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Questions and Answers
What is a defining characteristic of cross-pollination?
Which agent is NOT typically responsible for pollination?
What occurs during double fertilization in flowering plants?
Which floral structure is part of the Gynoecium?
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What is the primary role of the endosperm in seed development?
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Which floral symmetry is characterized by radial arrangement of parts?
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At which stage of embryogenesis does the embryo sac form?
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What happens immediately after pollen germination on the stigma?
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Study Notes
Sexual Reproduction in Flowering Plants
Pollination
- Definition: Transfer of pollen from anther to stigma of the same or another flower
- Agents: Bees, butterflies, moths, birds, bats, and wind (anemophily)
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Types:
- Self-pollination: within the same flower or between flowers of the same plant
- Cross-pollination: between flowers of different plants
- Pollinator attractants: Color, scent, nectar, and shape of flowers
Fertilization
- Definition: Fusion of male gamete (sperm) with female gamete (egg) to form a zygote
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Process:
- Pollen germination on stigma
- Pollen tube growth through style
- Sperm release from pollen tube
- Fusion of sperm with egg cell in ovule
- Double fertilization: One sperm fuses with egg cell, another with polar nuclei to form endosperm
Floral Morphology
- Flower structure: Sepals, petals, stamens, and carpels
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Reproductive organs:
- Androecium: stamens (male)
- Gynoecium: carpels (female)
- Floral symmetry: Radial (actinomorphic) or bilateral (zygomorphic)
Embryogenesis
- Definition: Development of embryo from zygote
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Stages:
- Zygote formation
- Cell division and growth
- Embryo sac formation
- Embryo maturation
- Endosperm development: Triploid tissue providing nutrients to embryo
- Seed formation: Mature embryo, endosperm, and seed coat
Sexual Reproduction in Flowering Plants
Pollination
- Pollination is the transfer of pollen from anther to stigma of the same or another flower.
- Agents of pollination include bees, butterflies, moths, birds, bats, and wind (anemophily).
- There are two types of pollination: self-pollination, which occurs within the same flower or between flowers of the same plant, and cross-pollination, which occurs between flowers of different plants.
- Flowers have attractants to lure pollinators, such as color, scent, nectar, and shape.
Fertilization
- Fertilization is the fusion of male gamete (sperm) with female gamete (egg) to form a zygote.
- The process of fertilization involves pollen germination on the stigma, followed by pollen tube growth through the style, then sperm release from the pollen tube, and finally the fusion of sperm with the egg cell in the ovule.
- Double fertilization occurs in flowering plants, where one sperm fuses with the egg cell to form a zygote, and another sperm fuses with the polar nuclei to form the endosperm.
Floral Morphology
- A flower consists of four main parts: sepals, petals, stamens, and carpels.
- The reproductive organs of a flower are the androecium (male, consisting of stamens) and the gynoecium (female, consisting of carpels).
- Flowers can have radial (actinomorphic) or bilateral (zygomorphic) symmetry.
Embryogenesis
- Embryogenesis is the development of an embryo from a zygote.
- The stages of embryogenesis include zygote formation, cell division and growth, embryo sac formation, and embryo maturation.
- The endosperm is a triploid tissue that provides nutrients to the developing embryo.
- A seed is formed when the embryo, endosperm, and seed coat are fully mature.
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Description
Learn about pollination and fertilization in flowering plants, including agents, types, and attractants.
