Plant Reproduction

Plant Reproduction

7.LS1.7 - Evaluate and communicate evidence that compares and contrasts the advantages and disadvantages of sexual and asexual reproduction

Asexual vs. Sexual Reproduction

​What is the difference between asexual and sexual reproduction?

• Asexual reproduction occurs when a portion of the plant develops into a separate new plant - the new plant is genetically identical.

• In plants, sexual reproduction requires two parent organisms, and fertilization occurs when the egg and sperm combine.

• In sexual reproduction, the offspring is a genetic combination of the two parents.

• One great advantage, or benefit, of asexual reproduction is that only one parent is needed to create an offspring.

Alternation of Generations

• Our bodies are made of two cell types: haploid and diploid cells.

• Most cells are diploid cells, except for sperm and eggs which are haploid.

• Some organisms have two life stages, called generations.

• One stage, or generation, uses only haploid cells, while the other uses only diploid.

• The Alternation of Generations refers to a life cycle which alternates, or switches, between haploid and diploid stages.

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• Fertilization occurs by the joining of the sperm and egg.

• A zygote then forms, leading to the creation of a plant.

• Spores are the daughter cells produced by haploid structures during the process of meiosis

• Spores grow by mitosis and form the haploid plant.

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Alternation of Generations Cycle

Multiple Choice

According to the chart, what process produces the haploid spores?

• meiosis

• mitosis

• fertilization

Multiple Choice

According to the chart, what process forms diploid zygotes?

• mitosis

• meiosis

• fertilization

• Some reproductive cells make sperm and eggs.

• When the sperm and egg join, fertilization occurs forming a diploid zygote.

• The diploid zygote forms a diploid plant.

The Haploid Generation

• Example: Flower

• Meiosis occurs in reproductive structures

• Spores are haploid structures and are also similar to seeds.

• Spores grow by mitosis and cell division, forming haploid generation.

The Diploid Generation

Alternation of Generations

Life Cycle of a Moss

• Not all plants grow from seeds - seedless plants grow from haploid spores, not seeds.

• Examples: Moss and Ferns

• Green moss plants are haploid plants and grow in moist habitats.

• They grow by mitosis and cell division from haploid spores made by the diploid generation.

• They have male and female structures to produce eggs and sperm.

Image shown is diploid generation of moss.

Life Cycle of a Fern

• Also uses alternation of generations

• The diploid generations are green leafy plants often seen in the forest.

• Ferns produce haploid spores, which grow into tiny plants.

• The haploid plants produce eggs and sperm that form diploid generations.

Image shown is that of a diploid fern.

How do seed plants reproduce?

Two Types: Flowerless and Flowering Seed Plants

• pollen grains: forms from tissue in a male reproductive structure of a seed plant.

• has hard protective outer covering

• produce sperm cells, which are carried by wind, animals, or water

• these sperm cells can then fertilize the female reproductive structures, called pollination

• plants can't move to find a mate, so the production of pollen grains helps with fertilization

The Role of Pollen Grains

How do seed plants reproduce?

The Role of Ovules and Seeds

• ovule: female reproductive structure of a seed plant where the egg develops.

• during pollination, the sperm enters the ovule and fertilization occurs.

• from fertilization, a zygote forms and develops into an embryo

• embryo: an immature diploid plant that develops from a zygote.

• an embryo, its food supply, and a protective covering makeup the seed.

A seed contains the embryo, its food supply, and the protective outer coating.

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Structure of a

Seed

Reproduction in Flowerless Seed Plants

Flowerless Seed Plants are known as Gymnosperms.

• Gymnosperm means "naked seed"

• The most common gymnosperms are conifer, such as pines, firs, cypresses, and redwoods.

• The gymnosperm life cycle includes the alternation of generations.

• Cones are the male and female reproductive structures of conifers.

• Male cones = small, produce pollen grains

• Female cones = woody, berrylike, soft, produce eggs

Flowerless Seed Plants Reproduction

Reproduction in Flowering Seed Plants

​Flowering Seed Plants are Angiosperms.

• Most plants you see are angiosperms.

• Many animals depend on angiosperms for food.

• Reproduction begins in the flower- most flowers have male and female reproductive structures.

• Stamen = male reproductive organ in angiosperms

• Pistil = female reproductive organ in angiosperms

• Ovary = contains the ovules

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Structure of a Flower

Multiple Choice

What is the female reproductive structure in an angiosperm?

• stamen

• pistil

• sepal

• petal

Multiple Select

How do you currently feel about reproduction in plants?

• Great

• Good

• Okay

• Need More Practice