1.4.3
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What plants are the gymnosperms?
the conifers and their relatives
when did conifers evolve?
permian period, 280 mil
what is the makeup of the seed in terms of the life cycles?
Seed = embryo (2n) + food reserve (n) that can survive long dry/cold periods
what is important about the conifer mode of reproduction?
the seed replaces spore as dispersal agent
Name four changes in the the life cycle of the conifers in regards to plants that came before.
• life cycle involves to gametophytes • seeds start as ovule, the female gametophyte • in ovule, mega spores are not released and gametophyte is now carried by sporophyte • the male gametes are now pollen (microspores)
what is important about the advent of pollen for reproduction.
the need for water to be present is eliminated
what is characteristic of the progymnosperms? (extinct)
radial growth but reproduction by spores
what are the for living divisions of conifers today?
ginkophyta, cycadophyta, gnetophyta, and coniferophyta
of the four divisions of conifers alive today, which one has only one representative species left?
ginkophyta, the Chinese temple tree
what is characteristic about the sex of the ginkgo trees?
they have male and female trees
what are some medicinal uses of ginkgo? (2)
• treatment of memory loss and dementia 2. found to reduce the symptoms of intermittent claudation by 50%
the characteristics of genophyta
reproduction by cones but advanced wood like flowering plants
what does mormon tea come from?
from the plant family ephedra
what is mormon tea used for?
• used for colds as a decongestant • used as a weight loss supplement • used with caffeine for herbal ecstasy
what drug, derrived from the conifers, was recalled by Health Canada?
ephedrine
characteristics of cykadophyta?
• palm like frond but no flowers • reproduction by cones • highly toxic roots often used for rodentcides
Give three characteristics of conifers
terpene resins are used as defenses tallest and oldest species on the planet persistent leaves = evergreen
Give four ways that evergreens are adapted to the cold and arid conditions they are found in.
• winter leaves increase antioxidant levels • leaves increase antioxidant levels • needles collect and condense fog • advent of seeds means that the reproduction process is a lot more resiliant
what are the secondary compounds that conifers produce?
terpenes
what anticancer agent was discovered in the conifers?
taxol, found in taxus
what is so important about taxol chemically?
it prevents tubulin from assembling, and it cannot be produced by scientists