modifications for successful life on land
1. reduction of gametophyte size
2. the almighty seed
importance of seeds
-zygotes developed into sporophyte embryos with packaged food supply in a protective coating.
-replaces spores as means of dispersal
points of gametophytes being reduced
seed plants are even more reduced
reverses trend gametophyte/sporophyte relationship.
diploid generation can withstand solar radiation with extra chromosomes
megasporangium of seed plants, fleshy structure. Unlike a chamber of spores like ancestors.
female gametophyte develops within the wall of the ______ and is nourished by the _________
characteristics adapted for dry conditions
thick cuticle on leafs
stomata are in pits, less water loss
needles are megaphylls, i.e. leaves
Female gametophyte of pine is in the ___________
ovule, consists of nutritive tissue and archengonium.
Conifers are _________, male and female gametophyte develop from different types of spores produced by different _________.
pollen cones have ___________, under goes meiosis producing __________ microspores.
megaspores becomes female gametophyte, consists of _________ and ________
egg and endosperm mother cell
Ovulate has Megasporangia, each megasporangium (nucellus) is enclosed in a protective integuments wiht a single opening called __________
Pollen grain germinates in the ovule, forming ________, that begins to digest its way through the nucellus.
megaspore mother cell produces 4 megaspore, only which one will survive, giving rise to
the female gametophyte
fertilization occurs more than one year after pollination,
two sperm cells developed from pollen tube and pollen tube grown through nucellus to reach female gametophyte
new sporophyte, gets embedded in the female gametophyte, nourishes until capable of photosythesis, it is now a ________
seed; with (2n) embryo, food source (n) endosperm), seed coat 2n integuments of parent's.
scales of the cone releases winged seeds carried by the wind, this replaces the _________ as a means of dispersal.
evolved from seed beareing leaf, that became rolled into a tube. Made up of stigma, ovule, style.
modifications of fruits that aid in dispersal
shapes like kites for wind dispersal.
burr-like fruit cling to animal fur
edible fruit passes through digestive tract, dispersing miles away
The female gametophyte of angiosperms do not produce __________, located within an
angiosperm gametophyte has embryo sac with
eight haploid nuclei, but seven cells. One cell is (n+n) not 2n, this is the future endosperm.
double fertilization happens when
two sperm fertilize the (n+n) to form make (3n)endosperm and an egg, to make an embryo (2n)
angiosperm embryo develop with rudimentary roots and one or two seed leaves called,
cotyledons, ex. dicotyledons and monocotyledons.