Gymnosperms
In angiosperms and gymnosperms, is the more conspicuous take the sporophyte or gametophyte? What is the ploidy?
diploid, sporophyte
seed bearing pine cones are the male or female cones?
female
Where are eggs?
female cone
Megaspores occur in _____ _____ and form _____ gametophytes.
female cones; female.
What constitutes an ovule?
A megametophyte and its surrounding tissues.Also contains at least one archegonium with an egg cell.
Why is the development of seeds considered to be a great evolutionary advantage?
A seed permits a small but multicellular sporophyte to remain dormant until conditions are favorable for growth. While dormant, the young sporophyte is protected by a seed coat and is surrounded by a food supply.
Name 2 characteristics that distinguish angiosperms from gymnosperms
Angiosperms produce flowers, double fertillization, endosperms, and fruit.
How is sperm and egg carried in gymnosperms?
By wind, rather than free water.
What do pollen grains consist of?
4 nuclei and a pair of bladder like wings.
How are other gymnosperms different from pines?
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How are other gymnosperms similar to pine?
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Where are seeds on?
Cones (aka strobilli)
What is meant by the term heterosporous? What are the gametes called?
Development of two different spore type - two different sizes and sexes.
What do microsporangium produce?
Diploid microspore mother cells.
What is the function of the winglike extensions of a pine seed?
Dispersal by wind
Where on the pine branch was the terminal bud last year?
Examine the bud scar.
Recall that in ferns, the antheridia and archegonia on a prothallium mature at different times to avoid self-fertilization. How might the different location of male and female cones on a pine tree help to do the same?
Separating cones in tree discourages inbreeding
Dominant stage of Anthocerophyta
Gametophyte
Dominant stage of Bryophyta
Gametophyte
What is the function of each of the stoma in a pine leaf (needle)?
Gas exchange.
Which term best describes the life cycle of pines and other gymnosperms?
Heterosporous
How is fertilization more advanced/ complex in angiosperms and gymnosperms?
In angiosperms, they have double fertilization to produce the triploid endosperm and the diploid zygote.
How are pine needles or leaves arranged?
In bunches.
Where are the spores of pines located?
In cones
Where is pollen produced?
In male cones
Where does meiosis occur?
In the mother cells found in the sporangia
How do pollen grains get into the egg in the archegonium?
It grows a tube into the archegonium, where it releases its two nonmotile sperm nuclei. One sperm disintegrates; the other fuses with the egg to form a zygote
Why are pines called evergreens?
Leaves produced year round.
How can you tell where the terminal bud is?
Look at the distance from the bud scar to terminal bud.
On a pine tree, where do male cones form?
Lower branches
What is the male gametophyte in pines?
Mature pollen grain
Each megasporophyll bears two spore producing ____ on its upper surface.
Megasporangia.
What is the female spore?
Megaspores
Sporophylls of female cones are ____.
Megasporophylls
How are pine leaves different from those of broad leaved trees such as maples and oaks?
Shape and number of leaves.
Life cycle of a Pine
Meiosis produces 1N microspores and megaspores. Microspores develop into pollen. When pollen germinates, its is a mature microgametophytes. Megaspores are fertillized by pollen. Pollen grain germinates within the ovule and a pollen tube grows toward the egg. 15 months after pollination, a 2N zygote is formed. The embryo is now embedded in the megagametophyte and developed within the ovule. A pine seed forms, falls into the ground, and a seedling forms. The seedling develops into a large sporophyte (a pine tree). The mature sporophyte bears pollen bearing (male) cones and ovulate seed bearing (female) cones. The male cone develops into a scale with mother cells. The female one develops into a megaspore mother cell. Microspore mother cells (from the male cone) undergo meiosis to produce microspores. Megaspore mother cells develop into megaspores.
What do microspores develop into?
Microgametophytes
On the surface of each microsporophyll is a layer of cells called ___ that produced ____. These microsporophylls resemble ____.
Microsporangium; spores. scales
Sperm nuclei arise directly from _____. These form _______ and occur in the ____ of _____ _____.
