Population Class 10 ICSE Notes — Selina Biology Chapter 12

These population class 10 ICSE notes explain Chapter 12 of the Selina Concise Biology textbook in the order the book presents it. The chapter opens with the threat of rising population, then traces world population from the stone age to the present. Between those points it covers India’s census figures and the pressure on natural resources. It closes with the statistical terms and contraceptive methods used to control growth.

Download Population Class 10 ICSE Biology Chapter 12 PDF

Download the Population Class 10 ICSE Biology chapter PDF from the Selina Concise textbook to revise offline or print for practice. It is the full chapter as printed in the book — 11 pages, 15 sections, 35 questions.

What is inside Chapter 12

11 pages · 15 sections · 35 exercise questions

• PROGRESS CHECK: 3 questions
• PROGRESS CHECK: 2 questions
• PROGRESS CHECK: 2 questions
• PROGRESS CHECK: 3 questions
• PROGRESS CHECK: 25 questions

12.1 RISING POPULATION — A GLOBAL THREAT

The chapter opens with a direct warning. Rising population is a grave danger, not for any one country but for the world as a whole. Developing countries such as India face the problem most sharply.

Mass communication is the main tool used to spread awareness. Radio, television, the stage and the press all carry the message about the dangers of unchecked growth. These media reach people who never enter a classroom.

This section sets up the whole chapter. A population that grows faster than its resources cannot keep its people fed, housed or healthy. Every later section builds on this starting point. Treat section 12.1 as the chapter’s argument in one paragraph: growth is dangerous, and awareness is the first defence. The chapter belongs to the Selina Biology Class 10 collection, which covers the syllabus in book order.

12.2 WORLD POPULATION THROUGH THE AGES

The book estimates the world population about 50,000 years ago at roughly one million. Life then was primitive. Humans used tools of stone, sticks and bones, sheltered in caves, hunted animals and gathered fruits, roots and leaves. They lived in groups for safety and hunted large animals such as mammoths.

Around 10,000 years ago the population reached about 5.3 million, and life changed. People settled in communities and domesticated animals — the dog was the first. They learnt to sow crops and store food, which was the beginning of agriculture. Stone tools gave way to bronze and iron.

The book lists key dates worth quoting from this ICSE chapter:

• 5 billion crossed on 11 July 1987 — now observed as World Population Day
• about 5.6 billion in 1995, with more than 1,00,000 babies born every day
• 6 billion on 12 October 1999, the six-billionth baby born in Sarajevo
• a projected 10 billion around the year 2050
• India overtaking China to become the world’s most populous country by about 2025

12.3 RAPID RISE IN POPULATION

Two forces drove the rapid rise in population. The first was the scientific and industrial revolution, which began around the seventeenth century. Industries created jobs and comfort, and food production rose. The drawback was that crowded communities spread infectious diseases, while unbalanced diets caused nutritional diseases.

The second force was twentieth-century medical science. Antibiotics and prophylactic vaccinations — ‘prophylactic’ means guarding beforehand — sharply reduced deaths in all age groups. More children per family reached reproductive age, reproduced, and the growth rate climbed.

The book marks three cultural revolutions on the population curve: tool making, agricultural, and scientific industrial. Each one pushed population up until it stabilised, then the next revolution lifted it again. The curve ends with two question marks — no one knows whether population will keep rising rapidly, rise slowly, or stabilise. A simple memory hook for the three revolutions: Tool, Agriculture, Science.

12.4 POPULATION EXPLOSION — A SERIOUS GLOBAL CONCERN

Population explosion is the book’s term for a striking fact. About one-third of all the people who ever lived are alive today. The explosion began in the middle of the nineteenth century. Two-thirds of the present world population live in developing nations, and more than half of those people live below the poverty line. India and China together make one-third of the world’s people.

