CH. 35
Root apical meristems are found
in all roots.
The innermost layer of the root cortex is the
endodermis.
The root pericycle is the site where
lateral roots originate.
Onions are monocots with certain parts adapted for storage. From which of the following plant parts is the main storage structure formed?
leaf sheaths
Which of the following can be used to determine a twig's age?
number of apical bud scar rings
Which of the following plant parts absorbs most of the water and minerals taken up from the soil?
root hairs
Which of the following root tissues gives rise to lateral roots?
pericycle
A leaf would best be described as a
plant organ.
_____ provides cells for secondary growth.
Vascular cambium
What process is most important in the expansion of plant cells?
Water uptake
The primary growth of a plant adds __________, and secondary growth adds __________.
height, thickness
Many ornamental roses have sepals and multiple showy petals, but lack reproductive parts. Assuming that rose development follows the ABC hypothesis, which gene is most likely to be suppressed?
the C gene
Additional vascular tissue produced as secondary growth in a root originates from which cells?
vascular cambium
Which of the following cell types have unevenly thickened primary walls that support young, growing parts of the plant?
collenchyma cells
Which of the following accurately describes the structure of a leaf?
stomata can occur on both sides of a leaf
The vascular cambium gives rise to
secondary xylem and phloem.
How is the supply of vascular cambium maintained?
by the division of its cells
A student examining leaf cross sections under a microscope finds many loosely packed cells with relatively thin cell walls. The cells have numerous chloroplasts. What type of cells are they?
parenchyma
Which of the following is correctly matched with its tissue system?
cortex, with ground tissue system
The letter A indicates _____.
secondary xylem
Select the correct statement about plant growth.
A plant may produce juvenile and adult leaves at the same time.
Based on the data presented in the paper, evaluate the following statements about these three genes: LMI1 in Arabidopsis thaliana (AtLMI1) LMI1 in Cardamine hirsuta (ChLMI1) RCO in C. hirsuta Which of the following statements are true? Select all that apply.
AtLMI1 and ChLMI1 are orthologous genes. ChLMI1 and RCO are paralogous genes.
Which tissue(s) make(s) up the bark of the woody stem shown here?
Both secondary phloem and periderm
What is the main purpose of secondary growth in a woody stem?
It makes the stems and roots thicker.
Which of the following parts of a plant remains on the plant even after several years of growth?
Primary xylem
An initial cell in a plant apical meristem has a cuboidal shape. Predict the orientation of microtubules beneath the cell membrane if that cell will differentiate into procambium and ultimately a xylem vessel.
Rings of microtubules are oriented at right angles to the direction the cell will eventually expand.
The phase change of an apical meristem from the juvenile to the mature vegetative phase is often revealed by
a change in the shape of the leaves produced.
This stained light micrograph shows a cross section through a plant organ from Hakea purpurea, a shrub native to some arid regions of Australia. Identify whether this is a root, stem, or leaf.
a leaf
The following diagram is of a cross section of a plant leaf. Use the diagram to answer the question. Which of the following is the main function associated with structure Y?
absorption of carbon dioxide
Root hairs are important to a plant because they _____. See Concept 35.1 (Page)
increase the surface area for absorption
What is the function of cork?
insulation and waterproofing
Secondary growth NEVER occurs in _____.
leaves
Which of the following is unique to the shoot apical meristem region?I) the region of cell division II) leaf primordia III) cells that will give rise to the protoderm, ground meristem, and procambium
only II
What class of genes act as developmental control genes to generate the diverse morphologies of plants and animals on Earth?
homeobox genes
Bark is generally thought to be the tough outer layer of the stem; however, it is composed of all tissues exterior to the vascular cambium. From the following list, which tissues make up bark?
primary phloem, secondary phloem, and periderm
Cellular differentiation and morphogenesis in plants depends primarily on _____. See Concept 35.5 (Page)
regulation of gene expression
Cellular differentiation and morphogenesis in plants depends primarily on __________.
regulation of gene expression
The following diagram is of a cross section of a plant leaf. Use the diagram to answer the question. Which of the following is the main function associated with structure X?
retention of water
Which of the following structures is correctly paired with its function?
sclerenchyma-supporting cells with thick secondary walls
Which of the following is a common feature of secondary xylem and cork cells?
they are both composed of dead cells at maturity
Cell division in the vascular cambium adds to the circumference of a tree trunk and the diameter of roots and stems by adding new __________ to the layer's interior and __________ to the layer's exterior.
xylem, phloem
Evolutionary biologists have coined the term exaptation to describe a common occurrence in the evolution of life: A limb or organ evolves in a particular context but over time takes on a new function. What are some examples of exaptations in plant organs?
tendrils of a pea plant bulb of a tulip spines of a garden rose
The following are characteristics of plant cells but not animal cells except
the absence of mitochondria.
