GRE Subject Test: Biology : Divisions of Life and Viruses

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

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Example Questions

Example Question #2 : Plant Evolution

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

Possible Answers:

The differences between a tree and a seed

A life cycle that includes a multicellular haploid stage

The need for external pollinators

Gamete-producing sporophytes

A life cycle which includes a unicellular haploid stage

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

sporophyte . . . sporophyte

gametophyte . . . sporophyte

gametophyte . . . gametophyte

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.

Example Question #1 : Evolution

Which of the following is false of the phylum chordata?

Possible Answers:

They have a coelom

They have a notochord at some point in their development

They are protostomes

They have bilateral symmetry

Correct answer:

They are protostomes

Explanation:

All chordates are deuterostomes, not protostomes. During early development, the formation of the blastopore leads to the growth of the digestive tract. In protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus.

All chordates have a notochord during development, which eventually gives rise to the nervous system. Chordates also have a coelom, or fluid filled cavity, somewhere within the body and they all exhibit bilateral symmetry.

Example Question #1 : Speciation And Phylogenetics

Which of the following is not necessary for designation as a chordate?

I.  A notochord

II.  Vertebrae

III.  A post-anal tail

IV.  Gill arches 

V.  A dorsal, tubular nervous system

Possible Answers:

III

V

II

IV

I

Correct answer:

II

Explanation:

Chordates must have, at some point in their embryogenesis, all features except vertebrae. Although the vast majority of chordates are vertebrates, Amphioxus has only a notochord. This primitive organism never develops vertebrae. Man has gill arches, and remnants of these are seen in certain congenital malformations. The notochordal remnants can give rise to the tumor known as a chordoma. The brain has ventricles (it is tubular) and it is certainly dorsal. Finally, human tail persists in about one per million live births.  

Example Question #1 : Speciation And Phylogenetics

Which of the following statements about chordates is true?

Possible Answers:

Their anus forms from the blastopore

They are protostomes

All chordates are vertebrates

They lack a coelom 

Correct answer:

Their anus forms from the blastopore

Explanation:

The phylum chordata has a few key characteristics. They are deuterostomes, meaning that the anus arises from the blastopore. They have a coelom that arises from the mesoderm during development, and at some point they have a tail, pharyngeal slits, and a notochord.

Vertebrata is a subphylum of chordata, so not all chordates are vertebrates (though all vertebrates are chordates).

Example Question #1 : Identifying Animals

Which of the following organelles is/are mainly present in animal cells?

I. Peroxisome

II. Centrioles

III. Flagella

Possible Answers:

II only

I and III

III only

I only

II and III

Correct answer:

II only

Explanation:

Centrioles are generally only found in animal cells, but have been found in a variety of eukaryotes. There are a small subset of plants that do contain centrioles. Some plant cells have flagella and peroxisomes.

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