CHAPTERS 25 & 27: Plants

High School Biology Class

CHAPTER 25-1

SEXUAL REPRODUCTION IN SEEDLESS PLANTS

Reproduction in Seedless Plants

Nonvascular & Seedless Vascular (seedless plants) reproduce by making gametophyte spores.

A) Archegonium structures produce egg spores that are large, contain lots of cytoplasm, and cannot move.

B) Antherdium structures produce sperm spores that are small, have flagella, and reach eggs by swimming through water.

Fertilization for seedless plants usually occurs during or soon after rain, when the spores are covered with water.

Only then can the sperm swim to the egg.

Once together they form a sporophyte, which can then continue its life cycle.

Reproduction in Seedless Plants

CHAPTER 25-2

SEXUAL REPRODUCTION IN SEED PLANTS

Gymnosperms & Angiosperms (seed plants) do not release spores in rain like other plants.

Instead, their spores remain within their tissues and develop into male or female gametophyte seeds.

Reproduction in Seed Plants

Reproduction in Seed Plants

Examples of Seed Structures:

a) Pollen Grain - male gametophyte(wind and animals transport pollen

grains)

b) Ovule - female gametophyte(remains with the plant)

Reproduction Terms

Seed Coat - the hardened outer cell layers of an ovule that protects the embryo.

Pollination - transfer of pollen grains from the male structures to the female structures.

Reproduction Parts

Cotyledon - leaf-like structures (seed leaves) that are a part of the embryo.

a. Gymnosperms – have two or more cotyledons

b. Angiosperms:

i. Monocots – have 1 cotyledon

ii. Dicots – have 2 cotyledons

Gymnosperms – type of plant where gametophytes develop within cones.

Angiosperms – type of plant where the gametophytes develop within flowers.

Reproduction in Seed Plants

Angiosperm - Flowers

Flowers Have Four Whorls:

1. Sepals – the outermost (first) whorls for protection when the flower is a bud.

2. Petals – the second whorls are used to attract the pollinators.

Angiosperm - Flowers

3. Stamens – third whorl that make pollen.Anther – pollen-producing sac on top of

stamen.

4. Pistils – fourth whorl produces ovules.Ovary – the pistil’s swollen lower portion is the spot where the ovules develop.

Style – the stalk that rises from ovary.

Stigma – the swollen, sticky tip of style.

Examples of Flower Pollinators:

a. Bees

b. Flies

c. Moths

d. Hummingbirds

e. Bats

f. Wind

CHAPTER 25-3

ASEXUAL REPRODUCTION

IN PLANTS

CHAPTER 27-1

HOW PLANTS GROW AND DEVELOP

Seed Growth

Seeds sprout in response to the environmental conditions.

A seed cannot sprout until water and oxygen penetrate the seed coat.

Seed Growth

Germination - process in which a plant embryo resumes its growth.

Patterns of Growth

1) Primary Growth – growth that increases the strength or height of a plant.

Apical Meristems – located at the lips of stems & roots perform primary growth.

Patterns of Growth

2) Secondary Growth – growth that increases the width of stems and roots.

Vascular Cambium – meristems that lie under the cuticle (bark) produce secondary growth.

Three Types Of Plants

Based On Life Spans of the Plant

A) Perennials:

A plant that lives for several years.

Examples:i. Herbaceous - Chrysanthemums, Daffodils, Irises

ii. Woody - Trees, Shrubs, Vines

B) Annuals:

A plant that completes its life cycle and then dies within one growing season.

Examples:Sunflowers, Beans, Corn, Weeds

C) Biennials:

Flowering plants that take two growing seasons to complete their life cycle.- 1st Season: produces roots and shoots- 2nd Season: produces flowering stalk

Examples:Carrots, Parsley, Onions

Any Questions?

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