CBSE Class 8 Science Question 5 of 12

Reaching the Age of Adolescence — Question 5

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Question 5

Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.

Answer

Below table shows the names of endocrine glands and hormones secreted by them:

Endocrine glandHormones
TestisTestosterone
OvaryOestrogen
ThyroidThyroxin
AdrenalAdrenalin
PituitaryGrowth hormone
PancreasInsulin

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.