Title: Chapter 38: Angiosperm Reproduction
1Chapter 38 Angiosperm Reproduction
1. The life cycle of an angiosperm.
2Figure 38.2 An overview of angiosperm reproduction
3Chapter 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?
4Figure 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)
5Chapter 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
6Chapter 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?
7Figure 38.6 Growth of the pollen tube and double
fertilization
8Chapter 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
9Figure 38.7 The development of a eudicot plant
embryo
Suspensor
Suspensor
10Figure 38.8 Seed structure
11Chapter 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?
12Figure 38.9 Developmental origin of fruits
13Chapter 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
-
-
14Figure 39.11 Gibberellins mobilize nutrients
during the germination of grain seeds
2
15Figure 38.10 Two common types of seed germination