CBSE Questions for Class 11 Medical Biology Anatomy Of Flowering Plants Quiz 16 - MCQExams.com

• Monocot root vascular bundles are radial in the arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch. 
• Monocot stem vascular bundles are numerous in number and the xylem is endarch. 
• 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 and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 

Endarch is the arrangement in which the protoxylem is directed towards the centre and metaxylem elements towards the periphery. The development of the xylems in this arrangement follows the centrifugal pattern. It is the characteristics of the stem of flowering plants.

Whereas exarch is the arrangement in which the protoxylem is directed towards the periphery and metaxylem towards the centre. The development of the xylem in this arrangement follows the centripetal pattern. It is the characteristics of roots.

• At the time of flowering, the vegetative shoot apex transforms into reproductive shoot apex (reproductive phase).
  
• This transformation of shoot apex is induced by florigen and light.
• The summit zone of reproductive shoot apex is active as the rate of cell division is greater and it forms stamens and carpels.
• Whereas, the flank zone is less active in reproductive shoot apex and it forms sepals and petals. So, the correct answer is 'Vegetative apex changes into reproductive apex'.

• Brachysclereid is a more or less an isodiametric sclereid typically occurring in the pith, cortex and bark of stems and in certain fruits like pears and apple. 
• Macrosclereids are column shaped and are commonly found in the epidermis and underlying layers of the seed coat.
• Osteosclereids are columnar and are similar to macrosclerids except that they are enlarged at the ends making them bone-shaped. 
• Astrosclereids are branched, pointed, irregular (often star-shaped sclereids) as in xerophytes. 

• According to tunica-corpus theory shoot apex is divided into two tissue zones known as tunica and corpus.
  
• The shoot apex is composed of two layers of cells of tunica and corpus  (layer L1, L2 and L3 to denote the outer layer of tunica, the inner layer of tunica and corpus respectively).
• According to Korper-Kappe theory, the cells in the root apex divide in a T-shaped pattern.
• The outer part of the root apex is called the Kappe and the cells here divide horizontally first and the lower cell divides longitudinally ( right angles to the plane of the first division).
• The inner part of the apex is the Korper. and the cells in this region forms an inverted T pattern as here the second division takes place in the upper cell. 
• So, the correct answer is 'Korper is equivalent to corpus and kappe to tunica'.

The small strip of cambium formed between the vascular bundles in dicot stem is called inter fascicular cambium. It is formed by the dedifferentiation of parenchyma present in the medullary rays.

So, the correct option is ‘Medullary rays’.

In dicotyledonous trees, growing in temperate regions, due to maximum seasonal variations two types of secondary xylems are formed, spring or early wood and autumn wood or latewood. These two kinds of wood together form into a ring of wood called annual rings. These annual rings are useful in indicating the age of the trees.

During secondary growth, intra and interfascicular cambia join together and form into a ring of cambium called vascular cambium. The cells in the vascular cambium undergo periclinal divisions and undergo elongation radially, produces secondary vascular tissues and ray parenchyma. It leads to an increase in girth of the stem.

The inner most part of the cortex in root and dicot stem is endodermis. it is single layered. Cells are barrel shaped and thick walled. On the radial walls and tangential walls, ligno suberised thickenings are present. These are called Casparian thickenings. Some of the endodermal cells lack casparian bands. These are called passage cells. These cells are present opposite to the protoxylem cells. Endodermis acts as check point, and prevents the outflow of water and minerals from the stele into cortex, and also acts as a barrier in the inflow of water and mineral from cortex and stele.

So, the correct option is ‘dicot stems and all types of roots’.

A.Monocot leaf – vascular bundles are covered by parenchymatous bundle sheath.

B. Monocot stem – vascular bundles are covered by sclerenchymatous fibres. So these are called fibrovascular bundles.

C. Monocot root – there is no any covering around the vascular bundles.

D. Dicot stem – there is no any covering around the vascular bundles.

So, the correct option is ‘Monocot stem’.

Pericycle is the outer most part of the stele. In dicot root, pericycle is continuous, parenchymatous and single layered.

• Casuarina is a genus of oak tree species belonging to the family Casuarinaceae.

• All the cells in the structure of roots can be traced back to few apical cells which are called initials.

• In Casuarina, only two rows of initials are observed at the root apex. 

• One of the layers gives rise to the stele and the other to the cortex and root cap.