The growth curve shows a sharp dip shortly after 1000 AD. Severe epidemics caused it, above all the Black Death — plague — spread by the bite of the rat flea. After the scientific and industrial age, growth accelerated until the population more than doubles in about 35 years. The world reached 7 billion on 31 October 2011, and could reach 50 billion by the end of this century.

The book gives six reasons for the sharp rise:

• better health care for all age groups
• fewer deaths from better medical aid and regular vaccination programmes
• food shortages minimised by the green revolution
• improved nutrition, especially for growing children
• large-scale immunisation against fatal diseases
• fewer infant deaths, so more newborns survive

The key point is sobering. Even a couple with only 2-3 children raises the total population, because more of those children now survive to reproductive age and reproduce.

12.5 A HIGHLY SIMPLIFIED MODEL OF POPULATION GROWTH

Section 12.5 walks through the model in Table 12.1. Imagine 20 people forming 10 couples, each couple having 4 children. The children pair off at the reproductive age of 20-30 years and repeat the pattern in every generation.

The running totals show the effect. After the first generation the total is 60; after the second, 140; after the third, 300; after the fourth, 600. In about 60 years the population has multiplied ten times.

You can run the same model with different starting numbers. Take 30 people forming 15 couples, each with 4 children. Year 1 gives a total of 90 people. Each generation follows the same pattern, so at year 60 the total is 900 — again a tenfold rise. The growth factor depends on the number of children per couple, not on the starting size.

The book applies the model to India, which has already passed 1.21 billion. It adds a startling projection: with no checks, in 700 years only 1 square foot of earth per person would remain. The five problems of fast growth are decreasing open spaces, shrinking forests, industrialisation polluting air, water and soil, a shortage of drinking water, and pollution as a health hazard.

12.6 POPULATION IN INDIA

India’s census figures run from 1901 to 2011. The population rose from 238 million in 1901 to 1,210 million in 2011. There was one fall — in 1911-21 — and growth has been steady since, very high since 1951.

You can read the table by subtraction. From 1981 (685 million) to 1991 (846 million), the increase was 161 million in ten years. From 2001 (1,027 million) to 2011 (1,210 million), it was 183 million. The only decade with a fall is 1911-21, when the figure dropped from 252 to 251 million.

Current figures in the book: a little more than 1.32 billion, growing at 52 per minute, 3,120 per hour, 74,480 per day and 2-7 crore per year. Yet 35 of every 1,000 babies die at birth, and 45 of 1,000 do not survive beyond age five. More than 100 pregnant women per 1,00,000 die while delivering.

Two named milestones help you remember. Aastha, the officially designated billionth Indian, was born on 11 May 2000 in New Delhi. Nargis, the seven-billionth world baby, was born near Lucknow on 31 October 2011.

The book lists seven reasons for India’s explosion: illiteracy, traditional beliefs, high infant mortality, economic reasons, religious and social customs, the desire for a male child, and lack of recreation. Birth rates are falling worldwide — India’s dropped from 5.4 in 1970-1975 to 2.8 in 2005-2010.

12.8 RISING POPULATION — PRESSURE ON NATURAL RESOURCES

A resource, the book defines, is any substance — natural or artificial — any energy, or any organism used by humans for their welfare. Six resources are under pressure: food, water, land, forests, energy and minerals. A memory hook: Five Wild Lions Feast Every Morning.

The core contrast is food. Unchecked population grows in geometric progression — 1, 2, 4, 8, 16 — multiplying at each step. Food production rises in arithmetic progression — 1, 2, 3, 4, 5 — adding at each step. Food therefore runs short. Clean water also becomes scarce as rivers, ponds and lakes get polluted, and usable land shrinks as it is built over.

Forests are the most important resource. They provide timber, firewood, resins, medicines and wood-pulp. They release oxygen by photosynthesis, bring rain through transpiration, prevent floods by holding soil, absorb carbon dioxide and stabilise climate, and house wild animals. Deforestation brings droughts, flash floods, soil erosion, extinction of species and global warming. The remedy is afforestation.

