Chapter 30
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. How many chromosomes should be in a megasporangium nucleus?
16
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. How many chromosomes should be in an embryo nucleus after fertilization?
16
Human survival depends on the produce of __________.
angiosperms
A stamen consists of _____.
anther and filament
In pines, the female gametophyte contains _____, each of which contains a(n) _____.
archegonia ... egg
Which arranges the structures from largest to smallest, assuming that they belong to two generations of the same angiosperm?
carpel, ovary, ovule, embryo sac, egg
What statement about the pine life cycle is correct?
conifer pollen grains contain male gametophytes
What function is an advantage of seeds compared to spores?
containing a nutrient store for a developing sporophyte
In spruces and pines, what is an advantage of having needlelike leaves?
decreased surface area, reducing water loss
Which adaptations of land plants are likely to cause human health problems?
defenses against being eaten & adaptations related to wind dispersal of pollen
What is the process by which a trait present in an ancestral organism is modified by natural selection over time in descendants of that ancestor?
descent with modification
The embryo is...
diploid
The sporophyte generation is...
diploid
When you look at a pine or maple tree, the plant you see is a __________.
diploid sporophyte
What is unique to flowering plants?
double fertilization
What is a correct statement describing the life cycle of angiosperms?
double fertilization in the life cycle of seed plants results in the production of a diploid zygote and a triploid endosperm nucleus
What is a characteristic of all angiosperms?
double internal fertilization
After fertilization of the ovule, the _____ develops into the embryo of the mature seed
embryo
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 is similar to which structures in angiosperms?
endosperm
Suppose that the cells of seed plants, like the cells of human skin, produce a pigment upon increased exposure to ultraviolet radiation. What types of plant cells is most likely to produce this pigment?
epidermal cells of sporophyte megaphylls
In pine, the embryo develops within the __________.
female gametophyte
In gymnosperms, megaspores develop into __________.
female gametophytes
What statement correctly describes a portion of the pine life cycle?
female gametophytes use mitosis to produce eggs
What generation in the conifer cycle directly produces the megasporangium of pine ovules?
female sporophyte
What generation in the conifer life cycle most directly produces the integument of a pine seed?
female sporophyte
What structures directly produces the fruit of angiosperms?
female sporophyte
Which answer arranges the characteristics of plants in the order in which they evolved, from most ancient to most recent?
gametophyte dominance, sporophyte dependence; -> sporophyte dominance, gametophyte independence; -> sporophyte dominance, gametophyte dependence
In plants, the ________ produces haploid gametes (eggs and sperm) by mitosis, whereas the ________ produces haploid spores by meiosis.
gametophyte; sporophyte
Which organisms are the closest relatives of pine and spruce trees?
gnetophytes, cycads, and ginkgos
The gametophyte generation is...
haploid
The megaspore is...
haploid
In the pine, microsporangia form _____ microspores by _____.
haploid ... meiosis
Imagine that you wanted to know if speciation is more rapid in plant groups pollinated by bees or hummingbirds. To do this, you identified 20 genera of angiosperms that contained species pollinated by both types of animals. There were substantially more species in the groups that were pollinated by bees. What conclusions are most consistent with your data?
hummingbirds promoted speciation less than did bees
In pines, an embryo is a(n) _____.
immature sporophyte
Within a gymnosperm megasporangium, what develops before the others after fertilization occurs?
megaspore
In pine trees, pollen grains get to the ovule via the _____.
micropyle
In angiosperms, what is correctly paired with its chromosome count?
microspore - n
What characteristic is functionally important in gametophyte cells of both angiosperms and gymnosperms?
mitochondria
What type of cell division does the generative of a male angiosperm gametophyte cell undergo to produce sperm cells?
mitosis
Stamens, sepals, petals, carpels, and pinecone scales are types of what structures?
modified leaves
Of the four haploid cells produced by a pine cone's megasporocyte (megaspore mother cell), _____ survive(s).
one
What is present in angiosperms but not in gymnosperms?
ovaries
What contains multiple gymnosperm ovules?
ovulate cone
What is a characteristic that distinguishes gymnosperms and angiosperms from other plants?
ovules
Unlike most angiosperms, grasses are pollinated by wind. As a consequence, some unnecessary parts of grass flowers have almost disappeared. What parts would you expect to be most reduced in a grass flower?
petals
In addition to seeds, which of the following characteristics is unique to seed-producing plants?
pollen
The adaptation that made possible the colonization of dry land environments by seed plants is most likely the result of the evolution of _____.
pollen
What is a key feature of seed plants facilitating life on land?
pollen
The male gametophytes of flowering plants are also referred to as _____.
pollen grains
What problems will likely increase if the human population continues to increase?
reduction in plant & animal diversity
In flowering plants the integuments of the ovule develop into a(n) _____.
seed coat
Gymnosperms were most abundant during the _____.
