Tag: botany

Questions Related to botany

Which type of vascular bundles are found in monocot 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. Collateral, open, endarch

  2. Radial, open, diarch

  3. Radial, open, mesarch

  4. Collateral, closed, endarch

Show answer
Correct Option: D
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 centrifugal or endarch. 

Each vascular bundle has a covering, called as 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. 

In monocot stems, secondary growth cannot occur, because vascular bundles are

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. Scattered

  2. Open

  3. Closed

  4. Radial

Show answer
Correct Option: C
Explanation:

Secondary growth refers to the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate and gives rise to primary tissue. 

In monocot stem vascular bundles are closed, because cambia is absent. So, secondary growth can not occur
So, the correct answer is ' Closed'

What is the characteristics of a vascular bundle of monocot 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. Open and surrounded by a sclerenchymatous bundle sheath

  2. Closed and not surrounded by bundle sheath

  3. Closed and surrounded by bundle sheath

  4. Open and not surrounded by a bundle sheath

Show answer
Correct Option: C
Explanation:

In a monocot stem the vascular bundles are not arranged in a circle but are usually scattered throughout the ground tissue. There is no clearly defined pith as there is in many dicotyledonous species. 

The vascular bundles of monocotylenous plants do not contain a layer of meristematic tissue (cambium) as the dicots do. Thus, no new cells can be formed inside the vascular bundles of monocots and their vascular bundles are termed as closed, whereas those of dicot plants are open. Bundle sheath is developed either partly or completely surrounding the vascular bundle. Thus, option C is correct.

The character of monocot 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. Net-veined leaves

  2. Annual rings

  3. Seed with two masses of stored food

  4. Conducting strands scattered in ground tissue

Show answer
Correct Option: D
Explanation:

In a monocotyledenous stem the vascular bundles are not arranged in a circle but are usually scattered throughout the ground tissue. There is no clearly defined pith as there is in many dicotyledonous species. 

As in the dicots the xylem of the bundles is pre-orientated toward the middles of the stem. The vascular bundles of monocotylenous plants do not contain a layer of meristematic tissue (cambium) as the dicots do. Thus no new cells can be formed inside the vascular bundles of monocots and their vascular bundles are termed closed whereas those of dicot plants are open. So, no annual rings in monocots as, there is no secondary growth. 
Net veined leaves and seed with two masses of stored food are characteristics of dicots. Thus, option D is correct.

An example of monocots showing secondary growth in 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. Lilium

  2. Cocos

  3. Asparagus

  4. Yucca

Show answer
Correct Option: D
Explanation:

Secondary growth is increase in the circumference / girth of the plant organs due to the formation of secondary tissues in stelar and extra stelar regions. Normally secondary growth takes place in roots and stem of dicotyledons and gymnosperms. Due to lack of cambium in monocotyledons, secondary growth is absent. But exceptionally, secondary growth takes place in some monocotyledons, such as palm, Yucca, Dracaena etc. 

Conjoint, collateral and closed vascular bundles are 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. Monocot stem

  2. Monocot root

  3. Dicot stem

  4. Dicot root

Show answer
Correct Option: A
Explanation:

In 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 centrifugal. 

Each vascular bundle has a covering called as '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. 

Cambium found in vascular bundles of dicot 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. Intercalary meristem

  2. Fascicular cambium

  3. secondary meristem

  4. All of the above

Show answer
Correct Option: B
Explanation:
Fascicular cambium is present in vascular bundles of dicot stem.  It is present between xylem and phloem of vascular bundle. 
So, the correct answer is 'Fasicular cambium'

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:

Atactostele is a type of eustele, found in monocots, in which the vascular tissue in the stem exists as scattered bundles. Most seed plant stems possess a vascular arrangement, which has been interpreted as a derived siphonostele and is called as eustele. There is also a variant on the eustele found in monocots, like maize and rye. The variation has numerous scattered bundles in the stem and is called as an atactostele.

The stele present in Equisetum 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. Haplostele

  2. Actinostlele

  3. Plectostele

  4. Siphonostele

Show answer
Correct Option: D
Explanation:

  1. Haplostele consist of smooth ore of xylem which is surrounded by a phloem ring.ex-Seleginella
  2. Actinostele consist of star shape xylem core with many radiating arms.ex-Lycopodium
  3. Plectostele consist of xylem core broken into a number of parallel plates.ex-Lycopodium clavatum
  4. Siphonostele is a protostele with central pith and considered to be the most advance stele.ex-Equisetum.
So the correct option is "Siphonostele".

Which of the following tissue is absent in vascular bundles of monocot 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. Xylem

  2. Phloem

  3. Cambium

  4. All of the above

Show answer
Correct Option: C
Explanation:

In monocots, xylem and phloem are organized in vascular bundles scattered throughout the stem. As the plant grows, monocot stems generate new vascular bundles for the new tissue. Monocot stems in general possess a simpler arrangement than that found in dicots; the main elements of the stem are merely the vascular bundles and the pith that surrounds them.