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Is the quiescent centre only found in monocot roots?

Is the quiescent centre only found in monocot roots?


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I read that the quiescent centre is present between the dermatogen and calyptrogen. As calyptrogen is only present in monocot root, does that mean quiescent centre is only found in monocot roots?


Note that quiescent centers are typically defined by cell division activity not anatomical placement and are not confined to monocots.

For example, this paper discusses the quiescent center in Arabidopsis roots1.


Reference: 1: Doerner, P. (1998). Root development: quiescent center not so mute after all. Current Biology, 8(2), R42-R44.


The origins of the quiescent centre concept

To learn how new concepts are conceived and developed is a way to understand scientific progress, appreciate important achievements, and develop one's own skill at evolving new concepts. In plant developmental biology, the concept of quiescent centre (QC) is widely taken as an example of a stem cell population which, in this particular case, gives rise to most root tissues. Here we draw attention to the question of how the concept of the QC was conceived. It is appropriate to do so at this time because, as we show here, the concept was conceived 60 years ago. However, in marking this Jubilee event we do not consider either the subsequent history of the concept or the work done to more closely define the properties of the QC but, rather, to address how the QC was discovered, both conceptually and experimentally, and the evolution of its terminology.


Branching of the root

The branching of the root takes place in the older parts and does not directly involve the apical meristem. The tissues concerned are the endodermis and the layer immediately beneath it, the pericycle. The endodermis participates in root branching in certain lower plants with apical cells. A cell of this layer enlarges and forms a tetrahedral cell, which becomes the new apical cell by further divisions a hemispherical volume of tissue forms around it—the whole constituting a new apex.

In many other plants, including gymnosperms and angiosperms, the lateral roots develop from the pericycle. Cells in this layer enlarge and begin to divide until a dome of tissue develops. Called the incipient apex, the dome pushes out the surrounding endodermis, which may itself resume divisions, its daughter cells enlarging to create a sheath around the new root tip. During further growth, the dome assumes an organization like that of the primary root apex. At first, all cells are meristematic then, while the primordium is still small, cells in the central zone cease DNA synthesis, and this zone becomes the new quiescent centre. Beyond it, the root cap is produced, and, at the base, initial cells begin to develop the cell files that become the vascular cylinder, cortex, and epidermis. The vascular tissues differentiate from the base outward, and link eventually with xylem and phloem of the parent root. All this development occurs before the tip of the new root emerges from the tissues of the parent root. The growth of the new tip into the cortex first pushes out the endodermal sheath, if one is present, and then bursts it. The cortical cells are themselves crushed and probably resorbed as the root grows on, until finally the tip breaks through the epidermis.

In most roots, new laterals are initiated in the pericycle opposite to the protoxylem ridges. They tend accordingly to form vertical ranks along the length of the root, reflecting the number of bands of protoxylem. Although lateral roots arise in quite a different way from leaves and axillary shoots at the stem apex, there are certain common features. Pericyclic cells about to produce a root primordium synthesize ribonucleic acid, in anticipation of the period of growth and morphogenesis that will result in a new apex. The same behaviour is seen in the cells of the annular zone, from which leaf primordia arise at the stem apex, and also in the axillary zones at a slightly lower level, from which new stem apices develop.


MATERIALS AND METHODS

Plant growth conditions and tissue collection

Corn caryopses (Zea mays var. Merit, Asgrow Seed Co., Kalamazoo,MI) were imbibed and germinated in the dark at 25°C for 2 days. Tissues were collected by surgical removal of the root cap, and excision of the QC(Feldman and Torrey, 1976). In this cultivar the QC is separable from the proximal meristem (PM)(Fig. 1D) as a consequence of a weak, thin-walled junction, making possible routine, clean dissections of isolated QCs (Fig. 1B-D). After excision of the QC, the 0.5-1 mm stump of meristematic tissue (the PM)bordering the basal side of the QC (Fig. 1D) was also collected. As tissues were collected, they were either frozen immediately on dry ice, or, for enzyme analysis, the tissue was placed directly into the cold extraction buffer.

