Reaching the Age of Adolescence

Read the statements given below and fill up the blanks with the correct words listed in the box.

deep, ductless, nutrients, thyroxine

(a) The meal that includes all __________ is a balanced diet.
(b) Insufficient production of __________ in the tadpoles leads to their incomplete development.
(c) Endocrine glands are also called __________ glands.
(d) After attaining puberty boys develop a__________ voice.