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ICSE Class 8 Biology Question 3 of 10

Endocrine System and Adolescence — Question 3

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Question

Question 1(c)

Distinguish between the following pair on the basis of the words indicated in the brackets.

Insulin and Glucagon (function)

Answer

Difference between Insulin and Glucagon on the basis of function:

CharacteristicInsulinGlucagon
FunctionInsulin lowers blood glucose levels by facilitating the uptake of glucose into cells and its conversion to glycogen in the liver and muscles.Glucagon raises blood glucose levels by promoting the conversion of glycogen back to glucose in the liver and muscles.
Reaching the Age of Adolescence - Web Content | Bright Tutorials
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ICSE Class VIII | Academic Year 2026-2027
9403781999
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Biology | Chapter 6: Reaching the Age of AdolescenceWeb Content

Reaching the Age of Adolescence – Interactive Study Guide

Quick Overview

Adolescence (11–19 years) is a period of significant physical, emotional, and hormonal changes. Puberty marks its beginning, when the body becomes capable of reproduction.

Changes During Puberty

ChangeIn BoysIn Girls
Body shapeBroad shoulders, muscularWider hips, rounded body
VoiceDeeper (Adam's apple)Higher-pitched
Hair growthFacial hair, body hairUnderarm, leg hair
ReproductiveSperm production beginsMenstruation begins

Hormones at a Glance

Key Hormones
  • Testosterone (from testes) → Male secondary characters
  • Oestrogen (from ovaries) → Female secondary characters
  • Pituitary gland → Triggers testes/ovaries (master gland)

Menstrual Cycle Summary

28-Day Cycle

Ovary releases egg → Uterus lining thickens → If NOT fertilised → Lining breaks down → Menstruation (3–5 days) → Cycle repeats

Menarche: First period (10–12 yrs). Menopause: Periods stop (~45–50 yrs).

Self-Test Questions

Test Yourself
  1. Define puberty and adolescence.
  2. List 4 secondary sexual characters in boys.
  3. What is the role of oestrogen during puberty?
  4. Why is a balanced diet important during adolescence?
  5. How is the sex of a child determined?

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Endocrine System - Web Content | Bright Tutorials
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BRIGHT TUTORIALS
ICSE Class VIII | Academic Year 2026-2027
9403781999
Excellence in Education
Biology | Chapter 7: Endocrine SystemWeb Content

Endocrine System – Interactive Study Guide

Quick Overview

The endocrine system consists of ductless glands that secrete hormones into the blood. Hormones are chemical messengers that regulate growth, metabolism, reproduction, and response to stress.

Endocrine vs Exocrine at a Glance

FeatureEndocrineExocrine
DuctsDuctlessHave ducts
SecretionHormones (into blood)Enzymes, sweat (through ducts)
ExamplesPituitary, thyroid, adrenalSalivary, sweat, liver

Master Table: Glands, Hormones, Functions

GlandHormoneFunctionDisorder
PituitaryGHGrowthDwarfism / Gigantism
ThyroidThyroxineMetabolism (needs iodine)Goitre / Cretinism
ParathyroidParathormoneCalcium regulationTetany
AdrenalAdrenalineFight-or-flightAddison's disease
PancreasInsulin / GlucagonBlood sugar regulationDiabetes mellitus
TestesTestosteroneMale characters—
OvariesOestrogenFemale characters—

Feedback Mechanism

How It Works

High hormone level → Gland reduces production. Low hormone level → Gland increases production.

Example: High blood sugar → Insulin released → Sugar absorbed by cells → Sugar drops → Insulin production stops.

Self-Test Questions

Test Yourself
  1. Why is the pituitary gland called the master gland?
  2. What is goitre? How can it be prevented?
  3. Differentiate between insulin and glucagon.
  4. What happens during a fight-or-flight response?
  5. Explain the feedback mechanism with the example of blood sugar.

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