Which parameter is used to measure the growth in flat organs like leaves?

The efficiency index of growth in plants represents . . . . . . .

$A$ rubber band stretches and reverts back to its original position. Bubble gum stretches,but it would not return to its original position. Is there any difference between the two processes? Discuss it with respect to plant growth. [Hint: Elasticity (reversible),Plasticity (irreversible)]

Find out the correct statement$(s)$.
$(a)$ Growth in plants is internal/intrinsic and open-ended.
$(b)$ Formation of cellular materials is called real or protoplasmic growth.
$(c)$ Plant growth is diffused only during the early embryonic stage.

Define the term: Etiolated position.

Which of the following is the result of metabolism?