CBSE Questions for Class 11 Medical Biology Anatomy Of Flowering Plants Quiz 9 - MCQExams.com

In the dicotyledonous trees growing in temperate regions, because of the existence of maximum seasonal variations, during secondary growth, vascular cambium is more active during the spring season and produces spring wood and whereas in the autumn season, it is less active and produces autumn wood or latewoods. These two kinds of wood together form into annual rings or growth rings.

In monocot stem, vascular bundles are covered outside by sclerenchymatous fibres. So they are called fibro vascular bundles.

A.Apical meristem – meristem present in the apices of plant parts, found in all higher plants.

B.Primary meristem – meristem formed from embryonic tissues or promeristem. eg:Fascicular cambium – found in dicotyledons

D.Intercalary meristem – meristem present in between permanent tissues, found in monocotyledons

A. Monocot root – many radial vascular bundles with exarch xylem are present.

B. Dicot root – two to four radial vascular bundles with exarch xylem are present.

C. Monocot stem – Many collateral, conjoint, closed vascular bundles with endarch xylem are present.

D. Dicot stem – Many collateral, conjoint, open vascular bundles with endarch xylem are present.

A.Stem – collateral, conjoint, vascular bundles are present.

B.Monocot stem – collateral, conjoint, closed vascular bundles are present.

C.Dicot stem – collateral, conjoint, open vascular bundles are present.

D.Root – Radial vascular bundles are present.

A.Polyarch – stele with many xylem strands, is found in monocot roots.

B.Monoarch – stele with one xylem strand, is found in Trapa.

C.Endarch – protoxylem is present towards the centre, and metaxylem is present towards the periphery, is found in dicot and monocot stems.

D.Exarch – protoxylem is towards the periphery, metaxylem is towards the centre, is found in dicot and monocot roots.

• In each vascular bundle, the xylem and phloem are separated by tissues called vascular cambium. 
• It is a ring of cambium formed by the joining of intrafascicular and interfascicular cambium.
• In the dicot stem, cambium located between the primary xylem and phloem is the called the intrafascicular cambium.
• The medullary rays' cells join the intrafascicular cambium and turn into meristematic tissues to form the interfascicular cambium as a continuous ring of cambium.
• The cambial ring activates and starts to cut off the new cells. both the inner and outer side.
• The new cells formed towards the pith develop into the secondary xylem and the new cells that are formed towards the periphery develop into the secondary phloem.

The region present below the epidermis in monocot stem is hypodermis. It is composed with sclerenchyma. Sclerenchyma is dead mechanical tissue. It provides mechanical strength to the stem.

So, the correct option is 'Sclerenchyma’.

The layer with thick walled present around the vascular bundles is called Bundle sheath. It is sclerenchymatous in monocot stem vascular bundles, parenchymatous in dicot leaf and monocot leaf. It is absent in vascular bundles of dicot stem

So, the correct answer is ‘Dicot stem’

A.Collateral vascular bundle – xylem and phloem present on the same radius.These are found in stems and leaves.

B.Radial vascular bundle – xylem and phloem are present on different radii. These are found in roots.

C.Bicollateral vascular bundle – two phloems are  present on either side of the xylem and all are present on the same radius. These are found in the stems of Cucurbitaceae and Solanacae members.

D.Concentric vascular bundles – vascular tissues surrounds with one another. These are found in ferns.

In the protoxylem of monocot vascular bundles, some of the protoxylem cells disintegrate and form into a lysigenous cavity called Protoxylem lacunae. It stores water, so it is also called water cavity.

Secondary growth does not take place in monocotyledons, because of the absence of cambium between xylem and phloem in vascular bundles. These vascular bundles are called closed vascular bundles.

In dicot stem, endodermal cells are rich in starch grains. So it is also called endodermoid layer or starch sheath or starch layer.

A. Phelloderm – also called secondary cortex.

B. Phellem – also called cork.

C. Periderm – cork, cork cambium and secondary cortex together called periderm.

D. Phellogen – also called cork cambium.

A. Sieve tube – component of phloem

B. Medullary ray – component of the stele in dicot stem.

C. Sclereid – a type of sclerenchyma cells.

D. Tracheid – a component of xylem

A.Sunflower – Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

B.Pisum - Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

C.Maize – Ground tissue is undifferentiated.

D.Cucurbita - Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

The ligno-suberised thickenings present on the radial and tangential walls of the endodermal cells are called Casparian strips or Casparian bands.

A.Radial vascular bundles – present in roots.

B.Concentric vascular bundles – present in ferns.

C.Collateral vascular bundles – present in the stems and leaves.

D.Bicollateral vascular bundles – present in the stems of Cucurbitaceae and Solanaceae.

A.Rhizodermis – the outermost layer of tubular living cells in dicot root.

B.Epidermis – the outermost layer of dicot root.

C. Hypodermis – it is absent in dicot root.

D.Exodermis – outermost layer with suberised cell wall.

