BIO Test 3 Chap: 29-33
Rather than measuring the entire 6000-hectare (ha) forest, the researchers sampled arthropod diversity by intensively collecting as many arthropods as they could in 12 plots that measured 20 m * 20 m square. If 1 ha = 10,000 m2, how many hectares of forest did they sample in all?
4800 m2 * 1 ha>10,000 m2 = 0.48 ha
Draw a phylogeny of major populations of modern humans that would reject the out-of-Africa hypothesis.
A phylogeny of modern humans would reject the out-of-Africa hypothesis if the earliest branches to diverge from others in the phylogenetic tree were from any other region but Africa, such as Asia or Europe.
Explain why fungi that degrade dead plant materials are important to the global carbon cycle. Do you accept the text's statement that, without these fungi, "Terrestrial environments would be radically different than they are today, and probably much less productive"? Why or why not?
Accept. Along with a few bacteria, fungi are the only organisms that can digest wood completely. If the wood is not digested, carbon remains trapped in wood. Without fungi, CO2 would be tied up and unavailable for photosynthesis, and the presence of undecayed organic matter would reduce the space available for plants to grow.
Compare amniotic eggs to placentas.
Amniotic eggs and placentas are similar in that they both nourish and protect growing embryos; they are both made of a chorion, amnion, and yolk sac; and they are both adaptive strategies for life on land. The main difference is that amniotic eggs can be deposited outside the mother's body, protected in a shell filled with albumin, while the placenta is retained within the mother's uterus and relies on the exchange of nutrients, wastes, and gases with the mother.
ZIKV is a Baltimore class IV virus. Based on this classification, what do you know about the structure of its genome?
As a class IV virus, ZIKV has a linear, positive-sense, single-stranded RNA genome.
Based on your reading of this chapter, propose at least five traits that you think might have been most important in triggering diversification within phyla (examples: origin of hearing, origin of internal fertilization).
Many answers are possible, but yours should include traits either mentioned as key innovations in Section 30.2 (such as central nervous system, bilateral symmetry, segmentation) or in the themes of diversification in Section 30.3 (certain types of sensory organs, ecological roles, or feeding strategies).
If you were in charge of the government's budget devoted to stemming the AIDS epidemic, would you devote most of the resources to drug development or preventive medicine? Defend your answer.
Prevention is currently the most cost-effective program, but it does not help people who are already infected. Treatment with effective drugs not only prolongs lives but also reduces virus loads in infected people, so that they have less chance of infecting others.
What does reverse transcriptase do?
Reverse transcriptase converts positive-sense single-stranded RNA to double-stranded DNA in class VI and class VII viruses.
Use your understanding of insect evolution to predict two adaptations for terrestrial living that occurred in spiders.
Spiders have internal respiratory structures that minimize water loss, a waxy cuticle that minimizes water loss, and internal fertilization.
What features distinguish the seven major categories of viruses?
The type of genetic material included in the virion (classes I-V) and how the genome is replicated (compare classes I and IV with classes VII and VI, respectively).
Which of these characteristics does not apply to cnidarians?
have a central nervous system
Evaluate the following statements about mushrooms. Select True or False for each statement. T/F A diploid zygote is formed when a male spore fertilizes a female spore.
F (Spores grow into fungal hyphae; they are not involved in fertilization, and they are not designated as male and female.),
In the viral replicative cycle, what reaction do viral proteases catalyze? T/F They catalyze folding of long peptide chains into functional proteins.
False
In the viral replicative cycle, what reaction do viral proteases catalyze? T/F They catalyze polymerization of amino acids into peptides.
False
Use the data in the graph to analyze the following statements. Select T/F All taxa shown in the graph are insects.
False (Spiders are not insects.)
Pilobolus is a zygomycete, and the sporangia just described produce asexual spores. In contrast, which of the following best describes what happens during the sexual phase of its life cycle?
Hyphae from two compatible mating types fuse and form a zygosporangium.
About a third of insect species measured are in decline, meaning that their populations are shrinking due to habitat destruction, pollution, and other factors. Predict how this change affects the bee pollination of crops such as apples and almonds.
If bee populations are declining at the same or similar rate as for insects overall, losing a third of bee species could seriously affect the success of crops like apples and almonds. If these crops are not pollinated, they will not bear fruit for humans to eat.
What is the function of the arthropod exoskeleton?
It provides protection and functions in locomotion.
