Reaching the Age of Adolescence

Adolescence is the period of life, roughly between the ages of 11 and 19, during which the body undergoes changes that lead to reproductive maturity. The most important changes take place at puberty. In this chapter you will learn about these changes: a sudden increase in height, changes in body shape, a deeper voice in boys as the larynx grows into the Adam's apple, more active sweat and sebaceous glands that may cause pimples, and the development of the sex organs. You will also study the secondary sexual characters, and the emotional and intellectual changes that make adolescence a time of curiosity and independence. These changes are controlled by hormones released by endocrine glands. You will learn about the roles of the pituitary gland, testosterone and estrogen, thyroxine from the thyroid, insulin from the pancreas and adrenalin from the adrenal glands, about menstruation, how the sex of a baby is determined by X and Y chromosomes, and how a balanced diet, hygiene, exercise and avoiding drugs keep adolescents healthy.

Detailed Worksheet: Reaching the Age of Adolescence Section A - Definitions (10 marks) 1. Define adolescence and puberty. Why is adolescence also called the "teenage" period? (2 marks) 2. What are secondary sexual characters? Give two examples each in boys and girls. (2 marks) 3. What are hormones? How are endocrine glands different from other glands such as salivary glands? (2 marks) 4. Name the hormones produced by the testes and the ovaries, and the gland that controls their release. (2 marks) 5. What is menstruation? Define menarche and menopause. (2 marks) Section B - Calculations and Applications (15 marks) 6. A height chart shows that at 9 years of age a boy has reached about 75% of his full height. If a boy is 120 cm tall at 9 years, what will his full height probably be? If at 11 years he reaches 81% of his full height, what is his height then? (3 marks) 7. At 12 years of age, a girl has reached about 91% of her full height. If she is 136.5 cm tall at 12, calculate her probable full height. How much more will she grow? (3 marks) 8. A menstrual cycle lasts about 28 days. If menarche occurs at 12 years and menopause at 48 years, estimate the number of menstrual cycles in the reproductive life of a woman, taking 1 year as 365 days. (3 marks) 9. Humans have 23 pairs of chromosomes in each cell. (i) How many chromosomes are there in a body cell? (ii) How many are there in an egg or a sperm? (iii) Which pair of chromosomes determines the sex of a child, and how? (3 marks) 10. An adolescent's daily diet includes chapatis, rice, dal, milk, green leafy vegetables and fruits. Classify these foods by the main nutrient they provide. Why do adolescent girls especially need iron-rich foods? Name two such foods. (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram showing the positions of the endocrine glands in the human body: pituitary, thyroid, adrenal glands, pancreas, testes (in males) and ovaries (in females). (4 marks) 12. Draw a labelled diagram of the larynx in an adolescent boy showing the Adam's apple. Explain why the voice of boys becomes deep. (3 marks) 13. Draw a flowchart showing how the sex of a child is determined by the combination of an X or Y chromosome from the father with the X chromosome of the mother. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Explain the role of hormones in the metamorphosis of a frog and of insects. What happens to a tadpole if the water it lives in lacks iodine? Name the disease caused by iodine deficiency in humans. (5 marks) 15. A student says that the mother is responsible for the sex of the child. Evaluate this claim using the facts about X and Y chromosomes. Explain why it is wrong to blame the mother. (5 marks) 16. Adolescence can be a time of confusion and stress. Explain why adolescents should eat a balanced diet, keep their body clean, exercise regularly and say no to drugs. Suggest how they can find correct information and support about the changes in their bodies. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw all diagrams neatly in pencil, use correct scientific terms, and answer with sensitivity and respect.