Lesson 1 - Introduction to Plant Reproduction

Introduction to Plant Reproduction
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Vegetative Reproduction

•Vegetative reproduction is a form of asexual reproduction where the new plant
grows from parts of the old plant.

•Results in a clone of the original plant

•Advantages to vegetative reproduction:

•Faster

•Produces uniform offspring

•An agricultural technique to produce fruit without seeds

​Lesson 1

Introduction to Plant Reproduction

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Vegetative Reproduction

Naturally occurring vegetative reproduction

•Fragments of plants such as mosses can be scattered by the wind, and resume
growth in a new location.

•Some plants produce horizontal roots that can grow new plants, even after the
root is cut.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Vegetative Reproduction

Directed vegetative reproduction

•Farmers, horticulturists, and scientists can use buds, leaves, stems, or root
pieces from certain plants to grow new plants.

•Plant tissue can be placed on nutrient agar in sterile conditions to produce
hundreds of identical plants.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Alternation of Generations

•The life cycle of most plants includes a diploid (2n) sporophyte stage and a
haploid (n) gametophyte stage.

Multiple Choice

The sporophyte stage is the _______ stage.

• android

• haploid

• diploid

• triploid

Multiple Choice

The gametophyte stage is the _______ stage.

• android

• haploid

• diploid

• triploid

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Alternation of Generations

•The gametophyte stage produces gametes – egg and sperm.

•In nonvascular plants, the sperm must have a small amount of water to get to
the egg.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Alternation of Generations

•Fertilization of the egg forms the first cell of the sporophyte stage.

•As plants evolved, the sporophyte generation became larger and independent
of the gametophyte stage.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Moss Reproduction and Life Cycle

•Mosses exhibit a reproduction and life cycle characteristic of most nonvascular
plants.

•Gametophyte stage is dominant

Multiple Choice

Which stage is dominant is mosses?

• gametophyte

• sporophyte

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Moss Reproduction and Life Cycle

•There are both male and female forms of gametophyte.

•Eggs are produced in the female structure, called the archegonium.

•Sperm are produced in the male structure, called the antheridium.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Moss Reproduction and Life Cycle

•Flagellated sperm require water to reach the archegonium.

•Sperm move towards the archegonium in response to chemicals released by
the female gametophyte.

•This response is called chemotaxis.

•Fertilization of an egg results in a zygote, the first stage of a sporophyte.

Multiple Choice

Sperm move towards the archegonium in response to chemicals released by the female gametophyte is called...

• chemoreaction

• chemotaxis

• doyourtaxes

• getoffyouraxis

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Moss Reproduction and Life Cycle

•A mature sporophyte consists of a stalk with a capsule at its tip.

•Spores are released from the capsule when conditions are favorable.

•If a spore forms in a suitable place, it forms a protonema, a small structure that
can develop into a gametophyte and restart the cycle.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Fern Reproduction and Life Cycle

•The familiar frond structure is part of a fern’s
sporophyte stage.

•The fronds contain spore-producing structures
called sori.

•If a spore lands on suitable soil, it produces a tiny
heart shaped gametophyte called a prothallus.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Fern Reproduction and Life Cycle

•Prothalli develop both archegonia and antheridia.

•Fertilization results in a zygote, which starts the
sporophyte generation.

•Initially, the sporophyte grows on the prothallus
and receives support and nutrition

•Later, the prothallus disintegrates and the
sporophyte grows a rhizome that produces roots.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Conifer Reproduction and Life Cycle

•Conifers are heterosporous – they produce two types of spores that develop
into male and female groups.

Multiple Choice

Conifers are heterosporous – they produce two types of spores that develop into male and female groups.

• True

• False

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Conifer Reproduction and Life Cycle

Female cones

•At the base of each scale on a female cone are two
ovules.

•Each ovule has a megasporangium that produces
megaspores.

•One of the megaspores develops into the female
gametophyte.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Conifer Reproduction and Life Cycle

Male cones

•Each scale on the male cone contains hundreds of
sporangia.

•The sporangia produce microspores, which produce
the male gametophyte, or pollen grain.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Conifer Reproduction and Life Cycle

Pollination

•Pollination occurs when the pollen grain from one
species of a plant lands on the female reproductive
structure of a plant of the same species.

•The pollen grain is trapped in a sticky substance
called the pollen drop which is located near the
micropyle – the opening of the ovule.

Introduction to Plant Reproduction
Copyright © McGraw-Hill Education

Conifer Reproduction and Life Cycle

Seed development

•After pollination, the pollen grain grows a pollen tube
into the ovule.

•After fertilization, the zygote is dependent on the
female gametophyte while it undergoes cell division
and becomes an embryo

•As the embryo develops, the outside layer forms a
seed coat

•Seed development can take as long as three years.

Multiple Choice

Seed development can take as long as _____ years.

• two

• three

• four

• five