Tag: internal structure of stem(dicot and monocot)

Questions Related to internal structure of stem(dicot and monocot)

Lysigenous cavity in monocot stem vascular bundles develops by the dissolution of
botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. protoxylem

  2. metaxylem

  3. phloem

  4. ground tissue

Show answer
Correct Option: A
Explanation:

In monocot stem (Maize), the xylem appears Y shaped. The lowermost or innermost protoxylem undergoes disintegration to produce lysigenous cavities also called the protoxylem lacuna.

So, the correct answer is 'protoxylem'

Select the incorrect statement regarding the anatomy of a typical monocotyledonous stem
botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Phloem parenchyma is absent.

  2. Vascular bundles are scattered, conjoint, collateral and closed

  3. Each vascular bundle is surrounded by a bundle sheath.

  4. Ground tissue is differentiated into cortex, endodermis, pericycle and pith

Show answer
Correct Option: D
Explanation:

In a monocot stem (Example Maize), the stem is differentiated into Epidermis, hypodermis and ground tissue. In the ground tissue are embedded vascular bundles that are conjoint, colateral and closed.The vascular bundles are not enclosed by endodermis and pericycle.

So, the correct answer is 'Ground tissue is differentiated into cortex, endodermis, pericycle and pith'

Schlerenchymatous hypodermis is found in?

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Dicot root

  2. Monocot leaf

  3. Dicot stem

  4. Monocot stem

Show answer
Correct Option: D
Explanation:
The sclerenchymatous hypodermis is present in a monocotyledonous stem. It is 2-3 layered thick and lies below type epidermis. It is made up of thick-walled lignified sclerenchyma fibers.

So, the correct answer is 'Monocot stem'.
Secondary growth usually does not occur in
botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Stems and roots of dicots

  2. Stems and roots of gymnosperms

  3. Stems and roots of monocots

  4. Both (b) and (c)

Show answer
Correct Option: C
Explanation:

Stems of monocots do not have lateral or secondary cambium. Roots of both monocots and dicots do not have secondary or lateral cambium. Hence, true secondary growth does not occur in stems and roots of monocots. But, in some exceptional cases if secondary growth takes place due to dedifferentiation of tissue cells of the cortex, pericycle etc into meristematic tissue this type of secondary growth is called anomalous secondary growth.

So, the correct answer is 'Stems and roots of monocots'

The lacunae in the vascular bundles of monocot stem is

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. A mucilage canal

  2. Protoxylem lacuna

  3. Lysigenous cavity

  4. Both B and C

Show answer
Correct Option: D
Explanation:

The first xylem formed is called as protoxylem. Protoxylem is later torn apart and a cavity is formed. The entire protoxylem is dissolved hence, such cavity is called as lysigenous cavity. The protoxylem shows an empty space, called as 'lacuna'. 

This type of intercellular space arises through dissolution of entire cells, which are therefore called as lysigenous intercellular spaces. These cavities of intercellular spaces store up water, gases and essential oils in them. The examples are commonly found in water plants and many monocotyledonous plants.

Transverse section of a material exhibits conjoint collateral endarch and closed bundles scattered in a ground tissue, what should be the material?

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Monocot root

  2. Dicot root

  3. Monocot stem

  4. Dicot stem

Show answer
Correct Option: C
Explanation:

Monocot stem vascular bundles are found irregularly scattered in the ground tissue. 

Towards the periphery, the bundles are smaller in size while towards the centre, they are larger in size. The smaller bundles are younger, while the larger ones are older. Hence, the arrangement is described as endarch. 
Each vascular bundle has a covering called bundle sheath formed by a single layer of sclerenchyma cells. The vascular bundle encloses both xylem and phloem. Xylem is found towards the inner surface and phloem towards the outer surface. Cambium is absent. Hence the vascular bundles are described as conjoint, collateral and closed. 
Dicot stem vascular bundles are eight in number, arranged in form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as endarch. 
Dicot root vascular bundles are described as radial, open and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 
Monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch. 

T.S. of a material exhibits conjoint collateral endarch and closed bundles scattered in a ground tissue. What should be the material?

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Monocot root

  2. Dicot root

  3. Monocot stem

  4. Dicot stem

Show answer
Correct Option: C
Explanation:

Monocot stem vascular bundles are found irregularly scattered in the ground tissue. Towards the periphery, the bundles are smaller in size while towards the centre, they are larger in size. The smaller bundles are younger, while the larger ones are older. Hence, the arrangement is described as endarch. 

Each vascular bundle has a covering called bundle sheath formed by a single layer of sclerenchyma cells. The vascular bundle encloses both xylem and phloem. Xylem is found towards the inner surface and phloem towards the outer surface. Cambium is absent. Hence the vascular bundles are described as conjoint, collateral and closed. 
Dicot stem vascular bundles are eight in number, arranged in form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as endarch. 
Dicot root vascular bundles are described as radial, open and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 
Monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch. 

Atactostele is found in

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Dicot stem

  2. Monocot stem

  3. Dicot root

  4. Monocot root

Show answer
Correct Option: B
Explanation:

Monocot stems, in which the stele consists of many vascular bundles in a complex arrangement, are said to have an atactostele. 

Atacostele is atype of eustele, found in monocots, in which the vascular tissue in the stem exists as scattered bundles. Thus, option B is correct. 

Stem of date palm increases in girth due to activity of:

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Intercalary meristem

  2. Apical meristem

  3. Lateral meristem

  4. None of the above

Show answer
Correct Option: B
Explanation:

Date palm is a monocot and lack lateral meristem; the meristem present along the sides causing the increase in girth of the plant. 

Apical meristem is present at the tips of root and shoot and give rise to primary permanent tissue systems. The apical meristem causes increase in height of the date palm from growing tips. The apical meristem is modified to form temporary meristem which serves the function of lateral meristem, divide and produce new cells. Enlargement of these peripheral cells cause increase in girth of the date palm. 
The apical meristem, which is separated from apices due to formation of permanent tissues in between, is termed as intercalary meristem; it is internodal in position and carries out localized growth. 
Thus, the correct answer is option (B).

Lysigenous cavity and 'Y'-shaped xylem occurs in

botany internal structure of root, stem and leaf internal structure of monocot stem internal structure of monocots internal structure of stem(dicot and monocot)

  1. Dicot stem

  2. Monocot root

  3. Monocot stem

  4. Dicot root

Show answer
Correct Option: C
Explanation:

Lysigenous intercellular spaces is type of intercellular space arises through dissolution of entire cells, which are therefore called as lysigenous cavity. These cavities of intercellular spaces store up water, gases and essential oils in them. The examples are commonly found in water plants and many monocotyledonous stems. The secretory cavities in Eucalyptus, Citrus and Gossypium are good examples. In monocot stem the vascular bundle encloses both xylem and phloem. Xylem is found towards the inner surface and phloem towards the outer surface. Cambium is absent. Hence, the vascular bundles are described as conjoint, collateral and closed. In the xylem, there are two metaxylem and two protoxylem vessels arranged in the shape of Y.