary history of animals?
A) Morphological changes usually do not result from molecular changes.
B) Molecular data can be gathered in the lab, while morphological data must be gathered in the field.
C) Some phyla vary too widely in morphological characteristics to be classified accurately.
D) Sequence data can be gathered faster than morphological data, and morphological data provides a different perspective.

Answer: D

You find what you believe is a new species of animal. Which of the following characterisitics would enable you to argue that it is more closely related to a flatworm than it is to a roundworm?
A) It is shaped like a worm.
B) It has a mouth and an anus.
C) it is a suspension feeder.
D) It has no coelom.

Answer: D

Which characteristic is shared by cnidarians and flatworms?
A) dorsoventrally flattened bodies
B) a distinct head
C) radial symmetry
D) a digestive system with a single opening

Answer: D

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.
A) a platyhelminth
B) an arthropod
C) an annelid
D) a mollusk

Answer: A

Nematodes and arthropods both ________.
A) grow by shedding their exoskeleton
B) are suspension feeders
C) have ciliated larvae
D) develop an anus from the blastopore (pore) formed in the gastrula stage

Answer: A

While sampling marine plankton in a lab, a student encounters large numbers of fertilized eggs. The student rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a true coelom. These eggs probably belonged to a(n) ________.
A) arthropod
B) echinoderm.
C) mollusc.
D) nematode.

Answer: C

All arthropods ________.
1) undergo complete metamorphosis
2) have jointed appendages
3) molt
4) have segmented bodies
5) have an exoskeleton or cuticle

A) 1, 2, and 4
B) 2, 3, 4, 5
C) 1, 4, 5
D) 3 and 5

Answer: B

Which of the following combinations correctly matches a phylum to its description?
A) Nematoda - segmented worms, closed circulatory system
B) Platyhelminthes - radial symmetry, polyp and medusa body forms
C) Echinodermata - bilateral symmetry as a larva, water vascular system
D) Cnidaria - flatworms, gastrovascular cavity, acoelomate

Answer: C

Which of the following is a characteristic of all chordates at some point during their life cycle?
A) post-anal tail
B) jaws
C) four-chambered heart
D) vertebrae

Answer: A

Which extant chordates are postulated to be most like the earliest chordates in appearance?
A) lancelets
B) adult tunicates
C) amphibians
D) reptiles

Answer: A

Which of the following characteristics is shared by a hagfish and a lamprey?
A) paired fins
B) jaws
C) a well-developed notochord
D) a rasping tongue

Answer: C

Vertebrates and tunicates share
A) a notochord and a dorsal, hollow nerve cord.
B) a high degree of cephalization.
C) the formation of structures from the neural crest.
D) an endoskeleton that includes a skull.

Answer: A

The earliest known mineralized structures in vertebrates are associated with which function?
A) reproduction
B) feeding
C) locomotion
D) defense

Answer: B

Suppose, while out camping in a forest, you found a chordate with a long, slender, limbless body slithering across the ground near your tent. This critter could be ________.
A) a mammal
B) a lamprey
C) a skate
D) an amphibian

Answer: D

Jaws first occurred in which extant group of fishes?
A) lampreys
B) chondrichthyans
C) ray-finned fishes
D) lungfishes

Answer: B

It is believed that the coelacanths and lungfish represent a crucial link between other fishes and tetrapods. What is the major feature in these fish in support of this hypothesis?
A) Their fins have skeletal and muscular structures similar to amphibian limbs.
B) They have highly evolved nervous and circulatory systems.
C) Like amphibians, they are tied to the water for reproduction.
D) They have lungs and are able to breathe air when water is scarce.

Answer: A

Which of the following characteristics evolved independently in mammals and birds?
A) jaws
B) bone
C) endothermy
D) amniotic eggs

Answer: C

Arrange these groups in order from most inclusive (most general) to least inclusive (most specific).

