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Knowledge Check: Unit 5 — Chapters 21–29

Knowledge Check: Unit 5 — Chapters 21–29

Test yourself on Unit 5: Biological Diversity (Chapters 21–29). Every question below was written from the chapters’ own text — their summaries, key terms, explanations, and tables — and none repeats a question from the section pages. There are no hints: treat it like a test. Questions are grouped by the section they come from, so a miss tells you exactly which section to review.

Chapter 21: Viruses

21.1 Viral Evolution, Morphology, and Classification

Newly discovered viruses hosted by which organisms can reach up to about 1000 nanometers in diameter, far larger than a typical virion?

The protein subunit that makes up a viral capsid is called a ________.

Why can’t the methods scientists use to classify prokaryotic and eukaryotic cells by shared genomic sequence, such as 16S rRNA analysis, be applied to classify most viruses by common ancestry?

Show model answer
Because most viruses probably evolved from different ancestors, viruses have no common genomic sequence that they all share. For example, the 16S rRNA sequence so useful for constructing prokaryote phylogenies is of no use for a creature with no ribosomes.

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21.2 Virus Infections and Hosts

The bacteriophage T4, which infects Escherichia coli in the human intestinal tract, is an example of a phage with which kind of replication cycle?

Dramatic biochemical and structural changes that a virus’s replication cycle produces in a host cell, sometimes destroying it, are called ________ effects.

What are the two ways an enveloped virus can enter a host cell after binding to its receptor, and which of the two is used only by enveloped virions?

Show model answer
Enveloped viruses have two ways of entering cells after binding to their receptors: receptor-mediated endocytosis, or fusion. Fusion only occurs with enveloped virions, which use special fusion proteins in their envelopes to cause the envelope to fuse with the plasma membrane of the cell, releasing the genome and capsid of the virus into the cell cytoplasm.

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21.3 Prevention and Treatment of Viral Infections

Which viral enzyme does Tamiflu (oseltamivir) inhibit to block new influenza virions from leaving their infected host cells?

The ‘drug cocktail’ combination approach that attacks HIV at multiple stages of its replicative cycle at once, so the virus cannot develop resistance to every drug simultaneously, is known by the acronym ________.

Why must the molecular targets of an antiviral drug be proteins encoded by viral genes, rather than molecules already present in a healthy host cell?

Show model answer
Because viruses use the resources of the host cell for replication and the production of new virus proteins, it is difficult to block their activities without damaging the host. It is important that the targeted proteins be encoded by viral genes and that these molecules are not present in a healthy host cell. In this way, viral growth is inhibited without damaging the host.

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21.4 Other Acellular Entities: Prions and Viroids

Which prion disease, native to humans in Papua New Guinea, was historically spread from person to person through ritualistic cannibalism?

Bovine spongiform encephalopathy (BSE), first detected in the United Kingdom, was spread between cattle by which practice?

How does a single PrPsc molecule introduced into the body lead to an exponential increase of the infectious prion protein?

Show model answer
Once introduced into the body, the PrPsc contained within the prion binds to PrPc and converts it to PrPsc. This leads to an exponential increase of the PrPsc protein, which aggregates.

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Chapter 22: Prokaryotes: Bacteria and Archaea

22.1 Prokaryotic Diversity

Autotrophic organisms that convert solar energy into chemical energy, and that appeared within one billion years of Earth’s formation, are called ________.

An organism that grows in a high sugar concentration is called a(n) ________.

What are Koch’s postulates, and what two criteria do they set for identifying an organism as the cause of a disease?

Show model answer
Koch’s postulates are guidelines developed by Robert Koch to identify the organisms responsible for specific diseases. They state that an organism can be identified as the cause of disease when it is present in all infected samples and absent in all healthy samples, and when it is able to reproduce the infection after being cultured multiple times.

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22.2 Structure of Prokaryotes: Bacteria and Archaea

According to the principle of the molecular clock, how does the similarity of two species’ genes and proteins relate to how recently those species diverged?

