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Sexual Reproduction In Plants

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Ferns and mosses are neither angiosperm nor gymnosperm. They reproduce sexually ... In Angiosperm the developing seed is surrounded by the walls of the ovary. ... – PowerPoint PPT presentation

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Title: Sexual Reproduction In Plants


1
Sexual Reproduction In Plants
  • Meeting the Challenge

2
Making New Plants
  • Many plants reproduce successfully through
    asexual reproduction.
  • Others use sexual reproduction to pass on their
    genetic material.
  • This is challenging because most plants do not
    move.

3
Meeting the Challenge
  • In animals the product of sexual reproduction is
    the zygote.
  • In plants the product of sexual reproduction is
    the seed.
  • The seed contains an embryo, a food supply and a
    seed coat (protects seed from dehydration).
  • Plants can be classified into two groups based on
    their seed type.

4
Angiosperms
  • Flowering plants
  • The seeds form inside the flowers.
  • When mature the seeds are enclosed in a case,
    such as a pod or a shell.
  • Look at page 60 - which are angiosperms?
  • Can you name other angiosperms

5
Gymnosperms
  • Gymnosperms do not produce flowers.
  • Seeds are produced inside cones.
  • Their seeds have a coat but they are not enclosed
    in a case.
  • Look at page 60 - which are gymnosperms?
  • Can you name other gymnosperms?

6
Others ??
  • Not all plants fall into these two categories.
  • Ferns and mosses are neither angiosperm nor
    gymnosperm.
  • They reproduce sexually without seeds.
  • Look on Page 60 - which do not produce seeds.

7
Sexual Reproduction in Angiosperms
  • More than one half of all known plants are
    angiosperms.
  • Some produce large, showy flowers (lily,
    tulip,etc,)
  • Some have very small, easily missed flowers
    (grasses)
  • Big or small, all flowers have the same function.

8
Purpose of Flowers
  • All of the plants reproductive organs are
    contained in the flower.
  • Female reproductive organ is called the pistil.
  • Male reproductive organ is called the stamen

9
Reproductive Organs In Angiosperms
10
Pollination and Fertilization in Angiosperms
  • Before seeds can develop inside the flower pollen
    grains from the anther must reach the stigma of
    the pistil.
  • Some plants self-pollinate - both male and female
    gametes come from the same plant.
  • What might be some of the advantages to this type
    of sexual reproduction?

11
Pollination and Fertilization in Angiosperms
  • Most angiosperms cross-pollinate.
  • Pollen from one plant is transferred to another
    plant.
  • Most common way to cross pollinate is to use the
    wind or insects.
  • Which type of pollination would produce the most
    seeds?

12
Development of a Pollen Tube
13
Seed Development in Angiosperms
  • While pollen tube is growing, cells inside ovule
    prepare for its arrival.
  • Once the sperm cell meets the egg, a zygote is
    formed.
  • Other cells in the ovule develop into the
    cotyledon which contains food.
  • Zygote now goes through mitosis to form an embryo.

14
  • In Angiosperm the developing seed is surrounded
    by the walls of the ovary.
  • As the ovary matures it becomes the fruit.

15
Seed Dispersal in Angiosperms
  • The fruit of an angiosperm aids in its dispersal.
  • Dispersal is the transport of the seed away from
    the parent.
  • Some launch their own fruits
  • Some need help from outside agents
  • Wind, animals, water

16
Germination and Growth
  • Germination - the process in which a seed begins
    to grow,
  • Some seeds can lay dormant for years.
  • Look at page 68 in text to see the germination of
    a bean plant.
  • What process is going on at the cellular level?

17
Sexual Reproduction of Gymnosperms
  • The life cycle is similar to angiosperms.
  • Gymnosperms do not bear flowers.
  • These plants are called conifers.
  • Usually male and female cones are produced in the
    same trees.
  • Seeds contain an embryo, food supply, and a coat
    - but no fruit.

18
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