1. The Cellular Basis of Inheritance: Life Cycles
Chapters 7 and 14

2. Life Cycles Fertilization and meiosis alternate in sexual life cycles
Meiosis reduces the chromosome number by half
Producing haploid cells
Fertilization, the joining of two gametes, restores the chromosome number
Producing diploid cells

3. Animal Kingdom Life Cycle
Animals use Gametic Meiosis
Diploid-dominant
Meiosis produces haploid gametes
Gametes do not divide (remain uni- cellular)
Fertilization produces a diploid zygote
Zygote undergoes mitosis to produce a multicellular diploid body (adult animal)

6. Fungus Kingdom Life Cycle
Fungus use Zygotic Meiosis
Haploid-dominant
Meiosis of the zygote produces haploid spores
Spores undergo mitosis to produce a multicellular haploid body (mycelium/fungus)
Mycelia of two fungi fuse and develop into a fruiting body (mushroom)
Fertilization produces a diploid zygote
Zygote remains uni-cellular
Zygote is the only diploid cell during the life cycle

7. a g mycelium Diploid Zygote Diploid Stage nuclear fusion meiosis
Haploid Stage
Cells with two nuclei
(n + n) form on gills g
spore (n)
at gill
margin
gill
Mitosis
cap
stalk
mycelium
cytoplasmic fusion
mycelium

8. Plant Kingdom Life Cycle
Plants use Sporic Meiosis
alternation of generations
Meiosis produces haploid spores
Spores undergo mitosis to produce a multicellular haploid body (gametophyte)
Fertilization produces a diploid zygote
Zygote undergoes mitosis to produce a multicellular diploid body (sporophyte)
Alternates between multi-cellular diploid and multi-cellular haploid bodies

9. multicelled sporophyte
mitosis
Meiosis
Haploid (n) Phase of Cycle
spores
zygote
Diploid (2n)
Phase of Cycle
Fertilization
gametes
mitosis
Figure 21.3 Generalized plant life cycle.
multicelled gametophyte
mitosis
Stepped Art
Fig, 21.3, p. 326

10. Plant Kingdom Life Cycle
Sporophyte (diploid, multicellular)
Produces flowers which contain the germ cells
Germ cells are located in the carpel (ova) and stamen (pollen)

11. Plant Kingdom Life Cycle
Production of the ova
Occurs in flowers within the pistil
Made up of 1 or more carpels
Stigma
Style
Ovary

12. Plant Kingdom Life Cycle
Production of the ova
Occurs in flowers within the pistil
The ovary contains 1 or more ovules which produce egg sacs
Meiosis of the ovules produces spores
Spores undergo mitosis to become the egg sac (gametophyte)
Meiosis
Spores
Egg Sac
Mitosis

13. an ovule
ovary wall
megasporocyte
integument
stalk
ovary (cutaway view)
Diploid Stage
Haploid Stage
Double Fertilization
Meiosis

14. Plant Kingdom Life Cycle
Production of pollen
Occurs in flowers in the stamen
Anther
Filament

15. Plant Kingdom Life Cycle
Production of pollen
The anther contains germ cells in pollen sacks
Meiosis produces spores
Spores undergo mitosis to become the pollen (gametophyte)

17. Plant Kingdom Life Cycle
Pollination
The transfer of pollen from an anther to a stigma (not fertilization)
Wind, insects, mammals, etc.
Released pollen lands on the stigma
Pollen grows a tube through the style to the ovary

18. Plant Kingdom Life Cycle
Fertilization
Two sperm enter the egg sac from the pollen tube
One fuses with the egg forming the diploid zygote
Develops into the embryo
The other fuses with the central cell to form a triploid endosperm

19. Plant Kingdom Life Cycle
Development
A seed develops from each mature fertilized ovule
Fruit develops from the ovary or other tissue
Embryo grows into a new mature sporophyte
Nutritive tissue
Embryo
Seed
Ovule
Ovary

22. Fig. 27-5, p.451