Fill in the following blanks with suitable words : (a) Sexual maturity is reached at___ (b) The changes which occur in boys and girls at puberty are brought about by various___ (c) Initially, girls grow___than boys. (d) The changes occurring in body and mind during adolescence are a natural part of___up. (e) The features which help us to distinguish between a mature boy and a girl are called___sexual characteristics. (f) The onset of puberty is controlled by___ (g) Menstrual cycle in women is controlled by___ (h) Each normal body cell in humans contains___pairs of chromosomes out of which___pair is of sex chromosomes. (i) X and Y chromosomes are called___chromosomes. (j) Early marriage and motherhood cause health problems in the___and the___ (k) The protective foods are___and___ (l) Thyroid and adrenals secrete their hormones when they receive instructions from___gland through its hormones. (m) Metamorphosis in amphibians is brought about by__