1. lobe-fins
2. amphibians
3. gnathostomes
4. osteichthyans
5. tetrapods

A) 4, 3, 1, 5, 2
B) 4, 3, 2, 5, 1
C) 4, 2, 3, 5, 1
D) 3, 4, 1, 5, 2

Answer: D

Which of these characteristics added most to vertebrate success in relatively dry environments?
A) the shelled, amniotic egg
B) the ability to maintain a constant body temperature
C) two pairs of appendages
D) bony scales

Answer: A

Mammals and birds eat more often than reptiles. Which of the following traits shared by mammals and birds best explains this habit?
A) endothermy
B) amniotic egg
C) terrestrial
D) ectothermy

Answer: A

Which of the following are the only extant animals that descended directly from dinosaurs?
A) lizards
B) crocodiles
C) snakes
D) birds

Answer: D

Which of these are amniotes?
A) amphibians
B) fishes
C) lungfish
D) turtles

Answer: D

Which of the following is the most inclusive (most general) group, all of whose members have fully opposable thumbs?
A) apes
B) Homo
C) anthropoids
D) primates

Answer: C

Unlike eutherians, both monotremes and marsupials
A) lack nipples.
B) have some embryonic development outside the uterus.
C) lay eggs.
D) are found in Australia and Africa.

Answer: B

In what respect do hominins differ from all other arthropoids?
A) opposable thumbs
B) eyes on the front of the face
C) bipedal posture
D) lack of a tail

Answer: C

Arrange the following taxonomic terms from most inclusive (most general) to least inclusive (most specific).

1. apes
2. hominins
3. Homo
4 anthropoids
5. primates

A) 5, 1, 4, 2, 3
B) 5, 4, 1, 2, 3
C) 5, 4, 2, 1, 3
D) 5, 2, 1, 4, 3

Answer: B

With which of the following statements would a biologist be most inclined to agree?
A) Humans and apes represent divergent lines of evolution from a common ancestor.
B) Humans evolved directly from Old World monkeys.
C) Humans represent the pinnacle of evolution and have escaped from being affected by natural selection.
D) Humans evolved from chimpanzees.

Answer: A

(TABLE) The table above 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) Homo floresiensis is most closely related to Australopithecus afarensis or A. africanus.
B) Hominins first evolved in and then radiated out from Asia.
C) A large brain is not necessarily required for toolmaking.
D) Body mass and braincase volume are completely unrelated.

Answer: C

The evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of ________.
A) shared ancestry
B) homology
C) convergent evolution
D) evolutionary divergence

Answer: C

As the size of some animals has evolved to greater sizes, the effectiveness of their adaptations that promote exchanges with the environment have also increased. For example, in many larger organisms, evolution has favored lungs and a digestive tract with ________.
A) larger cells
B) decreased blood supply
C) more branching or folds
D) increased thickness

Answer: C

Much of the coordination of vertebrate body functions via chemical signals is accomplished by the ________.
A) excretory system
B) integumentary system
C) respiratory system
D) endocrine system

Answer: D

If you were to view a sample of animal tissue under a light microscope and notice an extensive extracellular matrix surrounding a tissue, which tissue type would you most suspect?
A) striated muscle
B) nervous
C) connective
D) epithelial

Answer: C

Evolutionary adaptations that help diverse animals directly exchange matter between cells and the environment include
A) a gastrovascular activity, a two-layered body, and a torpedo-like body shape.
B) an external respiratory surface, a small body size, and a two-cell-layered body.
C) a large body volume; a long, tubular body; and a set of wings.
D) complex internal structures, a small body size, and a large surface area.

Answer: B

Most of the exchange surfaces of multicellular animals are lined with
A) connective tissue.
B) smooth muscle cells.
C) neural tissue.
D) epithelial tissue.

Answer: D

Interstitial fluid is
A) the fluid inside the gastrovascular cavity of Hydra.
B) the internal environment inside animal cells.
C) identical to the composition of blood.
D) a common site of exchange between blood and body cells.

