Which of the following is a major trend in land plant evolution?

• A) the trend toward smaller size

• B) the trend toward a gametophyte-dominated life cycle

• C) the trend toward a sporophyte-dominated life cycle

• D) the trend toward larger gametophytes

Which of the following lines of evidence would best support your assertion that a particular plant is an angiosperm?

• A) It produces seeds.

• B) It retains its fertilized egg within its archegonium.

• C) It lacks gametangia.

• D) It undergoes alternation of generations.

Which of the following characteristics is functionally important in cells of the gametophytes of both angiosperms and gymnosperms?

• A) diploid nuclei

• B) mitochondria

• C) endosperm

• D) chloroplasts

In addition to seeds, which of the following characteristics is unique to the seed-producing plants?

• A) sporopollenin

• B) lignin present in cell walls

• C) pollen

• D) megaphylls

Suppose that the cells of seed plants, like the cells of human skin, produce a pigment upon increased exposure to ultraviolet radiation. Rank the following cells, from greatest to least, in terms of the likelihood of producing this pigment.

• A) epidermal cells of sporophyte megaphylls, cells of a gametophyte, cells of a megasporangium, cells in the interior of a subterranean root

• B) epidermal cells of sporophyte megaphylls, cells of a gametophyte, cells in the interior of a subterranean root, cells of a megasporangium

• C) epidermal cells of sporophyte megaphylls, cells of a megasporangium, cells of a gametophyte, cells in the interior of a subterranean root

• D) epidermal cells of sporophyte megaphylls, cells in the interior of a subterranean root, cells of a megasporangium, cells of a gametophyte

Arrange the following in the correct sequence, from earliest to most recent, in which these plant traits originated.

• A) sporophyte dominance, gametophyte independence; sporophyte dominance, gametophyte dependence; gametophyte dominance, sporophyte dependence

• B) sporophyte dominance, gametophyte dependence; sporophyte dominance, gametophyte independence; gametophyte dominance, sporophyte dependence

• C) gametophyte dominance, sporophyte dependence; sporophyte dominance, gametophyte dependence; sporophyte dominance, gametophyte independence

• D) gametophyte dominance, sporophyte dependence; sporophyte dominance, gametophyte independence; sporophyte dominance, gametophyte dependence

In seed plants, which of the following is part of a pollen grain and has a function most like that of the seed coat?

• A) sporophyll

• B) sporopollenin

• C) stigma

• D) sporangium

In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a ________.

• A) moss sporophyte

• B) moss gametophyte bearing both male and female gametangia

• C) fern sporophyte

• D) fern gametophyte bearing only antheridia

A researcher has developed two stains for use with seed plants. One stains sporophyte tissue blue; the other stains gametophyte tissue red. If the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur?

• A) The pollen grains will be pure red.

• B) The pollen grains will be pure blue.

• C) The pollen grains will have red interiors and blue exteriors.

• D) The pollen grains will have blue interiors and red exteriors.

Which of the following sex and generation combinations directly produces the pollen tube of angiosperms?

• A) male gametophyte

• B) female gametophyte

• C) male sporophyte

• D) female sporophyte

The advantages of the reduced gametophytes in seed plants include ________.

• A) protection from ultraviolet radiation, gain of nutrients from its own photosynthesis, and protection from drying out

• B) protection from ultraviolet radiation, gain of nutrients from the sporophyte, and protection from drying out

• C) protection of the spores from ultraviolet radiation and drying out, and gain of nutrients from the sporophyte

• D) development of the seed

The advantages of seeds, compared to spores, include ________.

• A) using wind as a dispersal agent

• B) containing a nutrient store for a developing sporophyte

• C) relying on animals for pollination

• D) providing nutrition for animals

Unlike almost all ferns, seed plants ________.

• A) produce two kinds of spores

• B) have large gametophytes

• C) have vascular tissue

• D) can photosynthesize

One day, you go outside and see that the cars on the street are covered in a yellow "dust." Which of the following statements can be correctly applied to this "dust"?

• A) The dust is pine pollen and is so abundant because the pines are wind-pollinated.

• B) The dust is the spore production of ferns and is so abundant because the spores are wind-dispersed.

• C) The dust is the seed production of ferns and is so abundant because the seeds are tiny and take very little energy to produce.

• D) The dust is the seed production of pines and is so abundant because the seeds are tiny and take very little energy to produce.

Use the following information to answer the question.

In the United States and Canada, bats use one of two strategies to survive winter. They either migrate south, or they hibernate. Recently, those that hibernate seem to have come under attack by a fungus, Geomyces destructans (Gd), an attack that is occurring from Missouri to New England, Canada, and even the state of Washington. Many infected bats have a delicate, white filamentous mat on their muzzles, which is referred to as white-nose syndrome (WNS). The fungus invades the bat tissues, causes discomfort, and awakens the bat from its hibernation. The bat fidgets and wastes calories, using up its stored fat. The bat then behaves abnormally, leaving its cave during daytime in winter to search for food. Their food, primarily insects, is scarce during the winter, and the bats ultimately starve to death. Since 2006, it is estimated that over six million bats have perished from WNS.

The Gd mat on the fur of the bats should be expected to consist of ________.

• A) hyphae

• B) haustoria

• C) yeasts

• D) basidia

What do fungi and arthropods have in common?

• A) The haploid state is dominant in both groups.

• B) Both groups are predominantly autotrophs that produce their own food.

• C) Both groups use chitin for support.

• D) Both groups have cell walls.

Fungi have an extremely high surface-to-volume ratio. What is the advantage of this characteristic to an organism that gets most of its nutrition through absorption?

• A) The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

• B) The lower volume prevents the cells from drying out too quickly, which can interfere with absorption.

• C) This high ratio creates more room inside the cells for additional organelles involved in absorption.