Show model answer
According to the molecular clock, the more recently two species have diverged, the more similar their genes and proteins will be; species that diverged long ago will have more genes that are dissimilar.

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Which term describes a prokaryotic cell with a spiral shape?

An ancestor of modern Archaea is believed to have given rise to which other domain of life?

22.3 Prokaryotic Metabolism

Of the total nitrogen that prokaryotes release into the atmosphere, what percentage returns as ammonia, with the remainder returning as N₂ and N₂O?

Which organisms are the primary producers of organic carbon compounds from carbon dioxide?

In anoxic aquatic sediments, how is the methane that archaea produce ultimately converted back into carbon dioxide before it can escape into the atmosphere as methane?

Show model answer
In anoxic sediments, prokaryotes, mostly archaea, produce methane. This methane moves into the zone above the sediment, which is richer in oxygen, and supports bacteria called methane oxidizers that oxidize the methane to carbon dioxide, which then returns to the atmosphere.

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22.4 Bacterial Diseases in Humans

What percentage of Native Americans is estimated to have died from infectious diseases introduced by European conquerors?

A disease that primarily infects animals but can be transmitted to humans is called a ________.

Once a biofilm infection is established in the body, why is it especially difficult to eradicate with antibiotics?

Show model answer
Biofilms tend to be resistant to most methods used to control microbial growth, including antibiotics, because the matrix that attaches the cells to a substrate and to one another protects the cells from antibiotics or drugs. Because biofilms also grow slowly, they are less responsive to agents that interfere with cell growth, and they can resist up to 1,000 times the antibiotic concentrations used to kill the same bacteria when they are free-living.

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22.5 Beneficial Prokaryotes

Nitrogenase, the enzyme that fixes nitrogen, is inactivated by oxygen. How does a root nodule allow nitrogen fixation to take place without starving the bacteria of the oxygen they need for respiration?

Show model answer
The nodule provides an oxygen-free area for nitrogen fixation to take place. The oxygen is sequestered by a form of plant hemoglobin called leghemoglobin, which protects the nitrogenase but releases enough oxygen to support respiratory activity.

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Several species of bacteria can carry out the biotransformation of which toxic metal, an active ingredient of some pesticides and a by-product of battery production, into nontoxic forms?

What treatment has successfully reestablished a healthy gut microbial community in patients with severe diarrhea from a Clostridium difficile overgrowth after high-dose antibiotics?

Chapter 23: Protists

23.1 Eukaryotic Origins

Which process of nuclear division, in which replicated chromosomes are divided and separated using elements of the cytoskeleton, is universally present in eukaryotes?

In the 1960s, American biologist ________ of Boston University developed the endosymbiotic theory, later introducing new data in 1967 to support it.

What evidence from the mitochondrion’s own membrane structure supports the idea that mitochondria arose through endosymbiosis?

Show model answer
Most mitochondria are shaped like alpha-proteobacteria and are surrounded by two membranes; the inner membrane is bacterial in nature, and the outer membrane is eukaryotic in nature. The outer mitochondrial membrane was derived from the enclosing vesicle, while the inner membrane was derived from the plasma membrane of the endosymbiont.

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23.2 Characteristics of Protists

Protists that ingest food particles by engulfing them with the cell membrane and pinching off an intracellular vesicle are using a process called ________.

Movement toward light, achieved by coupling a protist’s locomotion strategy with a light-sensing organ, is called ________.

How can protists exhibit complex cellular organization even though most of them are unicellular?

Show model answer
A few protists live as colonies that behave in some ways as a group of free-living cells and in other ways as a multicellular organism. Some protists are composed of enormous, multinucleate, single cells that look like amorphous blobs of slime, or in other cases, like ferns. In some species of protists, the nuclei are different sizes and have distinct roles in protist cell function.

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23.3 Groups of Protists

Which giant, multinucleate amoeba has lost its mitochondria but replaced them with bacterial endosymbionts?

