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Questions and Answers
Which process leads to the death of a plant?
What characterizes annual plants?
What is a key feature of biennial plants?
What occurs during the double fertilization process in angiosperms?
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Which statement about perennial plants is true?
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What describes the phenomenon where male and female structures in a flower mature at different times?
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Which feature is typically associated with wind-pollinated angiosperms?
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How do dioecious plants differ from monoecious plants?
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Which factor does not influence the flowering of short-day plants?
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What is the primary characteristic of flowers that attract hummingbirds?
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The structure made up of the combined stamens is referred to as the:
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Which type of pollination occurs when pollen from one flower lands on the stigma of a different flower?
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Which of the following is not a characteristic of advanced flowers?
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What term refers to the process where some flowers may aid in pollination through scent to attract specific species?
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What type of plants are characterized by flowering irrespective of day length?
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Study Notes
Plant Life Spans
- Annual plants complete their life cycle in one growing season.
- Biennial plants live for two years, storing energy in the first year and flowering in the second.
- Perennial plants live for multiple growing seasons, producing seeds and fruits repeatedly.
- Deciduous plants lose all their leaves during a specific period of the year.
- Evergreen plants lose leaves throughout the year, never appearing bare.
- Woody plants typically live longer than herbaceous plants due to extensive secondary growth.
Germination
- Germination is the process by which a plant grows from a seed into a seedling.
- The radicle, or first root, emerges during germination.
- Environmental factors like light wavelength, temperature, and stratification (low temperature exposure) can influence germination.
Embryo Development
- Embryo development starts with fertilization of the egg cell.
- A pollen tube delivers two sperm cells to the angiosperm embryo sac.
- One sperm fertilizes the central cell, initiating endosperm development (3N).
- The other sperm fertilizes the egg, producing a zygote (2N).
- Cell division (mitosis) follows, resulting in embryo formation.
Double Fertilization
- Angiosperms undergo a unique process called double fertilization.
- A pollen grain landing on a stigma forms a pollen tube that penetrates the style.
- As the tube grows, cells divide into two sperm cells.
Diachogamy
- Separation of male and female structures in time.
- Stamens (male) and pistils (female) mature at different times in the same flower.
- Plants exhibiting diachogamy are known as dichogamous.
Promoting Outcrossing
- Separation of male and female structures in space or time to promote outcrossing.
- Dioecious plants produce either ovules (female) or pollen (male) exclusively.
- Monoecious plants have male and female flowers on the same plant that mature at different times.
Self-Pollination
- Often involves small, inconspicuous flowers that directly shed pollen onto the stigma.
- When pollinators are scarce, plants can rely on self-pollination for seed production.
- Offspring resulting from self-pollination may be more uniform and adapted to their environment.
Wind Pollination
- Some angiosperms rely on wind pollination.
- Such plants typically have:
- Small, green, odorless flowers.
- Reduced or absent corollas.
- Flowers grouped and hanging down in tassels.
Pollination
- The process of transferring pollen to the stigma.
- Self-pollination occurs when pollen from one flower pollinates the stigma of the same flower.
- Cross-pollination involves pollen from one flower pollinating the stigma of a different flower, promoting outcrossing.
- Pollination in many angiosperms depends on attracting pollinators.
Bee Pollination
- Bees are the most common insect pollinators.
- They often visit yellow or blue flowers.
- Some flowers have stripes or dots invisible to humans indicating the location of nectaries (guides for bees).
Butterfly and Moth Pollination
- Flowers visited by butterflies have flat "landing platforms".
- Flowers visited by moths are often white or pale in color and emit a strong scent.
Bird Pollination
- Flowers pollinated by birds are typically red in color and provide large amounts of nectar.
- These colors are not visible to insects.
- Hummingbirds obtain nectar from flowers that accommodate their beaks.
Other Animal Pollination
- Bats and small rodents can participate in pollination.
- Pollination signals can be species-specific.
- Monkeys are attracted to orange and yellow fruits and can disperse seeds.
Gamete Production
- Plant sexual life cycles involve an alternation of generations:
- Diploid sporophyte (2N) → haploid gametophyte (N)
- In angiosperms, the gametophyte generation is small and enclosed within the parent sporophyte's tissues.
- The male gametophyte is the pollen grain.
- The female gametophyte is the embryo sac.
Trends in Floral Evolution
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Floral Symmetry:
- Primitive flowers are radially symmetrical.
- Advanced flowers are bilaterally symmetrical (e.g., orchids).
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Flower Structure:
- A complete flower has four whorls:
- Calyx: Made up of sepals.
- Corolla: Composed of petals.
- Androecium: Collective term for stamens.
- Gynoecium: Collective term for carpels.
- Incomplete flowers lack one or more of these whorls.
- A complete flower has four whorls:
Light-Dependent Pathway (Photoperiodic Pathway)
- Short-day plants flower when daylight becomes shorter.
- Long-day plants flower when daylight becomes longer.
- Day-neutral plants flower regardless of day length.
- Plants flower based on day length to ensure favorable environmental conditions.
- Photoperiod manipulation in greenhouses allows for year-round flowering, such as poinsettias during winter holidays.
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Description
Explore the fascinating world of plant life spans, from annuals to perennials, and learn about the germination process that transforms a seed into a seedling. This quiz covers key concepts of embryo development and the various types of plants based on their life cycles. Test your knowledge and deepen your understanding of plant biology.
