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80 Cards in this Set

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What three reproductive traits define seed plants?
continued reduction of the gametophyte, seeds, and pollen
In seed plants, is the gametophyte or sporophyte independent?
the sporophyte
What advantages does sheltering female gametophytes inside the parent sporophyte offer?
The gametophytes are not exposed to environmental stresses (drought, UV, etc.) and can obtain nutrients from the parent.
Why has the gametophyte generation been preserved rather than eliminated?
possibly to filter out alleles affecting basic cell functions (because they won't survive anyway), but also to nurture the eventual growing gametophyte with its tissues
How are spores and seeds similar and different?
Both provide ways of withstanding harsh conditions, but the spore is unicellular while the seed is more complicated, with and embryo and a food package.
What types of spores do seed plants have?
megaspores, made in megasporangia, are the female egg-containing gametophytes, while microspores, made in microsporangia, are the male sperm-containing gametophytes.
What are integuments?
layers of sporophyte tissue protecting the megasporangium and forming the seed coat
Does a seed get fertilized?
No, the pollen, megaspore and integuments become the seed.
Are seed plant sperm cells flagellated?
in some gymnosperms but not in conifers or angiosperms
How does pollination work?
The microspore develops into a pollen grain, is released by the microsporangium, can travel long distances, and when it enters the vicinity of a megaspore, releases one or more sperm.
How is pollination an advantage over seedless vascular plants?
The sperm can be transported a lot further in seeds than from seedless gametophytes.
What is the extinct ancestor of gymnosperms and angiosperms called?
progymnosperms
Are gymnosperms and angiosperms monophyletic or paraphyletic?
monophyletic
What does gymnosperm mean?
naked seed
What is the main difference between angiosperms and gymnosperms?
Angiosperms have enclosed ovaries for the ovules and seeds to develop in, while gymnosperm ovules and seeds grow on specialized leaves called sporophylls
Which came first, gymnosperms or angiosperms?
gymnosperms
Did progymnosperms have seeds?
some did
When did gymnosperms radiate?
during the Carboniferous and early Permian
What happened in the Permian?
Pangaea formed, continental interiors dried up, some flora and fauna were taken over (mainly in the ocean), such as reptiles and gymnosperms.
What are the four extant phyla of gymnosperms?
ginkgo (Ginkgophyta), cycads (Cycadophyta), gnetophytes (Gnetophyta), and conifers (Coniferophyta)
What are the relative sizes of the four gymnosperm phyla?
Coniferophyta is large, while the others are tiny.
What are ginkgos?
one extant species, Ginkgo biloba, which has deciduous fanlike leaves, is present in cities because it can tolerate air pollution, and grows seeds that stink when they decay.
What are cycads?
palmlike plants with sporophyll-filled cones
What are gnetophytes?
There are three genera: Welwitschia (big straplike leaves in SW Africa), Gnetum (tropical trees and vines), and Ephedra (arid shrub known as Mormon tea)
What does conifer mean?
cone-carrier
What are conifers?
Most are large evergreen trees, and all have cones, clusters of scale-like sporophylls.
List 9 examples of conifers.
pines, firs, spruces, larches, yews, junipers, cedars, cypresses, and redwoods
How many conifer species are there?
~550, but they take up a lot of space
Which conifers are adapted to dry conditions and how?
Pines and firs have needle-shaped leaves with thick cuticles and buried stomata
Which conifers are deciduous?
the dawn redwood and tamarack
What's special about conifers?
Redwoods in northern California are more than 110 meters tall (only surpassed by eucalyptus trees in Australia), and bristlecone pines are very old, over 4k years old!
Describe the life cycle of a pine.
Trees bear two kinds of cones, ovulate and pollen, the pollen enters the micropyle, both the pollen and archegonium do meiosis, then fertilize, the scales of the ovulate cone break off, and the seed finds somewhere to grow into a seedling and eventually a mature pine.
What is Douglas fir used for?
house framing, plywood production, paper pulpwood railroad ties, boxes and crates.
How much can a sequoia weigh?
giants can weigh 2500 tons
What conifer is a "living fossil"?
the Wollemia pine, discovered near Sydney, only 40 of which exist
What phylum are all angiosperms in?
Anthophyta
How has angiosperm phylogeny changed in the last 10 years?
