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

(1) phellem – pericycle – endodermis – phloem

(2) phellem – phloem – endodermis – pericycle

(3) phellem – endodermis – pericycle – phloem

(4) pericycle – phellem – endodermis – phloem

The quiescent centre in root meristem serves as:-

1. site for storage of food which is utilized during maturation

2. reservoir of growth hormones

3. reserve for replenishment of damaged cells of the meristem

4. region for absorption of water

The sugarcane plant has:-

1. dumb-bell shaped guard cells

2. pentamerous flowers

3. reticulate venation

4. capsular fruits

In a plant organ which is covered by periderm and in which the stomata are absent, some gaseous exchange still takes place through.

(1) aerenchyma

(2) trichomes

(3) pneumatophores

(4) lenticels

Companion cells in plants are associated with

(1) vessels

(2) sperms

(3) sieve elements

(4) guard cells.

Cork cambium results in the formation of cork which becomes impermeable to water due to the accumulation of

(1) resins

(2) suberin

(3) lignins

(4) tannins

Which one of the following statements pertaining to plant structure is correct?

(1) Cork lacks stomata, but lenticels carry out transpiration.

(2) Passage cells help in transfer of food from cortex to phloem.

(3) Sieve tube elements possess cytoplasm but no nuclei.

(4) The shoot apical meristem has a quiescent centre.

Grafting is successful in dicots but not in monocots because the dicots have

(1) Vascular bundles arranged in a ring

(2) Cambium for secondary growth

(3) Vessels with elements arranged end to end

(4) Cork cambium

In the sieve elements, which one of the following is the most likely function of P-proteins?

(1) Deposition of callose on sieve plates

(2) Providing energy for active translocation

(3) Autolytic enzymes

(4) Sealing mechanism on wounding

In succulent plants the stomata open in night and close in day. Which among the following would be best hypothesis to explain the mechanism of stomatal action in night only?

(1) CO₂ accumulates, reduces pH, stimulate enzymes resulting in accumulation of sugars.

(2) Increase in CO₂ concentration, conversion of organic acids into starch resulting in the increased conversion into sugars resulting in K⁺ transport.

(3) Low CO₂ concentration accumulates organic acids resulting in the increased concentration of cell sap.

(4) CO₂ used up, increase pH results in accumulation of sugars.