The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 meters, is a source of high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts), fall to the forest floor. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow, self-incompatible flowers of Brazil nut trees admit only female orchid bees as pollinators.

Entrepreneurs attempted, but failed, to harvest nuts from plantations grown in Southeast Asia. Attempts to grow Brazil nut trees in South American plantations also failed. In both cases, the trees grew vigorously, produced healthy flowers in profusion, but set no fruit. Consequently, what is the likely source of the problem?

A) poor sporophyte viability
B) poor sporophyte fertility
C) failure to produce fertile ovules
D) failure to produce pollen
E) pollination failure

E

The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 meters, is a source of high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts), fall to the forest floor. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow, self-incompatible flowers of Brazil nut trees admit only female orchid bees as pollinators.

The harpy eagle, Harpia harpyja, is the largest, most powerful raptor in the Americas. It nests only in trees taller than 25 meters. It is a "sloth specialist," but will also take agouti. Thus, if these eagles capture too many agoutis from a particular locale, they might contribute to their own demise by

A) having too many offspring.
B) increasing habitat loss.
C) decreasing atmospheric CO2.
D) increasing the number of sloths.

B

For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.

Sexual reproduction has not been observed in Bd. A Bd sporangium initially contains a single, haploid cell. Which of the following processes must be involved in generating the multiple zoospores eventually produced by each sporangium?

1. S phase
2. cytokinesis
3. mitosis
4. meiosis

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

D

The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 meters, is a source of high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts), fall to the forest floor. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow, self-incompatible flowers of Brazil nut trees admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animals with teeth strong enough to crack the hard wall of Brazil nut fruits. It typically eats some of the seeds, buries others, and leaves still others inside the fruit, which moisture can then enter. The uneaten seeds may subsequently germinate.

The agouti is most directly involved with the Brazil nut tree's dispersal of

A) male gametophytes.
B) female gametophytes.
C) sporophyte embryos.
D) sporophyte megaspores.
E) female gametes.

C

Big Bend National Park in Texas is mostly Chihuahuan desert, where rainfall averages about 10 inches per year. Yet, it is not uncommon when hiking in this bone-dry desert to encounter mosses and ferns. One such plant is called "flower of stone." It is not a flowering plant, nor does it produce seeds. Under arid conditions, its leaflike structures curl up. However, when it rains, it unfurls its leaves, which form a bright green rosette on the desert floor. Consequently, it is sometimes called the "resurrection plant." At first glance, it could be a fern, a true moss, or a spike moss.

In which combination of locations would one who is searching for the gametophytes of flower of stone have the best chance of finding them?

1. moist soil
2. underground, nourished there by symbiotic fungi
3. south- or west-facing slopes
4. permanently shady places
5. far from any flower of stone sporophytes

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

C

For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.

The fact that infection by Bd causes lethargy in many infected amphibians can have what effect on efforts to accurately census the numbers of dead or dying amphibians at a particular time, in a particular habitat?
A) It can cause underestimation, due to infected amphibians preferring to seek out refuges relative to uninfected amphibians.
B) It can cause underestimation, due to increased predation on, and removal of, infected amphibians relative to uninfected amphibians.
C) It can cause overestimation, because infected frogs should be more readily observable to human census-takers than should uninfected amphibians.
D) All three of the above statements are plausible.
E) Two of the above statements are plausible.

E

Diploid nuclei of the ascomycete, Neurospora crassa, contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores.

If a single, diploid G₂ nucleus in an ascus contains 400 nanograms (ng) of DNA, then a single ascospore nucleus of this species should contain how much DNA (ng), carried on how many chromosomes?

A) 100, carried on 7 chromosomes
B) 100, carried on 14 chromosomes
C) 200, carried on 7 chromosomes
D) 200, carried on 14 chromosomes
E) 400, carried on 14 chromosomes

A

Diploid nuclei of the ascomycete, Neurospora crassa, contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores.

What is the ploidy of a single mature ascospore?

A) monoploid (/haploid)
B) diploid
C) triploid
D) tetraploid
E) polyploid

A

The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million years ago and were dominant forms during the Age of the Dinosaurs. Though their sperm are flagellated, their ovules are pollinated by beetles. These beetles get nutrition (they eat pollen) and shelter from the microsporophylls. Upon visiting megasporophylls, the beetles transfer pollen to the exposed ovules. In cycads, pollen cones and seed cones are borne on different plants. Cycads synthesize neurotoxins, especially in the seeds, that are effective against most animals, including humans.

Which feature of cycads makes them similar to many angiosperms?

1. They have exposed ovules.
2. They have flagellated sperm.
3. They are pollinated by animals.

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1, 2, and 3

C

For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.