Jezkova and Wiens used a type of graph called a linear regression to find correlations between variables such as the proportion of species per phylum with legs (on the y-axis) and the diversification rate per phylum (on the x-axis). Sketch a graph to show what a strong positive correlation between these two variables would look like and what the absence of a correlation would look like.
It's fine if you showed the linear trend without including data points, but this answer has data points for clarity. In general, the strength of a correlation (indicated with an R2 value between 0.0 and 1.0) is highest when there is a steep slope with the data points close to the line, rather than a flat slope with data points that are scattered.
Why is it ecologically significant that animals are heterotrophic and multicellular?
Many unicellular organisms are heterotrophic, but they can consume only small bits of food. Animals are multicellular, so they are larger and can consume larger amounts of food—making them important consumers in food webs.
Researchers studied mice embryos as a model organism to determine whether the cells of the ear bones originated from the same embryonic cells as the cells that form the jaw in other vertebrates (see BioSkills 11). Why would the researchers use mice instead of humans? Do the results from mice tell you something about your own ears? Why or why not?
Model organisms such as mice are used because they are short lived, easy to maintain, and easy to study (see BioSkills 11). It would be impractical to do similar experiments on human embryos, plus it is not culturally acceptable to conduct experiments on human embryos. Although early development in mice and humans is not identical, most processes are similar because they are both placental mammals that share a common ancestor with a similar developmental pattern. Therefore, the results from mice would likely be a good proxy for the patterns expected in humans.
The researchers observed a strong correlation between the number of arthropod species and the number of plant species in the San Lorenzo forest. Pose an evolutionary hypothesis to explain this correlation.
Most of the arthropod species are insects that experienced an adaptive radiation on land, thanks in part to their coevolution with plants, which were also experiencing an adaptive radiation on land. The more plants, the more types of habitats and food sources the insects could use, and the greater their ecological opportunity for speciation.
Table 29.1 mentions that chytrids are responsible for massive die-offs currently occurring in amphibians. Review Koch's postulates (see Ch. 26, Section 26.1); then design a study showing how you would use Koch's postulates to test the hypothesis that chytrid infections are responsible for frog deaths.
Study design: (1) Confirm that the chytrid fungus is found only in sick frogs and not healthy frogs. (2) Isolate the chytrid fungus and grow it in a pure culture. (3) Expose healthy frogs to the cultured fungus and see if they become sick. (4) Isolate the fungus from the experimental frogs, grow it in culture, and test whether it is the same as the original fungus.
Pose a hypothesis to explain why the evolution of the wing was such an important event in the evolution of insects.
The ability to fly allowed insects to disperse to new habitats and find new food sources efficiently.
Would you describe the association between Pilobolus and cows as a symbiotic relationship? Explain your answer.
The relationship between Pilobolus and cows might better be described as commensal; while Pilobolus benefits from this relationship by being dispersed by the cow and provided with a nutrient-rich environment in which to grow, cows may not derive much benefit from this relationship.
The graph below shows some of the data for the major arthropod groups collected. Notice that the scale on the y axis is logarithmic to make both small and large numbers legible on the same graph (see BioSkills 5). For example, there are about 400 species of spiders, but only 40 species of bees. About how many arthropods were found in total? About what percentage of these were beetles?
The total number of arthropods is about 6000 species. The total number of beetles is about 1000 + 200 + 700 + 1000 = 2900, which is about half, or 50 percent, of the species counted (rough estimate).
Researchers recently developed a mouse model for fetal brain defects associated with human ZIKV infection. To determine the effect of ZIKV on the number of neurons in the brain, ZIKV was injected into the brains of developing mouse embryos. Neurons were identified by staining sections of brain tissue with antibodies against NeuN, a neuronspecific protein (see BioSkills 6 for more information on using antibody probes), and the number of NeuNpositive cells per mm2 in specific regions was quantified. The results of three independent experiments are shown in the graph below. Use the P value provided to determine if the difference is significant or not (* means P 6 0.05; see BioSkills 3). Based on these results, what can you conclude?
The total number of neurons (NeuN+ cells) after ZIKV infection decreases significantly in comparison with the control, in which no virus was injected. These results suggest that embryonic infection causes significant neuronal loss in the developing brain.
Lawns are sometimes fertilized with nitrate that can be washed into neighboring woodlots by rain. If the trees in that woodlot are associated with EMF, what effect might the excess nitrate have on the fungi and/or trees?
The trees may take up the nitrate directly into their roots and rely less on the fungi.