• D) This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs.

If all fungi in an environment that perform decomposition were to suddenly die, then which group of organisms should benefit most, due to the fact that their fungal competitors have been removed?

• A) flowering plants

• B) protists

• C) prokaryotes

• D) grasses

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?

• A) fungal haustoria

• B) fungal enzymes

• C) increased oxygen levels

• D) larger bacterial populations

A fungal spore germinates, giving rise to a mycelium that grows outward into the soil surrounding the site where the spore originally landed. Which of the following accounts for the fungal movement, as described here?

• A) karyogamy

• B) mycelial flagella

• C) breezes distributing spores

• D) cytoplasmic streaming in hyphae

When pathogenic fungi are found growing on the roots of grape vines, grape farmers sometimes respond by covering the ground around their vines with plastic sheeting and pumping a gaseous fungicide into the soil. The most important concern of grape farmers who engage in this practice should be that the ________.

• A) fungicide might also kill the native yeasts residing on the surfaces of the grapes

• B) lichens growing on the vines' branches are not harmed

• C) fungicide might also kill mycorrhizae

• D) sheeting is transparent so that photosynthesis can continue

The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to ________.

• A) the ability to form haustoria and parasitize other organisms

• B) the potential to inhabit almost all terrestrial habitats

• C) the increased probability of contact between different mating types

• D) an extensive surface area well suited for invasive growth and absorptive nutrition

Some fungal species live in plants and can kill herbivores that feed on the plant. What type of relationship does this fungus have with its host?

• A) parasitic

• B) mutualistic

• C) commensal

• D) predatory

Some companies advertise and sell mycorrhizae to home gardeners and commercial farms, claiming that the presence of mycorrhizae improves plant growth and survival. If the company conducted experiments on plants with and without mycorrhizae, which of the following measurements would support their claim?

• A) smaller apple size in plants with mycorrhizae than in plants without mycorrhizae

• B) increased production of corn ears in plants with mycorrhizae than in plants without mycorrhizae

• C) increased need for fertilizer in plants with mycorrhizae than in plants without mycorrhizae

• D) increased mortality in plants with mycorrhizae than in plants without mycorrhizae

Some nematode worms suck plant juices from the roots of plants and are economically important agricultural pests. Some fungi are usually decomposers of plant material, but some trap and kill nematodes at times. Arthrobotrys traps and kills nematodes, especially when they lack nitrogen sources. These two facts suggest that farmers could find Arthrobotrys an important tool in combating nematode infestations. Which of the following research questions would make a good starting point for developing such a defense against plant-sucking nematodes?

• A) Does nitrogen fertilization of crops affect the likelihood that Arthrobotrys will trap and kill nematodes?

• B) Do nitrogen-fixing bacteria provide nitrogen to the fungi?

• C) What is the evolutionarily oldest method of trapping nematodes?

• D) What mechanisms do nematodes have that could allow them to escape from Arthrobotrys?

A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes are absolutely conserved, which of the following would be the best choice on which to base the phylogeny?

• A) genes involved in chitin synthesis

• B) collagen genes

• C) genes involved in directing segmentation development

• D) genes involved in eye-lens synthesis

Which of the following is (are) unique to animals?

• A) the structural carbohydrate, chitin

• B) nervous system signal conduction and muscular movement

• C) heterotrophy

• D) flagellated gametes

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 is most directly involved in the evolution of these variations in metamorphosis?

• A) artificial selection of sexually immature forms of insects

• B) changes in the homeobox genes controlling early development

• C) the evolution of meiosis

• D) the origin of a brain

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

• A) preying on animals

• B) ingesting materials

• C) consuming living, rather than dead, prey

• D) using enzymes to digest their food

Use the information to answer the question.

Trichoplax adhaerens is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 µm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.

Which of the following T. adhaerens traits is different from all other known animals?

• A) T. adhaerens is multicellular.

• B) T. adhaerens lacks muscle and nerve cells.

• C) T. adhaerens has cilia.

• D) T. adhaerens lacks cell walls.

What do animals ranging from corals to monkeys have in common?

• A) a mouth and an anus

• B) number of embryonic tissue layers

• C) some type of body symmetry

• D) presence of Hox genes

In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is that ________.

• A) we could not clone a larva from the somatic cells of such an adult insect

• B) such species must reproduce only asexually

• C) the descendants of these adults do not include a larval stage

• D) metamorphosis can no longer occur among the descendants of such adults

The fact that choanoflagellates and collar cells of sponges resemble each other supports the inference that ________.

• A) choanoflagellates are animals

• B) choanoflagellates are more closely related to sponges than they are to protists

• C) choanoflagellates and sponges are sister groups

• D) choanoflagellates and sponges evolved similar cell structures through convergent evolution

Which of the following would you classify as something other than an animal?

• A) sponge

• B) coral

• C) jellyfish

• D) choanoflagellate

The evolution of animal species has been prolific (current estimates of species numbers reach into the tens of millions). Much of this diversity is a result of the evolution of novel ways to ________.

• A) reproduce

• B) arrange cells into tissues

• C) sense, feed, and move

• D) form an embryo and establish a basic body plan

The last common ancestor of all animals was probably a ________.

• A) unicellular chytrid

• B) multicellular algae

• C) multicellular fungus

• D) flagellated protist

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

• A) true tissues

• B) hard parts

• C) bilateral symmetry

• D) embryos

One hypothesis suggests that the Cambrian explosion was caused by the rise of predator-prey relationships. This hypothesis is best supported by an increased incidence of which of the following fossil traces?

• A) worm burrows

• B) larger animals

• C) organic material

• D) hard parts

Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

• A) binary fission

• B) random segregation

• C) gene duplication

• D) chromosomal condensation

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of ________.