The following question is based on data from Northern Red Maples in the table below (from text box, p. 760). Which data above best illustrates phenotypic plasticity in leaf "toothiness"?
Rhode Island Grown, Florida Collected and Florida Grown, Florida Collected
The following question is based on the drawings of root or stem cross sections shown in the figure.Refer to the figure. A woody eudicot is represented by which of the following?
IV only
Some understory plants in dense tropical rain forests have very large leaves. Which of the following is the most likely selective advantage of these leaves?
Increased leaf surface area maximizes light absorption for photosynthesis under low light intensity.
Which of the following statements about the vascular cambium is true?
It is a layer of undifferentiated cells that develops into secondary xylem and phloem.
You find a plant unfamiliar to you and observe that it has vascular bundles scattered throughout the stem cross section. What should you conclude about the plant?
It is a monocot.
How might this organ be an adaptation for dry conditions?
It might prevent water loss by reduction of the stomatal number. It might preserve large amounts of water. It might perform photosynthesis.
Other than the transport of materials, what is another function that vascular tissue performs in a leaf?
The tissue functions as a skeleton that reinforces the shape of the leaf.
The veins of leaves are best described as which of the following? I) composed of xylem and phloem II) continuous, with vascular bundles in the stem III) finely branched to be in close contact with photosynthesizing cells
I, II, and III
The following question is based on the drawings of root or stem cross sections shown in the figure. Refer to the figure. A monocot stem is represented by which of the following?
II only
The following question is based on the figure below. In the diagram above, the dark "dots" represent axillary buds. Which diagram illustrates a compound leaf?
II only
The following question is based on the drawings of root or stem cross sections shown in the figure.Refer to the figure. Which of the following represents a plant at least three years old?
IV only
Apical meristems of dicots are at the tips of stems and the leaves have determinate growth. Apical meristems of grasses are at ground level, or slightly below, and the leaves have indeterminate growth from meristems at the base of each leaf. What does this mean when considering care of a lawn or soccer field?
If you mow one inch above ground level, apical meristems can continue to produce new leaves and cut leaves can continue growing.
Which of the following accurately describes meristematic plant cells?
Meristematic cells are undifferentiated cells that produce new cells.
What are the differences between the monocots and the eudicots? Sort the characteristics by whether they apply to the monocots or eudicots.
Monocots: secondary growth is unusual parallel major leaf veins stems with scattered vascular bundles adventitious roots Eudicots: widespread secondary growth branched major leaf veins stems with vascular bundles arranged in a ring
True or false? Primary growth can occur at both the apical and lateral meristems at the tips of the roots and stems in a plant.
False
Which of the following modified roots has a similar function as prop roots?
buttress roots
As the epidermis is pushed outward and sloughed off, it is replaced by tissues produced by the __________.
cork cambium
Which of the following is correctly matched with its tissue system? See Concept 35.1 (Page)
cortex ... ground tissue system
Which of the following best describes the driving force that pushes the root tip through the soil?
elongation of cells behind the root apical meristem
Which of the following tissues or cell types are always present in a monocot stem?
ground tissue beneath the epidermis
What tissue makes up most of the wood of a tree?
secondary xylem
Which of the following cells or tissues arise from lateral meristem activity?
secondary xylem
Which of the following cells transport sugars over long distances?
sieve-tube elements
The following question is based on the figure below. Which of the following must have occurred during development in the region between the root and stem circled on this diagram of an herbaceous eudicot?
the xylem in the root must split into separate strands in the stem
The following question is based on the diagram of three-years-old growth in a winter twig below. If you examined the cut surface at the base of this twig, how many growth rings should be present?