Answer: D

If you gently bend your ear, and then let go, the shape of your ear will return because the cartilage of your ear contains ________.
A) collagenous fibers.
B) elastic fibers.
C) reticular fibers.
D) adipose tissue.

Answer: B

Environmental influences appear to contribute to cellular mutations that lead to tumor growth. For example, certain diets lead to higher incidence of colon cancers, and overexposure to sunlight leads to higher incidence of skin cancers. The tissues in closest contact with a carcinogen or mutagen (anything that causes genetic mutations) are obviously the ones most likely to develop tumors. Carcinomas and melanomas account for well over half of all cancers. What type of tissue would you guess the term carcinoma and melanoma is most closely associated with?
A) muscle
B) connective
C) nervous
D) epithelial

Answer: D

An elephant and a mouse are running in full sunlight, and both overheat by the same amount above their normal body temperatures. When they move into the shade and rest, which animal will cool down faster?
A) The elephant will because it has the higher surface-area-to-volume ratio.
B) They will cool at the same rate because they overheated by the same amount.
C) The mouse will because it has the higher surface-area-to-volume ratio.
D) The elephant will because it has the lower surface-area-to-volume ratio.

Answer: C

The body's automatic tendency to maintain a constant and optimal internal environment is termed
A) balanced equilibrium.
B) physiological chance.
C) homeostasis.
D) static equilibrium.

Answer: C

Positive feedback differs from negative feedback in that
A) positive feedback benefits the organism, whereas negative feedback is detrimental.
B) the positive feedback's effector responses are in the same direction as the initiating stimulus rather than opposite to it.
C) the effector's response increases some parameter (such as body temperature), whereas in negative feedback it can only decrease the parameter.
D) positive feedback systems have only effectors, whereas negative feedback systems have only receptors.

Answer: B

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
A) maintains a higher basal metabolic rate.
B) expends more energy per kg of body mass than does the endotherm.
C) invests little energy in temperature regulation.
D) metabolizes its stored energy more readily than can the endotherm.

Answer: C

Most land-dwelling invertebrates and all of the amphibians
A) are ectothermic organisms with variable body temperatures.
B) alter their metabolic rates to maintain a constant body temperature of 37°C.
C) have a net loss of heat across a moist body surface, even in direct sun.
D) are endotherms but become thermoconformers only when they are in water.

Answer: A

The thin horizontal arrows in the figure above show that the
A) warmer arterial blood can bypass the legs as needed, when the legs are too cold to function well.
B) warmer venous blood transfers heat to the cooler arterial blood.
C) warmer arterial blood transfers heat to the cooler venous blood.
D) arterial blood is always cooler in the abdomen, compared to the temperature of the venous blood in the feet of the goose.

Answer: C

The temperature-regulating center of vertebrate animals is located in the
A) medulla oblongata.
B) thyroid gland.
C) hypothalamus.
D) subcutaneous layer of the skin.

Answer: C

Certain nutrients are considered "essential" in the diets of some animals because
A) only those animals use those nutrients.
B) the nutrients are subunits of important polymers.
C) these animals are not able to synthesize these nutrients.
D) the nutrients are necessary coenzymes.

Answer: C

Ingested dietary substances must cross cell membranes to be used by the body, a process known as
A) ingestion.
B) digestion.
C) hydrolysis.
D) absorption.

Answer: D

In the digestive system, peristalsis is
A) smooth muscle contractions that move food along the esophagus.
B) voluntary control of the rectal sphincters regulating defecation.
C) the transport of nutrients to the liver through the hepatic portal vessel.
D) a common cause of loss of appetite, fatigue, and dehydration.