When adult amphibian skin harbors populations of the bacterium, Janthinobacterium lividum (Jl), chytrid infection seems to be inhibited. Which of the following represents the best experimental design for conclusively determining whether this inhibition is real?

A) Inoculate uninfected amphibians with Jl, and determine whether the amphibians continue to remain uninfected by chytrids.
B) Inoculate infected amphibians with Jl, and determine whether the amphibians recover from infection by chytrids.
C) Take infected amphibians and assign them to two populations. Leave one population alone; inoculate the other with Jl. Measure the rate at which infection proceeds in both populations.
D) Take infected amphibians and assign them to two populations. Inoculate one population with a high dose of Jl; inoculate the other with a low dose of Jl. Measure the survival frequency in both populations.

C

The Brazil nut tree, Bertholletia excels (n = 17), is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 meters, is a source of high-quality lumber, and is a favorite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts), fall to the forest floor. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow, self-incompatible flowers of Brazil nut trees admit only female orchid bees as pollinators.

The same bees that pollinate the flowers of the Brazil nut trees pollinate orchids, which are epiphytes (in other words, plants that grow on other plants); however, orchids cannot grow on Brazil nut trees. These observations explain

A) the coevolution of Brazil nut trees and orchids.
B) why Brazil nut trees do not set fruit in plantations.
C) why male orchid bees do not pollinate Brazil nut tree flowers.
D) why male orchid bees are smaller than female orchid bees.
E) the importance of orchid and Brazil nut tree flowers for the production of orchid bee honey.

B

The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million years ago and were dominant forms during the Age of the Dinosaurs. Though their sperm are flagellated, their ovules are pollinated by beetles. These beetles get nutrition (they eat pollen) and shelter from the microsporophylls. Upon visiting megasporophylls, the beetles transfer pollen to the exposed ovules. In cycads, pollen cones and seed cones are borne on different plants. Cycads synthesize neurotoxins, especially in the seeds, that are effective against most animals, including humans.

On the Pacific island of Guam, large herbivorous bats called "flying foxes" commonly feed on cycad seeds, a potent source of neurotoxins. The flying foxes do not visit male cones. Consequently, what should be true?

A) The flying foxes are attracted to cycad fruit, and eat the enclosed seeds only by accident.
B) Flying foxes are highly susceptible to the effects of the neurotoxins.
C) The flying foxes assist the beetles as important pollinating agents of the cycads.
D) Flying foxes can be dispersal agents of cycad seeds if the seeds sometimes get swallowed whole (in other words, without getting chewed).

D

The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million years ago and were dominant forms during the Age of the Dinosaurs. Though their sperm are flagellated, their ovules are pollinated by beetles. These beetles get nutrition (they eat pollen) and shelter from the microsporophylls. Upon visiting megasporophylls, the beetles transfer pollen to the exposed ovules. In cycads, pollen cones and seed cones are borne on different plants. Cycads synthesize neurotoxins, especially in the seeds, that are effective against most animals, including humans.

61) Which feature of cycads distinguishes them from most other gymnosperms?

1. They have exposed ovules.
2. They have flagellated sperm.
3. They are pollinated by animals.

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1, 2, and 3

D

For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.

A researcher took water in which a Jl population had been thriving, filtered the water to remove all bacterial cells, and then applied the water to the skins of adult amphibians to see if there would subsequently be a reduced infection rate by Bd when frog skins were inoculated with Bd. For which of the following hypotheses is the procedure described a potential test?

A) the hypothesis that a toxin secreted by Jl cells kills Bd cells when both are present together on frog skin
B) the hypothesis that Jl cells infect and kill Bd cells when both are present together on frog skin
C) the hypothesis that Jl outcompetes Bd when both are present together on a frog's skin
D) the hypothesis that the presence of Jl on frog skin causes a skin reaction that prevents attachment by Bd cells

A

In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. Match the number of chromosomes present in each of the following onion tissues.

How many chromosomes should be in an embryo nucleus?
A) 4
B) 8
C) 16
D) 24
E) 32

C

All fungi are

A) symbiotic

B) heterotrophic

C) flagellated

D) decomposers

B

Which of the following characteristics of plants is absent in their closest relatives, the charophyte algae?

A) chlorophyll b

B) cellulose in cell walls

C) multicellularity

D) alternation of generations

D

Among the organisms listed here, which are thought to be the closest relatives of fungi?

A) slime molds

B) vascular plants

C) animals

D) mosses

C

The adaptive advantage associated with the filamentous nature of fungal mycelia is primary related to

A) the ability to parasitize other organisms

B) avoiding sexual reproduction until the environment changes

C) the potential to inhabit almost all terrestrial habitats

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

D