The Greek root ecto means "outer." Why are ectomycorrhizal fungi, or EMF, aptly named?
Their hyphae form dense mats that envelop roots but do not penetrate the cell walls.
The hyphae of arbuscular mycorrhizal fungi (AMF) form bushy structures after making contact with the plasma membrane of a root cell. What is the function of these structures?
They increase the surface area available for the transfer of nutrients.
Which protostome phyla successfully made the transition from water to land? Select True or False for each phylum. T/F Nematoda
True
Which protostome phyla successfully made the transition from water to land? T/F Annelida
True
Which protostome phyla successfully made the transition from water to land? T/F Arthropoda
True
Which protostome phyla successfully made the transition from water to land? T/F Mollusca
True
Which traits do not correlate strongly with diversification rate within phyla, but are likely to have been important in the original diversification of animal phyla during the Cambrian? T/F bilateral symmetry
True
Which traits do not correlate strongly with diversification rate within phyla, but are likely to have been important in the original diversification of animal phyla during the Cambrian? T/F mobile lifestyle
True
Which traits do not correlate strongly with diversification rate within phyla, but are likely to have been important in the original diversification of animal phyla during the Cambrian? T/F presence of a head
True
True or false? Both echinoderms and vertebrates have endoskeletons. Explain.
True; echinoderms have a calcium carbonate endoskeleton, and vertebrates have a bony endoskeleton made of calcium phosphate.
What does it mean to say that a hypha is dikaryotic?
Two independent nuclei, derived from different individuals, are present in each cell.
What is a lophophore?
a specialized filter-feeding structure
What do host cells provide for viruses?
all of the above
How is the opossum related to you? Select True or False for each statement. T/F An opossum is a marsupial, but I am a placental mammal.
true
Humans possess which of the following traits? Select True or False for each trait. T/F triploblasty
true
Humans possess which of the following traits? Select True or False for each trait. T/F viviparity
true
How is the opossum related to you? Select True or False for each statement. T/F The opossum and I are both tetrapods.
true in everyday English it's common to refer to "animals and humans" or "mammals and humans," but these phrases do not make sense in a biological context because humans are mammals, which are animals
What trait(s) characterize the vertebrates?
vertebrae and a cranium
Which of the following types of viruses would you expect to require periods of latency?
viruses that require a long time for transmission to new hosts
Compare and contrast the bacteriophage lytic cycle and lysogeny by addressing (1) the rate of replication of the viral genome, (2) production of virions, and (3) effect on the host cell.
(1) The rate of viral genome replication is much higher in the lytic cycle. In lysogeny, the viral genome can replicate only when the host cell replicates. (2) Only the lytic cycle produces virions. (3) The lytic cycle results in the host cell's death, while lysogeny allows the host cell to survive.
Explain the process of extracellular digestion that occurs during the growth of Pilobolus mycelia through dung.
14. Fungal mycelia release enzymes as they grow throughout dung. These enzymes break down undigested material into usable molecules, which are absorbed directly into the fungal mycelium.
Using high-speed video, researchers have measured several variables associated with sporangium discharge in various spore-shooting fungi. Based on the data in the table shown here, how do the launch speed and acceleration of Pilobolus compare with those of the other fungi? How does launch speed for each species compare with the top speed of 44 km/h reached by Jamaican athlete Usain Bolt during his 2009 world-record-setting race?
15. Launch speed and acceleration of Pilobolus sporangia are less than that of the other fungi. Usain Bolt's top speed of 44 km/h translates to about 12.2 m/s (since 1 km = 1000 m and 1 hour = 3,600 seconds). Therefore, Usain Bolt's top speed is slower than the launch speeds of Ascobolus and Podospora, and just slightly faster than the launch speed of Pilobolus.
The outer surface of a virion consists of either a membranous envelope or a protein capsid. How does the outer surface correlate with a virus's mode of exiting a host cell?
A virus with an envelope generally exits a host cell by budding. A virus that lacks an envelope generally usually exits by bursting the host cell (lysis).
Researchers have determined that host cells possess several different surface proteins that can serve as virus receptors for ZIKV. If you were to repeat the experiment described in Figure 33.8 using ZIKV instead of HIV, how would you expect the results to be different? Explain.
All of the samples treated with different antibodies would contain infected cells. If ZIKV can use more than one type of receptor, then samples that are treated with antibodies that specifically target one virus receptor will leave the other receptors available for attachment.
Which of the following nested groups best describes the taxonomic context for the San Lorenzo project?
Bilateria > Protostomia > Ecdysozoa > Arthropoda
Propose an explanation for why annelids and arthropods were thought to be closely related, before phylogenetic analyses in the late 1990s.
Both annelids and arthropods have segmented bodies, unlike other protostomes such as flatworms and nematodes.
One trait that is shared by the Lophotrochozoa and Ecdysozoa is __________.
Both groups are bilaterally symmetric triploblasts with the protostome pattern of development.
Which statement is true about endothermy in mammals and birds?
Endothermy arose independently in these two lineages.
Use the data in the graph to analyze the following statements. T/F If the researchers had sampled for mollusks, they probably would have found almost as many species as they did for arthropods.
False (There are far fewer mollusk species than arthropod species, as shown in Figure 31.1.)
Which traits do not correlate strongly with diversification rate within phyla, but are likely to have been important in the original diversification of animal phyla during the Cambrian? T/F terrestrial lifestyle
False (because all animals in the Cambrian lived in the ocean),
True or false? New major animal body plans have continued to evolve since the Cambrian about 550 million years ago.
False—almost all the major body plans arose rapidly during the Cambrian.
Lignin and cellulose provide rigidity to the cell walls of plants. But in most fungi, chitin performs this role. Why is it logical that most fungi don't have lignin or cellulose in their cell walls?
Fungi produce enzymes that degrade cellulose and lignin.
Most species of hominins are known only from Africa. Which species have been found in other parts of the world as well?
H. erectus, H. neanderthalensis, and H. floresiensis
Brachiopoda is a phylum within the Lophotrochozoa. Even though they are not closely related to bivalve mollusks (such as clams or mussels), brachiopods look and act like bivalve mollusks. Specifically, brachiopods suspension feed, secrete calcium carbonate shells with two valves that hinge together in some species, and attach to rocks or other hard surfaces on the ocean floor. How is it possible for brachiopods and bivalves to be so similar if they did not share a recent common ancestor?
If the distinct ancestors of brachiopods and mollusks lived in similar habitats and experienced natural selection that favored similar traits, then they would have evolved to have similar forms and habitats. This is called convergent evolution
Traveling and tourism have been badly affected in ZIKVaffected countries. What advice would you give a friend planning a trip to the Caribbean?
If your friend is pregnant, she should probably defer her travel plans due to the risk of mother-to-fetus transmission. Otherwise, advise your friend to take preventative measures such as using mosquito netting, protective clothing, and insect repellent.
Analyze the morphological data shown here and write a hypothesis to explain the origin of mammalian ear bones. (The cynodont shown is one of many extinct synapsid amniotes that lived early in the lineage that gave rise to mammals.)
In the developing ear bones of mammals. (This is where Bapx1 expression was indeed found.)
Gene expression patterns can be used to test hypotheses based on morphology. For example, the regulatory gene Bapx1 is expressed in the hinge of the developing lower jaw in fishes and reptiles. Where would you predict Bapx1 expression to occur in mammals?
In the developing ear bones of mammals. (This is where Bapx1 expression was indeed found.)
Genetic diversity in living human populations is highest in Africa and decreases as a function of distance traveled by the human migration that left Africa many millennia ago (see Figure 32.20). Draw a graph to show this trend. (Hint: What is the independent variable? What is the dependent variable? What kind of graph is appropriate for this kind of data? See BioSkills 2.) Add a label where you would expect to find a data point for the Yanomamö tribe of the Amazon rain forest in South America. Why is it important to use indigenous people for this study?
It is important to use indigenous people for this study to minimize the amount of gene flow (transfer of alleles from one population to another) that occurred during the history of the study populations due to immigration and interbreeding.
CAREFULLY Evaluate this statement: Evolution is said to occur when new traits accumulate over time, increasing complexity.
It is true that evolution occurs when new traits accumulate, but it is not true that evolution only occurs when new traits accumulate. Evolution can also occur when traits are lost, such as the loss of a coelom in flatworms, loss of a digestive system in tapeworms, and loss of a second pair of antennae in insects. Some lineages adapt to their environments by becoming less complex over time.
The illustration of the opossum skull shows that the ear bones are completely separated from the jawbone (as they are in all mammals). Pose a hypothesis to explain why this separation could be an adaptation that contributed to the radiation of mammals into diverse niches, including a nocturnal lifestyle.
