All AP Biology Resources
Example Questions
Example Question #3 : Understanding Xylem And Phloem
Which of the following best describes the primary role of xylem in plants?
Structural support of plants
Transport of nutrients
Photosynthesis
Transport of water
Transport of water
Xylem is a type of tissue present in vascular plants that is responsible for water transport within the organism. Types of cells contained within xylem include tracheids, vessel elements, parenchyma cells, and fibers.
Example Question #11 : Macrostructures
Xylem is responsible for water transport within plants. Which of the following forces makes the upward movement of water through the xylem possible?
Transpirational pull
All of these
Root pressure
None of these
All of these
The transport of water through xylem in plants includes the upward movement of water. The forces of transpirational pull and root pressure are responsible for counteracting gravity and producing water’s upward movement. Transpirational pull is defined as the surface tension caused by water evaporation that pulls water upward through xylem. Root pressure is characterized by the difference in water potential between the soil and plant, causing water to travel into plant roots.
Example Question #1 : Understanding Xylem And Phloem
Which of the following is not true regarding tracheids?
They are a type of cell in xylem tissue
They hold water against gravitational force
They have thick cell walls
They are square-shaped
They are square-shaped
Tracheids are elongated cells that are contained within xylem tissue. Tracheids are responsible for water and mineral transport. The thick cell walls of tracheids allow them to hold water against gravitational pull due to the adhesion property of water.
Example Question #1 : Understanding Xylem And Phloem
Which of the following is true regarding vessel elements in plants?
They have thick cell walls
They are not found in gymnosperms
They form tubular vessels
All of these
All of these
Vessel elements are a cell type contained within xylem tissue of angiosperms. Vessel elements aid in the transport of water and minerals. Morphologically, vessel elements are described as hollow tubular cells that have thick cell walls and are open at both ends.
Example Question #1 : Understanding Xylem And Phloem
What is the primary function of phloem in plants?
Wound repair
Transport of organic nutrients
Secretion of hormones
Photosynthesis
Transport of organic nutrients
Phloem is a type of tissue in vascular plants that transports organic nutrients. Among other components, phloem contains sieve elements, parenchyma cells, and supportive cells.
Example Question #1 : Understanding Xylem And Phloem
Which of the following is an accurate comparison between sieve tube elements and vessel elements?
Vessel elements are living cells and sieve tube elements are technically dead
Sieve tube elements are living cells while vessel elements are technically dead
Vessel elements transport nutrients while sieve tube elements transports mostly water
Sieve tube elements are in xylem tissue and vessel elements are in phloem tissue
Sieve tube elements are living cells while vessel elements are technically dead
Vessel elements are cells in phloem tissue that are technically dead. Upon maturation, the living material in the cells disappears while the cell wall remains; the cells are dead; however, sieve tube elements contain living tissue.
Example Question #1 : Understanding Xylem And Phloem
Which of the following are characteristics of companion cells in vascular plants?
They have a large number of ribosomes and mitochondria
They have a large number of ribosomes and mitochondria and are a specialized type of parenchyma cells
They do not contain a nucleus
They do not contain a nucleus and are a specialized type of parenchyma cells
They have a large number of ribosomes and mitochondria and are a specialized type of parenchyma cells
Companion cells are a type of specialized parenchyma cells in vascular plants. They contain a large number of ribosomes and mitochondria and perform cellular functions for sieve-tube elements, which they are connected to by plasmodesmata.
Example Question #51 : Plant Biology
Which of the following is true?
Xylem transports water and nutrients, and does not have nuclei, ribosomes, and vacuoles at maturity
Phloem transports sugars, and dies at maturity
Xylem transports water and nutrients, and dies at maturity
Phloem transports water and nutrients, and does not have nuclei, ribosomes, and vacuoles at maturity
Xylem transports sugars, and dies at maturity
Xylem transports water and nutrients, and dies at maturity
Xylem are water-conducting cells that transport water and nutrients. They die at maturity and leave behind secondary walls. Phloem transports sugars through sieve-tube elements, but do not have nuclei, ribosomes, and vacuoles. However, phloem remains alive at maturity.
Example Question #51 : Plant Biology
Of the following answer choices, which most accurately describes the mechanism that the stems of plants use to grow toward light?
The plant will grow away from other plants so as to minimize competition
Contractile cells on the light side of the stems dictate the growth toward light
Photosynthetic processes dictate the growth
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
Cells on the darker side of the stem elongate more than cells on the lighter side
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 #52 : Plant Biology
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?
Fibrous root systems are well adapted to soil where ground water is not close to the surface
Fibrous root systems consist of a series of roots that spread out from a major single root
Fibrous root systems usually penetrate deeply into the soil
Fibrous root systems do not penetrate deeply into the soil
Fibrous root systems do not penetrate deeply into the soil
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.