A small group of parasites, primarily of fish, once grouped with fungi but now thought to be closely related to animals, are called the ________.

How does the sinking of dead rhizarians’ tests contribute to the biological carbon pump that helps regulate atmospheric carbon dioxide?

Show model answer
When rhizarians die and their tests sink into deep water, the carbonates are out of reach of most decomposers, locking carbon dioxide away from the atmosphere. This process, by which carbon is transported deep into the ocean, is described as the biological carbon pump, because carbon is pumped to the ocean depths where it is inaccessible to the atmosphere as carbon dioxide.

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23.4 Ecology of Protists

The oomycete disease that causes discolored, withered grape leaves and nearly collapsed the French wine industry in the nineteenth century is called ________.

Widespread late blight caused by Phytophthora infestans precipitated which nineteenth-century catastrophe?

Why are saprobic protists essential to keeping organic carbon cycling through an ecosystem?

Show model answer
Saprobic protists have the essential function of returning inorganic nutrients to the soil and water. This process allows for new plant growth, which in turn generates sustenance for other organisms along the food chain. Without saprobe species, such as protists, fungi, and bacteria, life would cease to exist as all organic carbon became tied up in dead organisms.

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Chapter 24: Fungi

24.1 Characteristics of Fungi

Pigments associated with the fungal cell wall play a protective role against ________ radiation.

Fungi that only perform anaerobic respiration and often cannot survive in the presence of oxygen are called ________.

Why did scientists historically classify fungi as plants, and what does molecular evidence now show about their true evolutionary relationships?

Show model answer
Until recently, many scientists classified fungi as plants, since fungi, like plants, are mostly sessile and seemingly rooted in place and possess a stem-like structure as well as a root-like fungal mycelium in the soil. However, molecular biology analysis of the fungal genome demonstrates that fungi are more closely related to animals than plants.

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24.2 Classifications of Fungi

Which fungal phylum is the only one whose members have retained flagella, producing both flagellated gametes and diploid zoospores?

The fruiting body of an ascomycete, formed by the growth of many hyphae, is called a(n) ________.

Describe how sexual reproduction proceeds in the zygomycetes, from the fusion of compatible mating strains to the formation of new haploid spores.

Show model answer
Two opposing mating strains must be in close proximity for gametangia from the hyphae to be produced and fuse, leading to karyogamy. The developing diploid zygospores have thick coats that protect them from desiccation and other hazards, and they may remain dormant until environmental conditions are favorable. When the zygospore germinates, it undergoes meiosis and produces haploid spores, which grow into a new organism.

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24.3 Ecology of Fungi

Most members of the kingdom Fungi grow in which environment, rich in decaying plant and animal debris?

In an endomycorrhizal association, the branched structure that forms when fungal hyphae grow inside a plant root cell is called a ________.

Explain why some fungi, such as the fungus that produces black truffles, depend on being eaten by an animal to disperse their spores.

Show model answer
Animal dispersal is important for some fungi because an animal may carry fungal spores considerable distances from the source. Fungal spores are rarely completely degraded in the gastrointestinal tract of an animal, and many are able to germinate when they are passed in the feces. The black truffle is the fruiting body of an underground ascomycete, and animals eat truffles and disperse the spores.

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24.4 Fungal Parasites and Pathogens

Which fungal disease of cereal crops, especially rye, produces alkaloid toxins whose active ingredient is a precursor of the drug LSD?

The protein found in hair, skin, and nails that dermatophyte enzymes break down, causing conditions such as athlete’s foot and jock itch, is called ________.

Explain what an opportunistic mycosis is, and describe how the yeast Candida can cause one when conditions in the body change.

Show model answer
Opportunistic mycoses are fungal infections that are either common in all environments or part of the normal biota, and they mainly affect individuals who have a compromised immune system. The yeast Candida sp., a common member of the natural biota, can grow unchecked and infect the vagina or mouth if the pH of the surrounding environment, the person’s immune defenses, or the normal population of bacteria are altered.