It used to be split into monocots and dicots, but it seems some dicots diverged before the monocots split off; i.e. "dicots" was found to be paraphyletic
What are 7 examples of monocots?
lilies, orchids, yuccas, palms, grasses, sugar cane, and grains
What clade contains most dicots?
the eudicots
What are 6 examples of eudicots?
roses, peas, buttercups, sunflowers, oaks and maples
What are three dicots that branched off before monocots?
Amborella, water lilies, and the star anise
What does Amborella consist of?
one species, Amborella trichopoda, a small shrub only found on New Caledonia
What is improved in angiosperm xylem over gymnosperm xylem?
Along with tracheids, angiosperms have fiber cells and vessel elements.
Is gymnosperm or angiosperm pollination more 'random'?
Gymnosperm pollination is more random.
What is the primary purpose of a flower?
reproduction
What four types of modified leaves are present in a flower?
sepals, petals, stamens, and carpels
What are sepals?
green leaves at the bottom of a flower that hold the flower until it opens up
What are petals?
brightly-colored leaves designed to attract insects to pollinate the flower
Which components of a flower are directly correlated with reproduction?
stamens and carpels
What are stamens?
male sporophylls that make microspores in angiosperms
What are carpels?
female sporophylls that make megaspores in angiosperms
What's in a stamen?
the stem-like filament and pollen-producing anther
What's in a carpel?
an ovary with ovules in its base and a style connecting it to the stigma where pollen is caught
What's unique about angiosperm ovaries?
The seeds are enclosed in them.
How many carpels does an angiosperm flower have?
one, several, sometimes fused together at the base
What are fruits?
mature ovaries
What does a fruit do?
protects dormant seeds and helps them get dispersed
What are three ways a fruit can function and examples of each?
It can help the wind disperse the seed (dandelions), stick to animal fur and clothes (cockleburs) or be eaten by animals (berries)
What are pericarps?
fruits' tough outer wall
What are simple fruits?
fruits coming from one ovary, such as cherries or soybean pods
What are aggregate fruits?
fruits that come from a flower with multiple carpels, such as a blackberry
What are multiple fruits?
fruits that come from multiple flowers close together, such as pineapples
Describe the life cycle of an angiosperm from maturation to just before fertilization.
The anther makes microspores that develop into pollen grains which fly to the stigma of another flower, then start growing (germinate), extending a pollen tube down the style to the ovary, penetrating the micropyle pore into the ovary. Meanwhile, the ovules in the ovary have made the embryo sac, made of the egg and a couple other cells.
Describe the life cycle of an angiosperm from fertilization to maturation.
The pollen tube releases two sperm cells one of which fertilizes the egg, while the other fertilizes the main cell of the gametophyte, making the triploid endosperm (food supply). The seed then germinates and develops into a mature plant if conditions are right
What is cross-pollination?
transfer of pollen from one individual to another
How do plants insure cross-pollination?
The carpels and stamens can develop at different times, or can be more strategically positioned (stamens below carpels).
What are cotyledons?
seed leaves that develop and store food when the seed germinates, one if it's a monocot and two if it's a dicot
Why double fertilization?
maybe so that the food supply keeps up with the seed's germination, so food and development are not wasted
What are the four components of an angiosperm seed?
the embryo, endosperm, sporangium, and seed coat (which comes from the integuments)
When did angiosperms emerge?
around 130 million years ago, taking over the world around 65 million years ago, marking the transition between the Mesozoic and Cenozoic eras
How have angiosperms and animals developed a mutualistic symbiosis?
Angiosperms offered their fruit for the animals to eat in order to distribute its pollen far and wide.
How specific are angiosperms in attracting pollinators?
Some target single species, but most go for taxonomic groups with desirable characteristics (like hummingbirds)
What is special about humans' relationship with plants?
We have developed technology to maximize plant yields, affecting the plants directly.
Where does almost all of our agriculture come from?
angiosperms, including all fruits, vegetables and grains
What is the most common cause of tropical rain forest destruction?
slash-and-burn clearing for agriculture
At what rate is the tropical rainforest being cleared?
50 million acres per year, which would use it all up in 25 years
Overall, how many species are going extinct due to loss of habitat yearly?
hundreds of species per year
What are 8 secondary compounds of plants that we use as medicines?
atropine, digitalin, menthol, morphine, quinine, taxol, tubocurarine and vinblastine
How many known plant species are there?
250k
How many plant species do humans use?
around 2 dozen for almost all agriculture, and only 5k have been identified as potentially medicinally useful