30 Plant Diversity: The Evolution of Seed Plants Flashcards
What is the basic purpose of a seed?
To contain the embryo, its food supply, and a protective coat
Why are seeds advantageous over the methods employed by seedless plants?
- Does not need water for sperm to swim through
- Larger dispersal radius
- Allows for dormancy
Why are ferns not seen in the desert?
Their sperm needs water to travel between plants
Why are mosses typically found in moist conditions?
Their sperm needs water to travel between plants
In what organisms are the gametophytes the dominant life stage?
Mosses and other bryophytes
In what organisms are the sporophytes the dominant life stage?
Ferns and other seedless vascular plants, gymnosperms and angiosperms.
Describe the gametophytes of mosses and other nonvascular plants in terms of size and dependance.
Dominant
Describe the gametophytes of ferns and other seedless plants in terms of size and dependance.
Reduced, independent (photosynthetic and free-living)
Describe the gametophytes of seed plants (gymnosperms and angiosperms) in terms of size and dependance.
Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition
Describe the sporophytes of mosses and other nonvascular plants in terms of size and dependance.
Reduced, dependent on gametophyte for nutrition
Describe the sporophytes of ferns and other seedless vascular plants in terms of size and dependance.
Dominant
Describe the sporophytes of seed plants (angiosperms and gymnosperms) in terms of size and dependance.
Dominant
What is most common in seedless plants: heterospory or homospory?
Most seedless plants, including terms, are homosporous
Are seed plants homosporous or heterosporous?
All are heterosporous as they produce separate sperm (pollen) and eggs (ovules)
What produces megaspores?
Megasporangia
What are the structure of a seed in terms of whether they are derived from sporophytic or gametophyte tissue?
The seed coat is derived from the integument and thus the “grandparent generation” - hence 3 generations in a seed
The spore wall is surrounded by remnants of the megasporangium (sporophyte)
The food supply of the seed is from female gametophyte tissue.
The embryo in a seed is the new sporophyte.
What is the tough coating of the seed called?
The seed coat
What is the spore wall?
A thin layer between the seed coat and the interior of the seed
What is the purpose of the integument?
It protects the unfertilised ovule
What are the early gymnosperms called?
Progymnosperms
What are progymnosperms?
Species that are are transitional species between seedless vascular.
For example some were tall but had fern like leaves and were heterosporous but did not produce seeds
What does ‘paleozoic’ literally mean?
Early life
What does ‘mesozoic’ literally mean?
Middle life
What are the phyla of gymnosperms?
Cycadophyta, ginkgophyta, gnetophyta and coniferophyta.
What are plants in cycadophyta like?
They have large cones and palm like leaves
What group of plants are plasm trees?
Angiosperms
What gymnosperm phylum was particularly present at the time of the dinosaurs?
Cycadophyta
Into what groups are cycads classified?
They are gymnosperms in the phylum Cycadophyta
What are organisms in the phylum cycadophyta called?
Cycads