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24.5 Importance of Fungi in Human Life

Louis Pasteur’s development of a reliable strain of Saccharomyces cerevisiae for the French brewing industry in the 1850s was an early example of what?

Molds of which genus ripen many cheeses, including the wheels stacked in the caves of Roquefort, France, to capture the molds responsible for their blue veins?

Explain why fungal insecticides such as Beauveria bassiana pose little risk to animals and plants other than their target insect pest.

Show model answer
Fungal insecticides such as Beauveria bassiana are very specific to the insects they attack, and do not infect other animals or plants. Fungi are currently under investigation as potential microbial insecticides, with several already on the market.

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Chapter 25: Seedless Plants

25.1 Early Plant Life

What term describes a plant that produces two different sizes of spores — the smaller microspores and the larger megaspores?

In a life cycle where the diploid stage is dominant and the only haploid cells are the gametes, the cycle is described as ________.

In the vascular tissue of land plants, what does xylem transport, and what does phloem transport?

Show model answer
Xylem conducts water and minerals absorbed from the soil up to the shoot, while phloem transports food derived from photosynthesis throughout the entire plant.

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25.2 Green Algae: Precursors of Land Plants

Both Chlamydomonas and Ulva produce flagellated gametes. What additionally happens in the multicellular Ulva, but not in the single-celled Chlamydomonas, after fertilization?

The protist supergroup that now includes the brown and golden algae, once classified with the green algae in the kingdom Plantae, is called ________.

What has recent DNA sequence analysis of the charophytes shown about which order is most closely related to the embryophytes?

Show model answer
Recent extensive DNA sequence analysis of charophytes indicates that the Zygnematales are more closely related to the embryophytes than the Charales or the Coleochaetales.

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25.3 Bryophytes

In hornworts, thin branched cells called ________ surround the spores and help propel them farther into the environment.

Liverworts reproduce asexually by spreading small, complete pieces of plant called ________, produced in a cup on the thallus and splashed out by raindrops.

How do the calyptra and operculum protect a moss sporangium before its spores are released?

Show model answer
The calyptra, derived from the walls of the archegonium, covers the sporangium, and a structure called the operculum sits at the tip of the spore capsule. The calyptra and operculum fall off when the spores are ready for dispersal.

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25.4 Seedless Vascular Plants

Compared to the thin rhizoids that anchor a bryophyte, what advantage do a vascular plant’s roots provide?

The vascular plants, whose more than 260,000 species represent over 90 percent of Earth’s vegetation, are also called ________.

What is the difference between primary succession and secondary succession, as illustrated by moss and liverwort colonization?

Show model answer
Mosses and liverworts are often the first macroscopic organisms to colonize an area, both in a primary succession, where bare land is settled for the first time by living organisms, and in a secondary succession, where soil remains intact after a catastrophic event wipes out many existing species.

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Chapter 26: Seed Plants

26.1 Evolution of Seed Plants

In seed plants, which of the following develops into a female gametophyte that produces eggs?

In seed plants, the gametophytes shrank while the ________ became prominent structures.

In seed plants, how do the sperm of cycads and Ginkgo differ from the sperm of modern gymnosperms and all angiosperms, and how are they nonetheless delivered to the female gametophyte?

Show model answer
The sperm of modern gymnosperms and all angiosperms lack flagella, but in cycads, Ginkgo, and other primitive gymnosperms, the sperm are still motile and use flagella to swim to the female gamete; however, they are delivered to the female gametophyte enclosed in a pollen grain.

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26.2 Gymnosperms

In a pine’s male cones, haploid microspores develop into male gametophytes through which process?

In pines, the cone that contains two ovules per scale is called the ________.

Why are conifers more susceptible than deciduous trees to leaf infestations?

Show model answer
Most conifers do not lose their leaves all at once, so they cannot shed parasites and restart with a fresh supply of leaves in spring.

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26.3 Angiosperms

In an angiosperm ovule, a diploid megasporocyte undergoes meiosis to produce how many haploid megaspores?

