Anatomy of Flowering Plants Test 5

Anatomy : The study of internal structure of the plant with the help of section cutting is called Internal Morphology or Anatomy.

A group of structurally similar or dissimilar cells that perform a common function and have a common origin is called a tissue. A plant is made up of different kinds of tissues. The complex tissues are, however, composed of different kinds of cells and they perform different types of functions.

• A meristem may be defined as the group of cells which divide continuously to give rise to new cells.
• A meristem is the tissue in most plants containing undifferentiated cells, found in zones of the plant where growth can take place.
• Meristematic cells give rise to various organs of the plant and keep the plant growing.
• Meristematic cells are incompletely or not at all differentiated and are capable of continued cellular division. Furthermore, the cells are small and protoplasm fills the cell completely. The vacuoles are extremely small.
• The cytoplasm does not contain differentiated plastids, although they are present in rudimentary form- proplastids.
• Meristematic cells are packed closely together without intercellular cavities.
• The cell wall is a very thin primary cell wall.

Thus, the correct answer is option C.

Embryo is made up of specific embryonic meristem consisting of undifferentiated cells.

Pollen of Pinus do not have meristems. A meristem is the tissue in most plants containing undifferentiated cells, found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing. Meristematic cells are incompletely or not at all differentiated, and are capable of continued cellular division.

Thus, the correct answer is option D.

Bamboo, grass and mint stem elongate by the activity of Intercalary meristems. Intercalary meristem at base of leaves or nodes of grasses is responsible for primary growth. Meristems are classified by their location as apical located at root and shoot tips, lateral in the vascular and cork cambia, and intercalary at internodes, or stem regions between the places at which leaves attach and leaf bases. Intercalary meristem cells possess the ability to divide and produce new cells, as do apical and lateral meristems. They differ, however, in being situated between regions of mature tissue, such as at the base of grass leaves, which are themselves located on mature stem tissue.
Thus, the correct answer is option C.

Histogens are tissue producing definite zones or regions in the apical. meristem. Dermatogen, periblern and plerorne are the three regions of histogen.

Maximum growth of root takes place in the back side portion of the root apex. Apex portion is made up of root cap and then follows the region of cell division where meristematic tissues are present.

According to histogen theory by Hanstein, the three principal tissues of the root, vascular cylinder, cortex and epidermis originate from three groups of initial cells or histogens, in the apical meristem plerome, periblem and dermatogen respectively. A fourth histogen, the calyptrogen produces the root cap. 
Therefore, the correct answer is option C.

Many plants growing in aquatic habitats do not possess roots because there is little requirement for absorption of water and mineral salts, e.g., Wolffia, Utricularia, Myriophyllum, Ceratophyllum. In other aquatic plants, roots develop only for balancing (e.g., Lemna, Pistia) and fixation (e.g., Hydrilla). The root cap is a section of tissue at the tip of a plant root. It is also called as calyptra. Root caps contain statocytes which are involved in gravity perception in plants. If the cap is carefully removed the root will grow randomly. The root cap protects the growing tip in plants. It secretes mucilage to ease the movement of the root through soil and may also be involved in communication with the soil microbiota. Since, roots in Pistia are only for balancing, root cap is not required. So, root cap is absent in Pistia. 

Thus, the correct answer is option B.

According to histogen theory, as proposed by Hanstein, the root and shoot apices have three distinct meristematic regions, called as histogens. These are namely dermatogens, periblem and plerome. The dermatogens makes uniseriate epidermis by anticlinal divisions, periblem forms cortex and plerome serve as progenitor of stele (pericycle, vascular bundles, pith rays or medullary rays and pith). 

Casuarina is exception to this theory and has two histogens. Ranunculus is also exception to this theory and has one histogens. 

Monocotyledons have four histogens, calyptrogen being the fourth one that makes root cap. Thus the correct answer is option D.

Apical meristem and cambium are undifferentiated tissue capable of division and maturation whereas parenchyma are found after differentiation from meristem.

The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems. It is found in woody and many herbaceous dicots, gymnosperms and some monocots (monocots usually lack secondary growth).

Embryonic tissue in plants refers to the actively growing cells but more than often this term is used to describe the early formation of tissue during its first growth stages. It thus refers to the sporophyte, gametophyte embryos from seedlings as well as meristematic tissues which are always in embryonic state. Under this condition, the growth of this tissues takes place through cell division and the cells of the embryo divide.
Therefore, the correct answer is option C.

On the basis of origin and development, meristem is grouped as promeristem, primary and secondary meristem. Promeristem includes undifferentiated, actively dividing apical initials which are derived from embryonic tissues and give rise to primary meristem. Primary meristem is derived from promeristem or embryonic meristem and produce primary permanent tissues of primary plant body. Secondary meristem develops from permanent tissues during secondary growth and gives rise to secondary tissues. Secretory tissues are the permanent primary tissues, which are derived from promeristem.

Thus, the correct answer is option B

Plant tissue culture is a technique of growing root, shoot, tissues, and organs artificially in an ascetical medium which contain all the essential nutrients for the growth.

