Gymnosperms Flashcards
What are some characteristics of Gymnosperms?
Classified as vascular, seed producing land plants.
Photoautotrophic, eukaryotic and multicellular.
Produce naked seeds and have needles for photosynthesis.
What two types of cones do Gymnosperms produce?
Male pollen cones - contains pollen (male gametophyte)
Female ovulate cones - produces the female gametophyte (with eggs)
What are both male and female cones made of?
Scales
What do the Male scales contain and what process do they go through?
Scales contain Microsporangia (2N)
Each cell of the microsporangia undergoes meiosis to produce 4 microspores (N) They will grow into a pollen grain.
What do Female cones contain and what process do they go through?
Each scale contains 2 Megasporangia (2N)
Each cell in the Megasporangia undergoes meiosis to produce 4 cells. Only 1 survives, it is a Megaspore (N)
What process do Megaspores go through and what do they produce?
Undergoes mitosis to produce Female gametophyte.
Gametophyte produces Archegonia (N) which contains 1 egg (N) each.
What is Pollination in Gymnosperms?
An act of transferring pollen grains from the pollen cone to ovulate cone.
How do pollen grains help in pollination?
With its sperm nucleus, pollen grains are carried by the wind with the aid of air sacs or air bladders to the ovulate cone.
Pollen grains stick to the base of the ovules on the ovulate cone.
When does Fertilization occur in Gymnosperms?
When the sperm nucleus (N) combines with the egg nucleus (N) to form a zygote (2N).
The zygote will then develop into an embryo by Mitosis.
What do the pollen grains do in Fertilization?
The pollen grains germinates, forming a pollen tube that works its way through the Megasporangium. It arrives at the female gametophyte as the latter matures its archegonia.
What does the Pollen tube do?
Discharges its sperm nuclei into the archegonia.
What does the Female gametophyte become?
Becomes stored food, endosperm (N), which will feed the sporophyte after germination.
What generation are dominant and what generation is microscopic?
Sporophyte (2N) generation is dominant.
Gametophyte (N) generation is microscopic
What does Phloem do in Gymnosperms?
Transports sugars from photosynthesis, mixed with h2o (‘cell sap’) in the needles to the rest of the plant.
At maturity these are living cells.
What does Xylem do in Gymnosperms?
Transports h2o and minerals from roots to needles and stems.
Dead at maturity, known as soft wood.