Chapter 27: Evolution of Seed Plants
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Principles of Biology 2
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116 Terms
What three major features contributed to the success of seed plants
Pollen, seeds, and wood.
Why was pollen important to plants living on land
It allowed sperm to reach the egg without requiring external liquid water.
What is pollen
The male gametophyte of a seed plant.
What does pollen contain
The male gametophyte and sperm cells.
What is a pollen tube
A tube produced by germinating pollen that transports sperm toward the egg.
What is sporopollenin
A tough substance in the pollen wall that resists dehydration and chemical damage.
What are microspores
Spores that develop into male gametophytes.
What are megaspores
Spores that develop into female gametophytes.
What does heterosporous mean
Producing two different types of spores: microspores and megaspores.
What is a megasporangium
The structure where megaspores develop.
What is an ovule
A megasporangium surrounded by integument.
What does an ovule become after fertilization
A seed.
What is pollination
The arrival of pollen at the appropriate location near the female gametophyte.
Does pollination equal fertilization
No. Pollination is pollen transfer; fertilization is the fusion of sperm and egg.
What are the three generations represented in a seed
Parental sporophyte → seed coat
Female gametophyte → nutrient tissue
New sporophyte → embryo.
What is seed dormancy
A state in which the embryo remains alive but does not grow.
Why is seed dormancy useful
It allows embryos to survive unfavorable environmental conditions.
How long can some seeds remain viable
Many can remain viable for decades, some more than 100 years, and rare examples for much longer.
What is a seed bank
A collection of dormant seeds present in an area.
What environmental conditions can stimulate seed germination
Fire, heavy rain, proper temperature, disturbance, and sometimes passage through an animal digestive tract.
What is secondary growth
Growth that increases the diameter/thickness of stems and roots.
What tissue produces secondary xylem
Vascular cambium.
What is wood
Secondary xylem.
Why is wood important
It provides support and helps transport water, allowing plants to grow taller.
What are gymnosperms
Seed plants whose ovules and seeds are not enclosed in an ovary/fruit.
What are the four major gymnosperm groups
Cycads, ginkgos, gnetophytes, and conifers.
Which gymnosperm group contains the most species?
Conifers
Approximately how many conifer species are there
About 700.
Where are gymnosperms especially successful today
High latitudes and high elevations.
What are the two types of pine cones
Female seed-bearing cones and male pollen-bearing cones.
What is a female cone
A seed-bearing structure containing ovules.
What is a male cone
A pollen-producing structure containing microsporangia.
What is a megastrobilus
A female/seed-bearing cone.
What is a microstrobilus
A male/pollen-bearing cone.
What happens when pollen reaches a pine ovule?
The pollen germinates and produces a pollen tube that delivers sperm.
Why is fire important to some lodgepole pine populations
Fire opens tightly closed cones and allows seeds to be released.
Are fleshy structures around some gymnosperm seeds true fruits
No. Gymnosperms do not produce fruits because they do not have ovaries enclosing their seeds.
Why do fleshy gymnosperm seed structures help reproduction
They attract animals that help disperse the seeds.
What is the oldest living single organism mentioned in the chapter
The bristlecone pine, which can live for about 5,000 years.
What are angiosperms?
Flowering plants.
What is the defining reproductive structure of angiosperms
The flower.
What major structure encloses angiosperm ovules
The carpel.
What does the ovary become after fertilization
The fruit.
What does an ovule become
A seed.
What are the two major functions of flowers
Reproduction and attracting/using pollinators.
What are stamens
The male reproductive structures of flowers.
What are the two parts of a stamen
Filament and anther.
What is an anther
The structure that contains microsporangia and produces pollen.
What is a carpel
A female reproductive structure containing ovules.
What are the three main parts of a carpel
Stigma, style, and ovary.
What is the stigma
The part where pollen lands.
What is the style
The structure connecting the stigma to the ovary.
What is the ovary
The structure containing the ovules.
What are petals
Flower structures that commonly help attract pollinators.
What are sepals
Structures that protect the developing flower bud.
What is the corolla
The collection of petals.
What is the calyx
The collection of sepals.
What is a perfect flower
A flower with functional male and female reproductive structures.
What is an imperfect flower
A flower that has only male or only female reproductive structures.
What does monoecious mean
Male and female flowers occur on the same plant.
What does dioecious mean
Male and female reproductive structures occur on separate plants.
What is the difference between pollination and fertilization
Pollination transfers pollen to the stigma; fertilization occurs when sperm fuses with the egg and/or polar nuclei.
How are most gymnosperms pollinated
By wind.
How are most angiosperms pollinated
By animals.
Name three ways flowers attract insect pollinators
Nectar, odors, and visual markings such as UV nectar guides.
What are nectar guides
Visual markings that help direct pollinators toward nectar.
What color are many bird-pollinated flowers
Red
Why are many bird-pollinated flowers relatively odorless
Birds generally rely more on vision than smell.
What is double fertilization
A process in angiosperms in which one sperm fertilizes the egg and another sperm fuses with the polar nuclei.
What does sperm + egg produce
A diploid zygote.
What does the zygote become
The embryo/new sporophyte.
What does the second sperm + two polar nuclei produce
Usually triploid endosperm.
What is the function of endosperm
It provides nutrients to the developing embryo.
Why is double fertilization important
It produces both the embryo and the nutrient tissue needed to support it.
What is a fruit
A mature ovary, usually containing seeds.
What is a simple fruit
A fruit that develops from one carpel or fused carpels of one flower.
What is an aggregate fruit
A fruit that develops from several separate carpels of one flower.
What is a multiple fruit
A fruit that develops from a cluster of flowers/inflorescence.
What is an accessory fruit
A fruit that includes tissues other than the carpel.
What is an example of a multiple fruit
Pineapple
How do animals help disperse fruits
They eat fruits and later deposit the seeds elsewhere or carry fruits/seeds on their bodies.
What are the two largest angiosperm clades
Monocots and eudicots.
How many cotyledons does a monocot embryo have
One
How many cotyledons does a eudicot embryo have
Two
What are examples of monocots
Grasses, cattails, lilies, orchids, and palms.
What are examples of eudicots
Most familiar herbs, vines, trees, and shrubs.
What is the typical leaf venation of monocots
Parallel
What is the typical leaf venation of eudicots
Branching/network venation.
How is vascular tissue arranged in monocot stems
Scattered.
How is vascular tissue arranged in eudicot stems
In a ring.
What type of root system is common in monocots
Fibrous roots.
What type of root system is common in eudicots
Taproots
What is the typical flower-part pattern of monocots
Parts in multiples of three.
What is the typical flower-part pattern of eudicots
Parts in multiples of four or five.
What is the typical pollen pattern of monocots
One furrow or pore.
What is the typical pollen pattern of eudicots
Three furrows or pores.
What are ecosystem services provided by plants
Oxygen production, carbon dioxide removal, soil formation, erosion control, climate moderation, and support of other organisms.
Why are plants important to terrestrial food webs
They are primary producers.
What is a primary producer
An organism that produces organic food from inorganic materials, usually through photosynthesis.
What are three examples of medicinal plants and their products
Opium poppy → morphine → pain relief
Pacific yew → paclitaxel → cancer treatment
Cinchona → quinine → malaria treatment.