chapter 30: the evolution of seed plants 1.what are the 3 most important reproductive adaptations?...
TRANSCRIPT
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?
- Reduction of the gametophyte- Advent of the seed – replaced spore - Evolution of pollen – male gametophyte
- Air dispersal instead of sperm swimming
Sporophyte dependent on gametophyte (mosses and other bryophytes).
(a) Large sporophyte and small, independent gametophyte (ferns and other seedless vascular plants).
(b)
Microscopic femalegametophytes (n) inovulate cones(dependent)
Sporophyte (2n),the flowering plant(independent)
Microscopic malegametophytes (n)inside these partsof flowers(dependent)
Microscopic malegametophytes (n)in pollen cones(dependent) Sporophyte (2n)
(independent)
Microscopic femalegametophytes (n)inside these partsof flowers(dependent)
Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms).
(c)
Gametophyte(n)
Gametophyte(n)
Sporophyte(2n)
Sporophyte(2n)
Figure 30.2 Gametophyte/sporophyte relationships
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?
- Reduction of the gametophyte- Advent of the seed – replaced spore as - Evolution of pollen – male gametophyte
2. How does an ovule become a seed?- Fertilization- Growth of the embryo
Figure 30.3 From ovule to seed
Unfertilized ovule. In this sectionalview through the ovule of a pine (a gymnosperm), a fleshy megasporangium is surrounded by a protective layer of tissue called an integument. (Angiosperms have two integuments.)
(a) Fertilized ovule. A megaspore develops into a multicellular female gametophyte. The micropyle, the only opening through the integument, allows entry of a pollen grain. The pollen grain contains a male gametophyte, which develops a pollen tube that discharges sperm.
(b) Gymnosperm seed. Fertilization initiates the transformation of the ovule into a seed, which consists of a sporophyte embryo, a food supply, and a protective seed coat derived from the integument.
(c)
Integument
Spore wall
Megasporangium(2n)
Megaspore (n)
Male gametophyte(within germinatingpollen grain) (n)
Femalegametophyte (n)
Egg nucleus (n)
Dischargedsperm nucleus (n)
Pollen grain (n)Micropyle
Seed coat(derived fromintegument)
Food supply(femalegametophytetissue) (n)
Embryo (2n)(new sporophyte)
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?2. How does an ovule become a seed?3. What’s the difference between a megaspore & a microspore?
- Megasporangia megaspores female gametophytes (eggs)- Microsporangia microspores male gametophytes (sperm)- Recall seed plants are heterosporous
4. What are gymnosperms?- “naked seed” plants- Pines, spruce, fir, sequoia, yews, junipers, ginkgo - Most lumber & paper products- The gymnosperm life cycle…
Figure 30.6 The life cycle of a pine
Ovule
Key
Haploid (n)Diploid (2n)
Megasporocyte (2n)
Integument
Longitudinalsection ofovulate cone
Ovulatecone
Pollencone
Maturesporophyte(2n)
Longitudinalsection ofpollen cone
Microsporocytes(2n)
Pollengrains (n)(containing malegametophytes)
Micropyle
Germinatingpollen grain
Megasporangium
MEIOSIS
Sporophyll
Microsporangium
Figure 30.6 The life cycle of a pine
MEIOSIS
Survivingmegaspore (n)
Germinatingpollen grain
ArchegoniumIntegumentEgg (n)
Femalegametophyte
Germinatingpollen grain (n)
Dischargedsperm nucleus (n)
Pollentube
Egg nucleus (n)
Ovule
Key
Haploid (n)Diploid (2n)
Megasporocyte (2n)
Integument
Longitudinalsection ofovulate cone
Ovulatecone
Pollencone
Maturesporophyte(2n)
Longitudinalsection ofpollen cone
Microsporocytes(2n)
Pollengrains (n)(containing malegametophytes)
Micropyle
Germinatingpollen grain
Megasporangium
MEIOSIS
Sporophyll
Microsporangium
Figure 30.6 The life cycle of a pine
FERTILIZATION
Seed coat(derived fromparentsporophyte) (2n)
Food reserves(gametophytetissue) (n)
Embryo(new sporophyte)(2n)
Seeds on surfaceof ovulate scale
Seedling
MEIOSIS
Survivingmegaspore (n)
Germinatingpollen grain
ArchegoniumIntegumentEgg (n)
Femalegametophyte
Germinatingpollen grain (n)
Dischargedsperm nucleus (n)
Pollentube
Egg nucleus (n)
Ovule
Key
Haploid (n)Diploid (2n)
Megasporocyte (2n)
Integument
Longitudinalsection ofovulate cone
Ovulatecone
Pollencone
Maturesporophyte(2n)
Longitudinalsection ofpollen cone
Microsporocytes(2n)
Pollengrains (n)(containing malegametophytes)
Micropyle
Germinatingpollen grain
Megasporangium
MEIOSIS
Sporophyll
Microsporangium
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?2. How does an ovule become a seed?3. What’s the difference between a megaspore & a microspore?4. What are gymnosperms?
