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Plant Reproduction. Chapter 24. Chapter 24 Vocabulary. 24.1 Pollen Cone Seed Cone Ovule Pollen Tube Sepal Petal Stamen Filament Anther Carpel Ovary Style Stigma. Embryo Sac Endosperm Double Fertilization 24.2 Dormancy Germination 24.3 Vegetative Reproduction Stolon

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chapter 24 vocabulary
Chapter 24 Vocabulary

24.1

  • Pollen Cone
  • Seed Cone
  • Ovule
  • Pollen Tube
  • Sepal
  • Petal
  • Stamen
  • Filament
  • Anther
  • Carpel
  • Ovary
  • Style
  • Stigma
  • Embryo Sac
  • Endosperm
  • Double Fertilization

24.2

  • Dormancy
  • Germination

24.3

  • Vegetative Reproduction
  • Stolon
  • Grafting
  • Budding
essential questions
Essential Questions:
  • What are the reproductive structures of gymnosperms and angiosperms?
  • How does pollination differ between angiosperms and gymnosperms?
alternation of generations
Alternation of Generations
  • All plants have a life cycle in which a diploid sporophyte generation alternates with a haploid gametophyte generation.
  • Gametophyte plants produce male and female gametes.
  • When the gametes join, they form a zygote that begins the next sporophyte generation.
  • In seed plants the diploid sporophyte is the recognizable plant.
  • The gametophyte is hidden inside of the cones (gymnosperms) and flowers (angiosperms).
gymnosperm life cycle
Gymnosperm Life Cycle
  • Takes place in cones, which are produced by a mature sporophyte plant.
  • Pollen Cones = Male Cones
    • Produce Male Gametophyte = Pollen Grains
    • One pollen grain will divide to produce two sperm nuclei.
  • Seed Cones = Female Cones
    • Produce Female Gametophytes.
    • Ovules in which the female gametophyte develops are found near the base of each scale.
    • When mature, the ovules contain a few large egg cells, each ready for fertilization by the sperm nuclei.
gymnosperm pollination
Gymnosperm Pollination
  • The gymnosperm life cycle takes two years to complete.
  • The cycle begins in the spring as the male cones release enormous numbers of pollen grains.
  • The wind carries the pollen to the female cones and are caught in a sticky secretion called the pollination drop.
gymnosperm fertilization development
Gymnosperm Fertilization & Development
  • If a pollen grain lands near an ovule, the grain splits open and begins to grow a pollen tube, which contains two haploid sperm.
  • Once the pollen tube reaches the female gametophyte, one sperm disintegrates and the other fertilizes the egg contained within the female gametophyte.
  • More than one egg cell can be fertilized but only one embryo will develop.
  • Fertilization produces a diploid zygote– the new sporophyte plant.
flower structure
Flower Structure
  • Flowers are reproductive organs that are composed of four kinds of specialized leaves: sepals, petals, stamens, and carpels.
flowers sepals petals
Flowers: Sepals & Petals
  • Outermost circle of floral parts contains the sepals, which are green and resemble leaves.
    • Sepals enclose the bud before it opens and protects the flower while it is developing.
  • Petals are found just inside the sepals and are often brightly colored to attract insects and other pollinators to the flower.
  • Sepals and petals are sometimes called sterile leaves because they do not produce reproductive cells.
flowers stamens
Flowers: Stamens
  • Stamen is the male part and produces the haploid male gametophyte
    • Consists of an anther and a filament.
      • Filamentis a long, thin stalk that supports the anther.
      • Antheris an oval sac found at tip of filament and is where meiosis takes place, producing male gametophytes i.e. pollen grains.
flowers carpels
Flowers: Carpels
  • Carpel is the female part and produces the haploid female gametophyte
    • Innermost flower parts, also called pistils.
    • Each carpel has a base that forms an ovary containing ovules that produce female gametophytes.
    • A narrow stalk called the style attaches the ovary to the stigma.
    • Stigma is a sticky portion on the end of the style where pollen grains land.
angiosperm life cycle
Angiosperm Life Cycle
  • Begins when mature sporophyte produces flowers.
  • Each flower contains anthers and an ovary.
  • Inside anthers, each cell undergoes meiosis and produces four haploid spore cells.
  • Each of these cells becomes a pollen grain with a thickened cell wall to protect it when it is released from the anther.
angiosperm life cycle cont
Angiosperm Life Cycle Cont…
  • Ovary contain the ovules in which female gametophyte develops.
  • A single diploid cell goes through meiosis to produce four haploid cells, three of which disintegrate.
  • Remaining cell undergoes mitosis to produce eight nuclei.
  • Eight nuclei and surrounding membrane are called embryo sac.
angiosperm life cycle cont1
Angiosperm Life Cycle Cont…
  • Embryo sac is contained within ovule and is the female gametophyte.
  • The egg nucleus, near the base of the gametophyte, is the gamete and will become the zygote if fertilization takes place.
  • The zygote grows into a new sporophyte plant also called a seedling.
angiosperm pollination development
Angiosperm Pollination & Development
  • Once gametophytes have developed inside the flower, pollination takes place.