The root cap protects the growing tip in plants. It secretes mucilage to ease the movement of the root through soil, and may also be involved in communication with the soil microbiota. The purpose of the root cap is to enable downward growth of the root, with the root cap covering the sensitive tissue in the root.

The cells contain lower concentration of RNA, DNA and protein than other cells of root apex.

Quiescent centre is unusual in shoots, but it is universal in roots of higher plants. Though the occurrence of QC was reported in vascular cryptogams (e.g. Equisetum arvense) later investigations have established that the entire root apex of vascular cryptogams is mitotically active. Quiescent centre maintains a strict boundary in closed meristem. As a result the derivatives of QC also maintain a strict boundary in the apical zone.

In plants, there are different kinds of plant meristems based on cell divisions:-

a) Rib or File meristem- when the division occurs along only one plane i.e, it is either periclinal or anticlinal.

b) Plate meristem- when the division occurs along both planes i.e, it is periclinal as well as anticlinal.

c) Mass- when division occurs along no fixed plane so a mass of cells are formed.

The two types of cell division are:-

Anticlinal division-  The cell divisions are perpendicular to the adjacent layer of cells, as a result, a column of cells is obtained.

Periclinal division- The cell division occurs parallel to the tissue as a result, rows of cells are obtained. 

So, the correct answer is 'Both periclinal and anticlinal divisions in one plane'.

According to histogen theory, apex of root is made up of dermatogen, periblem and pleurome.

Marginal meristem is the meristem located along the margin of a leaf primordium and forming the leaf blade. The apical meristem or growing tip, is a completely undifferentiated meristematic tissue found in the buds and growing tips of roots in plants. 
Intercalary meristems are capable of cell division, and they allow for rapid growth and regrowth of many monocots. Intercalary meristems at the nodes of bamboo allow for rapid stem elongation, while those at the base of most grass leaf blades allow damaged leaves to rapidly regrow. 
In mass meristem the cells divide in all planes to form bulk of tissue. this type of meristem takes part in the formation of cortex, pith, endosperm and sporangia. 
Therefore, the correct answer is option D. 

The spatial pattern of the arrangement of leaves is called as phyllotaxy whereas the time between successive leaf initiation events is called as the plastochron and the rate of emergence from the apical bud is the phyllochron. 
The plastochron index and the leaf plastochron index are ways of measuring the age of a plant dependent on morphological traits rather than on chronological age. Use of these indices removes differences caused by germination, developmental differences and exponential growth. 
Plastochron is not related to distance between two successive leaf primodial, region of origin of root branch and region of origin of stem branch.  
Thus, the correct answer is option A. ​

Apical cell theory by Nageli in 1858, stated that in large number of cryptogams single solitary cell has been found to form the growing point and it was supposed that similar condition exists in higher plants too. The presence of complex growing apices in higher plants cannot be explained by this theory. 
Thus, the correct answer is option A.

In parenchyma of hydrophytes, large air cavities are formed. Due to the presence of air the plants become buoyant.

The phragmoplast is a plant cell specific structure that forms during late cytokinesis. It serves as a scaffold for cell plate assembly and subsequent formation of a new cell wall separating the two daughter cells. The phragmoplast can only be observed in Phragmoplastophyta which includes the Embryophyta.

Totipotency means the ability of  single cell to divide & diiferentiate into complete plant body . In plants, growth mainly occurs by the activity of meristematic cells.  The new cells are continously produced by the cell division in a meristem. At maturity, meristmatic cells are fully developed & functional, having the capability of totipotency  means when provided all necessary conditons, nutrients at any stage of life, it can develop into new plant tissue . These are present at the apex of every root & shoot known as root apex & shoot apex  respectively.

Parenchyma cells are thin-walled meristematic cells.

Parenchyma cells are living cells. They are at the constant state of division. They have large central vacuoles, which allow the cells to store and regulate ions, waste products and water. These are majorly distributed as ground tissue. Tissue specialised for food storage is commonly formed of parenchyma cells. 
Collenchyma and sclerenchyma involve in mechanical support. 
Aerenchyma involves in gas exchange.
Thus, option A is correct.

Parenchyma is a simple tissue which is composed of thin-walled polyhedral, isodiametric living cells with sufficient cytoplasm and one or more nuclei. These tissues serve the purpose of storage, photosynthesis gaseous exchange and much more but do not provide mechanical support to the plant and hence, lack cell wall thickening or lignin deposition which is a characteristic feature of mechanical tissues. They have cellulosic cell wall without any thickening or lignin deposition. Parenchymatous cells are characterized by the presence of well-developed intercellular spaces, as in the case of aerenchyma.
Therefore, the correct answer is option D.
 

Parenchyma : It is very primitive type of tissue. It is first evolved tissue. Remaining all different types of tissuesare derived from this tissue.  so it is also called as fundamental tissue l Parenchyma name coined by Grew.
1. It is a living tissue.

2. It is first differentiated tissue derived from meristem.

3. It is a universal tissue.

4. Flesh of a fruit is mainly composed of parenchyma.