Download Chapter 31.3

A New Generation Begins
AP Biology
Spring 2011
 Pollen
Formation:
• In _______, large numbers of diploid “__________
mother” cells divide by meiosis to form four
___________ microspores
• Each microspore will divide by _________ and
differentiate to form _________ __________
• Each pollen grain consists of an inner cell
located in the cytoplasm of the outer cell; both
cells are surrounded by a ______________ ______
 Egg
Formation:
• In the _______, a mass of tissue form ovules
(potential seeds) enclosed by integuments
(protective tissue)
• A ________ “megaspore mother” cell divides by
meiosis to produce ______ _________
megaspores, three of which ________________
 Egg
Formation:
• The surviving _______ undergoes three rounds of
mitosis with no _________ division generating a
single cell with eight haploid nuclei
• Ultimately the cytoplasm divides _________ to
produce seven cells; one ________ egg cell, one
__________ mother cell with two haploid nuclei,
and five cells that support the process of
___________________
 When
a pollen grain lands on a ________,
pollination has occurred
 After a pollen grain lands on a stigma,
one of the two pollen cells forms a ______
_____; the other cell divides by mitosis to
produce ____ sperm cells
 Guided by chemical cues, the pollen
tube grows through the tissues of the
______ to an ovule
 When
the _________ _______penetrates
the embryo sac, the two sperm cells
travel down the pollen tube and
complete the ________ fertilization event
• One sperm fuses with the egg nucleus to form a
diploid zygote
• The other sperm nucleus fuses with the two
endosperm nuclei in the endosperm mother cell
to yield a triploid endosperm, which will nourish
the young developing plant
 http://www.youtube.com/watch?v=Gq8N
Wh98wQs