Questions and Answers
Self-pollination guarantees genetic variation in plants.
False
The endosperm is formed when one male gamete fuses with the egg and the other fuses with polar nuclei.
True
Wind-pollinated flowers are characterized by bright colors and sweet scents to attract pollinators.
False
Dormancy allows plants to begin germination during cold winter months.
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Vegetative propagation involves gametes and fertilization.
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The sporophyte stage of a plant is haploid and spends most of its life cycle as a diploid.
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Pollination is the process of transferring pollen from the stigma to the anther.
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Male and female gametes in flowering plants are produced during the gametophyte stage.
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The carpel is the male sexual organ of the flower.
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The fusion of male and female gametes results in the formation of a diploid zygote.
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Asexual reproduction requires two parents to produce offspring.
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Phototropism refers to a plant's growth in response to light.
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Geotropism causes roots to grow against gravity.
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Auxins are plant hormones that play a role in growth regulation.
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Root tubers are unable to produce new plants during winter.
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Study Notes
Plant Reproduction
- Flowering plants have a life cycle with two main stages: sporophyte (diploid) and gametophyte (haploid).
- Sporophytes produce spores through meiosis while gametophytes produce male and female gametes.
Flower Structure and Functions
- Sepal: Provides protection to the flower.
- Petal: Brightly colored to attract insect pollinators via color and fragrance.
- Stamen: Male reproductive organ producing male gametes.
- Filament: Thin stalk that supplies food and water to the anther.
- Anther: Sac-like structure that produces pollen through meiosis.
- Stigma: Receives pollen and is located at the top of the carpel.
- Ovary: Site of fertilization.
- Carpel: Female reproductive organ of the flower.
Fertilization Process
- Development begins from a zygote (fertilized egg), which forms into a sporophyte with roots and shoots.
- Male gametes fuse with female gametes to create a diploid zygote.
- Pollination occurs when pollen from an anther lands on the stigma of another flower.
- Sufficient pollination is essential for sexual reproduction, seed, and fruit formation as well as genetic variation.
Double Fertilization
- After pollination, the tube nucleus travels down the style to the micropyle in the ovary, dividing by mitosis to create two male gametes.
- One male gamete fuses with the egg, while the other fuses with polar nuclei to form endosperm for nourishment.
Pollination Methods
- Self-pollination: Pollen transfers from anther to stigma on the same plant; guarantees reproduction but reduces genetic variation.
- Cross-pollination: Pollen moves between different plants of the same species; promotes genetic diversity.
Adaptations of Pollination
- Wind-pollinated flowers: Long stamens, feathery stigmas, large amounts of light pollen, minimal color or scent.
- Insect-pollinated flowers: Bright petals and unique shapes attract pollinators; sticky pollen aids collection.
Seed Dispersal Methods
- Wind: Example - sycamore.
- Animal: Example - burdock seeds attach to fur.
- Self-dispersal: Example - pea plants explode their pods.
- Water: Example - seeds can float and disperse via water.
Dormancy and Vegetative Propagation
- Dormancy: Temporary growth pause to ensure survival during adverse conditions like winter.
- Vegetative propagation: Asexual reproduction without gametes; involves a single parent, rapid process, and produces identical offspring.
Root Tubers and Artificial Propagation
- Root tubers remain dormant and can grow new plants once conditions improve.
- Cuttings are portions removed from a parent plant and grown into new, independent plants.
Tropisms in Plants
- Tropism: Directional growth response to environmental stimuli, e.g., light or gravity.
- Phototropism: Stems grow toward light for optimal photosynthesis.
- Geotropism: Roots grow down towards gravity, and shoots grow up against gravity.
Auxins
- Auxins are plant hormones that regulate growth and response to stimuli.
Plant Families
- Various plants, such as buttercup, daisy, violet, pansy, nettle, and sunflower, are identified by their Latin names.
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Description
Explore the fascinating life cycle of flowering plants, focusing on the two key stages: sporophyte and gametophyte. This quiz includes the structure and function of flower parts, helping you understand how plants reproduce and attract pollinators.