Answer: A

You discover a new species of bacteria that grows in aquatic environments with high salt levels. While studying these bacteria, you note that their internal environment is similar to the salt concentrations in their surroundings. You also discover that the internal salt concentrations of the bacteria change as the salt concentration in their environment changes. The new species can tolerate small changes in this way, but dies from large changes because it has no mechanism for altering its own internal salt levels. What type of homeostatic mechanism is this species using to regulate its internal salt levels?
A) assimilation
B) integration
C) regulation
D) conformation

Answer: D

The function of mechanical digestion is to break down large chunks of food into smaller pieces. Why is this important? Smaller pieces of food ________.
A) have more surface area for chemical digestion than do larger pieces of food
B) are more easily stored in the stomach than are larger pieces of food
C) are easier to excrete than are larger pieces of food
D) do not taste as good as larger pieces of food

Answer: A

A zoologist analyzes the jawbones of an extinct mammal and concludes that it was an herbivore. The zoologist most likely came to this conclusion based upon ________.
A) the shape of the teeth
B) the size of the mouth opening
C) the position of muscle attachment sites
D) the angle of the teeth in the mouth

Answer: A

In a well-fed human eating a Western diet, the richest source of stored chemical energy in the body is
A) fat in adipose tissue.
B) glucose in the blood.
C) protein in muscle cells.
D) glycogen in muscle cells.

Answer: A

Because the foods eaten by animals are often composed largely of macromolecules, this requires the animals to have mechanisms for
A) elimination.
B) dehydration synthesis.
C) enzymatic hydrolysis.
D) regurgitation.

Answer: C

Examine the digestive system structures in the figure above. Bacteria that produce vitamins as products are residents of location
A) 3.
B) 4.
C) 5.
D) 7.

Answer: C

Examine the digestive system structures in the figure above. The highest rate of nutrient absorption occurs at location(s)
A) 3 only.
B) 4 only.
C) 1 and 4.
D) 3 and 4.

Answer: B

Circulatory systems compensate for
A) temperature differences between the lungs and the active tissue.
B) the slow rate at which diffusion occurs over large distances
C) the problem of communication systems involving only the nervous system.
D) the need to cushion animals from trauma.

Answer: B

Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have
A) an open circulatory system.
B) a closed circulatory system.
C) a gastrovascular cavity.
D) branched tracheae.

Answer: B

To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n)
A) open circulatory system.
B) hemocoel.
C) four-chambered heart.
D) two-chambered heart.

Answer: C

Atria contract ________.
A) immediately after systole
B) just prior to the beginning of diastole
C) during systole
D) during diastole

Answer: C

Which of the following is the correct sequence of blood flow in birds and mammals?
A) left ventricle → aorta → lungs → systemic circulation
B) right ventricle → pulmonary vein → pulmocutaneous circulation
C) pulmonary vein → left atrium → left ventricle → pulmonary circuit
D) vena cava → right atrium → right ventricle → pulmonary circuit

Answer: D

If a molecule of CO₂ released into the blood in your left toe is exhaled from your nose, it must pass through all of the following except
A) the pulmonary vein.
B) an alveolus.
C) the trachea.
D) the right atrium.

Answer: A

The velocity of blood flow is the lowest in capillaries because
A) the capillary walls are not thin enough to allow oxygen to exchange with the cells.
B) the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system.
C) the diastolic blood pressure is too low to deliver blood to the capillaries at a high flow rate.
D) the systemic capillaries are supplied by the left ventricle, which has a lower cardiac output than the right ventricle.

Answer: B

A normal event in the process of blood clotting is the
A) production of erythropoietin.
B) conversion of fibrin to fibrinogen.
C) activation of prothrombin to thrombin.
D) increase in platelets.

Answer: C

For a healthy 20-year-old at rest, arterial blood pressure is typically ____ mm Hg at systole and ____ mm Hg at diastole.
A) 120; 70
B) 70: 120
C) 140; 90
D) 90; 140

Answer: A

Small swollen areas in the neck, groin, and axillary region are associated with
A) increased activity of the immune system.
B) a broken limb.
C) blood sugar that is abnormally high.
D) dehydration.

Answer: A

Countercurrent exchange in the fish gill helps to maximize
A) endocytosis.
B) blood pressure.
C) diffusion.
D) active transport.

Answer: C