10 Questions
Which generation is dominant in seed plants?
Sporophyte
What is the main difference between the mechanisms of pollination in seed plants?
Wind pollination in gymnosperms vs. insect pollination in angiosperms
What is the role of the stamen in an angiosperm flower?
Produces pollen
What are the advantages of self-fertilization in plants?
Increased chance of disease resistance
How does double-fertilization occur in angiosperms?
One sperm fertilizes the egg, the other forms endosperm
Which mechanism of pollination is commonly used by gymnosperms?
Wind pollination
What is the primary disadvantage of self-fertilization in plants?
Decreased adaptability to changing conditions
During double-fertilization in angiosperms, what is the primary function of the second sperm cell?
Initiating endosperm formation
What are the main differences in the reproductive structures between gymnosperms and angiosperms?
Gymnosperms produce cones, while angiosperms produce flowers
In seed plants, which part of the flower contributes to fruit development after fertilization?
Carpel
Study Notes
Seed Plant Adaptations
- Seed plants adapted to reproduce without water by developing mechanisms to prevent water loss and protect their gametes.
- They produce seeds, which are structures that allow for reproduction without free water.
- Seeds contain embryos that are resistant to desiccation and can survive until they germinate.
Alternation of Generation
- Alternation of generation is the life cycle of seed plants, which consists of two phases: sporophyte and gametophyte.
- Sporophyte phase is diploid, producing spores that undergo meiosis to form haploid gametophytes.
- Gametophyte phase is haploid, producing gametes that fuse to form a diploid zygote.
- In seed plants, the sporophyte generation is dominant.
Pollination Mechanisms
- Seed plants use various mechanisms for pollination, including:
- Wind pollination (anemophily)
- Insect pollination (entomophily)
- Bird pollination (ornithophily)
- Bat pollination (chiropterophily)
Angiosperm vs. Gymnosperm Pollination
- Angiosperms (flowering plants) are pollinated by animals, primarily insects, and have adaptations to attract pollinators.
- Gymnosperms (conifers and cycads) are primarily pollinated by wind.
Angiosperm Flower Structure
- The sepal protects the flower bud.
- The petal attracts pollinators.
- The stamen produces pollen.
- The carpel contains the ovules and develops into a fruit.
Self-Fertilization
- Self-fertilization allows for reproductive assurance, but can lead to inbreeding depression.
- Plants that are self-fertilizing are often found in areas with limited pollinator availability.
- Plants that are not self-fertilizing are often found in areas with abundant pollinator availability, and require cross-pollination to reproduce.
Double-Fertilization
- In angiosperms, double-fertilization occurs when one sperm fertilizes the egg, and another sperm fertilizes the central cell of the embryo sac.
- This results in the formation of a diploid zygote and a triploid endosperm.
Asexual Reproduction
- Seed plants can naturally reproduce asexually through mechanisms such as:
- Vegetative propagation (e.g., runner plants)
- Apomixis (producing seeds without fertilization)
- Agamospermy (producing seeds without fertilization)
Test your knowledge on the adaptations of seed plants enabling them to reproduce without water, alternation of generation, pollination mechanisms, and differences in pollination between angiosperms and gymnosperms.
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