three
Which of the following are water-conducting cells that are dead at functional maturity?
tracheids and vessel elements
Which of the following are produced by lateral meristems?
wood and cork
A plant has the following characteristics: a taproot system, several growth rings evident in a cross section of the stem, and a layer of bark around the outside. Which of the following best describes the plant?
woody eudicot
Which of the following is true for an emerging lateral root to function?
xylem of the new lateral root connects to the xylem of the original root
The following question is based on this cross section of a monocot stem. Which of the following is NOT a pattern of vascular bundles evident in this stem?
xylem toward the outside of each bundle, phloem toward the center
Which of the following is the correct sequence of the zones in the primary growth of a root, moving from the root cap toward the stem?
zone of cell division, zone of elongation, zone of differentiation
Growth and development of plant parts involves which of the following processes? I) cell division to produce new cells II) enlargement and elongation of cells III) specialization of cells into tissues
I, II, and III
How does the difference show that structure fits function?
In both leaves, the structure fits the function because the arrangement of mesophyll cells maximizes photosynthesis.
How does the internal anatomy of a tea leaf differ from that of an iris leaf?
In the tea leaf, mesophyll cells are divided into two layers, with the lower part of the leaf having a loosely arranged spongy layer with large air spaces, and the upper part having a palisade layer of tightly packed cells. In contrast, the iris leaf has both layers made of evenly distributed cells with no large air spaces.
How did the evolution of lignin affect vascular plant structure and function?
It drives out water and strengthens the cell wall. It is one of the major constituents of the secondary wall of tall plants. It is synthesized in the cells that become part of the transport system.
Which one of the following statements is true?
Monocot stems have scattered vascular tissue, whereas eudicot stems have vascular tissue arranged in a ring.
In the concluding paragraph, the authors suggest that the results of their investigation into the role of the RCO gene in C. hirsuta, its relationship to the LMI1 gene, and the loss of the RCO gene in A. thaliana support a broad principle of regulatory evolution: that evolution favors mutations that minimize pleiotropy. Why would evolution favor mutations that minimize pleiotropy?
Mutations with greater pleiotropic effects are more likely to be harmful to the fitness of organisms and are thus removed from the population by natural selection.
The image below is a cross section through a young root tip with a layer of root cap cells surrounding the developing epidermis and interior tissues. The darker epidermal cells are stained to express the homeotic gene GLABRA-2. Which of the following best predicts what will be the appearance of this part of the mature root?
Only the unstained cells will develop root hairs.
Select the best description of the significance of the meristems of plants.
Plant meristems are permanently embryonic regions within the plant body.
Which structure determines the direction of root growth by sensing gravity?
Root cap
How might this difference relate to the orientations of the leaves?
Tea leaves are horizontally oriented and are more likely to receive light on the upper surface. In contrast, iris leaves are vertically oriented with both sides illuminated during the course of the day.
True or false? Plant growth involves both the production of new cells by mitosis and the expansion of cell volume.
True
Shoot elongation in a growing bud is due primarily to which of the following?
cell elongation localized in each internode
Most of the growth of a plant body is the result of
cell elongation.
Vascular cambium forms wood toward the stem's _____ and secondary phloem toward the stem's _____.
center ... surface
The primary growth of a plant adds _____ and secondary growth adds _____. See Concept 35.2 (Page)
height ... girth
Where is primary growth occurring in an old tree?
in young branches where leaves are forming
Which of the following best describes the growth of most plant structures, except for flowers?
indeterminate
Which of the following biological molecules is specific to woody sclerenchyma cells?
lignin
According to the ABC hypothesis for flower formation, which of the following outcomes would be expected for a plant that only expresses its A and C flower genes?
only sepals and carpels will form
Suppose a flower had normal expression of genes A and C and expression of gene B in all four whorls. Based on the ABC hypothesis, what would be the structure of that flower, starting at the outermost whorl?
petal-petal-stamen-stamen
Increasing the number of stomata per unit surface area of a leaf when atmospheric carbon dioxide levels decline is most analogous to which of the following human adaptations?
putting more red blood cells into circulation when atmospheric oxygen levels decline
The bark of a tree trunk includes which of the following tissues?
secondary phloem and layers of periderm
Cellular differentiation is responsible for __________.
some epidermal cells in Arabidopsis becoming root hair cells while others become hairless epidermal cells.
