Section 1 Plant Reproduction Chapter 24 Reproduction in Nonvascular Plants, continued Life Cycle of a Moss • A moss sporophyte grows from a gametophyte and remains attached to it. • Spores form by meiosis inside the spore capsule. Therefore, as in all plants, the spores are haploid. • The spore capsule opens when the spores are mature, and the spores are carried away by wind or water.

Section 1 Plant Reproduction Chapter 24 Life Cycle of a Moss

Section 1 Plant Reproduction Chapter 24 Reproduction in Seedless Vascular Plants • Seedless vascular plants can reproduce sexually only when a film of water covers the gametophyte. • Some ferns, for example, have sporophytes that are as large as trees. The sporophytes produce spores in sporangia. • A cluster of sporangia on a fern frond is called a sorus.

Section 1 Plant Reproduction Chapter 24 Reproduction in Seedless Vascular Plants, continued Life Cycle of a Fern • During the life cycle of a fern, a fertilized egg, or zygote, grows into a new sporophyte. • The diploid sporophyte produces spores by meiosis. • The haploid spores fall to the ground and grow into haploid gametophytes.

Section 1 Plant Reproduction Chapter 24 Life Cycle of a Fern

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Objectives • Distinguishthe male and female gametophytes of seed plants. • Describethe function of each part of a seed. • Summarizethe life cycle of a conifer. • Relatethe parts of a flower to their functions. • Summarizethe life cycle of an angiosperm.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Reproductive Structures of Seed Plants • The tiny gametophytes of seed plants develop within specialized structures that form in the reproductive parts of a flower.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Reproductive Structures of Seed Plants, continued • A male gametophyte of a seed plant develops into a pollen grain, which has a thick protective wall. • A female gametophyte of a seed plant develops inside an ovule, which is a multicellular structure that is part of the sporophyte. • The transfer of pollen grains from the male reproductive structures of a plant to the female reproductive structures of a plant is called pollination. • A pollen tube grows from a pollen grain to an ovule and enables a sperm to pass directly to an egg.

stamen filament anther Section 2 Sexual Reproduction in Seed Plants Chapter 24 Pollen Grain Formation

stigma style carpel ovary Section 2 Sexual Reproduction in Seed Plants Chapter 24 Ovule Formation in an Angiosperm

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Seeds • A seed forms from an ovule after the egg within it has been fertilized. • The outer cell layers of an ovule harden to form the seed coat as a seed matures. • Leaflike structures called cotyledons, or seed leaves, are a part of a plant embryo.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Seed Structure

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Parts of a Seed

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Cones • The gametophytes of gymnosperms develop in cones, which consist of whorls (circles) of modified leaves called scales. • Pollen cones produce large quantities of pollen grains that are carried by wind to female cones. • At the time of pollination, the scales of a female cone are open, exposing the ovules. When a pollen grain lands near an ovule, a slender pollen tube grows out of the pollen grain and into the ovule.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Cones, continued Life Cycle of a Conifer • In pines, as in all plants, a diploid zygote results from sexual reproduction. The zygote develops into an embryo, which then becomes dormant (inactive). • The embryo and the surrounding tissues form a seed. When their seeds are mature, seed cones open, and the seeds fall out. • When conditions are favorable for growth, the seeds grow into new sporophytes.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Life Cycle of a Conifer

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Flowers • Flower parts are arranged in four concentric whorls. The outermost whorl consists of one or more sepals, which protect a flower from damage while it is a bud. • The second whorl consists of one or more petals, which attract pollinators. • The third whorl consists of one or more stamens, which produce pollen.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Flowers, continued • Each stamen is made of a threadlike filament that is topped by a pollen-producing sac called an anther. • The fourth and innermost whorl of a flower consists of one or more pistils, which produce ovules. • Ovules develop in a pistil’s swollen lower portion, which is called the ovary. Usually, a stalk, called the style, rises from the ovary.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Floral Structure

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Flowers, continued Flowers and Their Pollinators • Many flowers have brightly colored petals, sugary nectar, strong odors, and shapes that attract animal pollinators. • Flowers are a source of food for pollinators such as insects, birds, and bats. • Many flowers, such as those of grasses and oaks, are pollinated by wind. Wind-pollinated flowers are usually small and lack bright colors, strong odors, and nectar.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Flowers and Animal Pollinators

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Flowers, continued Life Cycle of an Angiosperm • Following fertilization in an angiosperm, the zygote and the tissues of the ovule develop into a seed, which grows into a new sporophyte. • The adult sporophytes of angiosperms produce spores by meiosis. • The fusing of three haploid (n) cells forms a triploid (3n) cell that develops into endosperm. This is a process called double fertilization.

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Formation of a Female Gametophyte

Section 2 Sexual Reproduction in Seed Plants Chapter 24 Formation of a Male Gametophyte

Section 3 Asexual Reproduction Chapter 24 Objectives • Summarizethe characteristics of organic compounds. • Comparethe structures and function of different types of biomolecules. • Describethe components of DNA and RNA. • Statethe main role of ATP in cells.

Section 3 Asexual Reproduction Chapter 24 Vegetative Reproduction • Plants reproduce asexually in a variety of ways that involve nonreproductive parts, such as stems, roots, and leaves. • The reproduction of plants from these parts is called vegetative reproduction. • Many of the structures by which plants reproduce vegetatively are modified stems, such as runners, bulbs, corms, rhizomes, and tubers.

Section 3 Asexual Reproduction Chapter 24 Stems Modified for Vegetative Reproduction

Section 3 Asexual Reproduction Chapter 24 External Structures of Kalanchoë

Section 3 Asexual Reproduction Chapter 24 Internal Structures of Kalanchoë

Section 3 Asexual Reproduction Chapter 24 Plant Propagation • Growing new plants from seed or from vegetative parts is called plant propagation. • Rhizomes, roots, and tubers can be cut or broken into pieces with one or more buds that can grow into new shoots. • In another technique called tissue culture, pieces of plant tissue are placed on a sterile medium and used to grow new plants.

Section 3 Asexual Reproduction Chapter 24 Methods of Vegetative Plant Propagation

Standardized Test Prep Chapter 24 Multiple Choice Use the drawing of a plant seed below to answer questions 1–3.

Standardized Test Prep Chapter 24 Multiple Choice, continued 1. Which structure is the embryonic root? A. A B. B C. C D. D

Standardized Test Prep Chapter 24 Multiple Choice, continued 2. Which structure is the source of nutrients for the embryo? F. A G. B H. C J. D

Standardized Test Prep Chapter 24 Multiple Choice, continued 3. What type of plant produced this seed? A. nonvascular plant B. gymnosperm C. dicot D. monocot

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