Question

Annual rings are well demarcated in trees growing in
A) Shimla
B) Bombay / Delhi
C) Madras
D) Udaipur

Answer 1

Hint: Every year, there is formation of new cells on tree stems that is one ring per year. This causes annual rings to form. The ring formation is dependent on climate too.

Complete step by step answer:
-The areas which have constant temperature, the growth is uniform and there is no discrete appearance of rings. The regions like at equatorial regions, the climatic variation is almost constant throughout the year. The secondary growth of xylem and phloem tissues is continuous and constant.
-In climate variations, the sudden drop in temperature and sudden increase in temperature, the growth of secondary growth of xylem and phloem tissues is disturbed and gets paused and resumes forming a darker ring each year.
-In regions like Bombay, Delhi, Madras and Udaipur, they have tropical plants which do not have sharp change in climatic variations. Shimla is a temperate region which has deciduous vegetation and shows well demarcated annual rings.
-Sharp climatic conditions are seen in places like Shimla. This affects the annual ring -formation and is clear and easily seen.

The correct option is A.

Note:
The darker ring is due to inactivation of procambium. It is seen that procambium are inactive in winter and thus halting of differentiation of procambium causes dark ring appearance. In drought conditions, same, there is no differentiation of procambium and these result in two or more rings per year and this ring is called pseudo annual rings.