Transcript Ch. 38 Angiosperm Reproduction and Biotechnology notes

Ch. 38 Angiosperm Reproduction
and Biotechnology
Objectives:
L.O. 2.31 The student can connect concepts in and across domains to show that timing and coordination
of specific events are necessary for normal development in an organism and that these events are
regulated by multiple mechanisms.
L.O. 2.32 TSIAT use a graph or diagram to analyze situations or solve problems (quantitatively or
qualitatively) that involve timing and coordination of events necessary for normal development in an
organism.
L.O. 2.33 TSIAT justify scientific claims with scientific evidence to show that timing and coordination of
several events are necessary for normal development in an organism and that these events are regulated
by multiple mechanisms.
L.O. 2.34 TSIAT describe the role of programmed cell death in development and differentiation, the reuse
of molecules, and the maintenance of dynamic homeostasis.
L.O. 2.35 TSIAT design a plan for collecting data to support the scientific claim that the timing and
coordination of physiological events involve regulation.
L.O. 2.36 TSIAT justify scientific claims with evidence to show how timing and coordination of
physiological events involve regulation.
L.O. 2.37 TSIAT connect concepts that describe mechanisms that regulate the timing and coordination of
physiological events.
38.1 Flowers, Double Fertilization, and Fruits are
Unique Features of the Angiosperm Life Cycle
• Alteration of generations
– Multicellular haploid (n) gametophyte and diploid
(2n) generations sporophyte.
Key
Haploid (n)
Diploid (2n)
n
Gametes
Haploid multicellular organism
(gametophyte)
n
Mitosis
n
n
MEIOSIS
FERTILIZATION
n
Diploid
multicellular
organism
(a) Animals
Zygote 2n
Mitosis
Mitosis
n
n
Spores
Gametes
MEIOSIS
2n
n
2n
Diploid
multicellular
organism
(sporophyte)
FERTILIZATION
2n Zygote
Mitosis
(b) Plants and some algae
Flower Structure and Function
• Flowers are angiosperm’s reproductive organ system.
• Flowers’ size, shape, color, odor, organ arrangement,
and time of opening are largely influenced by the
type of pollinator.
Stamen
Anther
Filament
Petal
Carpel
Stigma
Style
Ovary
Anther
Germinated pollen grain (n)
(male gametophyte)
Ovary
Ovule
Embryo sac (n)
(female gametophyte)
Pollen tube
FERTILIZATION
Sepal
Egg (n)
Sperm (n)
Receptacle
(a) Structure of an
idealized flower
Key
Haploid (n)
Diploid (2n)
(b) Simplified angiosperm
life cycle
Zygote
(2n)
Mature sporophyte
plant (2n)
Germinating
seed
Seed
Seed
Simple
fruit
Embryo (2n)
(sporophyte)
Video: Flower Plant Life Cycle (time lapse)
© 2011 Pearson Education, Inc.
Pollination
• Transfer of pollen from an anther to a stigma.
– Wind (grasses and trees)
– Water (aquatic plants)
– Animals; insects, birds, etc.
Abiotic Pollination by Wind
Pollination by Bees
Pollination by Moths
and Butterflies
Pollination by Flies
Pollination by Bats
Anther
Moth
Fly egg
Stigma
Moth on yucca flower
Common dandelion
Pollination by Birds
under normal light
Blowfly on carrion
flower
Hazel staminate flowers
(stamens only)
Hazel carpellate
flower (carpels only)
Common dandelion under
ultraviolet light
Hummingbird
drinking nectar of
columbine flower
Long-nosed bat feeding
on cactus flower at night
Video: Bee Pollinating
© 2011 Pearson Education, Inc.
Video: Bat Pollinating Agave Plant
© 2011 Pearson Education, Inc.
Coevolution
• The evolution of interacting
species in response to changes in
each other
• Many flowering plants have
coevolved with specific pollinators
• The shapes and sizes of flowers
often correspond to the pollen
transporting parts of their animal
pollinators
– Ex: Darwin correctly
predicted a moth with a 28
cm long tongue based on the
morphology of a particular
flower
Development of Male
Gametophytes in Pollen Grains
• Each anther has 4
microsporangia (pollen sacs)
• Within this are
microsporocytes (2n similar
to animal follicle)
• These undergo meiosis
producing microspores.
