28. Plants

Seed Plants

Explain the difference between homosporous and heterosporous plants. Where are the microsporangium and megasporangium found in a tulip? What happens to the spores that are produced by these structures?

Angiosperms Vs Gymnosperms  |Quick differences in 3 minutes |

Gymnosperms and Conifers (honors updated)

 Only angiosperm pollen grains form pollen tubes. 

 No. Both types of seed plants have pollen grains that form pollen tubes. 

 Double fertilization only occurs in gymnosperms. 

 No. Double fertilization is more prevalent in angiosperms. In angiosperms, one sperm fertilizes the egg and another fuses with two nuclei, forming endosperm. In some gymnosperms, double fertilization results in two embryos. 

 Only gymnosperms can contain male and female sporangia on the same plant. 

 No. Most angiosperms contain male and female sporangia within the same flower. 

 Only angiosperms have reduced gametophytes. 

 No. This is a trait of all seed plants. 

 Only the sperm of angiosperms combine with two central cell nuclei to form triploid endosperm. 

Consider the nutrient source for an embryonic angiosperm.

Of the following, which is a difference in how reproduction occurs in gymnosperms compared to angiosperms?

 No. The pollen grain carries the male gamete. The ovule houses the female gametophyte and develops into the seed coat. 

 No. The ovary develops into a fruit, and the ovule houses the female gametophyte and develops into the seed coat. 

 No. Fertilization of the egg gives rise to an embryo. The female gametophyte, which produces the egg, is housed within the ovule. 

 No. Fertilization of the egg gives rise to an embryo, which is contained within a seed. However, the ovary does develop into a fruit. 

Consider where the female gametophyte is found.

After fertilization, the __________ develops into a seed, and the __________ develops into a fruit.

 No. This is an adaptation common to all seed plants, but there is a better answer. 

 All of the listed responses are correct. 

Consider the general trends seen in the evolution of plants.

Which of the following adaptations is common to all seed plants?

 No. Gametophytes produce the male and female gametes. 

 No. The mature ovules are enclosed within the fruit. 

 No. The ovules are contained within the ovary, the wall of which will later develop into fruit. 

When seed plants reproduce, what do they make?

The eggs of seed plants are fertilized within ovules, and the ovules then develop into __________.

 union of the two sperm nuclei, forming a zygote 

 union of one sperm nucleus with the egg nucleus and the disintegration of the other sperm nucleus 

 fusion of both sperm nuclei with the egg nucleus and the formation of a triploid zygote 

 No. The embryo sac is the female gametophyte. 

 union of one sperm nucleus with the egg nucleus and of the other sperm nucleus with two nuclei of the central cell, forming a triploid nucleus called the endosperm 

This process is unique to angiosperms.

The pollen tube releases two sperm cells into the embryo sac. The result of this is the __________.

 Seeds can survive for extended periods of time at reduced metabolic rates. 

 Seeds are single cells, demanding fewer nutrients from the parent plants. 

 Seeds can survive even in conditions that are unfavorable for the parent plants. 

 No. This is true, but spores can also survive under such conditions. 

 Most seeds are poisonous; therefore, they are not consumed by animals and persist in the environment for long periods of time. 

 No. It is not true to say that most seeds are poisonous. When an animal consumes seeds, it is often facilitating seed dispersal. 

 Seeds contain embryonic plants, an abundant food supply, and a protective covering. 

If you were going on a long trip in a hostile environment, how would you prepare for it?

Which of the following best states the advantages that seeds have over spores?

Gymnosperms and angiosperms have the following in common except
a. seeds.
b. pollen.
c. ovaries.
d. ovules.

Seed Plants - 1

 The sperm of gymnosperms do not require water or mobility for fertilization. 

 No. This is not evidence of a transition. The sperm of seed plants do not require water or mobility to fertilize an egg. 

 Some gymnosperms do not have reduced gametophytes. 

 No. Reduced gametophytes are a characteristic of all seed plants. 

 No. This is true, but it is not evidence of a transition from seedless to seed plants. 

 In gymnosperms, two sperm are discharged into the pollen tube. 

 The sperm of some gymnosperms have flagella. 

How did seedless plants reproduce?

Which of the listed examples is evidence provided by living gymnosperms of an evolutionary transition between seedless and seed plants?

Which of the following is not a characteristic that distinguishes gymnosperms and angiosperms from other plants?
a. dependent gametophytes
b. ovules
c. pollen
d. alternation of generations

Seed Plants: Gymnosperms

How did plants Evolve?

 No. Cross-pollination could be due to wind, but so could self-pollination. 

 No. Cross-pollination could be due to insects, but so could self-pollination. 

 its source of pollen is a different species of plant 

 No. The pollen source must be a plant of the same species. 

 pollen grains are transferred from a different flower on the same plant 

 pollen grains are transferred to a flower on a different plant 

"Cross" as in "not self."

A plant is said to be cross-pollinated if __________.

