All GRE Subject Test: Biology Resources
Example Questions
Example Question #1 : Understanding Alternation Of Generations
Which of the following refers to the principle of alternation of generations in plants?
The differences between a tree and a seed
Gamete-producing sporophytes
A life cycle which includes a unicellular haploid stage
A life cycle that includes a multicellular haploid stage
The need for external pollinators
A life cycle that includes a multicellular haploid stage
Plants have a multicellular haploid stage called the gametophyte. Gametophytes () produce gametes () through mitosis, which combine to produce a zygote (). The zygote grows into a multicellular, diploid sporophyte (), which produces spores () through meiosis. Those spores give rise to multicellular gametophytes.
Example Question #351 : Gre Subject Test: Biology
Fill in the blanks.
The __________ generation is dominant in the bryophyte life cycles, and the __________ generation is dominant in seedless vascular plants.
gametophyte . . . sporophyte
sporophyte . . . gametophyte
sporophyte . . . sporophyte
gametophyte . . . gametophyte
gametophyte . . . sporophyte
Bryophytes are nonvascular plants, such as mosses. Gametophytes are species that have haploid cells during their mature lives, while sporophytes are predominantly diploid during their adult phases.
Bryophytes have the gametophyte generation as dominant, with the sporophytes relying on the parental gametophyte. Starting with the evolution of seedless vascular plants, the gametophytes become reduced and are no longer the dominant life cycle. By the formation of angiosperms (seed plants), the gametophytes have become dependent on the parental sporophyte.
Example Question #1 : Plant Biology
Which of the following structures would be found in a tracheophyte, but not in a bryophyte?
Xylem
Plasmids
Cell walls
Chloroplasts
Xylem
All plants can be classified as either bryophytes or tracheophytes. Plants that contain transport vessels (xylem and phloem) are tracheophytes, while those without transport vessels are bryophytes. All plants contain cell walls and chloroplasts, but only a tracheophyte would contain xylem. Plasmids are structures that are almost exclusively found in bacteria or protozoans.
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