Biology 2 Exam #4

A student wrote in an exam, "jawless fishes (hagfishes and lampreys) are the ancestor of gnathostomes." Why was that answer incorrect?

Ancestors, in the sense that biologists use the term, are hypothetical species, not actual species, living or fossil. CorrectThis answer is correct. The ancestor in the biological sense is the hypothetical species represented by a node in a cladogram.

Tapeworms are internal parasitic worms that lack organs and segmentation. In which group are they classified?

Annelida IncorrectThis answer is incorrect because most annelids are segmented, and most parasitic annelids are ectoparasites. Mollusca -None of the answers are correct.

What is the difference between homosporous and heterosporous plants?

Homosporous plants produce only a single type of spore as a result of meiosis; heterosporous plants produce two types of spores as a result of meiosis. CorrectThis answer is correct because homosporous plants produce only a single type of spore as a result of meiosis, while heterosporous plants produce two types of spores as a result of meiosis.

The embryo of a particular animal has three germ layers. What else about this animal must be true?

It belongs to Bilateria. CorrectThis answer choice is correct. Bilateria contains all the animals with the third germ layer, mesoderm, in their embryos.

A student is helping his advisor classify a fossil that resembles a fish. The student incorrectly concludes that the fossil is an agnathan and not a gnathostome. The advisor points out the feature(s) that show(s) that the student misclassified the fossil. What feature(s) did the advisor point out to the student?

It has jaws. CorrectThis answer is correct because the fossil has jaws and therefore is not an agnathan.

In zygomycotes, gametangia fuse, and a zygosporangium develops. Which of the following is a characteristic of the zygosporangium?

It is heterokaryotic. CorrectThis answer is correct because the zygosporangium contains genetically distinct haploid nuclei.

Which animal has bilateral symmetry?

acoel flatworm CorrectThis answer is correct because Acoela belongs to clade Bilateria.

Complete the following sentence: The ancestral bilaterian was most likely...

acoelomate. CorrectThis answer choice is correct. The simplest bilaterians are true acoelomate flatworms that probably resemble the last common ancestor of all Bilateria.

What group of fungi are known for producing many different kinds of conidia?

ascomycotes CorrectThis answer is correct because ascomycotes produce conidia, or spores, during asexual reproduction.

Which of the following is not part of the moss gametophyte?

capsule CorrectThis answer is correct because the capsule is a part of the sporophyte generation; it contains the sporangium tissue that will produce the spores of the next gametophyte generation.

Which human pathogen closely related to fungi (or thought to possibly be a fungus) is responsible for causing a greater number of infections in AIDS patients?

microsporidia CorrectThis answer choice is correct because these organisms invade the tissues of AIDS patients.

Which of the following is a characteristic of a nonvascular plant?

photosynthetic structures CorrectThis answer is correct because all plants are photosynthetic.

A scientist is conducting embryological studies on a new species of invertebrate. She notices that it has spiral cleavage and a blastopore that develops into a mouth. How does she classify the new species?

protostome CorrectThis choice is correct because protostome embryos divide by spiral cleavage and have a blastopore that develops into a mouth.

How many legs does an insect have?

six CorrectThis answer is correct because all insects have six legs arranged in three pairs, hence the clade name Hexapoda.

Which characteristic cannot be associated with budding?

spore production CorrectThis answer is correct because during budding, spores are not produced.

Which stage of the plant life cycle is the dominant phase of seed plants?

sporophyte CorrectThis answer is correct because in seed plants as well as in ferns, the sporophyte, or spore-forming generation, is the most easily visible stage of the life cycle.

During what phase of its life cycle does a seedless vascular plant spend most of its life?

sporophyte CorrectThis answer is correct because, unlike nonvascular plants, vascular plants spend most of their time in the sporophyte stage.

What direct benefit does a plant provide to a fungus when they are in a mutualistic relationship?

the provision of nutrients CorrectThis answer is correct because photosynthetic plants provide nutrients to their symbiotic fungi.