Ascorbate and glutathione extraction and assay

For ascorbate or glutathione analysis 60-70 QCs (0.42 mg) and 20 PMs (11 mg) were homogenized in 70 μl or 150 μl, respectively, of the appropriate extraction buffer. Extraction and analysis of ascorbate and glutathione were carried out essentially following the protocol of Zhang and Kirkham (Zhang and Kirkham,1996), except that the total volume of the reactions was 100μl. Spectrophotmetric measurements were made on a Shimadzu UV160U spectrophotometer using Eppendorf Uvette microcuvettes. For each assay standard curves were run simultaneously. To determine whether the extraction procedure could result in an artifactual loss (oxidation) of reduced ascorbic acid (AA) or of reduced glutathione (GSH), converting the compounds to their oxidized forms [dehydroascorbate (DHA) or oxidized glutathione (GSSG),respectively] we `spiked' a sample of tissue at the beginning of the homogenization with a known amount of reduced AA or reduced GSH. In general,we were always able to recover 75-90% of the ascorbic acid or the glutathione in the reduced forms (data not shown). The values for endogenous AA and GSH were corrected accordingly. Each extraction was repeated at least three times with the variation indicated.

Enzyme extraction and assay

The activities of four AA/GSH cycle-associated enzymes were also measured:ascorbate oxidase (EC 1.10.3.3 AAO), dehydroascorbate reductase (EC 1.8.5.1DHAR), ascorbate free radical reductase [EC 1.6.5.4 AFR (monodehydroascorbate reductase)] and glutathione reductase (ED 1.6.4.2 GR). They were assayed according to procedures described previously: AAO(Kerk and Feldman, 1995), DHAR and AFR (Arrigoni et al., 1997)and GR (Zhang and Kirkham,1996). The final volumes for each assay were 100-150 μl.

Measurement of reactive oxygen intermediates

Measurements of reactive oxygen species (ROS)O2· - and H2O2 were carried out following the protocol of Schopfer et al.(Schopfer et al., 2001). H2O2 measurement was accomplished using a Bio-Tek FL600 microplate fluorescence reader, and readings compared to those from a simultaneously run standard curve. At least three replicates were averaged for each experiment.

Measurement of NADPH/NADP +

NADPH/NADP + , key regulators of the ascorbic acid/glutathione cycles, were measured following the protocol of Zhang et al.(Zhang et al., 2000). For each experiment 60 QCs and 20 PMs were extracted and a standard curve was prepared in a range from 0.02 to 0.1 mM NADPH. At least three replicates were run for each measurement. Using this protocol the limit of detectability is 10 -3 mM NADPH.

Immunolocalization of auxin (IAA)

Tissue for immunolocalization and binding of the auxin antibody were carried out essentially as described previously(Kerk and Feldman, 1995) using alkaline phosphatase for detection (anti-mouse IgG AP conjugate Promega,Madison, Wisc.). For visualization of the IAA distribution we used NBT/BCIP tablets for alkaline phosphatase (Roche). The monoclonal antibody used for this immunolocalization has been shown to be highly specific to free auxin inZea root tips (Shi et al.,1993), and was used previously on maize roots(Kerk and Feldman, 1995). Controls were again carried out to confirm specificity.