• A) mass extinction

• B) evolutionary stasis

• C) adaptive radiation

• D) a large meteor impact

Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________.

• A) arthropods evolved before vertebrates did

• B) extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates

• C) vertebrates evolved from arthropods

• D) arthropods have had more time to coevolve with land plants than have vertebrates

Cadherin proteins help animal cells stick (adhere) to each other. Choose which statement about cadherin in cancer cells that are metastasizing (spreading) throughout a patient's body is most likely correct.

• A) Cadherin proteins in metastasizing cancer cells are likely to have mutations that make them less "sticky."

• B) Cadherin proteins in metastasizing cancer cells are likely to have mutations that make them more "sticky."

• C) Mutations in cadherin proteins are unlikely to affect the metastasizing of cancer cells.

• D) Mutations in cadherin proteins accumulate at a constant rate that can be measured by a molecular clock.

Which of the following factors most likely contributed to the extinction of many Ediacaran life forms?

• A) predation by new species, poisoning from high carbon dioxide levels, and loss of developmental flexibility

• B) predation by new species, poisoning from high oxygen levels, and loss of habitat due to increased temperatures

• C) predation by new species, faster movement by new species, and increased developmental flexibility by new species

• D) loss of habitat due to increased temperatures, poisoning from high oxygen levels, and loss of developmental flexibility

Which tissue type or organ is not correctly matched with its germ layer tissue?

• A) nervous—mesoderm

• B) muscular—mesoderm

• C) stomach—endoderm

• D) skin—ectoderm

While looking at some seawater through your microscope, you spot the egg of an unknown animal. Which of the following tests could you use to determine whether the developing organism is a protostome or a deuterostome? See whether the embryo ________.

• A) develops germ layers

• B) exhibits spiral cleavage or radial cleavage

• C) develops a blastopore

• D) develops an archenteron

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) There is evidence of cephalization.

• B) The animal is triploblastic.

• C) The animal is clearly bilaterally symmetrical.

• D) You see a mouth, but not an anus.

Which of the following is a feature of the "tube-within-a-tube" body plan in most animal phyla?

• A) The outer tube consists of a hard exoskeleton.

• B) The outer tube consists of digestive organs.

• C) The mouth and anus form the ends of the inner tube.

• D) The two "tubes" are separated by tissue that comes from embryonic endoderm.

If you think of the earthworm body plan as a drinking straw within a pipe, where would you expect to find most of the tissues that developed from endoderm?

• A) lining the straw

• B) lining the space between the pipe and the straw

• C) forming the outside of the pipe

• D) forming the outside of the straw

Among protostomes, which morphological trait has shown the most variation?

• A) type of symmetry (bilateral versus radial versus none)

• B) type of body cavity (coelom versus pseudocoelom versus no coelom)

• C) number of embryonic tissue types (diploblasty versus triploblasty)

• D) type of development (protostome versus deuterostome)

What do all deuterostomes have in common?

• A) Adults are bilaterally symmetrical.

• B) Embryos have pharyngeal pouches that may or may not form gill slits.

• C) All have a spinal column.

• D) The pore (blastopore) formed during gastrulation becomes the anus.

Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Initially, the dye should be able to flow directly into the ________.

• A) blastopore

• B) blastocoel

• C) archenteron

• D) pseudocoelom

You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

• A) It is triploblastic.

• B) It has bilateral symmetry.

• C) It possesses sensory structures at its anterior end.

• D) Muscular activity of its digestive system distorts the body wall.

Use the information to answer the question.

One small animal phylum (Placozoa) contains only two species, Trichoplax adhaerens (T. adhaerens) and T. reptans. T. adhaerens is the only species seen in over a century. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed. Embryos up to, but not past, the 64-cell (blastula) stage have been observed.

On the basis of information in the paragraph, which of these should be able to be observed in T. adhaerens?

• A) a coelom

• B) the process of gastrulation

• C) eggs

• D) a radially symmetric larval form

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise 1 hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. This embryo may potentially develop into a(n) ________.

• A) turtle

• B) earthworm

• C) sea star

• D) sea urchin

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise 1 hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. If we were to separate these eight cells and attempt to culture them individually, then what is most likely to happen?

• A) All eight cells will die immediately.

• B) Each cell may continue development, but only into a nonviable embryo that lacks many parts.

• C) Each cell may develop into a full-sized, normal embryo.

• D) Each cell may develop into a smaller-than-average, but otherwise normal, embryo.

What was an early selective advantage of a coelom in animals? A coelom ________.

• A) contributed to a hydrostatic skeleton, allowing greater range of motion

• B) was a more efficient digestive system

• C) allowed cephalization and the formation of a cerebral ganglion

• D) allowed asexual and sexual reproduction

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

• A) These two subgroups have a common ancestor that was a deuterostome.

• B) The protostomes are a polyphyletic group.

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

• D) The lophotrochozoans are monophyletic.

Which of these statements, if accurate, would support the claim that the ancestral cnidarians had bilateral symmetry?

• A) Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.

• B) Cnidarians have fewer Hox genes than bilaterians.

• C) All cnidarians are acoelomate.

• D) The presence of collar cells.

An organism that exhibits a head with sensory equipment and a brain probably also ________.

• A) is bilaterally symmetrical

• B) has a coelom

• C) is segmented

• D) is diploblastic

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following would be a likely mechanism by which this pesticide works?

• A) The mosquito would develop a weakened exoskeleton that would make it vulnerable to trauma.

• B) The mosquito would have trouble digesting food, due to impaired gut function.

• C) The mosquito would have trouble with respiration and circulation, due to impaired muscle function.

• D) The mosquito wouldn't be affected at all.

Use the information to answer the question.

Trichoplax adhaerens is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.

T. adhaerens' body symmetry seems to be most like that of ________.

• A) most sponges

• B) cnidarians

• C) worms

• D) tetrapods

Use the information to answer the question.

Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions) on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plumules, usually located posteriorly, perform respiratory gas exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips.

If nudibranch rhinophores are located at the anterior ends of these sea slugs, then they contribute to the sea slugs' ________.

• A) segmentation

• B) lack of torsion

• C) development of a head

• D) identity as lophotrochozoans

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

• A) bilaterians, deuterostomes, vertebrates, tetrapods, amniotes

• B) bilaterians, deuterostomes, amniotes, vertebrates, tetrapods

• C) deuterostomes, bilaterians, amniotes, vertebrates, tetrapods

• D) deuterostomes, bilaterians, vertebrates, tetrapods, amniotes

The most ancient branch point in animal phylogeny is the characteristic of having ________.

• A) radial or bilateral symmetry

• B) diploblastic or triploblastic embryos

• C) true tissues or no tissues

• D) a body cavity or no body cavity

When a scientist describes the "body plan" of a phylum, he or she is implying that ________.

• A) organisms direct their own evolution in order to maximize their success

• B) animals evolve according to a pre-ordained plan

• C) the body shapes we see now have been more successful than others in the past

• D) mutations have arisen that allow only some shapes to be produced

Which of the following statements comparing symmetry in sessile and swimming animals is most probable?

• A) Radial symmetry is more advantageous for active swimming than is bilateral symmetry.

• B) Radial symmetry occurs most frequently in animals that catch their prey by rapid swimming.

• C) Bilateral symmetry allowed animals to evolve nerves.

• D) Bilaterally symmetric animals can be streamlined for swimming, but radially symmetric animals cannot.

The primary difference between a coelom and a pseudocoelom is ________.

• A) their developmental origin

• B) the manner in which they cushion the internal organs

• C) a coelom arises in the ectoderm, and a pseudocoelom arises in the endoderm

• D) a coelom occurs in triploblastic animals, and a pseudocoelom occurs in diploblastic animals

Nine-banded armadillos give birth to four offspring at a time. An amazing fact about these offspring is that they are genetically identical to each other. This fact suggests ________.

• A) the young undergo metamorphosis

• B) the embryo undergoes radial and indeterminate cleavage

• C) the first cell division of the fertilized egg is perpendicular to the vertical axis of the egg

• D) the species is pseudocoelomate

You find a new species of worm and want to classify it. Which of the following lines of evidence would allow you to classify the worm as a nematode and not an annelid?

• A) It is segmented.

• B) It is triploblastic.

• C) It has a coelom.

• D) It sheds its external skeleton to grow.

The common ancestor of the protostomes had a coelom. What does this suggest?

• A) All lophotrochozoans have a coelom.

• B) There are no pseudocoelomates within the protostomes.

• C) There are no acoelomates within the protostomes.

• D) The body cavity evolved before the lophophore.

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 have proposed that the ancestral cnidarian's were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that ________.

• A) all radially symmetric animals should be grouped together in one clade

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

• C) Hox genes play little actual role in coding for an animal's "body plan"

• D) cnidaria may someday replace porifera as the basal bilaterians

Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would ________.

• A) mean that sponges must no longer be classified as animals

• B) confirm the identity of sponges as "basal animals"

• C) mean that extinct sponges must have been the last common ancestor of animals and fungi

• D) require sponges to be reclassified as choanoflagellates

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) Molecular data can be gathered in the lab, while morphological data must be gathered in the field.

• B) Molecular data can be used to give an estimate of the time since two groups split.

• C) Morphological changes usually do not result from molecular changes.

• D) Some phyla vary too widely in morphological characteristics to be classified accurately.

If in the future the current molecular evidence regarding animal origins is further substantiated, which of the following statements would be correct with reference to fossil evidence that contradicts molecular evidence?

• A) The contrary fossil evidence will be seen as a hoax.

• B) The fossil evidence will be understood to have been interpreted incorrectly because it is incomplete.

• C) The fossil record will, henceforth, be ignored.

• D) Phylogenies involving even the smallest bit of fossil evidence will need to be discarded.

Which of the following statements concerning animal taxonomy is accurate?

• A) Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

• B) Kingdom Animalia is polyphyletic.

• C) Animals are more closely related to plants than to fungi.

• D) In the kingdom Animalia, most clades based on body plan or fossils have been found to be incorrect.

In the future, phylogenetic studies should be conducted to ________.

• A) resolve the branching patterns (evolutionary history) of the Lophotrochozoa

• B) discover the Hox genes in sponges

• C) discover the relationships between nematodes and platyhelminthes

• D) discover the larval stages of echinoderms

At one time, sponges were lumped into one phylum. Then, they were separated into several different phyla. Now, they are considered one phylum again. These changes indicate which of the following?

• A) Every phylogeny should be considered a hypothesis that must be revised in the light of new data.

• B) We need more fossil evidence of sponges.

• C) Molecular and morphological data often conflict when we try to reconstruct evolutionary history.

• D) The goal of making all taxonomic groups monophyletic is unrealistic.

Sponges and ctenophores have both been proposed as basal metazoans. Which of the following types of data support the idea that sponges are the basal group?

• A) sequences of cadherin genes, cleavage type, structure of collar cells, and bilateral symmetry of adults

• B) sequences of collagen genes, bilateral symmetry of adults, cleavage type, and fossil steroids

• C) fossil steroids, molecular clock, lack of tissues in sponges, and structure of collar cells

• D) structure of collar cells, bilateral symmetry of larvae, sequences of cadherin genes, and molecular clock

Sponges and ctenophores have both been proposed as basal metazoans. Imagine that you wanted to provide additional evidence to help resolve this question. Which of the following projects would be the best next step?