In which stage of its life cycle does a scyphozoan sea jelly have sex?

the swimming medusa stage CorrectThis answer is correct since the medusa stage produces gametes by meiosis.

What is the main function of mycelia in fungi?

to increase the surface area for absorption of nutrients and moisture CorrectThis answer is correct because mycelia increase the absorptive surface area of fungi, making the process of absorption much more efficient.

Which of the following trees is NOT an example of a seed plant?

tree fern CorrectThis answer is correct because the tree fern is a vascular plant that does not produce seeds.

Complete the following sentence: Insects that are characterized by holometabolous development...

undergo complete metamorphosis, which includes a pupal stage. CorrectThis answer is correct because insects that undergo complete metamorphosis, which includes a pupal stage, are termed holometabolous.

Which characteristic can be used to determine whether a newly discovered species is a protostome or deuterostome?

whether the initial embryonic opening becomes the mouth or the anus CorrectThis answer is correct because development of the gut proceeds differently in protostomes and deuterostomes.

Which of the following steps during ecdysis takes the longest in a winged insect such as a dragonfly, Aeshna cyanea?

wing expansion CorrectThis answer is correct because Aeshna cyanea wing expansion takes about 2.5 minutes to complete during ecdysis.

Which is a deuterostome?

you CorrectThis answer choice is correct. Vertebrates (including humans) belong to phylum Chordata, one of the few phyla included in clade Deuterostomia.

Which characteristic is true about basidiocarps?

They can grow extremely quickly. CorrectThis answer choice is correct because basidiocarps can develop in a matter of hours.

How were the earliest seed plants different from modern seed plants?

They formed seeds in small cup-like structures on their leaves. CorrectThis answer is correct because the earliest known seed plants had seeds contained in cupules along their fern-like leaves.

Complete the following sentence: Fungal mycelia growth is the result of...

an increase in the length of hyphae. CorrectThis answer is correct because increase in the length of hyphae results in fungal growth.

Which group of fungi do scientists think branched off first in the evolution of fungi?

chytridiomycotes CorrectThis answer choice is correct because scientists found evidence distinguishing these earlier fungi from the others.

What is the defining feature of cnidarians?

cnidocytes CorrectThis answer is correct because cnidarians are named for the specialized stinging cells that characterize this phylum.

Which of the following may be a contributing factor to a yeast infection?

compromised immune function CorrectThis answer choice is correct because when the immune system is compromised, Candida albicans can become pathogenic, grow unchecked, and create a yeast infection.

What benefits to humans can fungi provide?

culinary uses pesticides brewing medicinal uses All answers are correct. CorrectThis answer choice is correct because fungi are beneficial to humans in many ways.

Which of the following structures did the ancestor of all fungi have despite being lost in many species?

flagella CorrectThis answer choice is correct because the common ancestor of all fungi had a flagellum.

Complete the following sentence: The majority of the biomass in the deepest parts of the ocean is from...

holothurian echinoderms. CorrectThis answer is correct because sea cucumbers can be the most abundant organisms at abyssal depths.

Which of the following is most closely related to a spider?

horseshoe crab CorrectThis answer is correct because horseshoe crabs are chelicerates and are therefore the closet relative of spiders out of the listed options.

Complete the following sentence: Most fungal biomass exists as a long, thin filamentous structure called a...

hypha(e). CorrectThis answer is correct because multicellular fungi have developed networks of filaments called hyphae.

After which process or stage does a zygote form in a fungus?

karyogamy CorrectThis answer is correct because during karyogamy two nuclei fuse, forming a zygote.

Complete the following sentence: All invertebrates...

lack a notochord. CorrectThis answer choice is correct because the absence of a notochord is the definitive characteristic of invertebrates.

About how many species of insects are there on the planet?

likely between two and four million CorrectThis answer is correct because statistical modeling studies suggest this is the number of insect species that probably exist; most, however, have not yet been named.

Endoderm develops into what part of an adult bilaterian?

lining of the digestive system CorrectThis answer choice is correct. The endoderm layer of embryonic tissue develops into the adult tissues involved in food processing.