Winged maple seeds, also called whirligigs or ‘helicopters,’ have the botanical name ________.

In angiosperms, what distinguishes a monoecious plant from a dioecious plant, and what are examples of each?

Show model answer
In monoecious angiosperms, male and female flowers are separate but carried on the same plant, as in sweetgums and birches. In dioecious angiosperms, male and female flowers are found on separate plants, as in willows and poplars.

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26.4 The Role of Seed Plants

Ebony and Brazilian rosewood are two examples of tree species driven almost to extinction by which practice?

The plant Atropa belladonna, whose compound atropine is used to dilate eye pupils for eye exams, is commonly called the ________.

How do acacia ants (Pseudomyrmex spp.) benefit Mexican acacia trees, and what do the trees provide the ants in return?

Show model answer
The ants discourage herbivores by stinging and attacking leaf-eaters and insects, and they help remove potential plant pathogens, such as fungal growths; in return, the trees support the ants with shelter in the hollows of large thorns and food from sugary secretions produced at the ends of the leaves.

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Chapter 27: Introduction to Animal Diversity

27.1 Features of the Animal Kingdom

Which tissue type covers and protects both external and internal body surfaces, and may also have secretory functions?

Two of the five animal clades—the Ctenophora and the ________—entirely lack Hox genes.

Explain what parthenogenesis is and why only female animals typically produce parthenogenetic offspring.

Show model answer
Parthenogenesis is a form of uniparental reproduction in which progeny develop from a gamete without fertilization. Because of the nutrients stored in eggs, only females produce parthenogenetic offspring.

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27.2 Features Used to Classify Animals

In mammals, the coelom’s abdominal cavity houses the digestive organs, while which cavity houses the heart and lungs?

In protostomes, the cleavage pattern in which the developmental fate of each embryonic cell is already fixed at this early stage is called ________.

Explain why deuterostome development makes the existence of embryonic stem cells possible.

Show model answer
Deuterostomes undergo indeterminate cleavage, so their blastomeres are not yet committed to a specific cell fate at this early stage. A blastomere separated from the rest can even develop into a twin, and this flexibility is preserved in embryonic stem cells, which retain the ability to develop into any cell type until their fate is programmed at a later developmental stage.

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27.3 Animal Phylogeny

Which group did a recent reanalysis of molecular evidence reaffirm as the first animal phylum to diverge from the common ancestor of metazoans?

Molecular analysis using rRNA data revealed that lophophorates (including brachiopods and bryozoans), once classified as primitive deuterostomes, are actually protostomes most closely related to which pair of groups?

Explain what evidence supports the hypothesis that animals (Metazoa) evolved from an ancestor resembling modern colonial choanoflagellates.

Show model answer
The feeding cells of sponges, called choanocytes, closely resemble choanoflagellate protists. This similarity has been used to suggest that Metazoa evolved from a common ancestral organism that resembled the modern colonial choanoflagellates.

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27.4 The Evolutionary History of the Animal Kingdom

The trilobite, a dominant Cambrian-period arthropod, was among the first animals to exhibit which of the following?

In the Cenozoic Era, which group of animals radiated into the terrestrial and aquatic niches once occupied by dinosaurs?

Describe what the discovery of the Coronacollina acula fossils suggests about the earliest animals with hard body parts.

Show model answer
Fossils named Coronacollina acula, discovered in South Australia and dated back as far as 560 million years, are believed to represent the oldest animals with hard body parts. These sponge-like fossils show hard body parts and spicules that extended 20–40 cm from a thimble-shaped body.

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Chapter 28: Invertebrates

28.1 Phylum Porifera

Which class of sponges produces six-rayed, glassy siliceous spicules and no spongin?

The rearranging of sponge cells that lets them creep slowly along a substratum is called ________.

Why does temporal separation of egg and sperm production in a sequentially hermaphroditic sponge help increase genetic diversity?

Show model answer
Sponges may become sequentially hermaphroditic, producing oocytes first and spermatozoa later. This temporal separation of gametes produced by the same sponge helps to encourage cross-fertilization and genetic diversity.

