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 Multiple Choice QuestionsMultiple Choice Questions

1.

The quiescent centre in root meristem serves as a

  • site for storage of food which is utilized during maturation

  • reservoir of growth hormones

  • reserve for replenishment of damaged cells of the meristem

  • region for absorption of water


C.

reserve for replenishment of damaged cells of the meristem

Quiescent centre is a region in the apical meristem of a root where cell division proceeds very slowly. It is a hemispherical region of inactive cells present in between the root cap and the active meristematic region of root apex. This zone contains several hundred cells which are characterized by having lower concentration of DNA, RNA and protein. The quiescent centre acts as reservoir of cells and becomes active whenever the previously active initials get damaged or during the establishment of the secondary roots.


2.

In a dicotyledonous stem, the sequence of tissues from the outside to the inside is

  • phellem - pericycle - endodermis - phloem

  • phellem - phloem - endodermis - pericycle

  • phellem - endodermis - pericycle - phloem

  • pericycle - phellem - endodermis - phloem


C.

phellem - endodermis - pericycle - phloem

Phellem or cork is a tissue formed on the outer side of phellogen or cork cambium. It is protective in function.

Endodermis is the boundary between the cortex and the stele. It is a distinctly visible layer of cells immediately outside the vascular cylinder in roots and shoots.

Pericycle regulates the formation of lateral roots by rapidly dividing near the xylem elements of the root.

Phloem is the vascular tissue in plants which conducts sugars and other metabolic products downwards from the leaves.


3.

Plasmodesmata connections help in

  • cytoplasmic streaming

  • synchronous mitotic divisions

  • locomotion of unicellular organism

  • movement of substances between cells


D.

movement of substances between cells

A characteristic of most plant cells is the presence of cytoplasmic material that establish continuity between adjacent cells. These bridges are called plasmodesmata. These permit the free circulation of fluid, which is essential to the maintenance of plant cell toxicity.


4.

Passage cells are found in

  • dicot stem

  • monocot root

  • monocot stem

  • all of these


B.

monocot root

Passage cells are the unthickened cells in the endodermis of a root, found opposite to the protoxylem element through which solutions can diffusein the transverse direction. These are found in monocot root.


5.

Assertion : Monocot stem bears collateral open vascular bundles.

Reason : If cambium is absent such vascular bundles are called closed type.

  • If both Assertion and Reason are true and Reason is the correct explantion of Assertion

  • If both Assertion and Reason are true and Reason is not the correct explanation of Assertion

  • If Assertion is true but Reason is false

  • If Assertion is false but Reason is true.


D.

If Assertion is false but Reason is true.

Monocot stem bears collateral closed vascular bundle. In monocot stem cambium is absent and such vasular bundle is called closed type.


6.

Velamen is a specialized tissue found in

  • aerial roots of orchids

  • succulent leaves

  • pneumatophores

  • stilt roots


A.

aerial roots of orchids

Velamen is a dead spongy tissue present in epiphytic roots or hygroscopic roots. These roots are able to absorb water from moist atmosphere, dew and rain.


7.

Porous wood has abundance of 

  • vessels

  • fibres only

  • tracheids

  • sieve tubes


A.

vessels

Porous wood possesses abundant vessels. Due to the presence of vessels, hardwoods are called porous woods.


8.

Periderm includes

  • cork cambium only

  • cork cambium and cork

  • cork and secondary cortex

  • cork cambium, cork and secondary cortex


D.

cork cambium, cork and secondary cortex

Periderm formation occurs in the root and stems of dicots and gymnosperm in extra stelar region with the help of cork cambium. Periderm is external secondary protective tissue and compreses of cork, cork cambium and secondary cortex.


9.

Assertion : Water and mineral uptake by root hairs from the soil occurs through apoplast until it reaches endodermis.

Reason : Casparian strips in endodermis are suberized

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


B.

If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

The apoplast is the system of adjacent cell walls which is continuous through the plant. As water evaporates from the mesophyll cell walls into the intercellular air spaces, tension develops in the continuous stream of water in the apoplast, and water is drawn through the walls in a mass flow by the cohesion of water molecules. When water moving through spaces in the cell wall reaches the endodermis, it's progress is stopped by a waterproof substance called suberin which is deposited in cell walls in the form of bands called casparian strips. Therefore water and solutes must pass through the cell surface membrane and into the cytoplasm of the cells of the endodermis.


10.

Largest number of chloroplast is found in :

  • palisade tissue

  • spongy tissue

  • transfusion tissue

  • bundle sheath cells


A.

palisade tissue

Dorsiventral leaf of dicot plant consits of epidermis, mesophyll and vascular bundles. Mesophyll is further divided into palisade tissue and spongy tissue.

Palisade tissue is a upper layer that consists of closely arranged cells containing numerous chloroplasts. Spongy tissue consists of losely arranged cells. Most of the photosynthesis takes place in palisade tissue.