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

Bark refers to 

(1) Phellem + Phellogen + Phelloderm

(2) Periderm + Cortex

(3) Phellem + Phelloderm + Secondary phloem

(4) Periderm + Cortex + Pericycle + Secondary phloem

The branched sclereids present in hydrophytes are:-
(1) osteosclereids

(2) trichosclereids

(3) macrosclereids

(4) astrosclereids

Why are vascular bundles closed in monocots?

(1) Xylem and Phloem are present

(2) Xylem and phloem occur in separate bundles

(3) Vascular cambium is present between xylem and phloem

(4) Vascular cambium is not present

Given figure shows:-

(a) structure of lenticel
(b) hydathode showing gaseous vapour exchange
(c) fungus reproducing by spore formation
(d) algae reproducing by spore formation