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14.1 Plant Reproduction
Transcript of 14.1 Plant Reproduction
All plants have a life cycle involving alternation of generations. The cycle varies among species.
Sexual Reproduction in Seedless Plants
Sexual Reproduction in Seed Plants
Gametophytes are not free-living plants
is when the entire male gametophyte - not just the sperm lands on the female reproductive structure of another plant of the same species
are vascular plants with non-enclosed seeds
are vascular plants with seeds enclosed in protective tissue
Pollination does not require water to transport sperm to the female gametophyte, so the sperm in pollen grains do not have flagella. Instead, the transfer of sperm to egg occurs using a pollen tube - an extension of the pollen grain that grows towards the egg cell.
Sperm develops in pollen tube and moves toward the egg -->
fertilization occurs -->
zygote develops into an embryo -->
embryo + small supply of stored food is covered by a tough waterproof coat (makes a seed!) -->
seeds remain on plant with female reproductive structure until mature (few months - three years) -->
seeds released and carried away from parent plant by wind or animals
By: Kaitlin, Christine, Juanita, and Jesstina
- reproductive cell; haploid
- multicellular haploid stage; many cells still with one set of chromosomes
Divides through mitosis
- sex cells (sperm and egg)
- unicellular diploid structure
multicellular diploid stage
Cell divisions occur
Reproductive cells develop
Seedless plants can be
contain tissue for transporting substances. like stems, leaves with veins.
have no vascular tissue for retaining water or delivering to other parts of the plant body
In seedless plants, fertilization requires the sperm to swim from the male gametophyte to the egg in the female gametophyte. Therefore, water must be present and the sperm needs a flagellum.
Vascular plants have a dominant sporophyte generation and non-vascular plants have a dominant gametophyte generation
In both groups of seedless plants, the gametophyte is a free-living plant, independent of the sporophyte
Variations Among Flowers
Botanists (people who study plants) categorize flowers by their structures and pollination mechanisms
--> flowers with all 4 organs (Stamen, pistil, petals, sepals)
--> missing one or more of those organs
Structural Differences Cont.
Perfect Flowers --> contain pistil + stamen
Imperfect Flowers --> contain either pistil or stamen
they can bear both male and female flowers
all reproductive structures appear on one plant
carry either male or female flowers
The number of organs can distinguish if the plant is monocot or a dicot
When the petal number is a...
multiple of 3 -->
multiple of 4 or 5 -->
The number of sepals, pistils and stamens is often the same multiple as the petals
-- The transfer of pollen from male
Self-pollination and Cross-pollination
Self-pollinating - Pollinate themselves or another flower on the same plant
loss of genetic variation
Crossing-pollinating - Receive pollen from another plant
Many animal-pollinated flowers are brightly coloured, strong scents, produce a sweet liquid (
Bright colour/scents can attract insects (bees, butterflies)
Insects and small animals carry pollen from one flower to another
Some insects collect pollen as food
Bird-pollinated flowers --> give little/no aroma flowers (due to their poor sense of smell)
Usually lack colourful or fragrant flowers
Produce a lot of light pollen grains (easily to get pick up by the wind)
Stigma extends beyond the petals (expose it to wind)
Results of Reproduction
The final stage of plant reproduction is the formation of the seed.
Seed and Fruit Development
Increases the survival of the offspring.
- plants are split and replanted in a new location
Seed may grow into seedlings or remain dormant.
Seeds are dormant because of the lose of water and the metabolic process slows down.
is when a seed begins to grow after a period of dormancy.
Nutrients are made available to the embryo.
Food and oxygen allow cellular respiration.
Natural vegetative propagation
- growth from roots, stems, or leaves
- the cloning of a plant from a portion of its roots, stems, or leaves
The Life Cycle of Flowering Plants
Root Cutting -
A small section of root is placed in a growth medium
- When the stem of a plant is cut away, eventually it can grow independently
The three main stages include:
meiosis, germination, fertilization
An ovule containing the embryo sac inside the flower's ovary begins to grow; meiosis occurs
one female gametophyte
When mitosis occurs, a
In the anther, an immature
is produced, which is called a
When the pollen grain lands on the stigma of a flower, a tube cell forms from a pollen tube
As the pollen tube grows,
two sperm cells
The pollen grain is now a mature male gametophyte
Once the pollen tube reaches the ovule, two sperm cells are released
One cell fuses with the egg, forming a zygote - the new
The other sperm cell will fuses with the polar nuclei and nourishes the embryo as it grows
The fertilization of an angiosperm egg is called
The ovule will develop into the seed, and ovary develops into the fruit
- a leaf, or part of a leaf is cut and placed in a growth medium
- A shoot tip or part of a stem is cut from a parent plant and placed in a growth medium
- a section of one plant is joined to another
is the first part of the embryo to appear outside of the seed, collects the nutrients in the environment. The primary root of the plant.
is the region of the stem nearest to the seed.
When chloroplast are in the seedling's cells, above ground, photosynthesis can occur.
Seed Germination Cont.
The zygote develops into the embryo.
The sperm cell that fuses with the polar nuclei develop into the endosperm.
The endosperm matures and creates a seed coat.
is the outside layers of the ovule that hardens to form a protective tissue.
Artificial Propagation cont.
An outer part of bark is removed and enclosed with moss and is secured tightly with a plastic bag
Cell Culturing (Tissue Culturing)-
Small pieces of plant tissues are placed in a sterile nutrient medium containing chemicals to promote growth.