You have been hired as a field assistant for a researcher interested in the evolution of flower characteristics in orchids. Design an experiment to determine whether color, size, shape, scent, or amount of nectar is the most important factor in attracting pollinators to a particular species. Assume that you can change any flower’s color with a dye and that you can remove petals or nectar stores, add particular scents, add nectar by injection, or switch parts among species by cutting and gluing.

 Pollen grains with three openings, floral parts in multiples of three, netlike veins 

 No. Eudicots have floral parts in multiples of five. 

 One cotyledon, vascular bundles in rings, pollen grains with three openings 

 Scattered vascular bundles, netlike veins, floral parts in multiples of five 

 No. Eudicots have vascular bundles arranged in rings. 

 Leaves with parallel veins, taproot usually present, vascular bundles arranged in rings 

 No. Eudicots have leaves with netlike veins. 

 Two cotyledons, netlike veins, taproot usually present 

Review the general characteristics of monocots and eudicots.

Which of the following lists of features characterizes eudicots?

Seed Plants - 3

 No. This phylum includes the angiosperms. 

No. This phylum contains the genera Gnetum, Ephedra, and Welwitschia.

 No. This phylum consists of about 600 species of conifers. 

No. The only extant species of this phylum is Ginkgo biloba.

Review gymnosperm diversity.

Which gymnosperm phylum is characterized by large cones and fern-like leaves and thrived during the Mesozoic?

 No. The ovary wall gives rise to the pericarp. 

 No. The receptacle is part of the flower stem. 

 No. Endosperm is a nutritive tissue for the developing embryo. 

 No. The embryo and its food supply are enclosed by a seed coat formed from the integuments of the ovule. 

This is one of the major differences between angiosperms and gymnosperms.

In gymnosperms, the seed coat develops from the integument. In angiosperms, the seed coat develops from the __________.

Seed Plants | Biology | Botany

With respect to angiosperms, which of the following is incorrectly paired with its chromosome count?
a. egg—n
b. megaspore—2n
c. microspore—n
d. zygote—2n

Key features of seed plants facilitating life on land include three of the following four traits. Select the exception.
a. homospory
b. pollen
c. reduced gametophytes
d. seeds

Seed Plants - 4

Introduction to Seed Plants

 No. The carpel is the female part of a flower. 

 No. The seed is the mature ovule that surrounds the embryo and endosperm. 

The result is the production of a nutritive tissue.

The triploid nucleus of the embryo sac develops into the __________.

Where in an angiosperm would you find a megasporangium?
a. in the style of a flower
b. enclosed in the stigma of a flower
c. within an ovule contained within an ovary of a flower
d. packed into pollen sacs within the anthers found on a stamen

 No. The ovary is the site of ovum production, and ova are not transferred during pollination. 

 No. The stigma, style, and ovary are all parts of the carpel. 

 No. A sepal is a structure that encloses and protects the flower bud. 

 No. The stigma forms a portion of the carpel. 

The male gamete travels to the female gamete.

During pollination, pollen grains are transferred from the __________ to the __________.

No. Ginkgophytes are members of a group of gymnosperms including Ginkgo biloba.

 No. The microsporocytes give rise to microspores by way of meiosis. 

 No. These are found in ovulate cones and give rise to megaspores by way of meiosis. 

 No. The pollen grain contains the male gametophyte. A fertilized ovule would be found in the ovulate cone after fertilization. 

Sperm are produced in the pollen grain.

Each pollen grain of a gymnosperm contains a __________.

 No. The gametophyte is the haploid generation. 

 is larger and more conspicuous than the haploid stage 

 No. In mosses and bryophytes, the haploid stage is larger and more conspicuous than the diploid stage. 

 No. The diploid generation develops from a fertilized gamete. 

Remember that this question refers to all types of plants.

The diploid generation of the plant life cycle always __________.

 No. An ovule contains the female gametophyte and develops into the seed coat, not into the pea pod. Only a portion of the carpel is involved in the formation of the pea and pea pod. 

 No. The ovary does develop into the pea pod. However, a pollen grain, which carries the male gamete, does not develop into the pea. 

 No. The anther houses sporangia, which give rise to the male gametophyte. However, the pea does develop from the ovule and the tissues that it surrounds. 

 No. Endosperm is a food source found within a seed. The ovary develops into the fruit, not into the pea. 

A pea pod is a fruit.

A pea pod is formed from __________. A pea inside the pod is formed from __________.

 The sporophyte is dependent on the gametophyte. 

 No. In seed plants, the sporophyte is not dependent on the gametophyte. 

 The sporophyte is large, and the gametophyte is small and independent. 

 No. The seed plant gametophyte is not independent. 

 The spore is the main means of dispersing the offspring. 

 No. For seed plants, seeds are the main means of dispersing offspring. 

 A film of water is necessary for sperm to come in contact with eggs. 

 No. This is true of the flagellated sperm found in most seedless plants. 

 The gametophyte is reduced and dependent on the sporophyte. 

Which one of the following is true of seed plants but not true of seedless plants?

 No. Meiosis produces haploid megaspores. 

 Depending on environmental conditions, any of the listed responses may occur. 

 No. Megasporocytes always give rise to megaspores through meiosis. 

Review the gymnosperm life cycle.

