chapter 30

The taller a Brazil nut tree is, _____. 1. The more valuable it is as a source of lumber. 2. The less useful it is to harpy eagles. 3. The greater its photosynthetic rate relative to neighboring plants.

1 and 3

) Arrange the following structures, which can be found on male pine trees, from the largest structure to the smallest structure (or from most inclusive to least inclusive). 1. Sporophyte. 2. Microspores. 3. Microsporangia. 4. Pollen cone. 5. Pollen nuclei.

1, 4, 3, 2, 5

How many chromosomes should be in a megasporangium nucleus?

16

How many chromosomes should be in an embryo nucleus?

16

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 distinguishes them from most other gymnosperms?

2 and 3

How many chromosomes should be in an endosperm nucleus?

24

What adaptations should one expect of the seed coats of angiosperm species whose seeds are dispersed by frugivorous (fruit-eating) animals, as opposed to angiosperm species whose seeds are dispersed by other means? 1. The exterior of the seed coat should have barbs or hooks. 2. The seed coat should contain secondary compounds that irritate the lining of the animal's mouth. 3. The seed coat should be able to withstand low pHs. 4. The seed coat, upon its complete digestion, should provide vitamins or nutrients to animals. 5. The seed coat should be resistant to the animals' digestive enzymes.

3 and 5

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.

3 only

How many chromosomes should be in a generative cell nucleus?

8

People who attempted to plant Brazil nuts in hopes of establishing plantations of Brazil nut trees played roles most similar to those of _____.

Agoutis.

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 tall, 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal 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 now enter. The uneaten seeds may subsequently germinate. Orchid bees are to Brazil nut trees as ________ are to pine trees.

Breezes.

Which of the following is a characteristic of all angiosperms?

Double internal fertilization.

Oviparous (egg-laying) animals have internal fertilization (sperm cells encounter eggs within the female's body). Yolk and/or albumen is (are) provided to the embryo, and a shell is then deposited around the embryo and its food source. Eggs are subsequently deposited in an environment that promotes their further development, or are incubated by one or both parents. The yolk of an animal egg has what type of analog in angiosperms?

Endosperm.

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?

Flying foxes can be dispersal agents of cycad seeds if the seeds sometimes get swallowed whole (in other words, without getting chewed).

The laying of eggs has what type of analog in angiosperms?

Fruit dispersal.

The closest relatives of the familiar pine and spruce trees are _____.

Gnetophytes, cycads, and ginkgos.

The internal fertilization that occurs prior to shell deposition has what type of analog in angiosperms?

Growth of pollen tube and delivery of sperm nuclei.

Harold and Kumar are pre-med and pre-pharmacy students, respectively. They complain to their biology professor that they should not have to study about plants because plants have little relevance to their chosen professions. Which adaptations of land plants are likely to provide Harold with future patients?

II and III

Many mammals have skins and mucous membranes that are sensitive to phenolic secretions of plants like poison oak (Rhus). These secondary compounds are primarily adaptations that _____.

Inhibit herbivory.

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

It lacks gametangia.

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

Male gametophyte.

Stamens, sepals, petals, carpels, and pinecone scales are all _____.

Modified leaves.

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

Pollen.

If one were to propose a new taxon of plants that included all plants that are pollinated by animals, and only plants that are pollinated by animals, then this new taxon would be _____.

Polyphyletic.

Refer to the paragraph on scarlet gilia. Late in the season, when only hawk moths were present, researchers painted the red flowers white. What would you expect?

Red flowers painted white would produce more fruits than red flowers would.

The shell of a fertilized animal egg has what type of analog in angiosperms?

Seed coat.

A botanist discovers a new species of land plant with a dominant sporophyte, chlorophylls a and b, and cell walls made of cellulose. In assigning this plant to a phylum, which of the following, if present, would be LEAST useful?

Spores.

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

Sporophyte embryos.

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

The pollen grains will have red interiors and blue exteriors.

Which of these is a major trend in land plant evolution?

The trend toward a sporophyte-dominated life cycle.

Immature seed cones of conifers are usually green before pollination, and flowers of grasses are inconspicuously colored. What does this indicate about their pollination?

They are wind pollinated.

Refer to the paragraph on scarlet gilia. Some plants changed their flowers to lighter colors, and some retained the same darker color all season. Which plants do you expect produced more fruit?

Those that changed their color to a lighter shade.

Among plants known as legumes (beans, peas, alfalfa, clover, for example) the seeds are contained in a fruit that is itself called a legume, better known as a pod. Upon opening such pods, it is commonly observed that some ovules have become mature seeds, whereas other ovules have not. Thus, which of the following statements is (are) true? 1. The flowers that gave rise to such pods were not pollinated. 2. Pollen tubes did not enter all of the ovules in such pods. 3. There was apparently not enough endosperm to distribute to all of the ovules in such pods. 4. The ovules that failed to develop into seeds were derived from sterile floral parts. 5. Fruit can develop, even if all ovules within have not been fertilized.

