chapter 30. 360 mya, seed plants evolved 13,000 years ago, humans began domesticating wheat, corn,...
TRANSCRIPT
Chapter 30
360 mya, seed plants evolved 13,000 years ago, humans began
domesticating wheat, corn, rice, and bananas
The gametophytes of seed plants are too small to be seen with the naked eye; and are protected by a seed.
Two main types: gymnosperms and angiosperms
The female reproductive structure is called an ovule
The male reproductive cell is called pollen. During pollination, a pollen grain combines
with an ovule... This becomes a zygote, which becomes an
embryo, which develops into a seed: consisting of the embryo, a food supply and a protective coating.
Resist harsh environments Disperse more widely Can survive extremes in heat and moisture Multicellular complex seeds have their own
nutrient supply Can remain dormant for days, months, or
years
Gymnosperms are vascular plants that bear naked seeds (seeds not enclosed in ovaries) in cones, aka “conifers”
There are 4 gymnosperm phyla you need to know:
Cycadophyta Ginkophyta Gnetophyta Coniferophyta
Phylum Cycadophyta = cycads Large cones, palm like leaves Thrived during the time dinosaurs were
alive
Phylum Ginkophyta = Gingko Biloba “Maidenhair tree” Fanlike leaves, turn gold in Autumn Ornamental trees that withstand pollution
Phylum Gnetophyta = gnetophytes Live in tropics (or desert) Vary greatly
Phylum Coniferophyta = conifers Largest phyla, includes cypresses,
redwoods, fir, juniper, sequoia, pine, yew
Grow in taiga in Northern Hemisphere Evergreen, retain leaves throughout
year
Angiosperms are flowering plants They are vascular plants with seeds
enclosed in ovaries (flowers or fruits) Only one phylum = Anthophyta
Flowers are specialized structures for sexual reproduction. Sepals are modified green petals that enclose the flower
before it opens Petals are brightly colored and attract pollinators
Stamens are male reproductive organs that produce pollen (male gametophytes)
They consist of a stalk called a filament, and an anther at the top where pollen is made.
Carpels (or pistils) are the female reproductive organs of flowers and produce ovules (eggs).
The ovary is the base which contains ovules, the style is the stalk, and the sticky top that receives pollen is called the stigma.
Fruits are mature, ripened ovaries (after pollination has occurred).
The thickened wall of the ovary is called the pericarp.
Fruits can be: Fleshy or dry Oranges,
strawberries, grapes
Beans, nuts, grains Fruits: Disperse seeds Are nutritious,
sweet, and colorful
Eggs + Sperm = Fertilization making a zygote
Zygote becomes an embryo then a seed
Seed is planted and becomes a flower
Flowers produce eggs and sperm via meiosis
Angiosperms are divided into 4 main categories:
Basal Angiosperms Magnoliids Monocots Dicots (Eudicots)
Basal angiosperms are the oldest flowers (first to evolve)
Include water lilies and star anise
Include 8,000 plants: magnolias, laurels, and black pepper plants
¼ of angiosperms In their seeds they have only one little seed
leave, called a cotyledon Include orchids, dates, lilies, barley
Dicots or eudicots: 2/3 of angiosperms Have 2 little cotyledons Very diverse: poppies, oak, roses, peas,
zucchini
Monocots Dicots
One cotyledon Parallel Leaf Veins Scattered Vascular
Tissue Branched roots Pollen grains with one
opening Petals in multiples of 3
Two cotyledons Netlike leaf veins Vascular Tissue
arranged in rings One main root,
“taproot” Pollen grains with 3
openings Petals in multiples of 4
or 5
The evolution of angiosperms and animals influenced each other
Insects (like bees) pollinate flowers and collect nectar and pollen to make honey
Birds (like hummingbirds) pollinate flowers and drink nectar
Nocturnal animals (like bats) pollinate cacti and get nectar.
6 crops: wheat, rice, corn, potatoes, cassava, and sweet potatoes make up 80% of all calories consumed by humans
Tea and coffee, cocoa and chocolate come from seed plants
Cloves, saffron, vanilla, pepper, mustard, cumin, basil, sage, mint and cinnamon (bark) do too
Wood and paper Medicine like aspirin and cancer drugs
Deforestation (for lumber and agriculture and grazing animals)-all due to population growth
Loss of plant diversity causes loss of insect and animal diversity
Will cause extinction, climate change, and missed discovery of potential medicine