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

In old dicot stems,a major part of the wood is filled up with tannins,resins,gums,etc. This part of the wood is called:

The youngest layer of secondary xylem in the wood of a dicot stem is located just:

The site of origin of lateral roots and the formation of cork cambium are features related to:

Which of the following pairs is correct in the study of secondary growth?

$I.$ Annual rings are formed as a result of seasonal environmental conditions.
$II.$ Tracheids/vessel elements are larger during periods when water is abundant.
$III.$ Tracheids/vessel elements have thicker walls during periods of water deprivation.
$IV.$ Wood formed in previous years is always darker than newer wood.
Select the combination of correct statements from the options given below.