NEET 2020 NEWS
NATIONAL LEVEL OFFLINE TEST
Plant Anatomy is considered to be the easiest and scoring section in the whole syllabus of Biology. The topic is very interesting and consists of 2- 3 questions in the paper that totals to 4 to 8 marks in the overall marks distribution of the paper. The most important topic from this chapter is Tissue System. This topic is quite fascinating but involves concepts that must be learned properly to score good marks in NEET.
Candidates can expect some direct questions from this chapter.
Ground Tissue System and Vascular Tissue System are some of the topics that need proper revision and attention. Check NEET Biology Syllabus
Candidates can go through the brief notes below to prepare well for the exam. We have also provided the solved sample questions to help candidates in understanding the type questions that they can expect from this chapter.
A Tissue is defined as a group of similar or dissimilar cells which have common origin and perform some specific functions.
Tissues are mainly divided into three categories: Meristematic Tissues or Meristems, Permanent Tissues and Secretory Tissues.
Below are given some of the characteristics of Meristematic Tissues:
Meristematic Tissues are metabolically very active and are capable of repeated divisions.
They contain immature and young cells.
They also contain a homogeneous thin wall.
Vacuoles are absent in meristematic tissues.
The shape of meristematic cells is isodiametric in shape.
Meristematic Tissues contain large nuclei and abundance of cytoplasm.
There is no intercellular space in Meristematic Tissues.
Chloroplast is absent in Meristematic Tissues.
They contain proto- plastids instead of plastids.
The Meristematic Tissues are further classified on the basis of their mode of origin, position or function. Below is given the detailed information about its division:
Promeristm or Primordial Meristem: The Promeristm originates from embryo and are therefore called Promeristm or Embryonic Meristem. Promeristm are present in the regions where an organ or a part of plant body is initiated.
Primary Meristem: A Primary Meristem is the one that originates from promeristem and retains its activities. It is located in the apices of roots, stems and leaf primordial.
Secondary Meristem: The Secondary Meristem always arise in the permanent tissues and have no typical promeristem.
Apical Meristem: This apical meristem is located at the growing apices of main and lateral shoots and roots. These cells are responsible for the linear growth of an organ.
Intercalary Meristem: Intercalary Meristem is the portion of apical meristems which are separated from the apex during the growth of axis and formation of permanent tissues.
Lateral Meristem: The lateral meristems occur lately in the axis, parallel to the sides of stems and roots. This type of meristem consists of initials which divide mainly in one place and increases the diameter of an organ.
Protoderm: Protoderm is the outermost layer of the apical meristem. It develops into the epidermis or the epidermal tissue system.
Procambiu: This type of tissue occurs inside the protoderm. The young cells that grow by elongation and differentiation give rise to the primary vascular system.
Ground Meristem constitutes the major part of the apical meristem. It mainly develops the ground tissues like hypodermis, cortex, endodermis etc.
Mass Meristem: Mass of cells is formed when the cell divide anticlinally in all planes. Example of this type of tissue is formation of spores, cortex, pith and endosperm.
Plate Meristem: Plate like area sof this tissue increases when the cell divide anticlinally in two planes. Example of this type of tissue is formation of epidermis and lamina of leaves.
Ribe or File Meristem: Row or column of cell is formed when the cell divide anticlinally in one plane. Example of this type of tissue is formation of lateral roots.
Permanent tissues are the types of tissues which are made up of mature cells which have lost their capacity to divide themselves further. These cells have attained a permanent shape, size and function. The cells of these tissues are either living or dead, thin-walled or thick-walled.
They are further divided into two types:
It is the most simple and unspecialized tissue.
It is concerned mainly with the vegetative activities of the plant.
Collenchyma is the tissue of primary body.
The term was coined by Schleiden in 1839.
The cells of this tissue contain protoplasm and are living in nature.
The cell walls are thickened at the corners.
It is made up of cellulose, hemicelluloses and pectin.
Sclerenchyma consists of thick walled dead cells.