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28.2 Phylum Cnidaria

Cnidocytes have large stinging organelles that usually contain a barb at the base of a long coiled thread; these organelles are called ________.

Which cnidarian class’s medusoid form has a muscular velum below the margin of the bell, making it a hydromedusa?

What is the adaptive benefit of the septal mesenteries that divide a sea anemone’s gastrovascular cavity into several chambers?

Show model answer
The adaptive benefit of the mesenteries appears to be an increase in surface area for absorption of nutrients and gas exchange, as well as additional mechanical support for the body of the anemone.

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28.3 Superphylum Lophotrochozoa: Flatworms, Rotifers, and Nemerteans

Embryonic development of nemertean worms proceeds via a ________ or trochophore-like larval stage.

Which method of sex determination do many rotifer species exhibit, in which a fertilized egg develops into a female and an unfertilized egg develops into a male?

Why might nemerteans be regarded as coelomic even though they are sometimes classified as acoels?

Show model answer
Nemerteans are sometimes classified as acoels, but because their closed circulatory system is derived from the coelomic cavity of the embryo, they may be regarded as coelomic.

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28.4 Superphylum Lophotrochozoa: Mollusks and Annelids

In which molluscan class does the mantle cavity itself form a tube open at both ends and serve as the respiratory structure, since ctenidia are absent?

The primitive ‘kidney’ structure that facilitates excretion in annelids, consisting of a convoluted tubule and an open, ciliated funnel, present in every segment, is called a ________.

How do deepwater tubeworm polychaetes living near hydrothermal vents obtain nutrition, despite having no digestive tract?

Show model answer
These deepwater tubeworms have no digestive tract, but have a symbiotic relationship with bacteria living in their bodies.

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28.5 Superphylum Ecdysozoa: Nematodes and Tardigrades

In marine nematodes, the excretory cells that are unique to nematodes are called ________.

In nematodes, the fusion of all nerve cords at the anterior end forms which structure, acting as the head ganglion or ‘brain’ of the roundworm?

After tardigrade development produces a fixed number of cells, how does further growth occur?

Show model answer
In tardigrades, development produces a fixed number of cells, with the actual number of cells being dependent on the species. Further growth occurs by enlarging the cells, not by multiplying them.

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28.6 Superphylum Ecdysozoa: Arthropods

Which layer of the arthropod cuticle is a thin, waxy, water-resistant outer layer that contains no chitin?

How is a crustacean’s brain formed, and what other nervous-system structures does a crustacean have?

Show model answer
Crustaceans possess a brain formed by the fusion of the first three segmental ganglia, as well as two compound eyes. A ventral nerve cord connects additional segmental ganglia.

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Winged insects, which bear jointed legs on the prothorax, mesothorax, and metathorax along with veined wings on the mesothorax and metathorax, are called the ________.

28.7 Superphylum Deuterostomia

The primitive gut cavity within the gastrula that opens outward via the blastopore is called the ________.

Which class of echinoderms is the only one whose adults show functional bilateral symmetry, due to an extended oral-aboral axis?

How do an echinoderm’s tube feet let it move and capture prey?

Show model answer
Tube feet can extend or retract based on the volume of water present in the system of that arm, allowing the animal to move and also allowing it to capture prey with their suckerlike action. Individual tube feet are controlled by bulblike ampullae.

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Chapter 29: Vertebrates

29.1 Chordates

In adult tunicates, which two of the five chordate characteristics remain after the notochord, nerve cord, and tail disappear during metamorphosis?

A member of Cephalochordata that is named for its blade-like shape is called a ________.

What does the term ’tetrapod’ mean, and which extant vertebrate groups does it include?

Show model answer
Tetrapod literally means “four-footed,” which refers to the phylogenetic history of various land vertebrates, even though in some tetrapods the limbs have been modified for purposes other than walking. Tetrapods include amphibians, reptiles, birds, and mammals.

