AP Biology : Understanding Other Plant Macrostructures

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Understanding Other Plant Macrostructures

Of the following answer choices, which most accurately describes the mechanism that the stems of plants use to grow toward light?

Possible Answers:

Cells on the darker side of the stem elongate more than cells on the lighter side

The growth of the stem is determined by metabolic processes, which are stimulated by light striking the stems

The plant will grow away from other plants so as to minimize competition

Photosynthetic processes dictate the growth

Contractile cells on the light side of the stems dictate the growth toward light

Correct answer:

Cells on the darker side of the stem elongate more than cells on the lighter side

Explanation:

Plants grow so as to maximize the elongation of their stems as much as possible. Cells on the lighter side of the stem are already being provided with photosynthetic energy, while cells on the darker side are receiving less of this energy input. This causes the cells on the darker side to elongate toward the energy source. When one side of the stem is longer than the other, it causes a curve in the growth, resulting in a directionality of the growth of the stem.

Example Question #36 : Plant Structures

Plant root systems can be generally categorized as either taproot systems or fibrous root systems. Which of the following is a characteristic of a fibrous root system?

Possible Answers:

Fibrous root systems are well adapted to soil where ground water is not close to the surface

Fibrous root systems do not penetrate deeply into the soil

Fibrous root systems usually penetrate deeply into the soil

Fibrous root systems consist of a series of roots that spread out from a major single root

Correct answer:

Fibrous root systems do not penetrate deeply into the soil

Explanation:

Fibrous root systems are common in seedless vascular plants and in most monocots, such as grasses. Many small roots grow from the stem of the plant and are considered adventitious (a term describing a plant organ that grows in an unusual location). 

Fibrous roots have no main root and do not penetrate deeply into the soil, usually penetrating only a few centimeters. As such, fibrous root systems are best adapted to shallow soil. This also helps prevent erosion, as the shallow, highly-branched roots hold the topsoil in place. 

Example Question #37 : Plant Structures

Which of the following is a type of stem?

Possible Answers:

Stele

Rhizomes

Lateral roots

Pith

Correct answer:

Rhizomes

Explanation:

Stems are one of the three basic plant organs, and consist of an alternating system of nodes (where leaves attach) and internodes (regions of the stem that span between nodes).

Some plants have evolved to have stems with additional functions, such as the ability to store food or to participate in asexual reproduction. These modified stems include rhizomes, bulbs, tubers and stolons.  

A rhizome is a horizontal shoot of the plant that grows just below the surface. Vertical shoots (and resulting leaves) grow from axillary buds on the rhizome. Examples of plants with rhizomes include irises, hops, and asparagus. 

Example Question #2 : Understanding Other Plant Macrostructures

Which of the following are true of the root cap?

Possible Answers:

It contains a zone of elongation, which lengthens the root

It contains xylem cells, which transport water to the leaves

It grows away from the pull of gravity

It protects the tip of the plant and secretes mucilage

It forms the outermost cuticle layer of the entire root

Correct answer:

It protects the tip of the plant and secretes mucilage

Explanation:

The root cap occurs on the end of any root. It protects the tip of a plant's root. Specifically, it protects the apical meristem of the plant, which lengthens the root and helps it grow. Also root cap secretes a polysaccharide slime called mucilage. The zone of elongation does occur in roots, but it is not contained to the root cap. The root cap grows towards the pull of gravity. The root cap occurs only on the tip of the root, not over the entire surface of the root. These cells only protect the root; they are not xylem cells, which function in transport of water and nutrients from the roots up to the leaves.

Example Question #39 : Plant Structures

Which of the following is not a usually function of the roots of a plant?

Possible Answers:

None of these

Providing stability

Obtaining water and nutrients from the soil

Performance of photosynthesis

Storage of carbohydrates

Correct answer:

Performance of photosynthesis

Explanation:

Roots are usually underground and not exposed to sunlight, do not usually contain chlorophyll, thus they do not perform photosynthesis. However, roots do provide stabiity, obtain water and nutrients from the soil, and store carbohydrates.

Example Question #41 : Plant Structures

Which of the following best describes where parenchyma cells can be found in plants?

Possible Answers:

All of these

Stems

Roots

Leaves

Correct answer:

All of these

Explanation:

Parenchyma cells make up a type of ground tissue in plants. Parenchyma cells compose most of the soft tissues in plants including leaves, roots, stems, and seeds. The functions of parenchyma cells include photosynthesis, storage, and wound repair.

Example Question #42 : Plant Structures

Which of the following is true regarding meristem tissue in plants?

Possible Answers:

It is present in areas of growth

All of these

There is a shoot and root apical meristem

It contains undifferentiated cells

Correct answer:

All of these

Explanation:

Meristem tissue contains undifferentiated cells and allows for plant growth. Apical meristems are found in areas of growth, which include the shoot and roots—cells in these tissues divide rapidly.

Example Question #3 : Understanding Other Plant Macrostructures

Which of the following best describes the location of the vascular cambium in plants?

Possible Answers:

In the tips of leaves

None of these

Between the xylem and phloem 

In the periderm

Correct answer:

Between the xylem and phloem 

Explanation:

The vascular cambium is a type of secondary meristem tissue located between the xylem and phloem of the stems and roots. Secondary meristem tissues are responsible for lateral growth; more specifically, the vascular cambium is responsible for secondary xylem and phloem development.

Example Question #4 : Understanding Other Plant Macrostructures

Which of the following is not true regarding the cork cambium?

Possible Answers:

It is a type of secondary meristem 

It is the source of secondary xylem and phloem growth

It is the source of secondary epidermis growth 

It is located in the periderm

Correct answer:

It is the source of secondary xylem and phloem growth

Explanation:

The cork cambium is a type of secondary meristem tissue found in the periderm. Cork cambium controls lateral growth; specifically, it is the source of secondary epidermis growth.

Example Question #45 : Plant Structures

Which of the following best describes what annual growth rings in trees represent?

Possible Answers:

New primary xylem growth

New vascular cambium growth

New cork cambium growth

New primary phloem growth

Correct answer:

New vascular cambium growth

Explanation:

Cutting into the trunk of a tree to create a horizontal cross section reveals rings, called annual growth rings. These rings show new vascular cambium growth over the course of a year. Differences in growth speed change the size of the growth rings.

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