Each annual growth ring has

The tissue which participates in the secondary growth is

Bark $= .....................$

Read the different components from $(i)$ to $(iv)$ in the list given below and tell the correct order of the components with reference to their arrangement from outer side to inner side in a woody dicot stem.
$(i)$ Secondary cortex $(ii)$ Wood $(iii)$ Secondary phloem $(iv)$ Phellem
The correct order is:

The balloon-shaped structures called $tyloses$:

Which of the following is the function of heartwood?