CBSE Class 8 Science Question 7 of 12

Reaching the Age of Adolescence — Question 7

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Question 7(a)

Adolescents should be careful about what they eat, because

  1. proper diet develops their brains.
  2. proper diet is needed for the rapid growth taking place in their body.
  3. adolescents feel hungry all the time.
  4. taste buds are well developed in teenagers.
Answer

proper diet is needed for the rapid growth taking place in their body.

Reason — Adolescence is a period of rapid growth. Therefore, a proper growth requires ample of nutrition.

Chapter Overview: Reaching the Age of Adolescence

This chapter covers the physical and emotional changes during adolescence and puberty, the role of hormones secreted by endocrine glands, sex determination in humans (XX/XY), and the importance of balanced nutrition, personal hygiene, and avoiding harmful substances during this critical growth period.

Board Exam Weightage: 4-6 marks | Difficulty: Moderate

Key Formulas & Concepts

ConceptDetails
Sex DeterminationXX = Female; XY = Male; Father's sperm determines sex
ThyroxineThyroid hormone; controls metabolism; needs iodine; deficiency → goitre
InsulinPancreatic hormone; controls blood sugar; deficiency → diabetes
Puberty AgeGirls: ~11 years; Boys: ~13 years (approximate onset)

Must-Know Concepts

  • Adolescence spans ages 11-19; puberty is the onset of reproductive maturity within this period
  • Secondary sexual characters: visible physical changes at puberty (facial hair in boys, breast development in girls)
  • Adam's apple is the enlarged voice box in boys (causes deeper voice)
  • Pituitary is the master gland (controls other endocrine glands)
  • Sex is determined by the father's sperm (X → girl, Y → boy), not by the mother
  • Balanced diet, exercise, hygiene, and avoiding drugs are essential during adolescence

Endocrine Glands and Hormones

GlandHormoneFunction
Pituitary (brain)Growth hormoneControls body growth; master gland
Thyroid (neck)ThyroxineControls metabolism; needs iodine
Pancreas (abdomen)InsulinRegulates blood sugar
Adrenal (on kidneys)AdrenalineFight or flight response
Testes (males)TestosteroneMale sexual characters, sperm production
Ovaries (females)OestrogenFemale sexual characters, egg development

Common Mistakes to Avoid

  • Thinking the mother determines the sex of the child (father's sperm determines it)
  • Confusing adolescence (age period) with puberty (onset of changes)
  • Mixing up endocrine (ductless, hormones into blood) and exocrine (duct) glands
  • Thinking hormones act instantly like nerve impulses (they are slower)

Scoring Tips

  • Draw the XX/XY cross diagram to explain sex determination
  • Create a hormone-gland-function table for quick revision
  • Learn physical changes during puberty for both boys and girls
  • Connect hormonal disorders to glands: goitre → thyroid, diabetes → pancreas

Frequently Asked Questions

Q: How many marks does this chapter carry in the exam?
A: Approximately 4-6 marks in the annual exam.

Q: What question types are commonly asked?
A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).

Q: Is this chapter important for competitive exams?
A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.