How do microphylls differ from megaphylls?

Each microphyll has only a single vascular strand, while megaphylls have more than one vascular strand. CorrectThis answer is correct because microphylls and megaphylls are two types of leaves that evolved independently; microphylls each have a single strand of vascular tissue, while megaphylls have more than one strand of vascular tissue. (Interestingly, megaphylls are thought to have evolved independently in at least three evolutionary lineages.)

Which of the following characteristics are cited as evidence for the evolutionary relationship between plants and charophytes?

sporopollenin-coated spores or zygotes and rings of cellulose-producing proteins CorrectThis answer is correct because these characteristics are both cited as evidence for the evolutionary relationship between green algae and plants.

Approximately how many species of extant amniotes are there?

25,000 CorrectThis answer choice is correct; the extant amniotes include approximately 5,000 species of mammals, 10,000 species of non-avian reptiles, and 10,000 species of birds.

How can mutations in transcription factor genes lead to differences in the body form and physiology of adults?

A mutant transcription factor gene could cause a structural gene to be expressed earlier than normal during embryonic development. A mutant transcription factor gene could cause a structural gene to be expressed later than normal during embryonic development. A mutant transcription factor gene could cause a structural gene to be expressed more strongly than normal during embryonic development. A mutant transcription factor gene could cause a structural gene to be expressed less strongly than normal during embryonic development. All of the answer choices are correct. CorrectThis answer is correct because all of the choices identify ways in which a transcription factor mutation could lead to changes in body forms and physiology; changing the time a gene is expressed during embryonic development or how strongly it is expressed (i.e., how much of the gene product is synthesized) will change the properties of the structure or process it controls.

Mosses have a thin cuticle that offers very little protection against dehydration. Why is this a beneficial trait for the moss?

A thin cuticle allows mosses to absorb moisture from their environment. CorrectThis answer is correct because mosses need to absorb moisture directly from the environment due to their lack of vascular tissues, which in vascular plants transport water over long distances.

Which statement correctly describes when a fungal spore will germinate after release?

After landing, environmental conditions must be adequate for germination to occur. CorrectThis answer is correct because spores will not germinate if there is not enough moisture or light or a warm enough temperature.

The amniotic egg is often called the "land egg" because from an evolutionary perspective the evolution of the amniotic egg freed amniotes from breeding in water. Many species of frogs lay eggs on land, however, and have no tadpole stage; instead, miniature frogs hatch from the eggs. Why are these species of frogs not considered to be amniotes?

Amniotic eggs have membranes that are derived from the embryo (the amnion is one of these membranes), and frog eggs lack these membranes. CorrectThis answer choice is correct. Amniotes are vertebrates with eggs that include an amnion as well as two other extra-embryonic membranes, the chorion and allantois.

Which of the following correctly describes how invertebrates move?

Arthropods, including insects, use jointed legs to walk. Some worms use wave-like contractions of muscles on alternate sides of the body to push against the fluid-filled coelom to move the animal forward. Bivalves use a muscular foot to burrow into sand. Cephalopods such as cuttlefish use fins for swimming. All answers are correct. CorrectThis answer choice is correct because each of the answer choices is a correct description of how invertebrates move.

Radial symmetry is characteristic of which phylum?

Cnidaria CorrectThis answer is correct because Cnidaria are Radiata.

Which of the following clades was recognized as part of the animal tree of life as a result of molecular studies that analyzed DNA sequences?

Ecdysozoa CorrectThis answer choice is correct. Ecdysozoa is a clade including animals that molt. This clade was recognized as a result of molecular studies involving ribosomal genes, establishing that molting organisms like arthropods and nematodes were closely related.

Which is characteristic of protostome embryos?

Embryonic cleavage is spiral. CorrectThis answer is correct because most protostomes are characterized by spiral cleavage.

What benefit do endophytes provide for their plant hosts?

Endophytes repel herbivorous insects. CorrectThis answer is correct because endophytes can either produce or induce the plant to produce a chemical that repels feeding insects.