NPA treatment

Roots were treated with NPA (sodium salt of naptalan N-1-napthylphthalamic acid Uniroyal Chemical Company), which is believed to inhibit polar auxin transport by binding to the auxin efflux carrier(Nemhauser et al., 2000). Using intact seedlings (with roots, 2-3 cm in length), the root was inserted through the center of a 1% agar `collar' (1 cm 2 × 3 mm thick)containing 10 -5 M NPA, and the collar positioned at the junction of the root with the seed. The NPA-treated roots were then returned to a tray lined with moistened filter paper, with the NPA collar resting on a glass slide, and not directly in contact with the filter paper. The trays were tightly covered and the roots returned to darkness. At the end of 24 hours of NPA treatment the roots' gravity response was visibly perturbed, with roots orienting randomly (data not shown). For immunolocalization, biochemical and histological studies, the NPA collar was removed from the root after 24 hours of treatment (or for some roots, after 48 hours of NPA treatment) and subsequently these roots used as described more fully in the section detailing the respective experiments. In order to assess more quantitatively the effects of NPA on auxin transport, we used roots previously treated for 24 hours with NPA, then excised the root from the seed (root now about 3 cm in length), and at the basal cut surface of the root (proximal to the NPA collar) placed a 1%agar block (approximately 1 mm 2 ) containing 1×10 -8 M 5[ 3 H]IAA (specific activity 16.7 Ci/mM Amersham). Roots with the attached agar `donor' blocks were returned to a moistened chamber and incubated for 12 hours in the dark. For control roots we used a plain agar collar. For most experiments 40 roots were used. Following incubation, the terminal 1 mm section (the root apex) and basal 1 mm section (the portion of the root in contact with the donor block) of the roots were excised, pooled,and then dissolved in 0.5 ml of tissue solubilizer (Amersham) for 15 hours at room temperature. Three mls of scintillation fluid (ScintiVerse, Fisher Scientific, Co.) were added to each vial and the samples counted in a scintillation counter (Beckman).

BrdU Incorporation

BrdU incorporation and detection were carried out as described previously(Kerk and Feldman, 1995).

Assaying oxidative activity (oxidative stress) in living tissues

Assaying oxidative activity (oxidative stress) in living cells was accomplished using a dye that is colorless when chemically reduced (when freshly obtained), but when oxidized, fluoresces green in UV (340 nm irradiation 530 nm emission) light. For this work we used carboxy-H2DCFDA(C-400) dye (Molecular Probes, Eugene Oregon, catalogue no. C-6827). This dye is oxidized by a wide variety of oxidants, and hence gives a general picture of the redox environment, rather than indicating the status of a specific oxidant. At physiological pH this dye has two negative charges facilitating it passive movement through membranes during loading. Upon oxidation the fluorescent product is reportedly trapped inside the cell facilitating long term observation (Collins et al.,2000 Ha et al.,1998 Xie et al.,1999). A 10 μM solution of dye was freshly prepared in water(pH 6.8) just prior to loading into the maize root tissue. In some cases root tissues had been previously treated with NPA for 24 or 48 hours and then allowed to grow for an additional 24 hours (no NPA) prior to being exposed to the dye. In order to facilitate entrance of the dye, root caps were removed just before loading. Seedlings with decapped roots were placed in Petri dishes on moistened filter paper and the tips of the roots immersed in 50 μl of the aqueous dye. Loading typically occurred for a period of 2-3 hours, which was followed by several washes of the roots in plain water. The QCs and the adjacent meristem (PM) were then dissected free, placed in water on a microscope slide, and immediately observed and photographed (in both white and UV light) with a Leica DM microscope. It was important to photograph the tissue immediately after exposing to UV light, since prolonged illumination(in excess of 45 seconds) induced the oxidation of the dye. Although this limited our observation time, in instances where the tissues initially showed no fluorescence, this UV-inducible fluorescence allowed us to determine that dye had indeed entered the cells, but had not been oxidized, under our experimental conditions.


Is the quiescent centre only found in monocot roots? - Biology

Taproot System:
Characterized by having one main root (the taproot) from which smaller branch roots emerge. When a seed germinates, the first root to emerge is the radicle, or primary root. In conifers and most dicots, this radicle develops into the taproot. Taproots can be modified for use in storage (usually carbohydrates) such as those found in sugar beet or carrot. Taproots are also important adaptations for searching for water, as those long taproots found in mesquite and poison ivy.
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Fibrous Root System:
Characterized by having a mass of similarly sized roots. In this case the radicle from a germinating seed is short lived and is replaced by adventitious roots. Adventitious roots are roots that form on plant organs other than roots. Most monocots have fibrous root systems. Some fibrous roots are used as storage for example sweet potatoes form on fibrous roots. Plants with fibrous roots systems are excellent for erosion control, because the mass of roots cling to soil particles.
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Root Structures and Their Functions:

Root Tip: the end 1 cm of a root contains young tissues that are divided into the root cap, quiescent center, and the subapical region.
Root Cap: root tips are covered and protected by the root cap. The root cap cells are derived from the rootcap meristem that pushes cells forward into the cap region. Root cap cells differentiate first into columella cells. Columella cells contain amylopasts that are responsible for gravity detection. These cells can also respond to light and pressure from soil particles. Once columella cells are pushed to the periphery of the root cap, they differentiate into peripheral cells. These cells secrete mucigel, a hydrated polysaccharide formed in the dictyosomes that contains sugars, organic acids, vitamins, enzymes, and amino acids. Mucigel aids in protection of the root by preventing desiccation. In some plants the mucigel contains inhibitors that prevent the growth of roots from competing plants. Mucigel also lubricates the root so that it can easily penetrate the soil. Mucigel also aids in water and nutrient absorption by increasing soil:root contact. Mucigel can act as a chelator, freeing up ions to be absorbed by the root. Nutrients in mucigel can aid in the establishment of mycorrhizae and symbiotic bacteria.
Quiescent Center: behind the root cap is the quiescent center, a region of inactive cells. They function to replace the meristematic cells of the rootcap meristem. The quiescent center is also important in organizing the patterns of primary growth in the root.
Subapical Region: this region, behind the quiescent center is divided into three zones. Zone of Cell Division - this is the location of the apical meristem (

0.5 -1.5 mm behind the root tip). Cells derived from the apical meristem add to the primary growth of the root. Zone of Cellular Elongation - the cells derived from the apical meristem increase in length in this region. Elongation occurs through water uptake into the vacuoles. This elongation process shoves the root tip into the soil. Zone of Cellular Maturation - the cells begin differentiation. In this region one finds root hairs which function to increase water and nutrient absorption. In this region the xylem cells are the first of the vascular tissues to differentiate.
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Mature Root: the primary tissues of the root begin to form within or just behind the Zone of Cellular Maturation in the root tip. The root apical meristem gives rise to three primary meristems: protoderm, ground meristem, and procambium.
Epidermis: the epidermis is derived from the protoderm and surrounds the young root one cell layer thick. Epidermal cells are not covered by cuticle so that they can absorb water and mineral nutrients. As roots mature the epidermis is replaced by the periderm.
Cortex: interior to the epidermis is the cortex which is derived from the ground meristem. The cortex is divided into three layers: the hypodermis, storage parenchyma cells, and the endodermis. The hypodermis is the suberinized protective layer of cells just below the epidermis. The suberin in these cells aids in water retention. Storage parenchyma cells are thin-walled and often store starch. The endodermis is the innermost layer of the cortex. Endodermal cells are closely packed and lack intercellular spaces. Their radial and transverse walls are impregnated with lignin an suberin to form the structure called the Casparian Strip. The Casparian Strip forces water and dissolved nutrients to pass through the symplast (living portion of the cell), thus allowing the cell membrane to control absorption by the root.
Stele: all tissues inside the endodermis compose the stele. The stele includes the outer most layer, pericycle, and the vascular tissues. The pericycle is a meristematic layer important in production of branch roots. The vascular tissues are made up of the xylem and phloem. In dicots the xylem is found as a star shape in the center of the root with the phloem located between the arms of the xylem star. New xylem and phloem is added by the vascular cambium located between the xylem and phloem. In monocots the xylem and phloem form in a ring with s the central portion of the root made up of a parenchymatous pith.
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Salicylic acid promotes quiescent center cell division through ROS accumulation and down-regulation of PLT1, PLT2, and WOX5