Which of the following structures is a modified horizontal shoot growing along the soil surface?
stolon
During primary growth, the primary xylem and phloem grow alongside each other, except for a layer of tissue in between them. These primary tissues will eventually be pushed away from each other during secondary growth. What growth process causes this to occur?
the accumulation of secondary xylem and secondary phloem
In a meristematic region, the cell plate during mitosis is perpendicular to the side of the stem. In what direction will the stem grow?
vertically in height
When is the polarity of a plant established?
when the shoot-root axis is established in the embryo
Which of the following structures cannot be formed by an axillary bud?
branch root
How do cells in a meristem differ from cells in other types of plant tissue?
they continue to divide
Plants and animals respond differently to the environment. Which statement most accurately compares the responses of plants and animals to changes in their environment?
Animals tend to respond to changes in their environment by movement; plants tend to respond to changes in their environment by growth.
What is a consequence of monocot vascular bundles not having a vascular cambium between the xylem and phloem?
Monocots have no secondary growth.
Use your knowledge of primary and secondary growth to visualize and explain how this happened.
Someone must have threaded it over a young woody branch: primary growth raised the bicycle off the ground. Secondary growth in the region of the tree notch enveloped the bicycle.
What evidence supports the authors' claim that the RCO gene evolved from LMI1-type genes through gene duplication?
The similarity in amino acid sequences of the proteins produced from the RCO and LMI1-type genes shows that they are derived from a common ancestral gene.
If you were an Arabidopsis researcher, how might you respond to this argument?
The many advantages of Arabidopsis include its small genome, short life cycle, small stature, prolific seed production, and ease of transformation. A wealth of genomic resources received from Arabidopsis already exists, such as a completely sequenced genome, a large mutant collection, and genome arrays that contain all of its transcripts. Experiments can be done more quickly, more cheaply, and more definitively on Arabidopsis than on crop plants such as cassava and plantain.
The scientific method is often presented as a series of linear steps that involves testing a hypothesis in a controlled experiment. How does this research compare with this common description of the scientific method?
The methods used in this paper differ from the standard description of the scientific method because the authors used comparative genetics to elucidate the evolutionary history and underlying mechanisms of genes that produce different leaf shape patterns in related species.
How do cells in a meristem differ from cells in other types of plant tissue? See Concept 35.2 (Page)
They continue to divide.
Why is it important for scientists to understand the genetic basis for variation in leaf shape between related species of plants?
This research advances our understanding of how the diversity of life has evolved.
The following diagram depicts a woody stem in its three main growth sections. Sort each growth process to the growth section in which it occurs.
Top section: Primary growth occurs from the apical meristem. Vascular cambium first forms. Middle section: Secondary xylem and phloem form from the vascular cambium. Vascular rays are formed. Cork cells replace the epidermis. Bottom section: Bark consists of all layers exterior to the vascular cambium. Most thickening is from secondary xylem. Periderm is formed by cork and the cork cambium.
Which of the following is not a type of primary meristematic cell found in apical meristems?
Vascular cambium
Which of the following describes an anatomical difference between roots and leaves?
a waxy cuticle covers leaves but is absent from roots
A plant that grows one year, without flowering, and then grows again the following year and produces flowers before it dies is described as which of the following?
a biennial
Which of the following cell types retains the ability to undergo cell division?
a meristem cell near the root tip
A strawberry plant mutant that fails to make stolons would suffer from
a reduction in asexual reproduction.
Which of the following arise(s), directly or indirectly, from meristematic activity?
all of the above (secondary xylem, leaves, and dermal tissue)
Heartwood and sapwood consist of
secondary xylem.
As this wagon passed from the middle of the Sequoia tree to the outside, what would be the order of tissues it passed through?
the annual rings, new xylem, vascular cambium, phloem, and bark
Which structure is correctly paired with its tissue system?
tracheid-vascular tissue
As a youngster, you drive a nail in the trunk of a young tree that is 3 meters tall. The nail is about 1.5 meters from the ground. Fifteen years later, you return and discover that the tree has grown to a height of 30 meters. About how many meters above the ground is the nail?
1.5
Why do plants need secondary growth?
To provide structural support for the plant