It makes sense that a separation of the jawbone (feeding function) from the ear bones (hearing function) would be adaptive, because it releases each structure from the constraint of the other and allows both to evolve independently. Ear bones could then have evolved to be different sizes or shapes, allowing different sensitivity to pitch or volume depending on the animal's niche. For example, acute hearing would be very adaptive in a nocturnal environment where vision is a poor source of information.
The mycelial growth habit leads to a body with a high surface-area to-volume ratio. Why is this important?
Mycelia have a large surface area for absorption.
If you come down with the flu, should your physician prescribe an antibiotic for you? Explain why or why not.
No. Most prescribed antibiotics are designed to disrupt the metabolic activity of unicellular infectious agents, like bacteria. Viruses rely on host-cell metabolism to replicate, so antibiotics would not be useful against them without also killing your cells.
By comparing the number of arthropod species that were common among the 12 plots sampled, the researchers estimated that the total number of arthropods in the whole San Lorenzo forest is 25,000 species. To come up with this estimate, what's one assumption the researchers had to make about the forest?
One of several possible answers: The researchers would have to assume that the diversity of species and number of unique species per area in parts of the forest that were not surveyed were comparable to the plots that were surveyed.
Propose an experiment to test whether Pilobolus shoots its sporangia preferentially toward light. Hypothesize why such a preference might be advantageous.
One possible approach would be to grow Pilobolus in a controlled room with a single light source at a distinct location. After sporangia are discharged, their location could easily be determined relative to the location of the light source. Sample hypothesis: Sporangia shot toward light may be more likely to land on turf that is fed on (and defecated on) by cows, because cows feed on photosynthesizing grass.
There is some evidence that pharyngeal slits occur in certain species of echinoderms that appear early in the fossil record. If confirmed, what do these data suggest?
Pharyngeal slits were present in the earliest echinoderms and lost later.
SCIENCE A sample of Jekova and Wiens' results is shown here. The R2 value represents the strength of the correlation (where 0.00 is lowest and 1.00 is highest). The P value represents the statistical significance (see BioSkills 3 to review how to interpret R2 and P values). Which five traits look most important?
Photoreceptors/eyes, skeleton, separate sexes, parasitic lifestyle, terrestrial lifestyle. You are identifying the traits with a high R2 but a low P value.
Consider the evolution of protostomes (Chapter 31) and deuterostomes (this chapter): (1) Compare adaptations in protostomes and deuterostomes for living on land. (2) Recall that changes in the expression patterns of tool-kit genes in arthropods such as insects enabled a dramatic diversification of their segmented appendages and bodies. Design an experiment to test whether this concept applies to vertebrates.
Protostomes and deuterostomes living on land both have mechanisms for preventing their eggs from drying out (e.g., thick membranes in snail and insect eggs; amniotic egg in tetrapods), preventing their skin from drying out (e.g., waxy cuticle in insects, scaly skin in reptiles), and keeping their respiratory surfaces from drying out (e.g., lungs in land snails and tracheal system in insects; lungs in tetrapods) (2) Vertebrate limbs are diverse in form and function (they can serve as arms, flippers, wings, etc.) but have homologous bones within. Molecular probes could be used to visualize the expression patterns of tool-kit genes such as Hox in the embryonic limbs of different vertebrate species to show how changes in the expression of homologous genes can cause changes to the structure and function of limbs.
Many mushrooms are extremely colorful. One hypothesis is that the colors serve as a warning to prevent animals from eating mushrooms, much like the bright yellow and black stripes on wasps help to deter potential predators. Design an experiment to test this hypothesis.
Study design: (1) Collect a large array of colorful mushrooms that are poisonous; also capture mushroom-eating animals, such as squirrels. (2) Present a hungry squirrel with a choice of mushrooms that have been dyed or painted a drab color versus others treated with a solution that is identical to the dye or paint used but uncolored. (3) Record which mushrooms the squirrel eats. (4) Repeat the test with many squirrels and many mushrooms.
To estimate the relative abundance of the major phyla, calculate how many named species of arthropods, mollusks, and nematode worms exist per named species of chordate (the phylum containing vertebrates, including humans; see Table 30.1). Do you think these calculations are likely to be underestimates or overestimates? Why?
There are about 18.5 named arthropods for every named species of chordate (1,200,000/65,000), about 1.3 named mollusks for every named species of chordate (85,000/65,000), and about 0.4 named species of nematode worm for every named species of chordate (25,000/65,000). These numbers are likely to be underestimates because there are probably many more arthropods, mollusks, and nematode worms than have been described, yet relatively few of the larger, more familiar chordates (mostly vertebrates) left to be described.