Salicylic acid (SA) plays a crucial role in plant immunity. However, its function in plant development is poorly understood. The quiescent center (QC), which maintains columella stem cells (CSCs) in the root apical meristem and typically exhibits low levels of cell division, is critical for root growth and development. Here, we show that the Arabidopsis thaliana SA overaccumulation mutant constitutively activated cell death 1 (cad1), which exhibits increased cell division in the QC, is rescued by additional mutations in genes encoding the SA biosynthetic enzyme SALICYLIC ACID INDUCTION DEFFICIENT2 (SID2) or the SA receptor NONEXPRESSER OF PR GENES1 (NPR1), indicating that QC cell division in the cad1 mutant is promoted by the NPR1-dependent SA signaling pathway. The application of exogenous SA also promoted QC cell division in wild-type plants in a dose-dependent manner and largely suppressed the expression of genes involved in QC maintenance, including those encoding the APETALA2 (AP2) transcription factors PLETHORA1 (PLT1) and PLT2, as well as the homeodomain transcription factor WUSCHEL-RELATED HOMEOBOX5 (WOX5). Moreover, we showed that SA promotes reactive oxygen species (ROS) production, which is necessary for the QC cell division phenotype in the cad1 mutant. These results provide insight into the function of SA in QC maintenance.

Additional Supporting Information may be found online in the supporting information tab for this article: http://onlinelibrary.wiley.com/doi/10.1111/jipb.13020/suppinfo

Figure S1. The root phenotype of WT and cad1-3 seedlings

Figure S2. Complementation analysis of cad1 mutant

Figure S3. SA contents in the roots of 5-d-old WT, cad1-3, sid2-2 and sid2-2 cad1-3 plants

Figure S4. Phenotype of WT, cad1-3, sid2-2, sid2-2 cad1-3, npr1-1 and npr1-1 cad1-3 plants

Figure S5. The expression analysis of RBOHD and RBOHF in WT, npr1-1 and npr3-1 npr4-3 plants

Figure S6. NBT staining for the WT, cad1-3, sid2-2, sid2-2 cad1-3, npr1-1 and npr1-1 cad1-3 mutants

Figure S7. DPI attenuates SA-promoted QC cell division and ROS accumulation

Figure S8. The expression analysis of ERF109, 114 and 115

Figure S9. High levels of SA have no effect on SHR and SCR expression

Figure S10. Proposed model for high-level SA-mediated QC cell division and CSC differentiation

Table S1. Primers used in this study

Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.


Anatomy of Dicot and Monocot Roots

The root is one of the key organs that helps distinguish between a dicot and a monocot plant.

Anatomy of a dicot root:
The outermost single-layered tissue of the dicot root is called the epidermis. On the epidermis, you will also find some extended epidermal cells which are unicellular root hairs. The epidermis is followed by cortex, which is formed of several layers of thin-walled parenchymatous cells. These cells have intercellular spaces.

The innermost layer of the cortex comprises barrel-shaped cells without any intercellular spaces. This layer is known as the endodermis. The tangential and radial walls of the endodermal cells have deposits of a water-impermeable, material or suberin, which is also called casparian strips. Suberin is a waxy, waterproof substance present in the cell walls of cork tissue in plants.

Going back to the transverse section of the dicot root, after the endodermis, a few layers of thick-walled parenchymatous cells are present in the tissue. This is known as the pericyle.

Secondary growth, such as initiation of lateral roots and vascular cambium, takes place in the cells of the pericycle. The pith in the tissue of the dicot root is extremely small and is undeveloped. Typically, there are two to four xylem and phloem patches in a dicot root. In the later stages, a cambium ring gets formed between the xylem and phloem.

Some radially arranged parenchymatous cells are found between the vascular bundles. These cells form the conjunctive tissue, which is specialised for storage of water. The tissues present inside the endodermis, namely the pericycle, vascular bundles and pith are collectively known as stele.

Anatomy of monocot root:
In many aspects, it is similar to the dicot root. On comparing the two roots, we find the monocot root also consists of epidermis, cortex, endodermis, pericycle, vascular bundle and pith. However, there are some differences. The monocot root can have many xylem bundles, sometimes as many as six, whereas the dicot root does not have quite as many. Moreover, in a monocot root, the pith is well developed.

Although, dicot and monocot roots have some structural similarities, they differ in the number of xylem bundles and size of the pith and cortex. Moreover, secondary growth takes place only in the dicot root. In other words, these roots thicken over time.

Summary

The root is one of the key organs that helps distinguish between a dicot and a monocot plant.