• A) more extensive study of DNA sequences in the bilateria

• B) ultrastructural (that is, electron microscope) comparisons of choanoflagellates and sperm cells from arthropods

• C) measurements of molecular clocks from the Lophotrochozoa

• D) more extensive studies of DNA sequences in both groups

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

• A) Sponge ancestors never had tissues.

• B) Modern-day sponges have lost the ability to form tissues.

• C) Multicellular, modern-day choanoflagellates can form tissues.

• D) Sponges do not have nerve cells.

One of the characteristics unique to animals is

• A) gastrulation.

• B) multicellularity.

• C) sexual reproduction.

• D) flagellated sperm.

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.

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

Which part of a plant absorbs most of the water and minerals taken up from the soil?

• A) root cap

• B) root hairs

• C) the thick parts of the roots near the base of the stem

• D) storage roots

Prop roots are the modified aerial adventitious roots of corn that ________.

• A) enable the root system to obtain oxygen

• B) support tall, top-heavy plants

• C) enable the root system to anchor

• D) wrap around other plants to support tall, top-heavy plants

Strawberries have modified horizontal shoots growing along the surface, which are referred to as ________.

• A) rhizomes

• B) tubers

• C) stolons

• D) rhizoids

An axillary bud in the stem can potentially form a ________ in a variety of plants based on evolutionary adaptations.

• A) lateral branch

• B) thorn

• C) flower

• D) lateral branch, thorn, and flower

Onion leaves have been modified for the purpose of ________.

• A) defense (protect from predators)

• B) storage

• C) support

• D) reproduction

________ is a relatively indigestible strengthening polymer that accounts for more than a quarter of the dry mass of wood.

• A) Cellulose

• B) Starch

• C) Lignin

• D) None of these choices

When you eat Brussels sprouts, you are eating ________.

• A) immature flowers

• B) large axillary buds

• C) petioles

• D) storage leaves

Some of the largest leaves in the world can be found on plants near the floor of dense tropical rain forests. Which of the following precursors for photosynthesis is most likely limited in these large leaves?

• A) oxygen

• B) carbon dioxide

• C) glucose

• D) light

Leaf thickness represents a trade-off between ________.

• A) light collection and carbon dioxide absorption

• B) water retention and carbon dioxide absorption

• C) water retention and oxygen absorption

• D) light collection and oxygen absorption

One important difference between the anatomy of roots and the anatomy of leaves is that ________.

• A) only leaves have phloem and only roots have xylem

• B) root cells have cell walls and leaf cells do not

• C) a waxy cuticle covers leaves but is absent from roots

• D) vascular tissue is found in roots but is absent from leaves

• E) leaves have epidermal tissue but roots do not

Which structure is correctly paired with its tissue system?

• A) root hair—vascular tissue

• B) guard cell—vascular tissue

• C) companion cell—ground tissue

• D) tracheid—vascular tissue

The vascular bundle in the shape of a single central cylinder in a root is called the ________.

• A) cortex

• B) stele

• C) periderm

• D) pith

Which of the following cell types retains the ability to undergo cell division?

• A) a parenchyma cell near the root tip

• B) a functional sieve tube element

• C) a tracheid

• D) a stem fiber

Which of the following have unevenly thickened primary walls that support young, growing parts of the plant?

• A) parenchyma cells

• B) collenchyma cells

• C) sclerenchyma cells

• D) tracheids and vessel elements

Which of the following is correctly paired with its structure and function?

• A) sclerenchyma—supporting cells with thick secondary walls

• B) ground meristem—protective coat of woody stems and roots

• C) guard cells—waterproof ring of cells surrounding the central stele in roots

• D) periderm—parenchyma cells functioning in photosynthesis in leaves

Which of the following are water-conducting cells that are dead at functional maturity?

• A) parenchyma cells

• B) collenchyma cells

• C) tracheids and vessel elements

• D) sieve-tube elements

Which of the following cells transport sugars over long distances?

• A) parenchyma cells

• B) sclerenchyma cells

• C) tracheids and vessel elements

• D) sieve-tube elements

Which of the following plants are annuals?

• A) azaleas

• B) roses

• C) blueberries

• D) wheat

Plant meristematic cells ________.

• A) are distributed evenly in all tissues throughout the plant

• B) are undifferentiated cells that produce new cells

• C) increase the surface area of dermal tissue by developing root hairs

• D) subdivide into three distinct cell types named parenchyma, ground meristem, and procambium

Which of the following arise, directly or indirectly, from meristematic activity?

• A) secondary xylem

• B) leaves

• C) dermal tissue

• D) secondary xylem, leaves, dermal tissue, and tubers

Compared to most animals, the growth of most plant structure is best described as ________.

• A) perennial

• B) weedy

• C) indeterminate

• D) primary

What is present in a shoot apical meristem region?

I) the region of cell division
II) immature buds and leaves
III) cells that will give rise to the protoderm, ground meristem, and procambium

• A) only I

• B) only II

• C) only III

• D) I, II, and III

Shoot elongation in a growing bud is due primarily to ________.

• A) cell division at the shoot apical meristem

• B) cell elongation directly below the shoot apical meristem

• C) cell elongation localized in each internode

• D) cell division at the shoot apical meristem and cell elongation directly below the shoot apical meristem

Apical meristems of dicots are at the tips of stems. Apical meristems of grasses are at ground level or slightly below, concealed by the leaves. What does this mean when considering care of a lawn or soccer field?

• A) If you mow right at ground level, the leaves can keep growing with no problem.

• B) Grass mowed two inches above ground level grows at a slower rate compared to grass mowed three inches above the ground level.

• C) If you mow two inches above ground level, most apical meristems will be cut down.

• D) If you mow two inches above ground level, the apical meristem can keep producing new cells.

In a meristematic region, the cell plate during mitosis is perpendicular to the side of the stem. In what direction will the stem grow?

