Question

Raj and Sarita are twins and have just turned thirteen. Both of them experience certain changes in their bodies.

Keeping the above context in view, answer the following questions.

1. State any two features of external physical changes that Raj and Sarita experience. List any one common physical change in them.     [3]
2. Explain the role of the endocrine system which causes such changes to take place.     [4]

Answer 1

1. 
   
   1. External physical changes in Raj:
      • Voice changes
      • Facial hair like a beard grows.
      • Narrowing of hips and broadening of shoulders.
      • Body becomes more muscular.
   2. External physical changes in Sarita:
      • Development of breasts
      • Broadening of hips
      • Curvaceous body
      • Change in pitch of voice.
   3. Common external physical changes in both Raj and Sarita:
      • Pimples/acne
      • Pattern of body hair
      • Growth of underarm hair and pubic hair.
2. Role of the endocrine system which causes such changes during adolescence:
   • The gonads produce male and female reproductive cells (sperms and ova respectively) they also release the sex hormones into the blood.
   • Primary sex characteristics are concerned with the development, structure and function of the gonads (testes and ovaries) and the genitalia (the penis and prostate in males and the vagina, uterus and uterine tubes in females).
   • The secondary sex characteristics are concerned with the development structure and functions of other external features like change of voice, body hair, broadening of shoulders, hips etc.
   • These changes in the endocrine system occur during the onset of puberty at early adolescence marked by the menarche in females and sperm Arche in males.