Chapter 38: Angiosperm Reproduction - PowerPoint PPT Presentation

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Chapter 38: Angiosperm Reproduction

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Title: Chapter 38: Angiosperm Reproduction


1
Chapter 38 Angiosperm Reproduction
1. The life cycle of an angiosperm.
2
Figure 38.2 An overview of angiosperm reproduction
3
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • No
  • Complete have all 4 floral parts sepal,
    petal, carpel, stamen
  • Incomplete lack 1 or more parts
  • Perfect flowers have both stamen carpels
  • Imperfect flowers missing either stamen or
    carpels
  • Stamenate have stamen
  • Carpellate have carpel
  • Monoecious have stamenate and carpellate
    flowers on same plant
  • Dioecious have stamenate and carpellate flowers
    on different plants
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?

4
Figure 38.4 The development of angiosperm
gametophytes (pollen grains and embryo sacs)
(a)
Development of a male gametophyte (pollen
grain). Pollen grains develop within the
microsporangia (pollen sacs) of anthers at the
tips of the stamens.
Development of a female gametophyte (embryo
sac). The embryo sac develops within an ovule,
itself enclosed by the ovary at the base of a
carpel.
(b)
Pollen sac (microsporangium)
Each one of the microsporangia contains diploid
microsporocytes (microspore mother cells).
Within the ovules megasporangium is a large
diploid cell called the megasporocyte
(megaspore mother cell).
Mega- sporangium
1
1
Micro- sporocyte
Mega- sporocyte
Ovule
MEIOSIS
Integuments
Each microsporo- cyte divides by meiosis to
produce four haploid microspores, each of
which develops into a pollen grain.
Micropyle
Micro- Spores (4)
2
The megasporo- cyte divides by meiosis and gives
rise to four haploid cells, but in most
species only one of these survives as the
megaspore.
2
Surviving megaspore
Each of 4 microspores
Female gametophyte (embryo sac)
MITOSIS
Ovule
Antipodel Cells (3)
Generative cell (well form 2 sperm)
Male Gametophyte (pollen grain)
Three mitotic divisions of the megaspore form
the embryo sac, a multicellular female
gametophyte. The ovule now consists of the
embryo sac along with the surrounding
integuments (protective tissue).
A pollen grain becomes a mature male gametophyte
when its generative nucleus divides and forms
two sperm. This usually occurs after a pollen
grain lands on the stigma of a carpel and the
pollen tube begins to grow. (See Figure 38.2b.)
Polar Nuclei (2)
3
3
Egg (1)
Synergids (2)
Integuments
Nucleus of tube cell
20 ?m
Key To labels
Ragweed Pollen grain
Embryo sac
75 ?m
100? m
100 ?m
Diploid (2n)
5
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?
  • How can plants prevent self-fertilization?
  • Genetic adaptations S genes
    self-incompatibility reject self
  • Anatomical adaptations pin thrum flowers
  • Temporal adaptations male female parts mature
    at different times

6
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?
  • How can plants prevent self-fertilization?
  • How does double fertilization occur why is this
    important?

7
Figure 38.6 Growth of the pollen tube and double
fertilization
8
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?
  • How can plants prevent self-fertilization?
  • How does double fertilization occur why is this
    important?
  • What happens after fertilization?
  • - Development of an embryo

9
Figure 38.7 The development of a eudicot plant
embryo
Suspensor
Suspensor
10
Figure 38.8 Seed structure
11
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?
  • How can plants prevent self-fertilization?
  • How does double fertilization occur why is this
    important?
  • What happens after fertilization?
  • How do fruits develop?

12
Figure 38.9 Developmental origin of fruits
13
Chapter 38 Angiosperm Reproduction
Biotechnology
  • Lets review the life cycle of an angiosperm.
  • Can all plants self-fertilize?
  • How does pollen (male gametophyte) the embryo
    sac (female
  • gametophyte) develop?
  • How can plants prevent self-fertilization?
  • How does double fertilization occur why is this
    important?
  • What happens after fertilization?
  • How do fruits develop?
  • What happens during dormancy? Germination?
  • --Seed remains dormant until germination is
    activated by
  • -heat
  • -light
  • -water
  • -extended cold weather
  • -animals digestive juices

14
Figure 39.11 Gibberellins mobilize nutrients
during the germination of grain seeds
2
15
Figure 38.10 Two common types of seed germination
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