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Questions and Answers
What is the outcome of the mitosis process in the Generative Cell of pollen?
What is the outcome of the mitosis process in the Generative Cell of pollen?
In what stage of pine reproduction do pollen grains drift down between open scales?
In what stage of pine reproduction do pollen grains drift down between open scales?
What is the result of the fertilization process in Gymnosperms?
What is the result of the fertilization process in Gymnosperms?
How long does it take for female cones to mature in Gymnosperms?
How long does it take for female cones to mature in Gymnosperms?
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What is the number of cells in the male gametophyte (Pollen) in Gymnosperms?
What is the number of cells in the male gametophyte (Pollen) in Gymnosperms?
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What is the primary function of apical meristems in plants?
What is the primary function of apical meristems in plants?
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What is the characteristic of seeds that allows them to be dispersed by wind or water?
What is the characteristic of seeds that allows them to be dispersed by wind or water?
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What is the main difference between gymnosperms and angiosperms?
What is the main difference between gymnosperms and angiosperms?
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What is the function of lateral meristems in plants?
What is the function of lateral meristems in plants?
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What is the characteristic of sporophyte and gametophyte in tracheophytes?
What is the characteristic of sporophyte and gametophyte in tracheophytes?
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Study Notes
Adaptations to Life on Dry Land
- Sporopollenin, a durable polymer, coats spores and pollen, allowing plants to thrive on land
- Alternation of generations enables plants to adapt to changing environments
- Apical meristems facilitate localized cell divisions at root and shoot tips
- Waxy cuticle and stomata help plants conserve water and regulate gas exchange
Seed Plants
- Originated around 360 million years ago
- Seeds consist of an embryo (2n) and its food supply (endosperm, 3n) covered by a seed coat
- Dispersed by wind, water, or animals
Characteristics of Seed Plants
- Highly reduced gametophytes, ovules, and pollen
- Better adapted to handle drought and UV radiation
Vascular Plants
- Divided into four extant phyla in three clades
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- Lycophytes (club mosses) - seedless plants
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- Pterophytes (ferns, whisk ferns, and horsetails) - seedless plants
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- & 4. Seed plants (gymnosperms and angiosperms)
Gametophyte and Sporophyte
- Gametophyte (multicellular) has been reduced in size relative to the sporophyte during the evolution of tracheophytes
- Haplodiplontic life cycle
Meristems
- Apical meristems cause primary growth (lengthening of plant) at shoot and root tips
- Lateral meristems cause secondary growth (widening of plant) at the cambium
Gymnosperms
- Plants with "naked seeds"
- Lack flowers and fruits, having cones instead
- Ovules exposed on a scale
- Examples: Pines, spruces, firs, cycads, cedars
- The coastal redwood is the tallest living vascular plant (379 ft tall)
- Bristlecone pine is the oldest living tree (> 4,789 years old)
Gymnosperm Reproduction
- No double fertilization
- Male gametophyte = pollen (five cells, including two sperm cells and a pollen tube cell)
- Female gametophyte = megagametophyte (many cells, including two arquegonia cells)
- Fertilization: one sperm unites with an egg cell, while the other sperm degenerates
Pine Reproduction
- Female cones take 2 or more seasons to mature
- Pollination stage: pollen grains drift down between open scales and into the micropyle
- Fertilization stage: pollen tube reaches archegonium, and one sperm unites with an egg cell
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Description
Explore the key adaptations that enabled plants to thrive on land, including sporopollenin, alternation of generations, and more. Learn about the evolution of seed plants and their characteristics.
