Tag: internal structure of root, stem and leaf

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.

So, the correct option is ‘Dicot of temperate regions’.

Cortex is middle region of the root and dicot stem, present between epidermis and stele.

So, the correct option is 'epidermis and stele'.

A.Vascular bundles arranged in a ring – found in T.s. of dicot stem

B.Scattered vascular bundles – found in T.s.of monocot stem

C.Closed vascular bundles – found in T.s.of monocot stem

D.Radial vascular bundles – found in T.s.of dicot and monocot roots.

So, the correct option is ‘Vascular bundles arranged in a ring’.

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.Pericycle – outer most part of the stele in roots and dicot stem.

B.Endodermis – innermost part of cortex in roots and dicot stem.

C. Cutinised – The outer walls of stem epidermal cells are cutinized i.e.covered by the cuticle.

D.Suberised – The walls of cork cells are suberized i.e. made up of suberin.

So, the correct option is ‘Endodermis’.

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.

So, the correct option is ‘There is no regulation of their opening and closing’.

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

C.Secondary meristem – meristem formed by the dedifferentiation of permanent tissues. eg:Inter fascicular cambium, cork cambium- found in dicotyledons

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

So, the correct option is ‘Primary meristem’.     

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.

So, the correct option is ‘vascular cambium’.

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.

So, the correct option is ‘Endarch’.

Latex is a milky white secretory material. It is secreted by a special tissue  called are Laticiferous tissues. These are found in the plants growing in tropical deciduous forests. These are present in two types, namely latex cells and latex vessels. Latex is used in the manufacture of rubber. In the plants