2 and 5

Arrange the following in the correct sequence, from earliest to most recent, in which these plant traits originated. 1. Sporophyte dominance, gametophyte independence. 2. Sporophyte dominance, gametophyte dependence. 3. Gametophyte dominance, sporophyte dependence.

3 → 1 → 2

Suppose that the cells of seed plants, like the skin cells of humans, produce a pigment upon increased exposure to ultraviolet radiation. Rank the following cells, from greatest to least, in terms of the likelihood of producing this pigment. 1. Cells of sporangium. 2. Cells in the interior of a subterranean root. 3. Epidermal cells of sporophyte megaphylls. 4. Cells of a gametophyte.

3, 1, 4, 2

Within a gymnosperm megasporangium, what is the correct sequence in which the following should appear during development, assuming that fertilization occurs? 1. Sporophyte embryo. 2. Female gametophyte. 3. Egg cell. 4. Megaspore.

4 → 2 → 3 → 1

Arrange the following structures from largest to smallest, assuming that they belong to two generations of the same angiosperm. 1. Ovary. 2. Ovule. 3. Egg. 4. Carpel. 5. Embryo sac.

4, 1, 2, 5, 3

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 tall, 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal 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 now enter. The uneaten seeds may subsequently germinate. If a female orchid bee has just left a Brazil nut tree with nectar in her stomach, and if she visits another flower on a different Brazil nut tree, what is the sequence in which the following events should occur? 1. Double fertilization. 2. Pollen tube emerges from pollen grain. 3. Pollen tube enters micropyle. 4. Pollination.

4, 2, 3, 1

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 tall, 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal 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 now enter. The uneaten seeds may subsequently germinate. Animals that consume Brazil nuts derive nutrition mostly from tissue whose nuclei have how many chromosomes?

51

How many chromosomes should be in an embryo sac nucleus?

8

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 a tube cell nucleus?

8

The fruit of the mistletoe, a parasitic angiosperm, is a one-seeded berry. In members of the genus Viscum, the outside of the seed is viscous (sticky), which permits the seed to adhere to surfaces such as the branches of host plants or the beaks of birds. What should be expected of the fruit if the viscosity of Viscum seeds is primarily an adaptation for dispersal rather than an adaptation for infecting host plants. It should ______.

Be nutritious to the dispersing organisms.

Which of the following is NOT functionally important in cells of the gametophytes of both angiosperms and gymnosperms?

Chloroplasts.

Which of the following statements is true of the pine life cycle?

Conifer pollen grains contain male gametophytes.

Conifers and pines both have needlelike leaves, with the adaptive advantage of _____.

Decreased surface area, reducing water loss.

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 tall, 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal 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 now enter. The uneaten seeds may subsequently germinate. 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 _____.

Decreasing their habitat.

If the beetles survive by consuming cycad pollen, then whether the beetles should be considered mutualists with, or parasites of, the cycads depends upon the ____.

Extent to which their overall activities affect cycad reproduction.

Which of the following statements correctly describes a portion of the pine life cycle?

Female gametophytes use mitosis to produce eggs.

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

Female sporophyte.

Which of the following sex and generation combinations directly produces the megasporangium of pine ovules?

Female sporophyte.

Which of the following sex and generation combinations most directly produces the integument of a pine seed?

Female sporophyte.

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

Fern gametophyte bearing only antheridia.

Scarlet gilia (Ipomopsis aggregata) usually has red flowers in an inflorescence of up to 250 flowers. In certain populations in the Arizona mountains, however, the flowers range from red to pink to white. In early summer, most of the flowers were red. Six to eight weeks later, the same individual plants were still present; the flowers ranged from pink to white, and few red flowers were present. The major pollinators early in the season were two species of hummingbirds active during the day; they emigrated to lower elevations, and the major pollinator later in the season was a hawk moth (a type of moth). The hawk moth was most active at sunset and later, and it preferred light pink to white flowers after dark. When hummingbirds were present, more red flowers than white flowers produced fruit. When only hawk moths were present, more white flowers produced fruit (K. N. Paige and T. G. Whitham. 1985. Individual and population shifts in flower color by scarlet gilia: A mechanism for pollinator tracking. Science 227:315-17). Refer to the paragraph on scarlet gilia. What is the significance of measuring fruit production?

It is a measure of pollination success.

he generative cell of male angiosperm gametophytes is haploid. This cell divides to produce two haploid sperm cells. What type of cell division does the generative cell undergo to produce these sperm cells?

Mitosis.

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 tall, 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. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.), a cat-sized rodent, is the only animal 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 now enter. The uneaten seeds may subsequently germinate. 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?

Pollination failure

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

Sporopollenin.

Native peoples traditionally use Brazil nuts to treat stomach ache, inflammation, hypersensitivity, and hepatitis. Consequently, a scientist should be interested in promoting _____.

The evaluation of Brazil nut chemicals for use as potential drugs.

The same bees that pollinate the flowers of the Brazil nut trees also 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 _____.

Why Brazil nut trees do not set fruit in monoculture plantations