• A) laterally in width

• B) vertically in height

• C) at a 45-degree angle from the ground

• D) away from the sun

Which of the following cells or tissues arise from lateral meristem activity?

• A) secondary xylem

• B) leaves

• C) trichomes

• D) tubers

Cells produced by lateral meristems are known as ________.

• A) dermal and ground tissue

• B) lateral tissues

• C) pith

• D) secondary tissues

Which of the following can be used to determine a twig's age?

• A) number of apical bud scar rings

• B) number of leaf scars

• C) number and arrangement of axillary buds

• D) length of internodes

A plant that grows one year, dies back, and then grows again the following year, produces flowers, and then dies would be considered ________.

• A) annual

• B) biennial

• C) perennial

• D) not very fit

Which of the following is the correct sequence of the zones in the primary growth of a root, moving from the root cap inward?

• A) zone of cell division, zone of elongation, zone of differentiation

• B) zone of differentiation, zone of elongation, zone of cell division

• C) zone of elongation, zone of cell division, zone of differentiation

• D) zone of cell division, zone of differentiation, zone of elongation

The driving force that pushes the root tip through the soil is primarily ________.

• A) continuous cell division in the root cap at the tip of the root

• B) continuous cell division just behind the root cap in the center of the apical meristem

• C) elongation of cells behind the root apical meristem

• D) continuous cell division of root cap cells

Mitotic activity by the apical meristem of a root makes which of the following more possible?

• A) increased delivery of water to the aboveground stem

• B) decreased absorption of mineral nutrients

• C) increased absorption of carbon dioxide.

• D) effective lateral growth of the stem

Which of the following root tissues gives rise to lateral roots?

• A) endodermis

• B) phloem

• C) epidermis

• D) pericycle

As a youngster, you drive a nail in the trunk of a young tree that is 3 meters tall. The nail is about 1.5 meters from the ground. Fifteen years later, you return and discover that the tree has grown to a height of 30 meters. About how many meters above the ground is the nail?

• A) 0.5

• B) 1.5

• C) 3.0

• D) 15.0

You find a plant unfamiliar to you and observe that it has vascular bundles scattered throughout the stem cross section. What do you conclude about the plant?

• A) It is probably an herbaceous eudicot.

• B) It will probably get annual rings of wood.

• C) It is probably a monocot.

• D) It could be either a young eudicot or a monocot.

Monocot vascular bundles do not have a vascular cambium between the xylem and phloem. This means that monocots ________.

• A) are much less efficient at conducting water and sugars

• B) have very thin stems

• C) do not produce wood in annual rings

• D) cannot produce lateral shoots

A student examining leaf cross sections under a microscope finds many loosely packed cells with relatively thin cell walls. The cells have numerous chloroplasts. What type of cells are they?

• A) parenchyma

• B) endodermis

• C) collenchyma

• D) sclerenchyma

The veins of leaves are ________.

I) composed of xylem and phloem
II) continuous, with vascular bundles in the stem and roots
III) finely branched to be in close contact with photosynthesizing cells

• A) only I

• B) only II

• C) only III

• D) I, II, and III

Increasing the number of stomata per unit surface area of a leaf when atmospheric carbon dioxide levels decline is most analogous to a human ________.

• A) breathing faster as atmospheric carbon dioxide levels increase

• B) putting more red blood cells into circulation when atmospheric oxygen levels decline

• C) removing red blood cells from circulation when atmospheric oxygen levels increase

• D) increasing the volume of its lungs when atmospheric carbon dioxide levels increase

A lateral root originates in the ________.

• A) pericycle

• B) cortex

• C) endodermis

• D) epidermis

Of the following plants, which stem has scattered vascular bundles?

• A) corn

• B) magnolia

• C) chrysanthemum

• D) hibiscus

The secondary mesophyll of leaves is made up of ________.

• A) parenchyma tissue

• B) collenchyma tissue

• C) sclerenchyma tissue

• D) parenchyma and collenchyma tissues

Where is primary growth occurring in an old tree?

• A) closest to ground level at the base of the tree

• B) in young branches where leaves are forming

• C) where the vascular cambium and cork cambium are located

• D) Nowhere; trees more than a year old have only secondary growth.

What tissue makes up most of the wood of a tree?

• A) primary xylem

• B) secondary xylem

• C) secondary phloem

• D) vascular cambium

A plant has the following characteristics: a taproot system, several growth rings evident in a cross section of the stem, and a layer of bark around the outside. Which of the following best describes the plant?

• A) herbaceous eudicot

• B) woody eudicot

• C) woody monocot

• D) herbaceous monocot

If you were able to walk into an opening cut into the center of a large redwood tree, when you exited from the middle of the trunk (stem) outward, you would cross, in order, ________.

• A) the annual rings, new xylem, vascular cambium, phloem, and bark

• B) the secondary xylem, cork cambium, phloem, and periderm

• C) the vascular cambium, oldest xylem, and newest xylem

• D) the secondary xylem, secondary phloem, and vascular cambium

Heartwood and sapwood consist of ________.

• A) periderm

• B) secondary xylem

• C) secondary phloem

• D) cork

Additional vascular tissue produced as secondary growth in a root originates from which cells?

• A) vascular cambium

• B) apical meristem

• C) endodermis

• D) xylem

The bark of a tree trunk is made up of ________.

• A) heart wood and sap wood

• B) heart wood

• C) secondary phloem

• D) secondary phloem and layers of periderm

The polarity of a plant is established when ________.

• A) cotyledons form at the shoot end of the embryo

• B) the shoot-root axis is established in the embryo

• C) the primary root breaks through the seed coat

• D) the shoot first breaks through the soil into the light as the seed germinates

Growth and development of plant parts involves ________.