• So, the correct answer is 'Two'.

A. Conduction of water – xylem conducts water.

B.Storage of water – water storage parenchyma

C.Storage of food – cortex stores reserve food materials.

D. Strength – hypodermis and pericycle in dicot stem provides strength.

So, the correct option is ‘Storage of food’.

A. Root – protoxylem is towards the pericycle and metaxylem is towards the medulla. It is called Exarch.

B. Stem – protoxylem is towards the medulla and metaxylem is towards the pericycle. It is called Endarch.

C. Leaves – the position of protoxylem and metaxylem is not specified.

D. Petiole – the position of protoxylem and metaxylem is not specified.

A.xylem is surrounded by phloem – hadrocentric or amphicribal vascular bundles

B.phloem is surrounded by xylem – Leptocentric or Amphivasal vascular bundles.

C.xylem and phloem occur on the same radius – collateral vascular bundle.

D.xylem and phloem are found on different radii – Radial vascular bundle.

A.Fascicular/intra fascicular cambium – a strip of cambium present between the xylem and phloem.

B.Interfascicular cambium – a strip of cambium present between vascular bundles in dicot stem is called interfascicular cambium.

C.Phellogen – a ring of cambium formed in the cortex of dicot stem due to dedifferentiation of parenchyma is called phellogen or cork cambium.

D.Procambium – primary meristems that forms primary vascular tissues is called procambium.

A.Endodermis - Inner most layer of cortex

B.Epidermis – outer layer of organs.

C.Exodermis – outer most layer of mature monocot root.

D.Hypodermis – it is present inner to the epidermis in stems.

In the stems of dicotyledonous trees growing temperate regions, during secondary growth, vascular cambial ring produces secondary phloem towards the outer side and secondary xylem towards inner side.  When secondary growth is going on, old secondary xylems pushed towards the centre, and young secondary xylems are present nearer to the vascular cambial ring or just inner to the vascular cambial ring.

A.Secondary xylem and secondary phloem – produced by vascular cambium.

B.Cork and secondary cortex – produced by cork cambium.

C. Secondary cortex and phloem – secondary cortex is produced by cork cambium and phloem is produced from procambium.

D. Cork – it is produced by cork cambium

Monocot root vascular bundles are radial in the arrangement. There are eight types of bundles each of xylem and phloem. Thus the condition is described as the polyarch. Xylem is detailed as an exarch.

Monocot stem vascular bundles are many in number and the xylem is the endarch.

Dicot stem vascular bundles are also eight in number but arranged in the 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 an endarch.

Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as an exarch.

So, the correct answer is 'Monocot root'

So, the correct answer is B.

A. Epiblema – root epidermis with root hairs is called epiblema

B. Pericycle – outer most part of the stele in roots and dicot stem, produces lateral branches

C. Cortex – middle of root and dicot stem internally

D. Endodermis – inner most part of the cortex

Development of xylem from the periphery to the centre is called centripetal xylem. It is found in roots.

A.Bicollateral closed vascular bundles – Not present in any plants

B.Bicollateral open vascular bundles – found in the stems of Cucurbitaceae members

C.Collateral open vascular bundles – found in the dicotyledonous stems.

D.Collateral closed vascular bundles – found in the monocotyledonous stems.

The large sized, slightly raised spots present on the surface of cork, in old dicot stems are called Lenticels. These are involved in the exchange of gases.

The small pores, present on the epidermis of grass leaves are called Hydathodes. In this guard cells are immovable. They perform guttation.

A.Pteridophytes – vascular bundles are absent.

B.Gymnosperms – vascular bundles are present in the form of rings.

C.Monocots – Scattered vascular bundles are present.

D.Dicot – vascular bundles are present in the form of rings.

E.Bryophytes – vascular bundles are absent.

• Dicot stem – collateral, conjoint, endarch, open vascular bundles present in the form of rings.
• Monocot stem – collateral, conjoint, endarch, closed vascular bundles present in the form of the scattered manner in a ground tissue.
• Dicot root – radial vascular bundles are present.
• Monocot root – radial vascular bundles are present.

In dicot root, radial vascular bundles, with little pith appears, secondary growth also takes place.

In dicotyledonous stems of temperate trees, during secondary growth, vascular cambial ring(narrow layer of thin-walled cells) produces secondary phloem towards outer side and secondary xylem or wood towards inner side.