plants & life cycles
DESCRIPTION
Plants & Life Cycles. Chapter 12. Major groups of “ plants ”. Blue-green bacteria Algae Fungi Mosses Ferns and allies Gymnosperms Angiosperms. Generalized Plant Life Cycle. SPOROPHYTE 2N. spore mother cells. zygote (2N). diploid generation. FERTILIZATION. MEIOSIS. - PowerPoint PPT PresentationTRANSCRIPT
Generalized Plant Life Cycle
FERTILIZATION
zygote(2N)
SPOROPHYTE2N
spore mother cells
MEIOSIS
spore
GAMETOPHYTEN
diploid generation
haploid generation
antheridium
archegonium
sperm
egg
Homospory and Heterospory
Homospory• All spore are the same, with regard to size and
“gender”• Each is capable of make a hermaphroditic, male
or female gametophyte
Heterospory• The spore are different in size and gender
• Microspore = small, male• Megaspore = large, female
• Each spore makes a specific gendered gametophyte
Summary of spore types in free-sporing and seed plants
• Bryophytes: Mosses & Liverworts• Homosporous
• Ferns and allies• Homosporous & Heterosporous
• Seed Plants: gymnosperms & angiosperms• heterosporous
Generalized Plant Life Cycle
FERTILIZATION
zygote(2N)
SPOROPHYTE2N
Specialized diploidreproductive cells(spore mother cells)
MEIOSIS
spores
GAMETOPHYTE(male or female)
N
Gametes(egg & sperm)
cell division& growth
cell division& growth
diploid generation
haploid generation
1. What do the terms haploid and diploid refer to?
A. Cell numberB. Eye numberC. Number of chromosomesD. Number of chromosome setsE. Number of nuclei
2. A life cycle illustrates the reproductive stages for an organism. What process causes the haploid stage to become diploid?
A. meiosisB. mitosisC. fertilizationD. sterilizationE. germination
3. What process causes the diploid stage to become haploid?
A. meiosisB. mitosisC. fertilizationD. sterilizationE. germination
1. Zygotic Life Cycle
FERTILIZATION
zygote(2N)
MEIOSIS
Gametophyte (plant may act as gametes)
Zygote is the only diploid portion of the sporophyte generationPresumably the “original” life cycle
2. Gametic Life Cycle
FERTILIZATION
zygote(2N)
SPOROPHYTE2N
Specialized diploidreproductive cells
MEIOSIS
Gametes(egg or sperm)
cell division& growth
Gametes are the only haploid portion of the gametophyteZygote grows mitotically
3. Sporic Life Cycle
FERTILIZATION
zygote(2N)
SPOROPHYTE2N
Specialized diploidreproductive cells(spore mother cells)
MEIOSIS
spores
GAMETOPHYTE(male or female)
N
Gametes(egg or sperm)
cell division& growth
cell division& growth
Both generations (N and 2N) mitotic divisionsAlternation of generations (sporophyte & gametophyte)
Major Evolutionary Advances
• Flowers - 140 mya
5,000mya
4,000mya
3,000mya
2,000mya
1,000mya
EarthForms
ProkaryoticCells
EukaryoticCells
MulticellularPlants
Vascular
tissue
Seeds
Flowers
• Life - 3,800 mya• Prokaryotic cell/autotrophic
• Eukaryotic cell - 1,400 mya• Multicellar plants - 1,000 mya• Vascular tissue - 430 mya• Needed on land - why?
• Seeds - 350 mya
Place on the time scale, the following events:
1. Earth formation2. Prokaryotes3. Eukaryotes4. Multicellular life5. Vascular tissue6. Seeds7. Flowers