• These undergo mitosis
producing 2 cells (pollen):
– Generative: forms 2 sperm
– Tube: used to transfer sperm to
ovule
Microsporangium
(pollen sac)
Microsporocyte
MEIOSIS
Microspores (4)
Each of 4
microspores
MITOSIS
Generative cell
(will form 2 sperm)
Male
gametophyte
(in pollen grain)
Nucleus of tube cell
20 m
Key to labels
75 m
(LM)
Ragweed pollen grain
(colorized SEM)
Haploid (n)
Diploid (2n)
Development of Female
Gametophytes (embryo sac)
Megasporangium
Ovule
MEIOSIS
Megasporocyte
Integuments
Micropyle
Surviving
megaspore
MITOSIS
Ovule
Antipodal cells (3)
Polar nuclei (2)
Egg (1)
Integuments
Synergids (2)
Haploid (n)
Diploid (2n)
100 m
Key to labels
Embryo sac
(LM)
Female gametophyte
(embryo sac)
• Occurs within the
megasporangium.
• The megasporocyte
undergoes meiosis making
megaspores.
• This undergoes mitosis
(w/o cytokinesis) making a
large cell with 8 nuclei. This
is the embryo sac.
(b) Development of a female gametophyte
(embryo sac)
Double Fertilization
• When pollen reaches the stigma, the tube forms, grow
down the style to the micropyle (hole in the underside of
the embryo sac).
• Each sperm has a job:
1. Fertilizes the egg
2. Combines with polar bodies making a triploid nucleus in a
large cell  endosperm (food storing tissue for seed)
2
1
Stigma
Pollen
grain
Pollen
tube
Ovule
2 sperm
Polar
nuclei
Style
Ovary
Egg
Ovule
Synergid
Polar
nuclei
Egg
Micropyle
2 sperm
3
Endosperm
nucleus (3n)
(2 polar nuclei
plus sperm)
Zygote
(2n)
Animation: Seed Development
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Seed Development, Form, and Function
• Endosperm develops as a food source (carbohydrates storage)
• The embryo divides into a basal cell (anchor) and terminal cell
(embryo) and cotyledon forms (another food supply)
• Seed dehydrates entering dormancy.
– This is an adaptation for when environmental conditions are right for
imbibition (uptake of water to start germination)..
Ovule
Proembryo
Endosperm
nucleus
Integuments
Zygote
Terminal cell
Basal cell
Zygote
Suspensor
Cotyledons
Basal
cell
Shoot
apex
Root
apex
Suspensor
Seed
coat
Endosperm
Fruit Form and Function
• Fruit is the ovary of the flower which protects
and aids in dispersal of the seed.
• Types of fruit:
Stigma
Carpels
Stamen
Flower
Style
Petal
Ovary
Stamen
Stamen
Sepal
Stigma
Pea flower
Ovule
Ovule
Raspberry flower
Carpel
(fruitlet)
Seed
Stigma
Ovary
Stamen
Pineapple
inflorescence
Each segment
develops
from the
carpel
of one
flower
Ovary (in
receptacle)
Apple flower
Remains of
stamens and styles
Sepals
Seed
Pea fruit
Raspberry fruit
(a) Simple fruit: 1 carpel
(b) Aggregate fruit:
many carpels
Pineapple fruit
(c) Multiple fruit:
Many flowers
Receptacle
Apple fruit
(d) Accessory fruit: carpel is the core,
The flesh is the receptable.
Seed Dispersal
Dispersal by Wind
Dandelion fruit
Dandelion “seeds” (actually one-seeded fruits)
Winged fruit of a maple
Tumbleweed
Winged seed of
the tropical Asian
climbing gourd
Alsomitra macrocarpa
Dispersal by Water
Coconut seed embryo,
endosperm, and endocarp
inside buoyant husk
Seed Dispersal
Dispersal by Animals
Fruit of puncture vine
(Tribulus terrestris)
Squirrel hoarding
seeds or fruits
underground
Ant carrying
seed with nutritious
“food body” to its
nest
Seeds dispersed in black bear feces
Animation: Fruit Development
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.