Tag: botany

Questions Related to botany

Endodermis mainly

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Acts as a water tight jacket

  2. Provides protection

  3. Maintains rigidity

  4. Help in transpiration

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Correct Option: A
Explanation:

The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells that are impregnated with hydrophobic substances (Casparian Strip) to restrict apoplastic flow of water to the inside. The endodermis is the boundary between the cortex and the stele. In many seedless vascular plants, the endodermis is a distinctly visible layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, an endodermis is absent from the stems but is present in roots. 

The endodermis helps regulate the movement of water, ions and hormones into and out of the vascular system. It may also store starch, be involved in perception of gravity and protect the plant against toxins moving into the vascular system. Thus, option A is correct. 

Periblem gives rise to

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Epidermis

  2. Cortex

  3. Pericycle

  4. Pith

Show answer
Correct Option: B
Explanation:

Histogen theory by Hanstein states that shoot apical meristem consists of three distinct zones- 

i) Dermatogen (external layer), which form outer covering of all organ of plant. 
ii) Periblem (middle layer) gives rise to cortex and endodermis. 
iii) Plerome (central layer) form pith and primary vascular bundle. Thus, option B is correct.

Which of the following does not contain pith?

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Siphonostele

  2. Protostele

  3. Eustele

  4. None of the above

Show answer
Correct Option: B
Explanation:

Protostele is the most primitive type of stele with central xylem surrounded by phloem and pericycle. Pith is absent in them. Medullation (appearance of pith) of a protostele with central pith is called as siphonostele and thus has central pith surrounded by xylem, phloem and pericycle. Separation of vascular strands by parenchyma in siphonostele give rise to eustele. Thus, the correct answer is option B.

Casparian strip occurs in:

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Pericycle

  2. Endodermis

  3. Epidermis

  4. Cortex

Show answer
Correct Option: A
Explanation:
The innermost layer of cortex forms endodermis, which has compactly arranged barrel shaped cells. The primary thin walled endodermis shows suberin deposition in form of bands or strips that run around the radial and end walls of the cells and forms Casparian strips. 
Thus, the correct answer is option B.

Cortex is formed from

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Cambium

  2. Procambium

  3. Ground meristem

  4. Protoderm

Show answer
Correct Option: C
Explanation:
  • In plants, the cortex forms the outermost layer of the stem or root which are surrounded by the epidermis layer. 
  • Cortex is made up of differentiated cells which are large and thin-walled parenchyma cells.
  • The outer cortical cells of the cortex have irregularly thickened collenchyma cells.
  • The parenchyma and collenchyma cells are a part of the ground tissue system.
So, the correct answer is 'Ground meristem'

Ground tissue having differentiated concentric layers is found in

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Dicot leaf

  2. Monocot leaf

  3. Dicot stem

  4. Monocot stem

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Correct Option: C
Explanation:

A. Dicot leaf – Mesophyll is the ground tissue. It is differentiated into palisade and spongy parenchyma.

B. Monocot leaf – Mesophyll is the ground tissue. It is not differentiated. It shows only spongy parenchyma.

C. Cortex is the ground tissue in dicot stem. It is differentiated into hypodermis, general cortex and endodermis.

D. Monocot stem – the region present inner to the hypodermis is ground tissue. It shows scattered arrangement of vascular bundles.

So, the correct option is ‘Dicot stem’.

Periblem forms

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Endodermis

  2. Cortex

  3. Both A and B

  4. Epidermis

Show answer
Correct Option: C
Explanation:
  • The shoot apical meristem (SAM) of a plant form three distinct meristematic zones called the Histogens.
  • These histogens are present at the growing shoot tip or root tip.
  • These tips consist of three histogens based on the type of cells they form.
  • Each of these histogens gives rise to tissues which are different from one another- dermatogen, periblem, plerome (principle tissues)
1) The dermatogen or the outer layer gives rise to the epidermis.
2) The periblem or middle layer gives rise to the cortex and the endodermis (compact living cells with hydrophobic substances) which is the innermost layer of the cortex.
3)The plerome or the inner layer gives rise to vascular tissues.
So, the correct answer is 'Both A and B'.

In cucurbita, hypodermis is formed of

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Sclerenchyma

  2. Collenchyma

  3. Parenchyma

  4. Aerenchyma

Show answer
Correct Option: B
Explanation:

The cortical region present below epidermis is called ‘ Hypodermis’. It is made up of collenchyma in dicotyledons and sclerenchyma in monocotyledons.

So, the correct option is ‘Collenchyma’.

What is correct about monocot stem?

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is absent

  2. Hypodermis is sclerenchymatous, vascular bundles are open, phloem parenchyma is absent

  3. Hypodermis is collenchymatous, vascular bundles are closed, phloem parenchyma is present

  4. Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is present

Show answer
Correct Option: A
Explanation:

A. The hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is absent – True in. monocot stem.

B. The hypodermis is sclerenchymatous, vascular bundles are open, phloem parenchyma is absent – False because vascular bundles are closed in monocot stem.

C. Hypodermis is collenchymatous, vascular bundles are closed, phloem parenchyma is present – false, because hypodermis is sclerenchymatous and phloem parenchyma is absent in monocot stem

D. Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is present – false, because, phloem parenchyma is absent in monocot stem.

So, the correct option is ‘Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is absent’.

Cellular layer covering plant organs is

botany plant tissue system ground tissue system ground tissues tissue systems

  1. Epidermis

  2. Hypodermis

  3. Cuticle

  4. Endodermis

Show answer
Correct Option: A
Explanation:
A. The epidermis is the outermost protective layer of cells which cover all the plant organs which act as a barrier against mechanical injury and also prevents water loss and infection.
B. Hypodermis consists of a layer of cells immediately that is present below the epidermis which is strengthened to provide protection and also store water.
C. The cuticle is a protective layer which is impervious to water and covers the epidermal cells of leaves and plant organs to prevent water loss.
D. Endodermis is the innermost layer of cortex which is made of compact living cells and is surrounded by rings that are impregnated with hydrophobic substances to prevent the apoplastic flow of water.
So, the correct answer is 'Epidermis'.