angiosperm reproduction chapter 38. angiosperm reproduction angiosperms have 3 unique features:...
Post on 02-Jan-2016
230 Views
Preview:
TRANSCRIPT
Angiosperm Reproduction
Angiosperms have 3 unique features: Flowers, Fruits, & Double Fertilization
Microsporangia Pollen sacs in the anther Diploid cells = meiosis male gametophyte
(pollen) Pollen has 2 haploid nuclei
Tube nucleus – 1 sperm develops into a pollen tube
Generative nucleus – divides into 2 sperm cells which remain inside the pollen tube
Ovary
Ovules form with a diploid cell Soon 4 haploid megapsores form Eventually get 8 haploid nuclei, but only
3 are most important 1 haploid nucleus = egg
Will combine with sperm nucleus to form the zygote
2 other nuclei are called polar nuclei Polar nuclei will fuse with sperm nucleus to
make 3n endosperm
Pollination
Pollen lands on stigma
Pollen tube made from pollen grain
Pollen tube grows down into the ovary
When pollen tube reaches ovule, double fertilization occurs
Double Fertilization
Double fertilization is the union of 2 sperm cells forming zygote & endosperm
Unique to angiosperms 1 sperm fertilizes the egg zygote
Zygote develops into the embryo sporophyte Other sperm combines with both polar
nuclei = 3n nucleus This 3n tissue endosperm Endosperm – food storing tissue in the seed
After double fertilization
Ovule develops into a seed Ovary develops into fruit which encloses
the seed Fruit protects the enclosed seed Fruit aids in dispersal by wind or animales
Seed coat – protects embryo & its food supply
Radicle – embryonic root Epicotyl – shoot tip with pair of miniature
leaves
Seed
As the seed matures, It goes dormant Low metabolic rate, growth and development
are suspended
Seed resumes growth given suitable environmental conditions for germination
Asexual Reproduction in Plants Asexual reproduction in plants is called
vegetative reproduction Fragmentation
Type of vegetative reproductive When a part of the parent plant is
separated and then generates into a new plant, genetically identical to parent plant
Self-fertilization is another means of asexual reproduction
top related