AP Biology : Understanding Vascular and Avascular Plants

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Classes Of Plant

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

sporophyte . . . sporophyte

gametophyte . . . 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:

Chloroplasts

Cell walls

Xylem

Plasmids

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 #2 : Evolutionary History

Which of the following is not an example of an advantage gained through the vascularization of plants?

Possible Answers:

Swimming sperm

Large size

Dominant sporophyte generation

Extensive root and shoot systems

Larger photosynthetic area

Correct answer:

Swimming sperm

Explanation:

Swimming sperm is a feature of avascular and early vascular plants, who needed to remain in moist environments in order to retain water. 

After gaining vascular systems, plants were able to circulate water and nutrients more efficiently, thus being able to grow larger, have more leaves, develop branched systems of roots and shoots to collect water and nutrients, and better dispersal of spores due to gains in size. 

Example Question #1 : Classes Of Plant

Which of the following best describes the pith: a tissue type present in vascular plants?

Possible Answers:

It is a tissue in non-vascular plants that transports nutrients throughout the plant

It contains no parenchyma cells

Pith is located in leaves

It is a tissue in vascular plants that transports nutrients throughout the plant

Correct answer:

It is a tissue in vascular plants that transports nutrients throughout the plant

Explanation:

Pith is a type of tissue located in the stems of vascular plants. It stores and transports nutrients throughout the plant. The pith is composed of parenchyma cells.

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