  • Most gymnosperms and some angiosperms are wind pollinated.
  • Most angiosperms are pollinated by animals.
  • Animals are mainly insects, birds, and bats that carry pollen from one flower to another.
  • Insect pollination is more efficient than wind pollination.
essential questions1
Essential Questions
  • How do seeds develop and germinate?
seed fruit development
Seed & Fruit Development
  • After fertilization, nutrients flow into the flower tissue and support the development of the growing embryo within the seed.
  • As angiosperms seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds.
    • A fruit is a ripened ovary that contains angiosperm seeds.
    • It refers to any seed that is enclosed within its embryo wall.
    • The ovary wall may be fleshy (grapes, tomatoes, peaches) or tough (pod of a bean).
seeds fruits cont
Seeds & Fruits Cont…
  • Some seeds are rigidly attached to the surface of the seed and some dry and form an aerodynamic shape like a maple seed.
  • Parts of the ovule toughen to form the seed coat, which is the outer layer of that protects the delicate embryo and its food supply
  • The ovary wall thickens and may join with other parts of the flower stem.
  • The structures together form a fruit that encloses the seeds.
seed dispersal
Seed Dispersal
  • Seeds spread by animals when the seed is contained in a fruit that entices them to eat it and thus spread the seeds.
    • Animals include insects, birds, and mammals.
    • Seeds spread by animals tend to be enclosed in fleshy, nutritious fruits that provide nutrition for the animal that eats it.
    • Seeds pass through digestive tract and sprout in the feces of the animals.
    • Advantageous to plant because it helps get the seed away from the parent plant – less competition and is more efficient than seeds spread by the wind.
  • Seeds spread by wind and water tend to be lightweight allowing them to be carried by the air or float on the surface of water.
seed dormancy
Seed Dormancy
  • Dormancy – embryo is alive but not growing.
    • Length of dormancy varies by species.
  • Environmental factors such as temperature and moisture can cause a seed to end its dormancy and germinate.
  • Adaptation for plants because it allows for long-distance dispersal, temperature extremes (forest fires), etc.
seed germination
Seed Germination
  • Germination - early growth stage of plant embryo.
  • Early seeds absorb water causing food-storage to swell, cracking open the seed coat.
  • The young root begins to grow and the seed leaves (cotyledon) emerges.
    • Monocot – one seed leaf (cotyledon).
    • Dicot – two seed leaves – two ways of germination.
monocot seed germination
Monocot Seed Germination
  • Monocots grow straight up with sheath covering shoot.
  • One embryonic leaf.
  • Seed remains underground.
dicot seed germination
Dicot Seed Germination
  • Two ways dicots grow:
    • cotyledon emerges above the ground and protects the plant (pumpkin).
    • cotyledon remains underground and provides food source for growing seedling (bean).
embryo anatomy
Embryo Anatomy
  • Epicotyl - Grows into the leaves of the plant
  • Hypocotyl - Becomes the stem
  • Radicle - Becomes the root
essential questions2
Essential Questions:
  • What is vegetative reproduction?
  • Describe plant propagation.
vegetative reproduction
Vegetative Reproduction
  • Vegetative reproduction: method of asexual reproduction that produces new plants from stems, plantlets, and underground stems.
    • Plant grows by mitosis alone – no sexual reproduction.
    • Enables plant to produce many offspring that are genetically identical to itself.
    • Plants can reproduce very quickly since it does not involve pollination or seed formation.
vegetative reproduction cont
Vegetative Reproduction Cont…
  • Plants can also reproduce by growing horizontal stems called stolons.
    • Ex – Strawberry Plants
  • Stolons produce roots when they touch the ground.
  • Some plants like bamboo grow underground stems that allow plants to send up new shoots.
plant propagation
Plant Propagation
  • Propagation uses cuttings, grafting, or budding to make many identical copies of a plant or to produce offspring from seedless plants.
  • Plant hormones are often used to stimulate cuttings to grow.
  • Grafting and budding are used to reproduce seedless plants and woody plants that do not produce strong root systems.
plant propagation cont
Plant Propagation Cont…
  • A piece of stem is cut from the parent plant and attached to another plant.
  • The cut piece is called the scion and the plant to which it is attached is called the stock.
  • When wood stems are used as scions, the process is called grafting.
  • When buds are used as scions, the process is called budding.
  • Grafting works best when plants are dormant because wounds created can heal before new growth starts.
agriculture
Agriculture
  • Agriculture is the systematic cultivation of plants.
  • Developed about 10,000 to 12,000 years ago.
  • Agriculture is the principal occupation of humans.
  • Most people of world depend on a few crop plants such as wheat, rice, and corn for the bulk of their food supply.
  • About 80% of US cropland is used to grow just four crops: corn, wheat, soybeans, and hay.