Anatomy of a dicot root:
The outermost single-layered tissue of the dicot root is called the epidermis. On the epidermis, you will also find some extended epidermal cells which are unicellular root hairs. The epidermis is followed by cortex, which is formed of several layers of thin-walled parenchymatous cells. These cells have intercellular spaces.

The innermost layer of the cortex comprises barrel-shaped cells without any intercellular spaces. This layer is known as the endodermis. The tangential and radial walls of the endodermal cells have deposits of a water-impermeable, material or suberin, which is also called casparian strips. Suberin is a waxy, waterproof substance present in the cell walls of cork tissue in plants.

Going back to the transverse section of the dicot root, after the endodermis, a few layers of thick-walled parenchymatous cells are present in the tissue. This is known as the pericyle.

Secondary growth, such as initiation of lateral roots and vascular cambium, takes place in the cells of the pericycle. The pith in the tissue of the dicot root is extremely small and is undeveloped. Typically, there are two to four xylem and phloem patches in a dicot root. In the later stages, a cambium ring gets formed between the xylem and phloem.

Some radially arranged parenchymatous cells are found between the vascular bundles. These cells form the conjunctive tissue, which is specialised for storage of water. The tissues present inside the endodermis, namely the pericycle, vascular bundles and pith are collectively known as stele.

Anatomy of monocot root:
In many aspects, it is similar to the dicot root. On comparing the two roots, we find the monocot root also consists of epidermis, cortex, endodermis, pericycle, vascular bundle and pith. However, there are some differences. The monocot root can have many xylem bundles, sometimes as many as six, whereas the dicot root does not have quite as many. Moreover, in a monocot root, the pith is well developed.

Although, dicot and monocot roots have some structural similarities, they differ in the number of xylem bundles and size of the pith and cortex. Moreover, secondary growth takes place only in the dicot root. In other words, these roots thicken over time.


Discussion

As depicted in a working model in Fig. 4e, we propose that, in the wild-type Arabidopsis PM zone, ROW1 is bound to the H3K4me3 present on the WOX5 promoter and represses its transcription to allow normal PM cell differentiation and elongation in the maturation zone. However, while we show that ROW1 is able to repress WOX5::GFP when ectopically expressed in the QC, deletion of the proposed ROW1-binding sites in the WOX5 promoter did not induce WOX5 expression in the PM (Supplementary Fig 6b). This suggests that the P3 and P4 promoter fragments are also necessary for WOX5 activation and we cannot conclusively exclude the possibility that ROW1-mediated repression of WOX5 in the PM is indirect.

In animals, the tumour suppressor protein ING2, which is also a PHD domain-containing protein, represses target gene transcription by binding to H3K4me3 histone markers 21 . In the QC, absence of ROW1 permits the expression of WOX5 and thus maintains the QC identity. Auxin is the only molecule previously known to modulate QC function and distal stem cell differentiation by negatively regulating WOX5 expression 13,14,15 . Significantly elevated WOX5 expression in cells immediately above the DM in the root tips of row1-3 may potentiate the diffusion of this small polypeptide, as was previously postulated 37 , to nullify ARF10/16 functions that prevented normal DM differentiation. We thus conclude that ROW1 is essential for the development of the whole stem cell niche in Arabidopsis roots by confining WOX5 expression specifically to within the QC. Also, in the wild-type background, WOX5::GFP signals disappeared after 3 days of auxin treatment (Supplementary Fig. 13a), whereas no such repression for ROW1::GFP in the wild type and WOX5::GFP in the row1-3 background were observed after the same treatment (Supplementary Fig. 13b,c), indicating that ROW1 may regulate WOX5 expression downstream of auxin signalling. ROW1 may be the first reported key repressor that maintains both the SAM 23,24 and the root apical meristem identity by interacting with two different master regulators of Arabidopsis stem cell development.


Solving the Morphology of Flowering Plants Multiple Choice Questions of Class 11 Biology Chapter 5 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Morphology of Flowering Plants Class 11 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 5 Biology Class 11 and cross-check your answers during preparation.