Mesozoic
What is a structure that is a separate generation from the plant sporophyte?
a male gametophyte within a pollen grain
What pair do the structures play comparable roles in the plant & animal life cycles?
a plant sporophyte & an adult animal
Which of the following arranges the structures found on male pine trees from the largest structure to the smallest?
sporophyte, pollen cone, microsporangia, microspores, pollen nuclei
In seed plants, what is part of a pollen grain and has a function most like that of the seed coat?
sporopollenin
In angiosperms, pollination is the transfer of pollen grain to the _____ of a flower on the same plant or another plant of the same species.
stigma
A carpel is composed of _____.
stigma, style, ovary
One day, you go outside and see that the cars on the street are covered in a yellow "dust." What statement can be correctly applied to this "dust"?
the dust is pine pollen and is so abundant because the pines are wind-pollinated
Which feature of cycads makes them similar to many angiosperms?
they are pollinated by animals
Immature seed cones of conifers are usually green before pollination, and flowers of grasses are inconspicuously colored. What does this indicate about how they are pollinated?
they are probably wind pollinated
Which feature of cycads distinguishes them from most other gymnosperms?
they are wind pollinated
Many mammals have skins and mucous membranes that are sensitive to secretions of plants like poison oak. These secondary compounds are primarily adaptations that function in which way?
to inhibit herbivory
Where in an angiosperm would you find a megasporangium?
within an ovule contained within an ovary of a flower
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. How many chromosomes should be in a generative cell nucleus?
8
What is found inside a pollen grain?
the male gametophyte
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. How many chromosomes should be in an endosperm nucleus?
24
In onions (Allium), cells of the sporophyte have 16 chromosomes within each nucleus. How many chromosomes should be in a tube cell nucleus?
8
All seed plants _____.
are heterosporous
Theobroma cacao (cacao) is the tree that produces seeds that are turned into chocolate. These trees provide many poor people in the tropics with some cash income. However, these farmers face many obstacles to production of their crop, including temperature and rainfall changes caused by atmospheric CO2 increases, and many diseases and pests. Analysis of the cacao genome showed that there is some (but not a lot) of genetic variation in the 10 major varieties. What strategy would be most useful in the long term in reducing pressures faced by cacao farmers?
crossbreed cacao strains that produce high-quality cacao beans and ones resistant to a disease
The internal parts of the pollen grains of seed-producing plants are most similar to what structures in seedless plants?
fern gametophyte bearing only antheridia
Angiosperms are different from all other plants because only they have _____.
flowers
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 internal fertilization that occurs in egg-laying animals prior to shell deposition is similar to what process in angiosperms?
growth of pollen tube & delivery of sperm nuclei
After fertilization of the ovule, the _______ develops into the seed coat
integument
What statement is true about the gametophyte tissue that surrounds the pine embryo?
it functions as a haploid food reserve
What is a characteristic that would best support your assertion that a particular plant is an angiosperm?
it lacks gametangia
The Brazil nut tree, Bertholletia excels, is native to tropical rain forests of South America and produces large nuts. The large white part of a Brazil nut that people eat serves what function in nature?
it provides energy & nutrition to a germinating seeding
What statement are correct with regard to what physicians and pharmacists need to know about plants?
land plants produce poisons & medicines
What structure most directly produces the pollen tube of angiosperms?
male gametophyte
After fertilization of the ovule, the _____ develops into the food supply of the mature seed
megaspore
What are the products of meiosis in the life cycle of a seed plant?
megaspores or microspores
The Brazil nut tree, Bertholletia excels, is native to tropical rain forests of South America. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and admit only female orchid bees as pollinators. 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 events should occur?
pollen transfer, pollen tube emerges from pollen grain, pollen tube enters micropyle, double fertilization
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. What statement best explains this observation?
pollen tubes did not enter all of the ovules in such pods, and fruit can develop even if all ovules within have not been fertilized.
What could best be investigated by measuring fruit production in plants?
pollination success
The major difference between angiosperms and gymnosperms comes from the __________.
presence or absence of a protective covering over the ovule
What describes a difference between wind-pollinated angiosperms compared with animal pollinated plants? Wind pollenated plants ________.
produce much more pollen because winds disperse pollen randomly
What is a statement that best describes an advantage of the reduced gametophytes in seed plants?
protection from drying out
What are the main components of a mature gymnosperm seed?
seed coat, embryo, & food supply
Why is seed dormancy adaptive for many plant species?
seed dormancy allows seeds to germinate when conditions are favorable for seedling growth
What statement describes a difference between seed plants and ferns?
seed plants produce two kinds of spores
The Brazil nut tree, Bertholletia excels, is native to tropical rain forests of South America. 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 into which moisture can then enter and allow the remaining seeds to germinate. The agouti is most directly involved in dispersal in which structure?
sporophyte embryos
The Brazil nut tree, Bertholletia excels, is native to tropical rain forests of South America. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilize themselves and 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. What statement best explains the failure to cultivate Brazil nut trees in these other locations?
the flowers were not pollinated due to the absence of female orchid bees
Mistletoe is a plant that lives on trees and gains nutrition from them (that is, it is a parasite). The fruit of the mistletoe is a one-seeded berry and is consumed by birds. In members of the mistletoe genus Viscum, the outside of the seed is 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 stickiness of Viscum seeds is primarily an adaptation for dispersal rather than an adaptation for infecting host plant tissues?
the fruit is nutritious to the dispersing organisms
A researcher has developed two stains to use for visualizing different tissues of 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 will he/she/they most likely observe?
the pollen grains will have red interiors and blue exteriors
What is the most beneficial adaptation of the seed coats in angiosperm species whose seeds are dispersed by fruit-eating animals, as opposed to angiosperm species whose seeds are dispersed by other means?
the seed coat should be resistant to the animal's digestive enzymes
What is a major trend in land plant evolution over the past 200 million years?
the trend toward a sporophyte-dominated life cycle