Evaluate the following statements about mushrooms. Select True or False for each statement. T/F A mushroom is a reproductive structure that consists largely of dikaryotic cells.
True
Evaluate the following statements about mushrooms. Select True or False for each statement. T/F Haploid spores are formed by meiosis in basidia.
True
Evaluate the following statements about mushrooms. Select True or False for each statement. T/F Mushrooms are part of the group that also includes bracket fungi, boletes, puffballs, and stinkhorns.
True
In the viral replicative cycle, what reaction do viral proteases catalyze? T/F They catalyze breaking of peptide bonds
True
In the viral replicative cycle, what reaction do viral proteases catalyze? T/F They catalyze cutting of polyprotein chains into functional proteins.
True
Use the data in the graph to analyze the following statements. Select T/F All taxa shown in the graph are terrestrial.
True
Use the data in the graph to analyze the following statements. Select T/F All taxa shown in the graph have segmented bodies and limbs.
True
Evaluate this statement: Animals evolved from simple to complex.
While it is generally true that early animals were simpler than later animals, evolution is more nuanced than a simple-to-complex story suggests. For example, many essential tool-kit genes evolved right at the base of the animal tree and were later coopted in various ways in different lineages. Also, sometimes traits are lost over time rather than gained, such as a coelom in flatworms and legs in snakes. Also, some traits—such as segmentation—evolved independently in different groups. Moreover, the lineages that were earliest to diverge from other animals did not stop evolving.
Suppose that a gene originally identified in nematodes (roundworms) is found to be homologous with a gene that can cause developmental abnormalities in humans. Would it be possible to use fruit flies as a model organism to study this gene? Explain.
Yes—if the same gene is found in nematodes and humans, it was likely found in the common ancestor of protostomes and deuterostomes. Therefore, fruit flies are also likely to have this gene. However, sometimes genes are lost during evolution, so it's possible that the ancestors to flies had the gene, but flies do not.
The researchers know that correlation does not equal causation. However, can the absence of a correlation enable you to reject a hypothesis of causation? How would the R2 values be different in a scenario where a single trait was important to diversification in many phyla versus a scenario where different traits were important to diversification in different phyla?
Yes—whereas a positive correlation between y and x does not necessarily mean that an increase in x causes an increase in y (there might be a third causative variable), the absence of a correlation between y and x suggests the absence of causation. The R2 value would be very high (close to 1.000) if a single trait was important to diversification in many phyla, but very low (closer to 0.000) if different traits were important to diversification in different phyla—because each phylum represents one data point in each regression.
Evolution often results in the co-option of a preexisting structure for a new use. Cite three examples from this chapter to support this statement. Evolution can also result in the loss of a trait. Cite three examples from this chapter.
[Many possible answers] Some examples: Lungs were co-opted for use as swim bladders. Fins were co-opted for use as limbs. Arms were co-opted for use as wings. Scales made of keratin were co-opted for use as feathers. Jawbones were co-opted for use as ear bones. Vertebrae were lost in hagfishes. Fins were lost in tetrapods. Tails were lost in adult frogs. Limbs were lost in caecilians and snakes. Amniotic eggs were lost in marsupials and placental mammals. Tails (after the embryonic stage) were lost in great apes, including humans.
Which of these choices is an example of homology (similarity due to common ancestry)?
cnidocytes (stinging cells) in jellyfish and sea anemones
13. Several lines of evidence suggest that after ZIKV is transmitted to a pregnant woman via the bite of an infected mosquito, the virus then directly infects cells of the placenta (Ch. 47, Section 47.4), gaining access to the fetal brain. Following attachment, the virion would most likely enter the placental cell by:
endocytosis
In a tube-within-a-tube body plan, what is the interior tube derived from?
endoderm
How is the opossum related to you? Select True or False for each statement. T/F An opossum is a mammal, but I am a human.
false
How is the opossum related to you? Select True or False for each statement. T/F An opossum is an animal, but I am a human.
false
Humans possess which of the following traits? Select True or False for each trait. T/F metamorphosis
false
Humans possess which of the following traits? Select True or False for each trait. T/F parthenogenesis
false
Which synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates?
multicellularity
Of the viruses highlighted in Section 33.4, predict which of the following would be able to make viral proteins if nothing more than its genome were injected into a suitable host cell.
pea mosaic ([+]ssRNA) virus
What two major lineages make up the living Amniota?
reptiles and mammals