Microspores; microgametophytes; scales; male cones
Sporophylls of male cones are ____.
Microsporophylls.
How do megaspores develop and what do they develop into?
Mitosis; megagametophyte.
What are sporophylls?
Modified leaves for reproduction that bear spores.
Are all of the pine cones the same size?
No
What is an integument in pines?
Outermost layers of tissue covering nucleolus of ovule; provides the seed coat
What is the function of each of the photosynthetic tissue (chlorenchyma) in a pine leaf (needle)?
Photosynthesis
Which of the following genera is an example of Phylum Coniferophyta? -Pinus -Zamia -Gingko -Welwitschia
Pinus
Explain the process of pollination.
Pollen sifts through the ovglifereous scales and sticks in a drop of resin at the micropylar end of an ovule. The pollen grain germinates and grows a tube into the archegonium, where it releases its two nonmotile sperm nuclei. One sperm disintegrates; the other fuses with the egg to form a zygote. The zygote, while in the ovule, develops into the embryo of a new sporophyte. The ovule is now a seeds and consists of an embryo, a seed coat (integuments of the sporangia), and a food supply (tissue of the megametophyte). The seed matures up to six months after fertilization.
What is the function of each of the epidermis in a pine leaf (needle)?
Protection, gas exchange, and preventing desiccation.,
What is the function of each of the resin duct in a pine leaf (needle)?
Protection, storage, wound-healing properties.
What is the function of each of the endodermis in a pine leaf (needle)?
Regulates transport in and out of vascular cylinder.
How do the structural features of pine leaves adapt the tree for life in dry environments?
Resin ducts provide for wound healing and the leaves are hardy/tough
Dominant stage of Anthophyta
Sporophyte
Dominant stage of Coniferophyta
Sporophyte
Dominant stage of Cycadophyta
Sporophyte
Dominant stage of Pterophyta
Sporophyte
What is the female gametophyte in pines?
Structure containing egg
What is an ovule in a pine?
Structure containing female gametophyte surrounded by nucellus and integuments.
Define integuments
Surrounds the nucellus and forms the seed coat.
Life cycle of a heterosporous plant
Syngamy produces 2N sporophyte which produces mega and microsporangium. Micro and megasporangium bear 2N spore mother cells which undergo meiosis. This produces 1N micro and mega spores that will develop into mega and microgametophytes. These gametophytes bear sperm and egg which undergo syngamy and the cycle begins again.
What forms the seed coat?
The integuments of the megasporophyll
What is pollination?
The transfer of pollen from male cones (where pollen is produces) to female cones, which house the eggs
What do gametophytes of of gymnosperms depend on?
They dependent on the large, free living sporophyte as the gametophytes are microscopic.
What do diploid microspore mother cells and how?
They produce microspores by meiosis.
What part of the female cone provides the food supply?
Tissue of the megagametophyte
What is the function of each of the vascular tissue in a pine leaf (needle)?
Transport of minerals, water, and organic transport.
T or F: The fern prothallus is an example of monoecious plant.
True
On a pine tree, where do female cones form?
Upper branches
On which surface of the ovuliferous scales are the pines seeds located?
Upper.
How many leaves are in a pine bundle?
Usually 1-8
How large is a staminate cone compared to a newly pollinated ovulate cone? A mature ovulate cone?
Varies with species, but ovulate cone is usually much larger.
How do microspores develop into microgametophytes and what are these microgametophytes called?
Via several mitotic divisions ; pollen grains
Are gymnosperm seeds "naked"?
Yes
Each ovuliferous scale of the female cone bears 2 _____, each of which produces a diploid _____ _____ _____.
megasporangia, megaspore mother cell.
What do megaspore mother cells produce and how?
megaspores via meiosis.
The scales on cones contain ____.
sporophylls
What contains the megagametophytes?
the ovule
Define nucellus
the tissue of the megasporangium immediately surrounding the megametophyte.
What does dioecious mean?
unisexual; male and female sex organs occur on separate plants
