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# 9.22: Angiosperm Life Cycle

Difficulty Level: At Grade Created by: CK-12
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Practice Angiosperm Life Cycle
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What's the most successful type of plant?

Flowering plants. Why? As you know, flowers come in many different styles and colors, and many are visually pleasing. This aids in pollination. Also notice the anatomy of this Hibiscus flower. Each part has evolved to play a role in the life cycle.

### Life Cycle of Angiosperms

Angiosperms, or flowering plants, are the most abundant and diverse plants on Earth. Angiosperms evolved several reproductive adaptations that have contributed to their success. Like all vascular plants, their life cycle is dominated by the sporophyte generation. A typical angiosperm life cycle is shown in Figure below.

Life cycle of an angiosperm.

The flower in Figure above is obviously an innovation in the angiosperm life cycle. Flowers form on the dominant sporophyte plant. They consist of highly specialized male and female reproductive organs. Flowers produce spores that develop into gametophytes. Male gametophytes consist of just a few cells within a pollen grain and produce sperm. Female gametophytes produce eggs inside the ovaries of flowers. Flowers also attract animal pollinators.

If pollination and fertilization occur, a diploid zygote forms within an ovule in the ovary. The zygote develops into an embryo inside a seed, which forms from the ovule and also contains food to nourish the embryo. The ovary surrounding the seed may develop into a fruit. Fruits attract animals that may disperse the seeds they contain. If a seed germinates, it may grow into a mature sporophyte plant and repeat the cycle.

See Life Cycle of a Flowering Plant at http://www.neok12.com/php/watch.php?v=zX7a67634c734659570d7845&t=Pollination for additional information.

### Summary

• In flowering plants, the gametophyte generation takes place in a flower, which forms on the mature sporophyte plant.
• Each male gametophyte is just a few cells inside a grain of pollen. Each female gametophyte produces an egg inside an ovule.
• Pollination must occur for fertilization to take place. Zygotes develop into embryos inside seeds, from which the next sporophyte generation grows.

### Practice

Use these resources to answer the questions that follow.

• http://www.hippocampus.org/Biology \begin{align*}\rightarrow\end{align*} Biology for AP* \begin{align*}\rightarrow\end{align*} Search: Cones, Flowers, and Seeds
1. Distinguish between the stamen and carpel.
2. What is the ovary?
3. Where is pollen produced?
4. How is pollen usually delivered?
5. How does sperm reach the egg?
• http://www.hippocampus.org/Biology \begin{align*}\rightarrow\end{align*} Biology for AP* \begin{align*}\rightarrow\end{align*} Search: Sexual Reproduction
1. How do haploid spores and gametophytes form?
2. Where does a seed come from?
3. Where does a fruit come from?
4. Describe the structure and function of the stamen.
5. Describe the structure and function of the carpel.
6. What is the female gametophyte?
7. Describe the coevolution of plants and animals.
8. Define monoecious.
9. Give examples of dioecious plants.
10. Define self-pollination.

### Review

1. State the functions of flowers and fruits in angiosperm reproduction.

2. Create your own cycle diagram to represent the life cycle of a daisy.

3. Relate the concept of alternation of generations to the ability of plants to adapt to a diversity of habitats.

4. Compare and contrast gymnosperm and angiosperm life cycles.

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### Vocabulary Language: English Spanish

angiosperm

Type of seed plant that produces seeds in the ovary of a flower.

fruit

Structure in many flowering plants that develops from the ovary and contains seeds.

pollinator

Animal that picks up pollen on its body and carries it directly to another plant of the same species.

sporophyte

Diploid generation in the life cycle of a plant; results from sexual reproduction with gametes; produces spores for asexual reproduction.

gametophyte

Haploid generation in the life cycle of a plant that results from asexual reproduction with spores and that produces gametes for sexual reproduction.

pollen

Tiny grains that bear the male gametes of seed plants and transfer sperm to female reproductive structures.

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