GRE Subject Test: Biology : Plantae

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Plant Evolution

What is a distinct feature of a C4 plant?

Possible Answers:

Closed stomata during the day

Carbon fixation

Light independent reactions

Bundle-sheath cells

Correct answer:

Bundle-sheath cells

Explanation:

Carbon fixation converts inorganic carbon dioxide into organic carbon compounds, such as glucose and cellulose. This is a characteristic function of both C3 and C4, and is a primary purpose of light independent reactions.

Closed stomata during the day is a characteristic of CAM plants, which allows for the conservation of water that is usually lost during photorespiration.

Bundle-sheath cells are a characteristic of C4 plants. The presence of bundle-sheath cells isolates rubisco, preventing rubisco from binding to oxygen during photorespiration.

Example Question #3 : Understand Inputs And Outputs, Purpose

Some organisms, such as green plants, are capable of obtaining energy directly from photosynthesis. These organisms are termed __________.

Possible Answers:

autotrophs

homotrophs

herbivores

primary consumers

heterotrophs

Correct answer:

autotrophs

Explanation:

Autotrophs are organisms that produce complex organic compounds from substances present in the surroundings. These organisms may do this through the use of energy from light or from inorganic chemical reactions.

In contrast, heterotrophs require organic input in order to generate biological compounds and are unable to use light or inorganic materials for energy.

Example Question #3 : Plant Biology

Which of the following refers to the principle of alternation of generations in plants?

Possible Answers:

The need for external pollinators

A life cycle that includes a multicellular haploid stage

A life cycle which includes a unicellular haploid stage

Gamete-producing sporophytes

The differences between a tree and a seed

Correct answer:

A life cycle that includes a multicellular haploid stage

Explanation:

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 #1 : Plantae

Fill in the blanks.

The __________ generation is dominant in the bryophyte life cycles, and the __________ generation is dominant in seedless vascular plants.

Possible Answers:

sporophyte . . . gametophyte

gametophyte . . . gametophyte

gametophyte . . . sporophyte

sporophyte . . . sporophyte

Correct answer:

gametophyte . . . sporophyte

Explanation:

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 #2 : Plant Biology

Which of the following structures would be found in a tracheophyte, but not in a bryophyte?

Possible Answers:

Cell walls

Chloroplasts

Plasmids

Xylem

Correct answer:

Xylem

Explanation:

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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