Which of the following characteristics is common to all fungi?

Fungi use extracellular digestion to break down food molecules. CorrectThis answer is correct because fungi secrete extracellular digestive enzymes to chemically break down their food sources into a form they can absorb.

Why is our understanding of the tree of life constantly changing?

Improvements in the tools scientists use to determine phylogenetic relationships lead to the modification of old models. CorrectThis answer is correct because new data allow scientists to improve their understanding of the path of evolution.

Which of the following correctly distinguishes the embryological development of protostomes and deuterostomes?

In deuterostomes, the coelom develops from folds of mesoderm. In protostomes, the mesoderm splits away to form the coelom. CorrectThis choice is correct because in deuterostomes, the coelom develops from folds of mesoderm. In protostomes, the mesoderm splits away to form the coelom.

Why wouldn't a scientist automatically place a photosynthetic organism into the same clade as land plants?

Photosynthesis occurs in many other organisms. CorrectThis answer is correct because photosynthesis is a characteristic widely distributed across the tree of life.

Which of the following correctly describes the role of prothoracicotropic hormone (PTTH) in metamorphosis?

Pupation fails to occur following removal of neurosecretory cells in the brain that secrete PTTH. CorrectThis answer is correct because neurosecretory cells in the brain secrete PTTH that stimulates prothoracic glands, which in turn release ecdysteroid hormones, which initiate molting and metamorphosis. Their removal prevents pupation.

Complete the following sentence: Most species are microscopic and possess well-developed organs in the protostome phylum...

Rotifera. CorrectThis answer is correct because rotifers are multicellular animals with organ systems yet are smaller than most protists.

What is the significant economic role played by seedless vascular plants in many societies?

Seedless vascular plants form the bulk of coal deposits, which can be used to generate power. CorrectThis answer is correct because most coal deposits were formed primarily by seedless vascular plants. Coal is of major economic importance because it can be used to generate power.

What feature of spike mosses prevents them from being classified as a true moss?

Spike moss sporophytes contain true vascular tissue; true mosses are nonvascular plants that do not contain vascular tissue. CorrectThis answer is correct because spike moss sporophytes contain true vascular tissue; true mosses are nonvascular plants that do not contain vascular tissue.

Brachiopods were traditionally thought to be deuterostomes because of their embryonic cleavage, but DNA sequencing studies revealed they were actually protostomes. How can these developmental and molecular studies be reconciled?

The ancestral bilaterian must have had deuterostome-like development, which was inherited unchanged by the modern deuterostomes and the brachipods, but changed somewhere in the history of other protostomes. CorrectThis answer choice is correct. Ancestral traits can be inherited unchanged by distant relatives, and this is the simplest explanation for why some protostomes have deuterostome-like embryonic traits: all bilaterians started out with deuterostome-like development, and only a subset of protostomes evolved a different form of development.

What happens if the corpora allata, two endocrine glands in the brain, are removed from a larval insect?

The larva will pupate at its next molt, resulting in a miniature adult. CorrectThis answer is correct because the corpora allata secrete juvenile hormone; therefore, removing them allows ecdysone to initiate pupation.

Which of the following can happen after a spore is released?

The spore can germinate into new mycelia. The spore can become inactive. The spore can travel through the air or water. The spore can be transported to a new area on other organisms. All answers are correct. CorrectThis answer is correct because all of the choices describe something a spore can do.

Complete the following sentence: The deuterostome clade with the most species is...

Vertebrata. CorrectThis answer is correct because there are over 60,000 species of vertebrates.

Complete the following sentence: We can tell that plants are closely related to charophyte algae because they share...

a similar peroxisome composition. CorrectThis answer is correct because peroxisome composition is evidence of an evolutionary relationship between charophytes and plants.

Which of the following services does a plant provide to a fungus when they form a mutualism?

a source of carbohydrates CorrectThis answer is correct because photosynthetic plants provide mutualistic fungi with a steady source of carbohydrates. Free-living fungi must obtain energy from organic molecules by external digestion and absorption.

