Gymnosperms Lab Exam 2 Flashcards
Seedless plants reproduce via
Spores
Seed plants reproduce via
Seeds
a structure in which the embryo (the young sporophyte) is shed from the parent plant, enclosed within a resistant coat, together with a supply of food that aids its establishment
Seed
Which plants are the majority of seed plants
Extant plants
Consist of an embryo
Seed
Seeds stores food which is called the
Endosperm
Modern seed plant the ovule consist of a nucellus envelope by one or two ____ with a ____
integuments with a micropyle
a micropyle is also called
apical opening
When fertile the nucellus contains a megagametophyte composed of _____ and ____
nutritive tissue and archegonia
After fertilization the integuments develop into a
seed coat; a seed is formed
A megaspore retained within a fleshy megasporangium
nucellus
Do seed plants require water for fertilization?
No
Development of the embryo (young sporophyte) within the ___retained within the ____
megagametophyte retained within megasporangium
The seed habit arose by 365 million years ago via fusion of vegetative tissues around the ____
megasporangium
This additional protective layer is called an
integument
The integument has a small opening called
Micropyle
Fertilization takes place through this part of the seed
Micropyle
an integumented megasporangium
Ovule
Following fertilization the integument will become the
seed coat
The pollen is shed at this stage and it carried by the wind to an immature ____
megastrobilus
During the spring pollination season the megastrobili (female cones) have their cone scales ___
Open
The pollen in the wind is caught and held by a sticky secretion. As the secretion dries up the pollen is drawn into the ____. The cone scales then grow together
micropyle
The pollen tube begins to digest through the ____ towards the developing megagametophyte
nucellus
The pollen tube begins to digest through the nucellus towards the developing
megagametophyte
Twelve months after pollination the generative cell divides to form a
sterile cell and a spermatogenous cell
Megastrobili (female cones) are ___ than the microstrobili.
Larger
A pair of ovules sit on top of a ___ which is subtended by a sterile bract.
seed-scale complex
Each ovule contains a _____ surrounded by a thick integument with an opening (micropyle) facing inward
multicellular nucellus
Each nucellus contains a megasporocyte (megaspore mother cell) which undergoes meiosis to produce
Four haploid cells
Three degenerate and the remaining one develops into the ___ over a six month period.
megagametophyte
At 13 months after pollination, inside the megagametophyte, a large number of free nuclear divisions take place, forming 2,000 free nuclei. Then cell walls form to make solid tissue. This gametophytic tissue will become the
stored food inside the mature seed
15 months after pollination 2 - 3 archegonia, each containing an egg, form. At this time the pollen tube reaches the archegonia and it discharges both sperm nuclei into the archegonia. One sperm ____ the egg, the other ___
fertilizes and the other degenerates
As the developing zygote divides to form the embryo ____ of cells are produced.
four tiers
These form suspensors which push the developing embryo deep into the ______. Simultaneously the integument forms the seed coat
gametophyte tissue
Developing stored food
Gametophyte tissue
As the developing zygote divides to form the embryo four tiers of cells are produced. These form ____ which push the developing embryo deep into the gametophyte tissue (developing stored food). Simultaneously the integument forms the seed coat
suspensors
push the developing embryo deep into the gametophyte tissue (developing stored food). Simultaneously the integument forms the seed coat
Suspensors
The seeds mature and they are shed during the ____, when the cone scales open. Therefore if takes about 2 1/2 years from pollination to the shedding of seeds
second autumn
