Anatomy of Dicot and Monocot Plants MCQ Quiz in मल्याळम - Objective Question with Answer for Anatomy of Dicot and Monocot Plants - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept: 

• ​Endodermis, phloem, pericycle, protoxylem, conjunctive tissue, metaxylem, Casparian strip, and passage cells make up the vascular bundle of a root.
• In monocot roots, the pith is big and well-developed.

​Explanation:

Option 1: Pericycle

• The pericycle forms a layer between the endodermis and the vascular bundle.
• It forms the outermost layer of the stele/ vascular cylinder.
• The pericycle is made up of thick-walled parenchymatous cells.

Option 2: Conjunctive tissue

• Between the xylem and phloem bundles of monocot and dicot plants is a thin strip of tissue known as conjunctive tissue.
• Conjunctive tissue can have parenchymatous cells or fibers with extremely thick cell walls as its constituent parts.
• Conjunctive tissue cells in older roots may be sclerenchymatous.
• Parenchymatous conjunctive tissue can be seen in soft monocot stems like corn, gingers, onions, etc.
• Fibrous conjunctive tissue can be seen in harder monocot stem-like many species of palm trees, bamboo, etc.

Option 3: Epidermis

• The epidermis is the outermost layer of the primary plant body.
• It is made up of elongated, compactly arranged cells, which form a continuous layer.
• Epidermis is usually single-layered.
• Epidermal cells are parenchymatous with a small amount of cytoplasm lining the cell wall and a large vacuole.

Option 4: Protoxylem

There are two types of primary xylem: protoxylem and metaxylem.

The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.

So, the correct answer is Conjuctive tissue.

Concept:

• A group of cells having similar structures and function is called tissue.
• A plant is made up of different types of tissues.
• Plant tissues are divided into two main types depending on whether the tissues can divide or not - Meristematic tissue and Permanent tissue.
• These tissue types are further divided into different types as follows:

 ​Explanation:

Phellem:

• ​The periderm is a secondary tissue. It replaces the epidermis when the epidermis gets damaged.
• A periderm consists of three zones - Phellogen, Phellem, and Phelloderm.
• Of these phellem is a layer of suberized cells that are produced by phellogen. It consists of flattened brick-shaped cells.
• Thus phellem forms an outermost layer in a dicot stem.

Pericycle:

• The pericycle forms a layer between the endodermis and the vascular bundle.
• It forms the outermost layer of the stele/ vascular cylinder.

Endodermis:

• It is the innermost layer of the cortex.
• It is found under the phellem.

Phloem:

• In a dicot stem, the vascular bundle is present at the center which forms a distinct ring.
• The vascular bundle comprises of xylem, phloem and cambium.
• Of these, the phloem is always located towards the outside of the bundle whereas the xylem is located towards the inner side of the bundle.
• Thus phloem is the tissue that is preceded by the pericycle.
• Thus from the above-given information, the sequence of tissues in a dicot stem will be:
• Phellem → Endodermis → Pericycle → Phloem
• This coincides with option 3. 

So the correct answer is option 3 (Phellem - Endodermis - Pericycle - Phloem).

Additional Information 

The correct answer is trichome.

Key Points

• A stem is the part of a plant above the ground.
• The plant cell has an outer epidermis, inner dermis, cortex region, and vascular tissues.
• Epidermal hairs present on a stem is trichome.
• These are the extension of the formed epidermis.
• It is multicellular in nature.
• It helps in preventing water loss.

Additional InformationCuticle:

• It is a waxy deposition present above the epidermis.
• It is thick and helps in preventing water loss.
• It is an adaptation of desert plants.

Root hairs:

• The root is present in the ground.
• The root hairs are the extension of the epidermis in the root.
• It increases the surface area for water absorption.

Mesophyll cell:

• .It is present in the leaf.
• It consists of spongy and palisade parenchyma.
• It contains chloroplast.

Adventitious bud:

• It is a vegetative structure.
• It helps in the vegetation reproduction of plants.
• It forms the new plant.
• It is present in the leaf's tip.

The correct answer is  Endodermis.

Concept:

• Cortex in Dicot Stems: The cortex is the region of the plant stem located between the epidermis and the vascular bundles. It primarily consists of parenchyma cells and often includes specialized cells for storage, photosynthesis, and other functions.
• Endodermis: The endodermis is the innermost layer of the cortex. It is a single layer of cells that forms a boundary between the cortex and the vascular cylinder (stele). The endodermis plays a crucial role in regulating the movement of water and nutrients from the cortex into the vascular tissues.
• Characteristics of Endodermis:
  • The cells of the endodermis often have thickened cell walls due to the presence of a band of suberin (Casparian strip), which helps control the flow of substances.
  • The endodermis ensures that all water and dissolved substances must pass through the plasma membrane of the endodermal cells, effectively filtering and regulating what enters the vascular system.

Explanation:

• Pith (A): The pith is the central part of the stem, located inside the ring of vascular bundles. It primarily consists of parenchyma cells and functions in storage and transport of nutrients. It is not part of the cortex.
• Pericycle (B): The pericycle is a layer of cells found just inside the endodermis in roots and is responsible for the initiation of lateral roots. In stems, it is usually not prominent or defined as a distinct layer.
• Endodermis (C): This is the correct layer, as it is the innermost layer of the cortex in both roots and stems of dicot plants.
• Phloem (D): Phloem is one of the components of the vascular bundles responsible for the transport of organic nutrients. It is not a part of the cortex but is located functionally within the vascular tissue.

Fig. Dicot stem.

The correct answer is  Hypodermis

Concept:

• The cortex in the dicot stem is the region of tissue located between the epidermis and the vascular bundles.
• It is composed of several sub-zones, each with specific structural and functional roles.
• The outermost sub-zone of the cortex is known as the hypodermis, which typically consists of collenchyma or sclerenchyma cells that provide mechanical support to the stem.
• Following the hypodermis, the next sub-zone is the general cortex, which usually comprises parenchyma cells involved in storage and photosynthesis.
• The innermost layer of the cortex is the endodermis, which regulates the flow of water and nutrients between the cortex and the vascular tissue.
• The pericycle, typically present in roots, is a layer of cells just inside the endodermis and is involved in the formation of lateral roots.
• The pith, also called the medulla, is located at the center of the stem and is responsible for storing nutrients and maintaining the integrity of the stem.

Explanation:

• Pericycle: This layer is found in roots and is involved in the formation of lateral roots. It is not a part of the stem's cortex.
• Hypodermis: The hypodermis is the outermost sub-zone of the cortex in dicot stems. It typically consists of collenchyma or sclerenchyma cells, providing additional support to the stem.
• Endodermis: This is the innermost layer of the cortex and surrounds the vascular bundles, regulating the flow of substances between the cortex and vascular tissues.
• Pith: The pith is located at the center of the stem, not the cortex. It serves as a storage area and supports the stem's structural integrity.

Fig. Dicot stem.

The correct answer is Monocot root and Dicot stem.

Explanation-

Pith is the central portion or core of certain types of plant stems and can be present in roots. It's composed largely of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. Pith can also be involved in storage and transportation of nutrients and water around the plant.

In a dicotyledonous stem, pith is well developed. This is due to the arrangement of its vascular bundles in a ring arrangement, which leaves a central space.

In monocotyledonous roots, the pith is well developed too. Here, the primary vascular tissues are scattered throughout the plant, resulting in a well-developed pith.

Conversely, Monocot stems have scattered vascular bundles without a defined cortex and pith region: Their anatomy differs from that of dicot stems.

The anatomy of dicot roots mainly comprises a central cylinder of xylem and phloem tissues surrounded by a cortex, with the pith being small or absent due to the large xylem star or xylem vessels

Key Points

Primary xylem is the xylem, formed from the procambium, and it is divided into two types:

1. Protoxylem
   • Protoxylem is the primary xylem that develops first during primary growth
   • It grows before the maturation of other plant organs
   • The cells are smaller in size, and whole protoxylem is less prominent
   • It is present on the periphery of the stem and inside of the root
   • It is less efficient in water transportation
2. Metaxylem
   • Metaxylem is formed after the protoxylem
   • It grows after the maturation of all plant organs
   • Cells are bigger in size, and the metaxylem is much more prominent
   • It is present on the inside of the stem and periphery of the roots
   • It is more efficient in water transportation

Position of protoxylem and metaxylem form various xylem patterns:

1. Endarch
   • Protoxylem is directed toward the center and metaxylem elements towards the periphery
   • Growth of the xylems represents the centrifugal
   • It is present in the stem of flowering plants
2. Exarch
   • Protoxylem is directed towards the periphery and metaxylem towards the center 
   • Growth of the xylem reflects the centripetal pattern
   • It is the feature of the root of flowering plants
3. Mesarch
   • Protoxylem develops first in the center of the strand in a primary xylem strand
   • It continues to develop both centrifugally and centripetally
   • It is present in shoots of ferns
4. Polyarch
   • On the basis of the number of protoxylem groups, roots are divided into monarch, diarch, triarch, tetrarch or polyarch
   • Polyarch condition has many protoxylems (12-20) alternating with phloem 
   • The root may be diarch (two xylem bundles as in tomato), triarch (Pea) tetrarch (Buttercup, Gram) pentarch or hexarch 
   • Due to presence of numerous xylem bundles and exarch conditions, xylem of monocot root is polyarch
5. Centrarch
   • Primary xylem forms a single cylinder in center of the stem and develops from the center outwards
   • Protoxylem is thus found in the central core and the metaxylem in a cylinder around it
   • Common in early land plants, such as "rhyniophytes", but not present in any living plants now

Explanation:

• The stems of seed plants typically have endarch development.
• Therefore, in a dicot stem, xylem is endarch.

Concept:

• A group of cells having similar structures and function is called tissue.
• A group of tissues that are derived from meristematic tissues forms the tissue systems in a plant.
• The function and structure of these tissues depend on their location in a plant body.
• Depending on their structure and location, there are three types of tissue systems in plants:
  • Epidermal tissue system: It forms the outer covering of the plant body and is comprised of the epidermal cells, stomata and epidermal appendages - the trichomes and hair.
  • Ground tissue system: Made up of simple tissues like parenchyma, collenchyma and sclerenchyma. It lies between the vascular and dermal tissues in a plant body.
  • Vascular tissue system: It is made up of complex tissues - xylem and phloem.

Explanation:

Statement 1: Protoderm forms the epidermal tissue system.

• ​This statement is correct.
• Protoderm is a thin layer of meristematic tissue.
• It gives rise to the epidermis.
• It functions as a protective covering around the various organs of the plant.
• Thus Protoderm forms the epidermal tissue system.

Statement 2: Procambium forms the vascular tissue system.

• ​This statement is correct.
• ​Procambium is a part of the primary meristem.
• It gives rise to the cambium and primary vascular tissues.
• Thus procambium forms a vascular tissue system.

Statement 3: Ground meristem forms the ground tissue system.

• This statement is correct.
• Ground meristem refers to the primary tissue of the growing tip of a stem or root. It excludes the epidermis and vascular bundles.
• Structures like the cortex, endodermis, pericycle medullary rays, and pith are formed from the ground meristem.
• These structures are made up of parenchyma cells apart from other cells. 
• The ground tissue system is made up of simple tissues like parenchyma.
• Thus, the ground meristem forms the ground tissue system.
• Thus, from the above-given information, all three given statements are correct. This coincides with Option 4.

So the correct answer is option 4(All of these).

Correct Answer: 3)

Solution:

Concept: 

• The cavity In the center of the stem is known as the pith.
• The pith or medulla is the tissue present in the stems of vascular plants.
• It is composed of soft, spongy parenchyma cells that store and transport nutrients.
• Generally, the pith is present in dicot plants and absent in monocots.

Explanation:

Option 1: Helianthus  – INCORRECT

• Helianthus is a dicot but the pith cavity is not disintegrated.
• Hence, this option is incorrect.

Option 2: Zea mays – INCORRECT

• Zea may is a monocot and in it pith cavity is absent.
• Hence, this option is incorrect.

Option 3 : Cucurbita – CORRECT

• Cucurbita is a dicot and in it pith cavity is present.
• Hence, this option is correct.

Option 4: Dracaena  – INCORRECT

• Dracaena is a monocot and in it pith cavity is absent.
• Hence, this option is incorrect.

So, the correct answer is option 3).

The correct answer is Dicot stem

Explanation:

Dicotyledonous stem

• The epidermis is the outermost protective layer of the stem and it has hair-like structures called trichomes, and a few stomata.
• The hypodermis is present below the epidermis and has collenchymatous cells.
• It provides mechanical strength to the young stem.
• Below the hypodermis are the parenchyma cells with intercellular spaces.
• The endodermis is the innermost layer; cells in this region are rich in starch.
• A layer called pericycle is present between the endodermis and phloem.
• In between the vascular bundles there are a few layers of radially placed parenchymatous cells, which constitute medullary rays.
• The vascular bundles are arranged in a ring, a characteristic feature of the dicot stem. 

Dicotyledonous root

• The outermost layer is epiblema with unicellular hair.
• The cortex has parenchyma cells with intercellular spaces.
• The innermost layer of the cortex is the endodermis.
• Besides the endodermis is the pericycle.
• The initiation of lateral roots and vascular cambium occurs in the pericycle.
• The pith is small.
• The dicot root also has a protoxylem; it is the xylem that develops during primary growth.
• Metaxylem is formed after the protoxylem during primary growth. 

Monocotyledonous stem

• The outer layer is called the endodermis below which the hypodermis is present.
• The hypodermis has sclerenchymatous cells.
• Below the hypodermis is a large number of vascular bundles that are scattered and surrounded by sclerenchymatous bundle sheath.
• The ground tissue is made up of a large number of parenchymatous cells.
• The vascular bundles are arranged in the same radius (conjoint) and are present without cambium (closed).
• The phloem parenchyma cells are not present and water-filled cavities are present within the vascular bundles.

Monocotyledonous root

• It is similar to the dicot root.
• It has an epidermis with root hair, cortex, endodermis, and pericycle.
• The xylem bundles are more in number than the dicot roots.
• The pith region is large.