Which feature is a characteristic shared by all groups of molluscs?

a three-part body plan CorrectThis answer is correct because all molluscan body plans are variations on the same basic three-part body plan.

Considering only the cells involved in sexual reproduction, at what point during the sexual reproductive cycle can asexual reproduction occur?

after spore release CorrectThis answer is correct because once a spore is released, it can enter either type of cycle.

Many marine invertebrates, including barnacles (from phylum Arthropoda), tube worms (phylum Annelida), and crinoids (phylum Echinodermata), have appendages like pasta strainers that are used to filter feed. Such filter-feeding appendages are ___.

analogous traits CorrectThis answer choice is correct. Since these three phyla are distantly related, filter feeding must have independently evolved in each group as an adaptation to catching plentiful food out of the surrounding water.

Which statement best describes the Radiata?

animals with body patterns that repeat around a central axis CorrectThis answer is correct because Radiata have planes of symmetry that intersect a central axis.

Which functional role of fungi best describes their ability to release mineral nutrients into an ecosystem for uptake by other organisms?

as decomposers CorrectThis answer is correct because as decomposers, fungi provide a service to ecosystems by releasing carbon and other minerals, making them available for uptake by other organisms.

Which order of structures and events correctly reflects the asexual life cycle of an ascomycote?

ascocarp → haploid spores → asexual reproduction CorrectThis answer choice is correct because ascocarps do form diploid cells that undergo meiosis to produce haploid spores; these spores develop and reproduce asexually to form conidia.

Which biogeochemical cycle is most directly influenced by the saprophytic action of fungi on cellulose and lignin?

carbon cycle CorrectThis answer is correct because fungi help convert complex forms of carbon (e.g., cellulose) into simpler forms such as glucose and carbon dioxide.

Which of the following groups of non-plant organisms is most closely related to plants?

charophyte algae CorrectThis answer is correct because the charophytes are a group within the green algae (which themselves are algae and protists) that are most closely related to plants.

Which nitrogen-containing compound is found in both fungal cell walls and arthropod exoskeletons?

chitin CorrectThis answer is correct because chitin is the nitrogenous compound that is found in the cell walls of fungi and arthropod exoskeletons.

Which group of plants belongs to the oldest lineage of extant seed plants?

cycads CorrectThis answer is correct because cycads are a clade in the oldest lineage of extant seed plants called gymnosperms.

Which characteristic is NOT shared by plants and both groups of green algae?

cytokinesis via a phragmoplast CorrectThis answer is correct because, while all plant cells divide via a phragmoplast, only the charophyte group within the green algae divides via a phragmoplast.

Complete the following sentence: An animal that is radially symmetric with a coelom must be a(n)...

echinoderm. CorrectThis answer choice is correct. Echinoderms are radially symmetric as adults, and possess a coelom used in movement.

A scientist studying a fossil identifies it as a cephalochordate, but his colleagues disagree with the identification. What feature of the fossil could have caused the scientist's colleagues to disagree with him?

endoskeleton CorrectThis choice is correct because cephalochordates do not have an endoskeleton.

Complete the following sentence: Animals can be distinguished from other eukaryotes because they...

exhibit all of the traits listed in the other answer choices. CorrectThis answer choice is correct. Animals are the multicellular, heterotrophic eukaryotes that are not bound by cell walls and are capable of movement at some point in their life cycle (for many marine animals, when they are swimming larvae).

Which of the following are features of the arthropod body plan?

exoskeleton, cephalization, segmentation CorrectThis answer is correct because the arthropod body plan is characterized by an exoskeleton, cephalization, bilateral symmetry, the presence of a coelom, and segmentation.

Which of the following groups include(s) species that show parental care for their young?

fishes amphibians non-avian reptiles mammals and birds All answers are correct. CorrectThis answer is correct because all of the groups listed in all the other answers include species that show parental care for their young.