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29.2 Fishes

Which of the following features do lampreys share with the gnathostomes, unlike hagfishes?

In fishes, a gas-filled organ derived from the gut that helps control buoyancy is called the ________.

Which bony fishes have reverted to a primarily cartilaginous skeleton, and what do nearly all other bony fishes have instead?

Show model answer
Nearly all bony fishes have an ossified skeleton with specialized bone cells (osteocytes) that produce and maintain a calcium phosphate matrix. This characteristic has been reversed only in a few groups of Osteichthyes, such as sturgeons and paddlefish, which have primarily cartilaginous skeletons.

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29.3 Amphibians

Which early tetrapod fossil had forelimbs more developed than its hind limbs, suggesting that it dragged itself along when it ventured onto land?

Frogs with more toxic skins have bright warning, or ________, coloration.

How do frogs use the papilla amphibiorum and papilla basilaris to detect different sounds?

Show model answer
Frogs use separate regions of the inner ear for detecting higher and lower sounds: the papilla amphibiorum is sensitive to frequencies below 10,000 hertz and is unique to amphibians, and the papilla basilaris is sensitive to higher frequencies, including mating calls, transmitted from the eardrum through the stapes bone.

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29.4 Reptiles

Which extraembryonic membrane’s blood vessels transport nutrients to the embryo’s circulatory system?

Most reptiles are ectotherms, but some members of which group maintain elevated thoracic temperatures and thus appear to be at least regional endotherms?

How does the structure of a snake’s jaw allow it to swallow large prey?

Show model answer
Most snakes have a skull that is very flexible, involving eight rotational joints. They also differ from other squamates by having mandibles without either bony or ligamentous attachment anteriorly. Having this connection via skin and muscle allows for great dynamic expansion of the gape and independent motion of the two sides, both advantages in swallowing big prey.

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29.5 Birds

Which type of feather has barbules that do not interlock, trapping air between adjacent feathers to reduce heat loss?

The group of birds that includes every species other than the Paleognathae is called ________.

What does the name ‘Enantiornithes’ mean, and how did this group of birds differ from modern birds?

Show model answer
Enantiornithes means “opposite birds,” which refers to the fact that certain bones of the shoulder are joined differently than the way the bones are joined in modern birds. Like Archaeopteryx, these birds retained teeth in their jaws, but did have a shortened tail. These birds formed an evolutionary lineage separate from that of modern birds, and they did not survive past the Cretaceous.

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29.6 Mammals

Which type of mammalian skin gland secretes substances used for chemical communication, as in skunks?

The family that includes the echidna, or spiny anteater, is called ________.

What is the function of the secondary palate, and why is it necessary for chewing?

Show model answer
Chewing requires the ability to breathe at the same time, which is facilitated by the presence of a secondary palate. The secondary palate separates the area of the mouth where chewing occurs from the area above where respiration occurs, allowing breathing to proceed uninterrupted while the animal is chewing.

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29.7 The Evolution of Primates

In primates, claws have been modified into which of the following?

The oldest known primate-like mammal is called ________.

How did the diet of Paranthropus differ from that of the australopiths, and what does the wear on its molars suggest?

Show model answer
Paranthropus were muscular and had large grinding teeth. Their molars showed heavy wear, suggesting that they had a coarse and fibrous vegetarian diet as opposed to the partially carnivorous diet of the australopiths.

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This knowledge check is written for Unit 5 (Chapters 21–29) of Biology 2e by Mary Ann Clark, Jung Choi, Matthew Douglas, and OpenStax, © OpenStax, licensed under CC BY-NC-SA 4.0. Access the original for free at openstax.org. Changes: every question is locally written from the pinned text of the chapters’ own modules — their section summaries, glossary definitions, body passages, and comparison tables — and none is transcribed from the book’s exercise sets, which the section pages already carry; no question carries a hint, and every self-check carries a rubric that decomposes a model answer made of the module’s own sentences.

The Evolution of PrimatesPlant Form and Physiology