12 Questions
What is the function of the integuments in an ovule?
To develop into the seed coat
What distinguishes gymnosperms from pterophytes?
Presence of seeds
If a pollen tube forms on the stigma of an angiosperm flower, it indicates that:
The stigma is receptive to pollination
During the evolution of seed plants, the size of the gametophyte:
Decreased
Which of the following phyla includes firs, cedars, cypresses, spruces, and pines?
Coniferophyta
In pines, what is the primary agent responsible for pollen transfer from male to female cones?
Wind
Which statement about pine cones is correct?
Pine cones found at the bottom of a pine tree are likely to be male cones.
What happens during the meiosis of the megaspore mother cell in most angiosperms?
Three of the four megaspores disappear, and only one develops into the functional megagametophyte.
Which of the following products can be derived from seed plants?
Food, fuels, building materials, and pharmaceuticals
During the evolution of seed plants, what has happened to the size of the gametophyte?
It has decreased significantly.
What characteristic distinguishes gymnosperms from pterophytes?
The presence of seeds
Which statement about the distribution of pine species is correct?
Pine species can be found in both the northern and southern hemispheres, but the majority are native to the northern hemisphere.
Study Notes
Seed Plant Reproduction
- Microspore production occurs in anthers.
- Integuments of the ovule develop into the seed coat.
Characteristics of Gymnosperms
- Gymnosperms are distinguished from pterophytes by the presence of seeds.
Seed Dispersal
- Seeds can be dispersed by soil, animals, wind, and water.
Pollination and Fertilization
- If the stigma of an angiosperm flower is receptive to pollination, a pollen tube is formed.
- Sperm reaches the archegonia via a pollen tube.
Evolution of Seed Plants
- During the evolution of seed plants, the size of the gametophyte has decreased.
- A gametophyte is the sexual phase in the life cycle of plants and algae that produces gametes (sperm and eggs) through mitosis.
Coniferophyta
- Firs, cedars, cypresses, spruces, and pines are all members of the phylum Coniferophyta.
- Coniferophyta is a division of plants within the gymnosperms that includes species such as pines, spruces, firs, and cedars.
Pine Characteristics
- All of the greater than 100 species of pines that exist today are native to the northern hemisphere.
- In pines, pollen is typically moved from male to female cones by wind.
- If collecting pine cones from the bottom edge of a pine tree, the pine cones would most likely be male and produce pollen.
Cycads
- Cycads look like palm trees, but differ from them because they do not produce flowers and have a multicellular gametophyte.
Angiosperms
- In most angiosperms, meiosis of the megaspore mother cell produces four megaspores, and three of them disappear, leaving only one megaspore to develop into the functional megagametophyte.
- Seed germination in angiosperms can be stimulated by passage through an animal digestive tract, exposure to fire, or a heavy rainfall.
Historical Context
- The origin of angiosperms was an "abominable mystery" to Darwin.
- The rapid diversification of angiosperms was puzzling to Darwin.
Test your knowledge on seed plants with questions about male and female pine cones, meiosis in angiosperms, products derived from seed plants, and the evolution of seed plants.
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