Chapter 28: Angiosperm Reproduction

A fruit develops from an _____________.

ovary

Order of Angiosperm Life Cycle

1. Sporophyte 2. Meiosis 3. Spores 4. Gametophytes 5. Mitosis 6. Egg or sperm 7. Fertilization 8. Zygote Then it starts from the beginning

Incomplete Flowers

A flower in which one or more of the four basic floral organs are either absent or nonfunctional. They are missing one of the following: sepals, petals, stamen, or carpels.

Ovary

A flower structure that encloses and protects ovules and seeds as they develop. Develops into a fruit, which encloses the red and aid in dispersal by wind or animals. When a seed germinates, the embryo develops into a new sporophyte.

Complete Flowers

A flower that has all four basic floral organs: sepals, petals, stamens, and carpals.

AReceptablengiosperms

A flowering plant which forms seeds inside a protective chamber called an ovary. They attract animal pollinators that help them reproduce sexually by transferring their pollen.

Seed Coat

A tough outer covering of a seed, formed from the outer coat of an ovule. Develops from integuments.

Pollination by Bees

About 65% of plants. Bees eat nectar & pollen, bees attracted to bright colors (yellow & blue), bees can see UV light. Nectar guides are markings that direct insects to the nectar-producing glands.

Seed Development

After double fertilization, each ovule develops into a seed.

Pollination by Flies

Creatures are drawn to flowers fragrant like dead/rotting flesh, pollen sticks to them and they move on. Flies mistake the flower for a rotting corpse and lay their eggs on it. Pollen is transferred in the process, but the fly larvae will have no carrion to eat when they hatch.

Pollination by Moths and Butterflies

Flower and strong, sweet fragrance are key. Butterflies like all bright colors, moths like white and yellows. Moth-pollinated flowers are usually white or yellow.

Three F's of Angiosperm Reproduction

Flowers, double fertilization, and fruits.

Fruit Structure and Function

Fruit is the mature ovary of a flower Fruits are classified based on their developmental origin Simple fruits develop from a single or several fused carpels Aggregate Fruits result from a single flower with multiple separate carpels Multiple fruits develop from a group of flowers called an inflorescence. Accessory fruits develop from other tissues

Angiosperm Life Cycle

Gametophyte development Sperm delivery by pollen tubes Double fertilization Seed Development

Unisexual Flowers

Have either stamens or carpels. They are a form of incomplete flowers that only have the female or male organs. Female: pistil - stigma, style, and ovary. Male: stamen, anther, and filament.

Monoecious

Having male and female reproductive organs in the same plant.

Anther

In an angiosperm, the terminal pollen sac of a stamen, where pollen grains containing sperm-producing male gametophytes form. Contains microsporangia (pollen sacs) that produce pollen (microgametophyte).

Endosperm

In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. Provides nourishment to the developing embryo in angiosperm seeds. Triploid (3n).

Sepals

Leaflike parts that cover and protect the flower bud.

Diecious

Male and female reproductive organs are in different plants. Male flowers with stamens. Female flowers with carpels.

Petals

Modified leaves which are usually bright in color to attract pollinators.

Abiotic Pollination by Wind

Occurs in angiosperms including grasses and many trees. About 20% of angiosperms use this method. Wind-pollinated angiosperms tend to produce small, inconspicuous flowers that lack nectar or scent and release large amounts of pollen.

Pollination by Birds

Occurs in plants that produce large, bright red or yellow flowers with little odor and large quantities of nectar. The petals of bird-pollinated flowers are often used into floral tube that fits the curve beak of the bird.

Pollination by Bats

Occurs in plants that produce light-colored, aromatic flowers.

Angiosperm Female Gametophyte

One cell in the megasproium, megaspore mother cell (2n) enlarges and undergoes meiosis, producing four megapodes (n), only one of which survives. The megaspore divides without cytokinesis, producing one large cell with eight haploid nuclei. This cell is partitioned into a multicellular female gametophyte, the embryo sac. The complete ovule consists of the embryo sac, enclosed by the megasporangium and surrounded by two integuments.

Carpels

The female reproductive organ of a flower, consisting of the stigma, style, and ovary. Has a long style with a sticky stigma on top that captures pollen. At the base of the style is an ovary containing one or more ovules.

Pistil

The female reproductive part of a flower. A single carpel or fused carpels.

Angiosperm Male Gametophyte

Pollen develops within the microsporangium, or pollen sacs, of anthers. Diploid microsporocytes (2n) undergo meiosis to produce four haploid microspores. Each microspore undergoes mitosis to produce two haploid cells: the generative cell and the tube cell. A pollen grain (n) consists of this two-celled male gametophyte and the spore wall. The generative cell will pass into the tube. After landing on a receptive stigma, a pollen grain absorbs water and germinates by producing a pollen tube. The pollen tube grows down the ovary, and discharges two sperm cell near the embryo.

How to angiosperms reproduce sexually?

Pollen grain is released from an anther. Pollen grain is transferred into the stigma and down the pollen tube. Once it is down the pollen tube, it reaches one of the ovules inside of the ovary. The pollen tube delivers sperm to an ovule, fertilizing the egg. The ovule becomes a seed and then the ovary becomes a fruit. The embryo develops into a plant.

Dispersal by Animals

Some sry fruits are adapted to attach to the skin or fur of passing animals. Others are collected and buried in the underground caches of animals. Edible fruits are broken down in the digestive system of animals and the seeds are dispersed in their feces. Some seeds have food bodies rich in fatty acids, amino acids, and sugars that are collected by ants.

Filament

Supports the anther.

Receptacle

The base of a flower; the part of the stem that is the site of attachment of the floral organs.

Double Fertilization

The fusion of gametes, occurs after the two sperm reach the female gametophyte. It takes two sperm to complete fertilization. One sperm fertilizes the egg, forming the zygote. The other sperm combines with the two polar nuclei, going rise to the triploid (3n), food storing endoderm.

Microgametophyte

The male gametophyte produced by a microspore, produces sperm.

Fruit

The mature ovary of a flower. It protects the enclosed seeds and aids in seed dispersal by wind or animals. Only develops in response to hormonal changes triggered by fertilization. In some fruits, the ovary wall dries out at maturity; in others the ovary wall remains fleshy.

Seed

The plant structure that contains a young plant inside a protective covering. A seed coat, embryo, and endosperm.

Stamens

The pollen-producing male reproductive organ of a flower, consisting of an anther and filament. A threadlike filament topped by an anther.

Flowers

The reproductive shoots of the angiosperm sporophyte; they attach to a part of the stem called the receptacle. Flowers consist of four parts: carpels, petals, stamens, sepals.

Pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants. Transfer of pollen from anthers to stem.

Wind-Pollinated Species

Usually have small or inconspicuous flowers and produce large amounts of pollen. Very small flowers.

Methods of Pollination

Wind, water, or animals

Dispersal by Wind

Winged fruits glide or spin through the air. Some fruits float through the air attached to umbrella like parachutes made of branched hairs.

A seed develops from a _____________.

seed

A fruit usually ripens at the same time that the ___________ complete development.

seeds