- “naked seed” plants- Pines, spruce, fir, sequoia, yews, junipers, ginkgo - Most lumber & paper products- The gymnosperm life cycle…
5. What are angiosperms?- Flowering plants
6. What is a flower?- Reproductive structure of an angiosperm
Figure 30.7 The structure of an idealized flower
Anther
Filament
Stigma
Style
Ovary
Carpel
Petal
ReceptacleOvule
Sepal
Stamen
Female structures
Male structures
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?2. How does an ovule become a seed?3. What’s the difference between a megaspore & a microspore?4. What are gymnosperms?5. What are angiosperms?6. What is a flower?
- Reproductive structure of an angiosperm7. What is a fruit?
- Mature ovary- Helps seed dispersal
Figure 30.8 Some variations in fruit structure
Ruby grapefruit, a fleshy fruitwith a hard outer layer andsoft inner layer of pericarp
(b)Tomato, a fleshy fruit with soft outer and inner layers of pericarp
(a)
Nectarine, a fleshyfruit with a soft outerlayer and hard innerlayer (pit) of pericarp
(c)
Walnut, a dry fruit that remains closed at maturity
(e)(d) Milkweed, a dry fruit thatsplits open at maturity
Figure 30.9 Fruit adaptations that enhance seed dispersal
Wings enable maple fruits to be easily carried by the wind.
(a)
Seeds within berries and other edible fruits are often dispersed in animal feces.
(b)
The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals.
(c)
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?2. How does an ovule become a seed?3. What’s the difference between a megaspore & a microspore?4. What are gymnosperms?5. What are angiosperms?6. What is a flower?7. What is a fruit?8. The angiosperm life cycle….
Figure 30.10 The life cycle of an angiosperm
Mature flower onsporophyte plant(2n)
Key
Haploid (n)
Diploid (2n)
Anther
Ovule withmegasporangium (2n)
Male gametophyte(in pollen grain)
Microspore (n)
MEIOSIS
Microsporangium
Microsporocytes (2n)
MEIOSIS
Generative cell
Tube cell
Survivingmegaspore(n)
Ovary
Megasporangium(n)
Female gametophyte(embryo sac)
Antipodal cellsPolar nucleiSynergidsEgg (n)
Pollentube
Sperm(n)
Figure 30.10 The life cycle of an angiosperm
Pollentube
Sperm
Stigma
Pollengrains
Pollentube
Style
Dischargedsperm nuclei (n)
Eggnucleus (n)
Mature flower onsporophyte plant(2n)
Key
Haploid (n)
Diploid (2n)
Anther
Ovule withmegasporangium (2n)
Male gametophyte(in pollen grain)
Microspore (n)
MEIOSIS
Microsporangium
Microsporocytes (2n)
MEIOSIS
Generative cell
Tube cell
Survivingmegaspore(n)
Ovary
Megasporangium(n)
Female gametophyte(embryo sac)
Antipodal cellsPolar nucleiSynergidsEgg (n)
Pollentube
Sperm(n)
Figure 30.10 The life cycle of an angiosperm
Nucleus ofdevelopingendosperm
(3n)
Zygote (2n)
FERTILIZATION
Embryo (2n)
Endosperm(foodsupply) (3n)
Seed coat (2n)
Seed
Germinatingseed
Pollentube
Sperm
Stigma
Pollengrains
Pollentube
Style
Dischargedsperm nuclei (n)
Eggnucleus (n)
Mature flower onsporophyte plant(2n)
Key
Haploid (n)
Diploid (2n)
Anther
Ovule withmegasporangium (2n)
Male gametophyte(in pollen grain)
Microspore (n)
MEIOSIS
Microsporangium
Microsporocytes (2n)
MEIOSIS
Generative cell
Tube cell
Survivingmegaspore(n)
Ovary
Megasporangium(n)
Female gametophyte(embryo sac)
Antipodal cellsPolar nucleiSynergidsEgg (n)
Pollentube
Sperm(n)
Double fertilization
Chapter 30: The Evolution of Seed Plants1. What are the 3 most important reproductive adaptations?2. How does an ovule become a seed?3. What’s the difference between a megaspore & a microspore?4. What are gymnosperms?5. What are angiosperms?6. What is a flower?7. What is a fruit?8. The angiosperm life cycle….9. Why is double fertilization important?
- Synchronizes food development with embryo development- Prevents angiosperms from wasting nutrients on unfertilized ovules
10. What are the 2 general types of angiosperms?- Monocots- Eudicots
Orchid(Lemboglossumrossii)
MonocotCharacteristics
Embryos
Leafvenation
Stems
Root
Pollen
Flowers
Pollen grain withone opening
Root systemUsually fibrous(no main root)
Vascular tissuescattered
Veins usuallyparallel
One cotyledon Two cotyledons
Veins usuallynetlike
Vascular tissueusually arranged
in ring
Taproot (main root)usually present
Pollen grain withthree openings
Zucchini (CucurbitaPepo), female(left) and male flowers
Pea (Lathyrus nervosus,Lord Anson’s blue pea),a legume
Dog rose (Rosa canina), a wild rose
Pygmy date palm (Phoenix roebelenii)
Lily (Lilium“Enchant-ment”)
Barley (Hordeum vulgare), a grass
Anther
Stigma
Californiapoppy(Eschscholziacalifornica)
Pyrenean oak(Quercuspyrenaica)
Floral organsusually in
multiples of three
Floral organs usuallyin multiples of
four or fiveFilament Ovary
EudicotCharacteristics
MONOCOTS EUDICOTS