I. Select the correct answer from the following questions:

Question 1.
Which one of the following is not a characteristic of root?
(a) Absence of buds
(b) Presence of chlorophyll
(c) Presence of root cap
(d) Presence of Unicellular hair

Answer: (b) Presence of chlorophyll

Question 2.
Roots that grow from any part of the plant body other than the radicle are called
(a) Tap roots
(b) Adventitious roots
(c) Modified roots
(d) Aerial roots

Answer: (b) Adventitious roots.

Question 3.
The place on stem or branch form where one or more leaves arise is called
(a) Apex
(b) Bud
(c) Internode
(d) Node

Question 4.
Which one of the following underground, fleshy structure is a stem?
(a) Carrot
(b) Potato
(c) Turnip
(d) Sweet Potato

Question 5.
Phyllode is a modification of
(a) Root
(b) Flower
(c) Petiole
(d) Bud

Question 6.
Potato tubers are formed at the tips of
(a) Primary roots
(b) Adventitious roots
(c) Petiole
(d) Stolons

Question 7.
Mesocarp and endocarp is the edible part of the fruit of
(a) Apple
(b) Mango
(c) Banana
(d) Litchi

Question 8.
Drupe is recognised by
(a) Stomy mesocarp
(b) Fleshy seed coat
(c) Thin seed coat
(d) Stony endocarp

Question 9.
What do you eat in coconut?
(a) Mesocarp
(b) Fruit wall
(c) Entire seed
(d) Embryo

Question 10.
The positions of shoot apex in monocot embryo is
(a) Lateral
(b) Basal
(c) Sub-terminal
(d) Terminal

Question 11.
In which one of the following plants the oil is stored in endosperm
(a) Coconut
(b) Ground nut
(c) Seasame
(d) Soyabean

Question 12.
In maize, the flower are
(a) Bisexual
(b) Unisexual but on the same plant
(c) Absent
(d) Unisexual but on different plants

Answer: (b) Unisexual but on the same plant

Question 13.
Epipetalous is condition of
(a) Aestivation of petal
(b) Placentation
(c) Stamens
(d) Position of ovary

Question 14.
A characteristic of angiosperm is
(a) Flower
(b) Root
(c) Seed
(d) All of these

Question 15.
An aspect of flower shown in floral formula but not in floral diagram is
(a) Aestivation
(b) Floral symmestry
(c) Position of ovary
(d) Cohesion of floral parts

Answer: (c) Position of ovary

Question 16.
In grass and banyan tree these are roots arising from parts of the plant other than the radicle, these are called
(a) Adventitious roots
(b) Fibrous root system
(c) Tap root system
(d) Tertiary root system

Answer: (a) Adventitious roots

Question 17.
In some leguminous plants the leaf base may become swollen, which is called the
(a) Pulvinus
(b) Lamina
(c) Petiole
(d) Leaf base

Question 18.
The arrangement of flowers on the floral axis is termed as
(a) Inflorescence
(b) racemose
(c) cymose
(d) thalamus

Question 19.
When the floral appendages are in multiple of 3,4 or 5 respec¬tively, a flower may be
(a) Trimerous
(b) Teramerous
(c) Pentamerous
(d) All of these types

Answer: (d) All of these types

Question 20.
A sterile stamen is called
(a) Staminode
(b) Stigma
(c) Apocarpous
(d) Syncarpous

Question 1.
Solanaceae is a large family, commonly called as the ‘…………’

Answer: Papilonoideae, Leguminosae

Question 3.
The following floral formula represents the …………… (Family: Brassicaceae)

Answer: calyx, perianth, androecium

Question 5.
The outer covering of endosperm separates the embryo by a layer called …………..

Question 6.
The embryo consists of one large and shield shaped cotyledon known as …………. and a short axis with a …………… and a radicle

Question 7.
Above the hilum, is a small pore called the …………..

Question 8.
If a fruit is formed without fertilisation of the ovary, it ……………

Answer: Parthenocarpic fruit.

Question 9.
The calyx is the outer most whorl of the flower and members are called ……………

Question 10.
If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called ……………

Question 11.
Flowers with bracts, reduced, leaf found in flower are called …………. and those without bracts, ……………

Answer: bracteate, ebracteate.