What morphological feature of chytrid fungi supports their early divergence within the fungal clade?

flagella CorrectThis answer choice is correct because opisthokonts are thought to have a unicellular, flagellated ancestor.

Complete the following sentence: Mycorrhizae are mutualisms between...

fungi and plant roots. CorrectThis answer is correct because mycorrhizae (fungal-root) are mutualisms between fungi and plant roots.

Which of the following does NOT occur during plasmogamy?

fusion of nuclei CorrectThis answer is correct because during plasmogamy only the cytoplasm of two cells combine, not the nuclei.

What life cycle phase dominates the life of a nonvascular plant?

gametophyte CorrectThis answer is correct because bryophytes have a gametophyte-dominant life cycle.

Complete the following sentence: A limitation of the flatworm body plan is...

gas exchange occurs by diffusion. CorrectThis answer choice is correct. Flatworms are limited to thin bodies and live in aquatic or wet environments where diffusion allows enough gas exchange.

After receiving a pheromone signal from an alternate mating type, what does the recipient fungi do?

grow hyphae toward the signal source CorrectThis answer is correct because once the pheromone binds to the receptor, the fungus begins to grow toward the signal source.

Complete the following sentence: The last common ancestor of bony fishes and tetrapods possessed...

lungs. CorrectThis answer is correct because the ancestral lung evolved into a swim bladder in bony fishes but stayed a lung in other fish lineages and tetrapods.

Which characteristic is shown by coenocytic fungi but not by other types of fungi?

multiple nuclei within a cell membrane CorrectThis answer is correct because coenocytic fungi have hyphae that lack septa and consist of a cytoplasmic mass with hundreds or even thousands of nuclei.

Which of the following terms refers to a fungal infection of an animal, such as athlete's foot?

mycosis CorrectThis answer is correct because an infection of a human caused by a fungus, or fungal parasite, is called mycosis.

Which group does NOT share the Opisthokonta clade with fungi?

plants CorrectThis answer choice is correct because despite resembling each other physically in some cases, plants and fungi do not share the same ancestor of this clade.

Which order of events is correct for the sexual reproduction cycle in most fungi?

plasmogamy → karyogamy → meiosis CorrectThis answer is correct because this order reflects the sexual reproductive cycle, which ends with meiosis followed by spore production.

What feature would you find in an adult tunicate?

post-anal tail pharyngeal gill slits notochord All answers are correct. IncorrectThis answer is incorrect because only one choice is found in adult tunicates. None of the answers are correct.

What is the purpose of the integuments in a seed plant?

protecting the embryo from environmental influences CorrectThis answer is correct because integuments are the layers of tissue that surround female gametophytes and protect them from drying out and other environmental stresses.

What are the two major lineages of Bilateria?

protostomes and deuterostomes CorrectThis answer is correct because the Bilateria split into protostomes and deuterostomes early in the evolution of the mesoderm.

What aspect of reproduction and development would a scientist examine most closely to classify an animal as a deuterostome?

role of the blastopore after gastrulation CorrectThis answer choice is correct. After gastrulation, the blastopore and the second opening have formed. If the blastopore becomes the anus, the animal is a deuterosome; if the blastopore functions as the embryonic mouth, the animal is a protostome.

What is the defining feature of Ctenophora?

rows of fused cilia used for locomotion CorrectThis answer is correct because ctenophores are named for their comblike rows of cilia used for locomotion.

A researcher finds a floating embryo in a plankton sample with no trace of mesoderm. It develops into a larva that metamorphoses into an adult with an incomplete digestive system. When the researcher sequences its DNA, he expects to find that this organism is a(n) ___.

sea anemone CorrectThis answer choice is correct. Embryos of cnidarians like sea anemones lack mesoderm, and the adults have a GVC with no anus.

You find a free-floating embryo in a plankton sample and observe that the cells do not rotate relative to one another during development, but rather the top cells are stacked directly above the cells beneath them. Which type of animal might this embryo belong to?

sea star CorrectThis answer is correct because sea stars are deuterostomes and exhibit radial cleavage as observed for this embryo.