What is the effect of rubbing on a leaf?

In plants,growth occurs by $...$ through their life span. Choose an appropriate option to complete the given $NCERT$ statement.

$A$ clinostat is used to study which of the following?

$A$ leaf of $20 \; cm^{2}$ grows $5 \; cm^{2}$ per hour and a leaf of $25 \; cm^{2}$ grows $5 \; cm^{2}$ per hour. The relative growth rate of leaf $A$ and $B$ respectively is:

Assertion $(A)$: Morphogenesis and differentiation occur during the process of growth.
Reason $(R)$: The number of cells increases during growth.

Plant organs can detect a change in their orientation with respect to gravity within: