Anatomy of Dicot and Monocot Plants MCQ Quiz - Objective Question with Answer for Anatomy of Dicot and Monocot Plants - Download Free PDF

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. 

The correct answer is C and D

Concept:

• The epidermis is the outermost protective layer of the stem. It is covered with a thin layer of cuticle, it may bear trichomes and a few stomata.
• The cells arranged in multiple layers between epidermis and pericycle constitute the cortex. It consists of three sub-zones.
  • The outer hypodermis, consists of a few layers of collenchymatous cells just below the epidermis, which provide mechanical strength to the young stem.
  • Cortical layers below hypodermis consist of rounded thin walled parenchymatous cells with conspicuous intercellular spaces.
  • The innermost layer of the cortex is called the endodermis. The cells of the endodermis are rich in starch grains and the layer is also referred to as the starch sheath.
• Pericycle is present on the inner side of the endodermis and above the phloem in the form of semi-lunar patches of sclerenchyma.
• In between the vascular bundles there are a few layers of radially placed parenchymatous cells, which constitute medullary rays.
• A large number of vascular bundles are arranged in a ring ; the ‘ring’ arrangement of vascular bundles is a characteristic of dicot stem.
• Each vascular bundle is conjoint, open, and with endarch protoxylem.
• A large number of rounded, parenchymatous cells with large intercellular spaces which occupy the central portion of the stem constitute the pith.

Fig: T.S of dicot stem

Explanation:

• Statement A: "The cells arranged in multiple layers between epidermis and pericycle constitute the cortex." - This statement is true. The cortex is a layer of tissue found between the epidermis and the pericycle.
• Statement B: "Cortex consists of three sub-zones." - This statement is true. The cortex in dicot stems typically consists of three sub-zones: the hypodermis, the general cortex, and the endodermis.
• Statement C: "Hypodermis consists of a few layers of collenchymatous cells just below the endodermis." - This statement is false. The hypodermis in dicot stems is found just below the epidermis, not the endodermis, and is typically made of collenchymatous cells providing mechanical support.
• Statement D: "The outermost layer of the cortex is called the endodermis." - This statement is false. The endodermis is the innermost layer of the cortex, not the outermost layer. The outermost layer of the cortex is the hypodermis.
• Statement E: "The cells of the endodermis are rich in starch grains." - This statement is true. The endodermis cells, also known as the starch sheath, often contain starch grains and are involved in regulating the flow of substances into the vascular system.

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 Ground tissue.

• The term cortex refers to the outermost layer of a structure.
• In the brain, the cortex most often refers to the cerebral cortex, although the cerebellum also has an outer layer called the cerebellar cortex.
• The three types of ground tissue: parenchyma, collenchyma, and sclerenchyma.
  • A function included photosynthesis, storage, regeneration, support, and protection.

Important Points

Additional Information

The correct answer is Ground tissue.

• The term cortex refers to the outermost layer of a structure.
• In the brain, the cortex most often refers to the cerebral cortex, although the cerebellum also has an outer layer called the cerebellar cortex.
• The three types of ground tissue: parenchyma, collenchyma, and sclerenchyma.
  • A function included photosynthesis, storage, regeneration, support, and protection.

Important Points

Additional Information

The correct answer is Epidermis.

Key Points

• Root hairs are slender projections originating from epidermal cells that function in nutrient and water uptake as well as in anchoring the root in the soil.
• In wild-type Arabidopsis, root hairs are formed by epidermal cells termed trichoblasts which overlie the boundary between two cortical cells

Additional Information

The correct answer is a type of epidermal tissue.

Key Points

• Stomatal guard cells are a type of epidermal tissue.
• The epidermal tissue system forms the outermost covering of the whole body plant.
• In the epidermal tissue system, the epidermis is the outermost layer of the main plant body.
• This layer is interrupted by stomata.
• The stomata are openings in the epidermis of most of the aerial parts of the plants, especially in the leaves.
• Each stomata is composed of two bean-shaped cells called guard cells, which enclose the stomatal pore.
• The stomatal guard cells are generally much smaller in size as compared to other epidermal cells.
• Stomatal guard cells help to regulate the rate of transpiration during photosynthesis by opening and closing the stomata. 

Concept:

1. Pith: 

It is the innermost part of tree consisting of cellular tissue which is used for nourishment of tree in young age.

2. Sapwood: 

It is the outer annual ring between heartwood and cambium layers. It is the living, outermost portion of a woody stem or branch.

3. Heartwood: 

The inner annual rings surrounding the pith are known as heartwood. It imparts rigidity to the tree.

4. Cambium Layer: 

It is a thin layer of sap between sapwood and the inner bark.

5. Inner bark: 

It gives protection to the cambium layer

6. Outer bark: 

It is the outermost part of the tree

7. Medullary sheath:

A thin radial fibres extending from pith to the cambium layer. 

Concept:

• Xylem and phloem are collectively termed vascular bundles. These may or may not have cambium.
• There are two types of vascular bundles:

      1.Conjoint vascular bundle - Xylem & phloem are present on the same radii.

• These can be further divided into three types (a) Collateral (b) Bicollateral & (c) Concentric

      2. Radial vascular bundle - Xylem & phloem are present on different radii in an alternate manner.

• Examples: Most of the roots (Dicot, a monocot, gymnosperm, fern-root)

Explanation:

• Conjoint Collateral vascular bundle: In this type of vascular bundle xylem and phloem are present on the same radius and phloem is present towards the periphery.
• These are of two types:

1. Open vascular bundle: If the cambium is present between the xylem and phloem, then it is said to be an open vascular bundle. Eg. Dicot stem.
2. Closed vascular bundle: When the cambium is absent between the xylem and phloem, then it is said to be a closed vascular bundle. Eg. Monocot stem

• The cambium present between the xylem and phloem in the open type of vascular bundle is responsible for the secondary growth like a woody stem in dicot plants.
• Thus, the correct option will be ''The presence of open vascular bundle is responsible for making the stem woody in dicot plants''.

Concept:

• Epidermis is the layer of cells present on the outside of plant structures such as stem, root, leaf, flower, fruit and seed.
• Epidermis comprises pavement cells, guard cells and subsidiary cells.
• Functions - 
  • Provides a barrier against water loss, infection and mechanical injury.
  • Helps regulate gas exchange.
  • Regulates transpiration.
  • Increases water absorption, etc.

Important Points

• Hair-like projections that extend from the epidermis are called trichomes.

Trichomes - 

• ​Trichomes are referred to as leaf hair.
• These can be singular or multicellular.
• The shape of trichomes helps in identifying a plant species.
• Trichomes are controlled by trichome specificity genes.
• The chemicals produced by trichomes in their glandular tips protect the plant from being eaten by insects.
• Apart from this, trichomes also produce secondary chemicals that are used as useful products such as fragrances and flavors.
• Some trichomes also contain irritants that can cause rashes in humans.
• In insectivorous plants like Drosera, trichomes secrete exudate that helps in trapping the prey.​

So the correct answer is option 4 (Trichomes).

Key Points

• Casparian strips are located on the roots of the endodermis of vascular plants.
• It is a band of cell wall material deposited on the radial as well as tangential walls of the endodermis.
• The endodermis is the innermost layer of the cortex. It is made up of parenchymatous cells.

Explanation:

• Casparian strips are made of suberin.
• Suberin is a water-impermeable and waxy material.
• It is a lipophilic, hydrophobic polyester biopolymer.
• It blocks the passive flow of water and solutes into the stele of a plant.
• Suberin prevents water from entering the pericycle.
• Thus, Casparian strips help in producing root pressure.

Additional Information

• Chitin - is the N-acetylglucosamine polymer found in the cell wall of fungi and exoskeletons of Arthropods.
• Cellulose - is a polysaccharide and a structural component of the primary cell wall of plants.
• Pectin - is a heteropolysaccharide present in the primary cell wall and middle lamella of plants.

Hence, the correct option is (4) Suberin.

The correct answer is Ground tissue.

• The term cortex refers to the outermost layer of a structure.
• In the brain, the cortex most often refers to the cerebral cortex, although the cerebellum also has an outer layer called the cerebellar cortex.
• The three types of ground tissue: parenchyma, collenchyma, and sclerenchyma.
  • A function included photosynthesis, storage, regeneration, support, and protection.

Important Points

Additional Information

The correct answer is Epidermis.

Key Points

• Root hairs are slender projections originating from epidermal cells that function in nutrient and water uptake as well as in anchoring the root in the soil.
• In wild-type Arabidopsis, root hairs are formed by epidermal cells termed trichoblasts which overlie the boundary between two cortical cells

Additional Information

Concept:

• Xylem and phloem together constitute vascular bundles.
• Vascular bundles can be of 3 types:
  • Conjoint vascular bundles - Here the xylem and phloem lie on the same radius.​​
  • Radial vascular bundles - Here the xylem and phloem are arranged in an alternate manner along the different radii. They are seen in roots.​
  • Concentric vascular bundle - Here the phloem completely surrounds the xylem (hadrocentric) or xylem completely surrounds the phloem (leptocentric). They are always closed types.​
• Conjoint vascular bundles can be of the following types:

1. Collateral vascular bundles -
   • Here the phloem strand is present outside the xylem strand.
   • The xylem and phloem lie together on the same radius such that the phloem is outwards and the xylem is inwards.
   • They are seen in stems and leaves.
   • Collateral vascular bundles can be: Open or Closed types.
2. Bicollateral vascular system -
   • Here the phloem lies on both sides of the xylem.
   • The phloem lies both outwards and inwards of xylem, such that the xylem is in the between.​

Key Points

• Plants with collateral open vascular bundles have cambium present between phloem and xylem.
• Dicotyledons stems have collateral open vascular bundles. They have the ability to form secondary xylem and phloem tissues because cambium is present between phloem and xylem. 
• Monocotyledons stems have collateral closed vascular bundles. They have no cambium present in them and do not form secondary tissues.
• The presence of cambium allows them to grow which is why they are called open.