In ovulate cones, megasporocytes undergo __________ and produce __________ megaspores.

Which of the following is a key feature of seed plants facilitating life on land?
(A)homospory
(B)pollen
(C)reduced sporophytes
(D)spores

 No. The filament is a stalk that bears the anther. 

 No. The style connects the stigma to the ovary. 

It is the uppermost portion of the carpel, and it is sticky.

The portion of a flower that receives the pollen is the __________.

 No. Nectar, for example, rewards pollinators. Fruit production is a result of successful pollination, but it usually occurs much later. 

 Food storage for the plant to use over the winter 

 No. Plants do not use fruit for the storage of food. It takes a lot of energy to maintain fruit; therefore, fruit usually drops from the plant before winter. 

 To distract herbivores from eating the leaves 

 No. The function of fruit is the dispersal and protection of seeds. 

 Depending on the plant species, any of the listed responses are possible. 

 No. When seeds develop from ovules, the ovary of a flower develops into a fruit, which protects the enclosed seeds and aids in their dispersal by wind or animals. 

Consider what you find in fruits.

Which of the following best describes the function of fruits?

Seed Plants - 2

 No. Until the late 1990s, these are the two groups that systematists used. 

No. The group formerly called dicots was divided into three new groups. Most of the dicots were placed in a group called eudicots.

No. The vast majority of species traditionally called dicots are now known as eudicots. The others are divided into several small lineages.

Add the prefix for "true."

The vast majority of angiosperms with two cotyledons formerly classified as __________ are now classified as __________.

 No. These six crops account for 80% of the calories consumed by humans. 

The number is staggering and has major ramifications for food supply safety.

Six major crops&#152;wheat, rice, maize, potatoes, cassava, and sweet potatoes&#152;contribute disproportionately to human diets. What percentage of all the calories consumed by humans is supplied by these crops?

 An asteroid hit Earth, leading to mass extinctions that made way for gymnosperms to take over lands where other plants had perished. 

 No. Many hypothesize that an asteroid collision may have led to the mass extinctions that occurred at the end of the Mesozoic. The planet has gradually cooled since, and angiosperms now dominate most terrestrial ecosystems. 

 Reptiles decreased in diversity and were replaced with amphibians better adapted for seed dispersal. 

 No. Actually, reptiles increased in diversity during this period. 

 The breakup of Pangaea changed the flora and fauna of Earth dramatically. 

 No. The formation of Pangaea may have been one reason for the climate change that occurred during the Permian. 

 No. Gymnosperm pollen is spread by wind, not by insects. 

What type of climate shift would favor an organism that does not require water for reproduction?

What global change occurring between the Carboniferous period and the Permian period likely contributed to the success of the gymnosperms?

 No. The process can take a year or longer. 

 No. It takes nearly three years to produce the male and female gametophytes, bring them together during pollination, and form mature seeds from the fertilized ovules. The period from pollination to fertilization takes about one year of that time. 

 Pollination occurs after fertilization. 

 No. Certainly not. Pollination is the process in which pollen comes in contact with parts of the plant containing ovules. This contact must occur in order for fertilization to occur. 

Review the gymnosperm life cycle. The question is asking about fertilization, not about the production of mature seeds.

In a typical conifer, how long does it take for fertilization to occur after pollination?

 No. Angiosperm flowers are lovely, but they are not critical for human survival. 

 No. It would be difficult to argue that sepals in general are important to human survival. 

 No. Bark is used for mulch and to make paper, but these are not crucial to human survival. 

 No. Cones are not produced in angiosperms. 

What other uses do humans have for angiosperms, besides food and medicine?

Besides the plant tissue that humans ingest, which angiosperm tissue is most directly important for human survival?

 No. Sepals protect the flower prior to its opening, and they are often photosynthetic. 

 No. Ovaries are female reproductive structures. 

 No. Fruits play a role in seed dispersal. 

Consider which of these is used to attract pollinators.

Like gymnosperms, many grasses and angiosperm trees are wind-pollinated. To conserve energy, these angiosperms do not produce complete flowers (complete flowers have all four of the basic parts). Which part would be unnecessary for wind-pollinated angiosperms?

 No. Seedlings sprout from dispersed seeds after germination. 

 No. These would be found in ovulate cones. 

 No. These would be found in ovulate cones after pollination. 

Cones produce spores.

What is located in the scalelike structures packed densely in pollen cones?

 No. The pollen grain is the male gametophyte (haploid) and produces the sperm. 

 No. However, this choice is partially correct. 

Pollen is produced by microsporangia.

The cells within pollen grains are __________ and together comprise the __________.

Angiosperms such as grasses, oaks, and maples are wind pollinated. The ancestors of these subgroups were probably pollinated by insects, however. As an adaptive advantage, why might a species “revert” to wind pollination? (Hint: Think about the costs and benefits of being pollinated by insects versus wind.) Why is it logical to observe that wind-pollinated species usually grow in dense stands containing many individuals of the same species? Why is it logical to observe that in wind-pollinated deciduous trees, flowers form very early in spring—before leaves form?

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