Answer: actinomorphic (regular), zymomorphic (bilateral)

Question 13.
A flower having only stamens or carpel is ………….

Question 14.
………….. is the pattern of arrangement of leaves on the stem or branch.

Question 15.
When the incisions of the lamina reach up to the midrib breaking it into a number of leaflets, the leaf is called ………….

III. Mark the statements True (T) or False (F):

Question 1.
The study of external features of plants is known as external morpholgy and that of internal features as anatomy.

Question 2.
The knowledge of external morpholgy of flowering plants is not essential for the study of all branches of botany.

Question 3.
The root is covered at the apex by a thimble-like structure called the not cap

Question 4.
A few millimetre above the root cap is the region of meristematic activity.

Question 5.
Tap roots of carrot, turnip and adventitious roots of sweet potato, get swollen and store food.

Question 6.
The main function of the stem is spreading out branches bearing leaves, flowers and fruits. It conducts water, minerals and photosynthates.

Question 7.
Underground stems of potato, ginger, turmeric, zaminkand modify to store food in them.

Question 8.
A typical leaf consists of three main parts: Leaf base, petiole and lamina.

Question 9.
In some leguminous plants the leafbase may become swollen, which is called the pulvinus.

Question 10.
The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets.

Question 11.
Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials.

Question 12.
Leaves are often modified to perform functions other than photosynthesis. They are converted into tendrils for climbing as in peas, or into spines for defence as in cacti.

Question 13.
Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs.

Question 14.
When a flower has both androecium and gynoecium, it is termed as bisexual.

Question 15.
A flower is asymmetric or irregular, if it cannot be divided into similar halves by any vertical plane passing through the centre as in canna.

IV. Match the items of Column I

Answer:
(a) → 4
(b) → 15
(c) →13
(d) → 14
(e) → 1
(f) → 3
(g) → 2
(h) → 5
(i) → 6
(j) → 7
(k) → 8
(l) → 9
(m) → 10
(n) → 11
(o) → 12

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A.I.C-D. is a recipient of a BIO2016-78955 grant from the Spanish Ministry of Economy and Competitiveness and a European Research Council, ERC Consolidator Grant (ERC-2015-CoG – 683163). I.B-P. is funded by the FPU15/02822 grant from the Spanish Ministry of Education, Culture and Sport N.B. by the FI-DGR 2016FI_B 00472 grant from the AGAUR, Generalitat de Catalunya and A.P-R. by the SEV-2015-0533 from the Severo Ochoa Programme for Centers of Excellence in R&D. M.I. and J.M. acknowledge support from the Spanish Ministry of Economy and Competitiveness and FEDER (EU) through grant FIS2015-66503-C3-3-P, from Ministerio de Ciencia, Innovación y Universidades / Agencia Estatal de Investigación / Fondo Europeo de Desarrollo Regional, Unión Europea through grant PGC2018-101896-B-I00 and from the Generalitat de Catalunya through Grup de Recerca Consolidat 2014 SGR 878 and 2017 SGR 1061. J.M. is funded by the Spanish Ministry of Education through BES-2016-078218. Y.S. and R.C.D. were funded by the Deutsche Forschungsgesellschaft (DFG) (grant STA12/12 1-1). A.I.C.-D.–A.C. collaboration was funded by the European Regional Development Funds and Marie Curie IRSES Project DEANN (PIRSES-GA-2013-612583). CRAG is funded by “Severo Ochoa Programme” from Centers of Excellence in R&D 2016-2019 (SEV-2015-485 0533).

AIC-D and MI designed and supervised the study. IB-P, NB, AP-R, MM-B and JV-B and performed the experiments. JM, DF and MI formulated the mathematical modelling. JM performed the numerical simulations of the mathematical models. YS and RCB performed and analysed the FRET-FLIM assays. SP and CM collaborated in the Y2H and BiFC assays. IB-P performed QC-specific transcriptomics experiments and data analysis in collaboration with RS and AC. IB-P, JM, MI and AIC-D wrote the manuscript and all authors revised the manuscript.


Watch the video: Botany Quiescent center (June 2022).


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