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15.1: Introduction to the Plant Kingdom

Difficulty Level: At Grade Created by: CK-12

Lesson 15.1: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Plants are multicelluar prokaryotes with cell walls made of cellulose.

_____ 2. In some plants, the male and female reproductive organs are on different plants.

_____ 3. Some plants have lost the ability to do photosynthesis.

_____ 4. In order to carry out photosynthesis, plants need water, carbon dioxide, and light.

_____ 5. A main purpose of roots is to absorb water and minerals.

_____ 6. During photosynthesis, plants release carbon dioxide into the air and use oxygen and argon.

_____ 7. Because plants photosynthesize, they don't need to carry out cellular respiration.

_____ 8. Plants remove water from the air and into the soil by transpiration.

_____ 9. Weeds are defined as highly desirable plants.

_____ 10. Alternation of generations refers to cycling between haploid to diploid generations.

_____ 11. In plants, gametophytes are haploid.

_____ 12. In plants, sporophytes are haploid.

_____ 13. Plants are believed to have evolved directly from prokaryotic cyanobacteria.

_____ 14. The earliest plants could easily reproduce in a dry environment with almost no water.

_____ 15. Development of a vascular system helped plants colonize dry land.

Lesson 15.1: Critical Reading

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Seed Plants Emerge

For reproduction, early vascular plants still needed moisture. Sperm had to swim from male to female reproductive organs for fertilization. Spores also needed some water to grow and often to disperse as well. Of course, dryness and other harsh conditions made it very difficult for tiny new offspring plants to survive. With the evolution of seeds in vascular plants, all that changed. Seed plants evolved a number of adaptations that made it possible to reproduce without water. As a result, seed plants were wildly successful. They exploded into virtually all of Earth’s habitats.

Why are seeds so adaptive on land? A seed contains an embryo and a food supply enclosed within a tough coating. An embryo is a zygote that has already started to develop and grow. Early growth and development of a plant embryo in a seed is called germination. The seed protects and nourishes the embryo and gives it a huge head start in the “race” of life. Many seeds can wait to germinate until conditions are favorable for growth. This increases the offspring’s chance of surviving even more.

Other reproductive adaptations that evolved in seed plants include ovules, pollen, pollen tubes, and pollination by animals.

  • An ovule is a female reproductive structure in seed plants that contains a tiny female gametophyte. The gametophyte produces an egg cell. After the egg is fertilized by sperm, the ovule develops into a seed.
  • A grain of pollen is a tiny male gametophyte enclosed in a tough capsule (see the figure above). It carries sperm to an ovule while preventing it from drying out. Pollen grains can’t swim, but they are very light, so the wind can carry them. Therefore, they can travel through air instead of water.
  • Wind-blown pollen might land anywhere and be wasted. Another adaptation solved this problem. Plants evolved traits that attract specific animal pollinators. Like the bee in the figure above, a pollinator picks up pollen on its body and carries it directly to another plant of the same species. This greatly increases the chance that fertilization will occur.
  • Pollen also evolved the ability to grow a tube, called a pollen tube, through which sperm could be transferred directly from the pollen grain to the egg. This allowed sperm to reach an egg without swimming through a film of water. It finally freed up plants from depending on moisture to reproduce.


1. Why did early vascular plants need to live in environment where there was plenty of water?

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2. What main advantage do seed plants have over the early spore-producing plants?

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3. Define what a plant seed is.

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4. What is the function of a plant ovule?

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5. How did the evolution of pollen benefit land plants?

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Lesson 15.1: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

  1. The earliest plants had
    1. leaves.
    2. stems.
    3. roots.
    4. none of the above.
  2. The flowers of a Venus fly trap
    1. carry out photosynthesis in the dark.
    2. secrete enzymes that can digest trapped insects.
    3. thrive in temperatures below freezing.
    4. all of the above
  3. Plants need oxygen because
    1. they carry out cellular respiration just like all other aerobic organisms.
    2. oxygen is consumed during photosynthesis to make carbon-containing organic molecules.
    3. the earth's atmosphere contains too much oxygen and too little carbon dioxide.
    4. none of the above
  4. Humans get which of the following kinds of products from plants?
    1. medicines
    2. dyes
    3. rubber
    4. all of the above
  5. Red-eyed tree frogs
    1. are green and do photosynthesis, so they do not need to eat or drink.
    2. are not frogs, because frogs never have red eyes.
    3. live in banana trees.
    4. none of the above
  6. When plants are transplanted into a new habitat that is not their native one,
    1. they always die immediately.
    2. due to a lack of predators and parasites in their new environment, they sometimes reproduce and spread so well that they outcompete native plants.
    3. they stop producing seeds and start making spores.
    4. they become parasitic plants.
  7. Vegetative reproduction is
    1. a type of asexual reproduction.
    2. a type of sexual reproduction.
    3. reproduction using seeds.
    4. reproduction using spores.
  8. Lignin
    1. is needed directly for photosynthesis.
    2. is a red pigment.
    3. provides structural support and waterproofing to plants.
    4. is the female reproductive cell in seed plants.

Lesson 15.1: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.


_____ 1. a seed-containing, ripened ovary

_____ 2. the diploid generation produced by sexual reproduction

_____ 3. a reproductive structure in angiosperms; may contain pollen and egg cells

_____ 4. modern seed plants that produce seeds in cones

_____ 5. flower-producing plant

_____ 6. a reproductive structure (present in flowers) that contains the female gametophyte

_____ 7. a water-proofing and strength-providing molecule in plant cell walls

_____ 8. a type of life cycle during which plants alternate between haploid and diploid generations

_____ 9. a structure for water absorption in nonvascular plants

_____ 10. a form of asexual reproduction from stem, roots or leaves

_____ 11. seed container in gymnosperms

_____ 12. haploid individuals produced by asexual reproduction


a. alternation of generations

b. angiosperm

c. cone

d. flower

e. fruit

f. gametophyte

g. gymnosperm

h. lignin

i. ovary

j. rhizoid

k. sporophyte

l. vegetative reproduction

Lesson 15.1: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. __________ occurs when the plant embryo grows and bursts through the seed coat.

2. __________, which contains male gametes, can be transported by wind and by insects.

3. __________ transports water from the roots, through the stem, and to the leaves.

4. A __________ is considered to be an unwanted plant.

5. Plants producing flowers are classified as __________.

6. Plants producing seeds in cones are classified as __________.

7. A water-absorbing structure in nonvascular plants is the __________.

8. Production of a new plant from a stem is a form of __________.

9. In a plant such as a fern, the diploid generation is called a __________.

10. In a plant such as a fern, the haploid generation is called a __________.

11. A __________ often contains petals, pollen, and one or more ovaries.

12. A __________ is a ripened ovary that contains seeds.

Lesson 15.1: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Name and describe several factors limiting the spread of nonvascular plants such as liverworts, hornworts, and mosses.

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