Anatomy of Flowering Plants Test - 52

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.

So, the correct option is ‘Epidermis and stele’.

• When the xylem and phloem are present on the same radii then it is called a collateral vascular bundle.
  
• It can be categorised into two types:-

1) Collateral- When the xylem and phloem strips occupy the same radii side by side where the xylem is present to the inner side whereas, the phloem is present to the outer side.

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.

• The secondary cortex which is also known as phelloderm is produced by phellogen or cork cambium. 
• The cork cambium or the phellogen is a lateral meristem which is responsible for the formation of periderm.
  
• The cells of the periderm which grows inward are known as phelloderm while the cells that grow outward is known as phellem or cork.
• The periderm layer has three distinct layers:-

1) phelloderm – is made up of living parenchyma cells which are present on the inner side of the cork cambium.
2) phellogen or cork cambium- gives rise to periderm
3) phellem or cork is made up of dead cells which have air-filled protective tissues.

A. Springwood is otherwise called latewood – False, sapwood is otherwise called early wood.

B. Autumn wood is otherwise called early wood – False, autumn wood is otherwise called late wood.

C. In old trees, the heartwood is involved in the conduction of water – False, heartwood is not involved in the conduction of water because xylem vessels are blocked by the formation of tyloses.

D. In old trees, the sapwood does not conduct water – False, because, in old trees, the sapwood conducts water.

E. Cambium cells present between primary xylem and primary phloem constitute intrafascicular cambium – True.

So, the correct option is ‘Cambium cells present between primary xylem and primary phloem constitute the intrafascicular cambium.

In dicot stems, secondary growth takes place by the formation of two types of cambia, namely, vascular cambium and cork cambium. Vascular cambium is formed by the joining of intra and interfascicular cambia. The cells divide periclinally and produce secondary vascular tissues and ray parenchyma. Cork cambium is formed by the dedifferentiation of cortical tissues present in the cortex. The cells undergo periclinal divisions, produces cork towards its outer side and secondary cortex towards its inner side.

So, the correct option is ‘Both A and B’.

• 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.
  
• These lateral meristems are located parallel to the longitudinal axis of the plants (stems or roots).
• 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.
• The cork cambium forms the thickened cork cells which protect the surface of the plant and also reduces water loss.
• 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.
• So, the correct answer is '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.
  
• 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

So, the correct answer is 'Increases girth'