Test 2 Review Questions -- Seedless Vascular Plants Flashcards
Why are paleobotanists so excited about the Devonian era?
- Marks origin of all major land plants
- Contains diverse group of now-extinct taxa that provide insight into plant evolution
What organisms are contained in the group Lycophytes?
Club mosses
Spike mosses
What do Lycophytes represent in the story of land plant evolution?
- First appearance of roots, stems, and true leaves
- First vascular plants
What are two methods of spore dispersal?
- Free-Sporing (by spores)
- Seeds
Free-Sporing
Organism disperses by spores
What are three shared derived characters that separate Lycophytes from Bryophytes?
- True vascular system
- True leaves
- True roots
What kind of leaves do club mosses and spike mosses (Lycophytes) have?
Microphylls
Microphylls
true leaves
True or False: Lycophytes contain megaphylls.
False
Sporophyll
Leaf with a sporangium associated with it
Sporangium
Receptacle where spores are formed
How are sporangia organized in Selaginella?
Strobili
Strobili
structure containing sporangia
Homospory
morphologically one type of spore (even if spores produce gametophytes of different sexes)
Heterospory
two types of spores produced: microspore and megaspores
How do gametophytes develop in homosporous organisms?
Exosporic
How do gametophytes develop in heterosporous organisms?
Endosporic
Exosporic
Gametophyte development outside of parent cell
Ex. egg hatches to produce baby chicken, chicken grows up outside of egg
Endosporic
Gametophyte development inside parent cell
Ex. egg hatches to produce fully grown chicken
Which plant groups are homosporous?
- Bryophytes
- Lycopodium
- Most ferns
- Equisetum
Which plant groups are heterosporous?
- Selaginella
- Isoetes
- Gymnosperms
- Angiosperms
What is an advantage of homospory?
Flexibility of spores, depending on group meaning sexual reproduction can occur
Ex. spores can lead to hermaphroditic gametophytes, ensuring fertilization
What is a disadvantage of homospory?
Outbreeding may not occur
What is an advantage of heterospory?
Assures outcrossing
Outcrossing
maximization of genetic diversity
What is a disadvantage of heterospory?
No alternative