The cells of Sclerenchyma vary in shape, size and origin.
The term was coined by Mettenius in 1805.
Xylem is made up of tracheids, vesselsm xylem fibres and xylem parenchyma.
The main transporting material of Xylem is two vessels and tracheids.
There are two primary xylem, Protoxylem and Metxylem.
Xylem has protoxylem at the centre.
Phloem is made up of companion cells, sieve tube elements, phloem parenchyma and phloem fibres in angiosperms.
In gymnosperm instead of sieve tube and companion cells, albuminous and sieve cells are present.
In monocotyledons, phloem parenchyma is absent.
Epidermal tissue comprises of the outer covering of the plants, such as epidermis, cuticle, stomata, epidermal extentions: trichomes in stem and root hair.
Guard cells of the epidermal tissue system are been- shaped and contain chloroplasts.
In this system, the root hairs are unicellular while the trichomes are multicellular in nature.
The grasses have a dumb- bell shaped guard cells.
Stomata regulate the gaseous exchange and water loss by transpiration.
The ground tissue system forms the major bulk of the tissues between epidermal and vascular tissues.
Examples of this tissue are cotex, pith, pericycle, etc.
They contain the simple tissues.
The mesophyll of leaves is a ground tissue which contains chloroplast.
The outermost layer of Dicotyledonous Root is the Epiblema which contains root hair.
Several layers of cortex present, that ends with innermost layer endodermis, which contains waxy material called suberin forming Casparian strips
There are two to six vascular bundles present in them.
The vascular bundles that are present are radial and Exarch vascular bundles.
The structure of the structure is similar to the dicotyledonous roots.
The difference lies in the fact that the xylem bundles are present in this.
There is no option of secondary growth.
Their pith is large.
The outermost layer of the dicotyledonous stem is the epidermis with cuticle.
The cortex consists of three layers; outermost hypodermis (collenchymatous), middle parenchymatous cortical layer and the endodermis containing starch grains
The vascular bundles present in them are scattered, conjoint and open and are arranged as a ring.
Stomata and trichomes are present on the epidermis.
The hypodermis present in them is sclerenchymatous.
The vascular bundles present in them are scattered, conjoint and closed.
These are also called as dorsiventral because of their distinct dorsal and ventral side.
They have reticulate venation.
The stomata in them is peent on the abaxial epidermis.
The vascular bundles are surrounded by bundle sheath cells.
The mesophyll is made up of the elongated palisade and oval or round spongy parenchyma cells.
These are also called as isobilateral because both of their sides are similar.
They have parallel venation.
The stomata in them are equally distributed on both sides.
The vascular bundles present are of the same size.
Some cells of the epidermis are modified to large cells called bulliform cells in grasses, they help in minimizing water loss.
The mesophyll is not differentiated between palisade and spongy parenchyma cells
Q1. Fibres associated with Phloem are:
Answer: (4) Bast Fibres
Q2. Passage Cells are found in:
All of these
Answer: (4) All of these
Q3. Healing of wound in plants takes place by activity of:
A) Intercalary meristem
B) Secondary meristem
C) Apical meristem
D) Lateral meristem
Answer: (B) Secondary Meristem
Q4. In angiosperms, Xylem is made up of:
Tracheids and Vessels
Vessels and Fibres
Tracheids and Fibres
All of these
Answer: (4) All of these
Q5. In the monocot root, we observe:
A) suberised exodermis, polyarch xylem, pith
B) exodermis, endarch, tetrarchclosedbundles
C) conjoint, collateral, open, polyarch vascular bundle
D) suberised exodermis, casparian strip, passage cells, cambium
Q6. Vascular Cambium forms xylem on inner side and phloem on outer side due to:
Effect of gravity
Shearing force of wind
Different action of hormones
Answer: (4) Different action of hormones
Q7. Meristematic tissues are composed of :
A) mature cell
B) fully differentiated cell
C) cells that cannot divide
D) immature cells with power to divide
Answer: D) immature cells with power to divide