I) cell division to produce new cells
II) enlargement and elongation of cells
III) specialization of cells into tissues

• A) only I

• B) only II

• C) only III

• D) I, II, and III

Totipotency is a term used to describe a cell's ability to give rise to a complete new organism. In plants, this means that ________.

• A) plant development is not under genetic control

• B) the cells of shoots and the cells of roots have different genes

• C) cell differentiation depends largely on the control of gene expression

• D) a cell's environment has no effect on its differentiation

The phase change of an apical meristem from the juvenile to the mature vegetative phase is often revealed by ________.

• A) a change in the morphology of the leaves produced

• B) the initiation of secondary growth

• C) a change in the orientation of preprophase bands and cytoplasmic microtubules in lateral meristems

• D) the activation of floral meristem identity genes

Most of the growth of a plant body is the result of

• A) cell differentiation.

• B) morphogenesis.

• C) cell division.

• D) cell elongation.

The innermost layer of the root cortex is the

• A) core.

• B) pericycle.

• C) endodermis.

• D) pith.

Heartwood and sapwood consist of

• A) bark.

• B) periderm.

• C) secondary xylem.

• D) secondary phloem.

The phase change of an apical meristem from the juvenile to the mature vegetative phase is often revealed by

• A) a change in the morphology of the leaves produced.

• B) the initiation of secondary growth.

• C) the formation of lateral roots.

• D) the activation of floral meristem identity genes.

Suppose a flower had normal expression of genes A and C and expression of gene B in all four whorls. Based on the ABC hypothesis, what would be the structure of that flower, starting at the outermost whorl?

• A) carpel-petal-petal-carpel

• B) petal-petal-stamen-stamen

• C) sepal-carpel-carpel-sepal

• D) sepal-sepal-carpel-carpel

Which of the following arise(s), directly or indirectly, from meristematic activity?

• A) secondary xylem

• B) leaves

• C) dermal tissue

• D) all of the above

Which of the following would not be seen in a cross section through the woody part of a root?

• A) sclerenchyma cells

• B) parenchyma cells

• C) sieve-tube elements

• D) root hairs

Penguins, seals, and tuna have body forms that permit rapid swimming, because ________.

• A) all share a recent common ancestor

• B) all of their bodies have been compressed since birth by intensive underwater pressures

• C) the shape is a convergent evolutionary solution, which reduces drag while swimming

• D) this is the only shape that will allow them to maintain a constant body temperature in water

As animals have evolved large body size, they have also evolved adaptations to improve exchange of energy and materials with the environment. For example, in many larger organisms, evolution has favored lungs and a digestive tract with ________.

• A) more branching or folds

• B) increased thickness

• C) larger cells

• D) decreased blood supply

Much of the coordination of vertebrate body functions via chemical signals is accomplished by the ________.

• A) respiratory system

• B) endocrine system

• C) integumentary system

• D) excretory system

Compared with a smaller cell, a larger cell of the same shape has ________.

• A) less surface area

• B) less surface area per unit of volume

• C) a smaller average distance between its mitochondria and the external source of oxygen

• D) a smaller cytoplasm-to-nucleus ratio

Both the endocrine and nervous systems transmit information around an animal's body. Which of the following is a characteristic of nervous system signals?

• A) allow gradual changes to take place in the body

• B) travel quickly, allowing rapid transmission of signals

• C) usually impact the entire body

• D) a voltage change must occur

Some animals have no gills when young, but then develop gills that grow larger as the animal grows larger. What is the reason for this increase in gill size?

• A) The young of these animals are much more active than the adult, which leads to a higher BMR (basal metabolic rate) and, therefore, a higher need for oxygen.

• B) Relative to their volume, the young have more surface area across which they can transport all the oxygen they need.

• C) The young have a higher BMR.

• D) Relative to their surface area, the young have more body volume in which they can store oxygen for long periods of time.

Evolutionary adaptations that help some animals directly exchange matter between the cells of their body and the environment include ________.

• A) a gastrovascular cavity, 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) an unbranched internal surface, a small body size, and thick covering

All animals, whether large or small, have ________.

• A) an external body surface that is dry

• B) a basic body plan that resembles a two-layered sac

• C) a body surface covered with hair to keep them warm

• D) most of their cells in contact with an aqueous medium

Interstitial fluid is ________.

• A) the internal environment inside animal cells

• B) identical to blood in composition.

• C) a site of exchange between blood and body cells

• D) found only in the lumen of the small intestine

Generally, epithelial cell layers are responsible for separating two fluids. For example, the epithelium of blood vessels in animals separates the blood from the interstitial fluid. What characteristic would you expect to see in an epithelium that was specialized for passive diffusion of materials from one fluid to another?

• A) a single layer of flattened cells

• B) many layers of cells stacked together

• C) large, cube-shaped cells

• D) loosely connected cells surrounded by an extracellular matrix

Most of the exchange surfaces of multicellular animals are lined with ________.

• A) connective tissue

• B) smooth muscle cells

• C) neural tissue

• D) epithelial tissue

Connective tissues typically have ________.

• A) little space between the membranes of adjacent cells

• B) the ability to transmit electrochemical impulses

• C) the ability to shorten upon stimulation

• D) relatively few cells and a large amount of extracellular matrix

In mammals, GH (growth hormone) is an endocrine signal that stimulates repair and growth of various tissues. Which of the following would be required for a tissue to respond to growth hormone?

• A) the presence of a growth hormone receptor on the responding tissue

• B) the responding tissue must be muscle

• C) nerve cells must attach to the responding tissue for growth hormone to work

• D) a voltage change must occur

Blood is best classified as connective tissue because ________.

• A) its cells are separated from each other by an extracellular matrix

• B) it contains more than one type of cell

• C) its cells can move from place to place

• D) it is found within all the organs of the body

Most types of communication between cells utilize ________.

