Section Outline

Section 24-1 24 –1 Reproduction With Cones and Flowers

A. Alternation of Generations B. Life Cycle of Gymnosperms 1. Pollen Cones and Seed Cones 2. Pollination 3. Fertilization and Development C. Structure of Flowers 1. Sepals and Petals 2. Stamens and Carpels D. Life Cycle of Angiosperms E. Pollination F. Fertilization in Angiosperms Go to Section:

Compare/Contrast Table

Section 24-1 Comparing Wind-pollinated and Animal-pollinated Plants Characteristics

Pollination method Relative efficiency of pollination method Plant types

Wind-pollinated Plants

Wind pollination Less efficient

Animal-pollinated Plants

Vector pollination More efficient Reproductive organs Adaptations that promote pollination Mostly gymnosperms and some angiosperms Angiosperms Cones Pollination drop Flowers Bright colors, sweet nectar Go to Section:

Figure 24–1 Evolution of the Gametophyte and the Sporophyte

Section 24-1

Gametophyte (N) Sporophyte (2N) Go to Section: Bryophytes Ferns Seed plants

Section 24-1

Figure 24–4 The Life Cycle of a Gymnosperm

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Section 24-1

Figure 24–5 The Structure of a Flower

Stamen Anther Filament Stigma Style Carpel Ovary Go to Section: Ovule Sepal Petal

Figure 24–7 The Life Cycle of an Angiosperm

Section 24-1

Anther (2N) Pollen grains (N) (male gametophyte) Haploid (N) Diploid (2N) Stigma Pollen tubes Style

MEIOSIS

Haploid cell (N) Ovary Seedling (2N) Mature sporophyte (new sporophyte) Endosperm Ovule Embryo sac (N) (female gametophyte) Egg cell Sperm Pollen tube Endosperm nuclei Embryo Endosperm (3N) (2N)

FERTILIZATION

Seed coat Fruit Zygote (2N) Go to Section:

Interest Grabber

Section 24-2 From Fruits to Nuts

Walk into any supermarket and you will likely see a variety of fruits. Would it surprise you to learn that many of the foods that you think of as vegetables, grains, and nuts are actually fruits?

1. Name three fruits that you have eaten.

2. Describe any seeds you found in the fruits.

3. What function do you think the fruit and seeds serve for a plant?

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Section 24-2

Section Outline

24 –2 Seed Development and Germination

A. Seed and Fruit Development B. Seed Dispersal 1. Dispersal by Animals 2. Dispersal by Wind and Water C. Seed Dormancy D. Seed Germination Go to Section:

Section 24-2

Concept Map

Monocots have 1 Cotyledon that Remains with the seed

Seed Germination

in Dicots have 2 Cotyledons that Emerge above ground Remain below ground Go to Section:

Interest Grabber

Section 24-3 Rooting for a Plant

People who have gardens or houseplants often grow extra plants by making cuttings —leafy stem pieces or small sprigs of plants—that are then partially buried in soil or in a special rooting mixture to “root.” In this process, the cut stems develop roots. When the roots are large enough, the cutting is potted or put into the ground, where it grows into a complete plant. This process works well with many plants, including begonias, geraniums, coleus, African violets, forsythia, and willow.

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Section 24-3

Interest Grabber

continued

1. For a gardener, what might be an advantage of growing plants from cuttings rather than from seeds?

2. Herbaceous plants, such as coleus, root faster than do woody plants, such as willow. How would you explain this difference?

3. How would plants grown from cuttings compare to the plant from which the cuttings were taken? Why would this be an advantage for a gardener?

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Section 24-3

Section Outline

24 –3 Plant Propagation and Agriculture

A. Vegetative Reproduction B. Plant Propagation 1. Cuttings 2. Grafting and Budding C. Agriculture 1. Worldwide Patterns of Agriculture 2. Changes in Agriculture Go to Section:

Compare/Contrast Table

Section 24-3 Method Cuttings Grafting Budding Comparing Plant Propagation Methods Procedure

A length of stem that includes lateral buds is cut from the parent plant and partially buried in soil or rooting mixture to take root.

A piece of stem is cut from the parent plant and attached to another plant.

A piece of lateral bud is cut from the parent plant and attached to another plant.

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Video

Life Cycle of Angiosperms QuickTime™ and a decompressor are needed to see this picture.

Click the image to play the video segment.

Go Online

Links from the authors on genetically designing flowers Interactive test Articles on agriculture For links on seed structure and function, go to www.SciLinks.org

enter the Web Code as follows: cbn-7242.

and

Interest Grabber Answers

1. What are some ways in which male reproductive cells in pollen might reach female reproductive cells?

Possible answers: pollen is carried on the wind, by animals, or by moving water.

2. How does the pollen adhere to the female reproductive structure?

The top of the female reproductive structure (stigma) is sticky.

3. Many people experience allergic reactions when pollen grains enter their respiratory systems. How do you think the pollen reached their bodies?

Pollen is carried on the wind; when people inhale, they take in the pollen. People can also get pollen into their bodies by touching first a plant and then their faces.

4. How might people who are allergic to pollen reduce their exposure to it?

Students may suggest that people wash their hands after handling plants or stay indoors when the pollen count is high.

Interest Grabber Answers

1. Name three fruits that you have eaten.

Possible answers: apples, strawberries, grapefruit, oranges 2. Describe any seeds you found in the fruits.

Small seeds in the apple core, tiny seeds on the outside of berries, large seeds within grapefruit sections, smaller seeds within orange sections 3. What function do you think the fruit and seeds serve for a plant?

Fruit attracts animals that spread seeds; seeds allow new plants to grow.

Interest Grabber Answers

1. For a gardener, what might be an advantage of growing plants from cuttings rather than from seeds?

Growing plants from cuttings is faster than growing them from seeds. Also, there is no need to shop for seeds.

2. Herbaceous plants, such as coleus, root faster than do woody plants, such as willow. How would you explain this difference?

Woody plants grow slowly, so it makes sense that they would develop roots slowly, too.

3. How would plants grown from cuttings compare to the plant from which the cuttings were taken? Why would this be an advantage for a gardener?

They would be just like the original plant. This is an advantage if the gardener wants many identical plants.

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