In which plant does the petiole expand and become green to synthesize food?

Main photosynthetic organs of $Lathyrus \text{ } sativus$ plant are

Two chief functions of leaves are

In which of the following plants are sunken stomata found?

What are scale leaves?

Which of the following two are the resultant of stipule modifications?
$I$. Spines in $Ziziphus$.
$II$. Tendrils in $Smilax$.
$III$. Tendrils in $Nepenthes$.
$IV$. Spines in $Argemone$.
$V$. Thorns in $Bougainvillea$.