• A) the exchange of cytosol between the cells

• B) the movement of the cells

• C) chemical or electrical signals

• D) the exchange of DNA between the cells

All types of muscle tissue have ________.

• A) striated banding patterns seen under the microscope

• B) cells that lengthen when appropriately stimulated

• C) a response that can be consciously controlled

• D) interactions between actin and myosin

Cardiac muscle cells are both ________.

• A) striated and interconnected by intercalated disks

• B) smooth and under voluntary control

• C) striated and under voluntary control

• D) smooth and under involuntary control

Muscle cells are organized to perform specific types of contractions within a tissue. Which of the following is a characteristic of smooth muscle?

• A) many cells fused together

• B) intercalated discs

• C) spindle-shaped cells with a single nucleus

• D) striations with sarcomeres

Food moves along the digestive tract as the result of contractions by ________.

• A) cardiac muscle

• B) smooth muscle

• C) striated muscle

• D) skeletal muscle

In many animals, fat is stored in specialized cells in the ________.

• A) bone

• B) muscle

• C) adipose tissue

• D) blood

Bone consists of ________.

• A) a mixture of hardened collagen and minerals.

• B) chondroitin sulfate secreted by chondrocytes.

• C) many columnar epithelial cells packed together.

• D) hardened fibrous connective tissue.

What is the name of the epithelial cell surface that faces the outside of an organ?

• A) apical

• B) basal

• C) interstitial

• D) lumen

Which organ system is responsible for protection against injury, infection, and dehydration?

• A) Reproductive system

• B) Excretory system

• C) Skeletal system

• D) Integumentary system

Which of the following is a true statement about body size and physiology?

• A) The amount of food and oxygen an animal requires and the amount of heat and waste it produces are inversely proportional to its mass.

• B) The rate at which an animal uses nutrients and produces waste products is independent of its volume.

• C) Small and large animals face different physiological challenges because an animal's body mass increases cubically while its surface area increases as a squared function.

• D) The wastes produced by an animal double as its volume doubles and triple as its surface area triples.

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) The elephant will because it has the lower surface-area-to-volume ratio.

• C) The mouse will because it has the higher surface-area-to-volume ratio.

• D) They will cool at the same rate because they overheated by the same amount.

You have a cube of modeling clay in your hands. Which of the following changes to the shape of this cube of clay will decrease its surface area relative to its volume?

• A) Pinch the edges of the cube into small folds.

• B) Flatten the cube into a pancake shape.

• C) Round the clay up into a sphere.

• D) Stretch the cube into a long, shoebox shape.

The metabolic rate of an animal is most accurately determined by ________.

• A) the amount of work done by an animal

• B) the amount of food consumed during a meal

• C) the amount of carbon dioxide produced by an animal in a given time.

• D) the amount of energy used by an animal in a given time

The migratory eel, Anguilla rostrata, is born and lives the juvenile (immature) part of its life in a freshwater environment, but then migrates thousands of miles through the ocean as an adult in order to breed. These eels are known to regulate their internal water and salt balance. What adaptations would you expect this eel to have in order to transition from fresh water to salt water at these two life stages?

• A) The juvenile eels would be better at removing salt from their bodies compared to adults.

• B) The adult eels would be better at removing salt from their bodies compared to juveniles.

• C) The juvenile eels would spend energy keeping water in their bodies.

• D) The adult eels would spend energy keeping salt in their bodies.

The metamorphosis of a tadpole to an adult frog involves a thorough reconstruction of the animal's body. All of the structural and physiological changes must be complete or the frog will not survive this transformation. Which type of regulation would ensure that the animal completed its transformation?

• A) positive feedback

• B) negative feedback

• C) feedback inhibition

• D) enzymatic catalysis

When the body's blood glucose level rises, the pancreas secretes insulin and, as a result, the blood glucose level declines. When the blood glucose level is low, the pancreas secretes glucagon and, as a result, the blood glucose level rises. Such regulation of the blood glucose level is the result of ________.

• A) catalytic feedback

• B) positive feedback

• C) negative feedback

• D) protein-protein interactions

The body's automatic tendency to maintain a constant and optimal internal environment is termed as ________.

• A) balanced equilibrium

• B) physiological chance

• C) homeostasis

• D) static equilibrium

An example of a properly functioning homeostatic control system is seen when ________.

• A) the core body temperature of a runner rises gradually from 37°C to 45°C

• B) the kidneys excrete salt into the urine when dietary salt levels rise

• C) a blood cell shrinks when placed in a solution of salt and water

• D) the blood pressure increases in response to an increase in blood volume

If a person were to travel to a time zone that was several hours ahead of their own, they may experience tiredness known as jet lag. Jet lag is due to a disruption of ________.

• A) homeostasis

• B) circadian rhythm

• C) body temperature

• D) nerve impulses

What would be an advantage for an animal that conforms to a changing environmental condition, such as temperature?

• A) The animal's internal temperature would remain constant, even though the external temperature had changed.

• B) The animal's internal temperature would change opposite to the change in the external temperature.

• C) The animal would spend more time looking for food.

• D) The animal would spend less energy regulating its internal temperature.

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) conformation

• B) regulation

• C) integration

• D) assimilation

Chum salmon (Oncorhynchus keta) are born in freshwater environments and then migrate to the sea. Near the end of their lives, they return to the freshwater stream where they were born to spawn. In fresh water, water constantly diffuses into the body and ions are lost from the body. In salt water, body water diffuses out of the body and excess ions are gained from the water. A salmon's gills have special cells to pump salt in or out of the body to maintain homeostasis. In response to the salmon's moves between fresh water and salt water, some cells in the gills are produced and others are destroyed. These changes made in the cells of the gills during the lifetime of an individual salmon are an example of which of the following?