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 either by active methods or passive methods.

• The secondary growth in plants occurs due to the cell division in the lateral meristems or secondary meristems that helps to increase the thickness or the girth of the plants.
  
• In vascular plants, the secondary growth occurs due to the activity of the two lateral meristems- the cork cambium and the vascular cambium.
• In woody plants, the secondary growth produces wood and gives shapes to the plant with a thickened trunk.

1. The cork cambium forms the thickened cork cells which protect the surface of the plant and also reduces water loss.
2. The vascular cambium is also known as fascicular cambium which develops within the vascular bundles that produce xylem to the inner side and phloem to the outer side

• Promeristem is a group of young meristematic cells in its early embryonic stage from which other meristems are derived. 
  
• Apical meristems are derived from promeristem and are present below the promeristem at shoot tip and root tip.
  
• The shoot apical meristem (SAM) consists of three distinct meristematic zones called the histogens.
  
• These histogens are present at the growing tips of a stem or a root.
• These tips consist of three histogens and each of these histogens gives rise to tissues which are different from one another- dermatogen, periblem, plerome (principle tissues)
• The dermatogen or the outer layer gives rise to the epidermis, periblem or middle layer gives rise to the cortex as well as the epidermis, plerome or the inner layer gives rise to vascular tissues.
• So, the correct answer is 'Promeristem derivative destined to produce specific areas'.

In internal structure of root and dicot stem, the region appears between epidermis and stele is cortex. In roots, cortex includes general cortex and endodermis, where as in dicot stems, cortex includes, hypodermis, general cortex and endodermis. In roots, cortex is concerned in the radial conduction of water, where as in dicot stems, it is concerned in the storage of food materials.

• In vascular plants, the secondary growth occurs due to the activity of the two lateral meristems- the cork cambium and the vascular cambium.
  
• The secondary growth in plants occurs due to the cell division in the lateral meristems or secondary meristems that helps to increase the thickness or the girth of the plants
• So, the correct answer is 'Girth'
  

a) Conjuctive present – applicable, because it is present between xylem and phloem.

b) Presence of protein compound in Casparian strips – not applicable, because, a lingo-suberised substance is present on the radial and tangential walls of the endodermis.

c) Polyarch xylem bundles – not applicable, because , in the stele of dicot root two to four xylem strands are present. So the stele is diarch to tetrarch.

d) Presence of pericycle – applicable – because, pericycle is outer most layer of the stele, and it is parenchymatous, take part in the production of lateral roots and vascular cambium.

• The secondary meristems are responsible for secondary growth in plants.
  
• They are also known as the lateral meristems as they surround the stem of a plant and help them to grow laterally i.e, increase in the radii.
• Vascular cambium produces secondary xylem and secondary phloem.
• Cork cambium or phellogen forms a layer of cells which produces a secondary protective layer of the stem called the periderm.
• Phellem or the cork is a tissue formed to the outer side of cork cambium which is composed of dead cells and is protective in function.
• Cork cambium is a secondary meristem
• So, the correct answer is 'Cork cambium'

• The procambium is derived from the apical meristematic tissue which forms the primary tissues of the vascular system.
  
• It is present between the primary xylem and primary phloem i.e, the intrafascicular cambium.
• When the cambial layer formed within the vascular bundles in the stems of a plant which forms a ring of tissues it is called the interfascicular cambium.
• The cambial layer present between the primary xylem and primary phloem is called the intrafascicular cambium. So, the correct answer is 'Interfascicular cambium'.
  

• The Tunica-corpus theory explains the planes of cell division in the shoot apex.
  
• It was proposed by Schmidt in 1924.
• It was proposed on the basis of the study of shoot apex.
• This theory is applicable only to shoot apex and not to root. 
  
• This theory divides the region (shoot apex) 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).
• The plasmodesmata connections exist between the cells of tunica and corpus.
• So, the correct answer is 'Shoot apex'

• The meristems in plants can be divided into 3 types- the apical meristem, the intercalary meristem and the lateral meristem. 
  
• Leaves are formed by the shoot apical meristem (SAM).
• The SAM swells to form the leaf primordium (undifferentiated tissue) which divides to form the leaf blades and the leaf sheaths.
• The leaf blades undergo cell division and get elongated.
• The flattened blade is formed by the marginal meristem present at the margins of the leaf axis.
• Meristem present on the sides increases the girth of the plant and is called lateral meristem (no role in leaf formation).
• So, the correct answer is 'Apical meristem'.

• Vascular tissues are concerned with the transportation of water, mineral and food.
• Phloem is a vascular tissue or conducting tissue, meant for the translocation of organic solutes or food.
• Collenchyma is a simple permanent living mechanical tissue that provides elasticity to the young stems.
• Mechanical tissues are the rigid cellular tissues, provides elasticity, flexibility to the different parts of the plant body. Stereome is a mechnical tissue.
•  So, the correct option is D.