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Plants (Angiosperm Reproduction (Pollination (Tube cell lengthens the…
Plants
Angiosperm Reproduction
Gametophytes
Male
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Formation
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male gametophyte consists of: pollen grain (n), generative cell and tube cell
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Female
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Formation
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embryo sac consists of: antipodal cells, polar nuclei, Synergids and egg (haploid)
Pollination
- Tube cell lengthens the pollen tube
- Pollen tube forms around ovary and generative cell splits into 2 sperm cells
- Pollen germinates and Tube cell begins to form pollen tube
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- Pollen tube approaches ovule along the bottom of the ovary
- Pollen tube penetrates ovule through micropyle, tube cell disintegrates and sperm cells enter ovule
- Fertilization of egg and fertilization of endosperm
Double Fertilization
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This process ensures that the endosperm only forms within seeds that have been fertilizes therefore preventing excess waste of nutrients on seeds that will not be fertilized
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After Fertilization
Seed matures, dehydrates and enter dormancy
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Imbibition: seed uptakes water when its dry causing the seed to expand and rupture. This begins the seeds growth into a plant
Growth
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Primary
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growth of length, so exposes the plant to more sunlight and soil to absorb nutrients from
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General
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Meristems
plant growth happens at meristem: tissue that remains embryonic, allowing for continual growth
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Reproduction
Pollination
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Types
self-fertilization
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some plants have developed mechanisms to prevent this from happening (carpel and stamen located differently, they mature at different times or self-incompatibility)
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biotic fertilization
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insects (bees, moths, butterflies, flies)
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Asexual
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Cons:
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offspring must be able to survive in the current environment, if not they will die
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Pros:
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stronger progeny, skips the weak seedling stage
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Structure
Organs
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Stems
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Leaves are attached and the stem grows to elongate and orient the leaves to maximize photosynthesis as well as reproductive functions
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Growth
Apical Bud
Bud at the tip of the stem, promotes vertical growth
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Roots
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SystemTypes
Fibrous Root
consists of a bunch of small thin roots that are just below the surface, generation point is the base of the stem
Taproot
consists of one main root that penetrates deep into the soil and acts as a structural stabilizer to keep plant upright, allowing plant to grow tall
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Adaptations
Root Hairs
increases the surface area of the roots with finger-like extensions which increases efficiency of absorption
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Tissues
Vascular
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Types
Xylem: transports mainly water with some dissolved minerals from the root system to the shoot system
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Stele
Vascular Cylinder
Located in the roots, a solid central bundle of vascular tissue
Vascular Bundle
found in the stem and leaves, separate stands of vascular tissues
Ground
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Note: not filler, provide some function for photosynthesis, short distance transport, storage and support
Dermal
Protective outer covering, protects against pathogens and physical damage
Non-woody plants: consists of epidermis - tightly packed cells and cuticles - waxy coating to prevent waterloss
Woody plants: periderm - harder outer coating (bark) that offers more protection than the epidermis, mainly found in the older stem and root sections.