Coal and petroleum are conventional fossil fuels. Petroleum may be exhausted within about 150 years, and coal a bit later. Non-conventional sources — solar, nuclear, tidal, wind and biogas — must be popularised. Minerals such as iron and copper are non-renewable: once finished, they can never be replaced.

12.9 POPULATION GROWTH AND URBANISATION CAUSING SERIOUS PRESSURE ON RESOURCES

This short section frames the next three. Urbanisation is the process by which villages turn into towns, towns into cities, and cities into megacities. Rising population and urbanisation together place serious pressure on resources. The book then looks at three sides of the problem.

12.9.1 Changing Face of the Earth

Urbanisation changes the physical face of the earth. The book lists the developments: residential buildings, markets, schools, hospitals, streets, roads, highways, railway lines, airports, industrial installations, godowns and reservoirs.

All these activities encroach on open land, neighbouring agricultural land and even forests. Natural vegetation is lost, and the environment — especially climatic conditions — degrades. The built environment steadily replaces the natural one. This is why urbanisation, not just population growth, counts as a pressure on resources.

12.9.2 Rising Living Standards of Growing Population

Living standards rise faster than population in many countries. The book’s examples are more household equipment — furniture, crockery, electric gadgets, decoration articles — more clothes per person, and personal conveyance such as cycles, motorcycles and cars, plus taxis and other transport.

The point is subtle. Even a family that limits its size uses more resources per person than its parents did. Demand grows twice over: more people, and more things per person.

12.9.3 Need to Check Exploitative Use of Resources

Some resources are non-renewable — once lost, lost forever. Others take a very long time to renew. Every citizen, the book argues, must become conscious of sustainable use.

Sustainable development means development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Three ways achieve it. Reduce the excessive use of natural resources. Recycle and reuse resources wherever possible. Use more renewable resources such as solar energy and wind power.

12.10 RATE OF POPULATION GROWTH MUST BE REDUCED

This is the formula section. Demography — from demos, people, and graphos, measurement — is the statistical study of human population, covering size, density, distribution and vital statistics. Population density is the number of individuals per square kilometre at any given time. The book’s 2016 figures: Netherlands about 407, Japan about 348, India about 392, and the US only about 33.

Birth rate, or natality, is the number of live births per 1000 people per year. Death rate, or mortality, is the number of deaths per 1000 people per year. Growth rate is the difference between the two. Population grows while birth rate exceeds death rate, and declines when birth rate is lower.

\text{Birth rate} = \frac{\text{live births}}{\text{total population}} \times 1000

Worked pattern: a town of 15,000 people records 510 live births in one year. Divide 15,000 by 1000 to get 15. Then 510 \div 15 = 34. The birth rate is 34 per 1000 people per year.

\frac{510}{15000} \times 1000 = 34 \text{ per 1000 people per year}

India’s birth:death ratio fell from 46:44 in 1901 to 37:14 in 1973. Both rates fell, but the death rate fell far more sharply because of better medical care. The result was a sharper rise in population. For a student revising this ICSE chapter, these four terms are the core of the section.

12.11 NEED FOR ADOPTING CONTROL MEASURES

When population density rises beyond a country’s means, problems follow. Per capita income comes down. Natural resources such as land, minerals, wood and fuel decrease. General health goes down.

A large population is the result of large families, and the quality of life falls. That is why population control measures are urgent.

For revision, note the pattern. The progress check in this section asks for the technical terms for the statistical study of human population, deaths per 1000 per year, individuals per square kilometre, and the difference between birth rate and death rate. These four definitions are the ones to memorise. The same terms reappear in the 25-question exercise at the end of the chapter.

12.12 POPULATION EDUCATION AND POPULATION CONTROL

The book gives six educational measures. The message must reach remote areas. People must learn the advantages of small families and the disadvantages of many children. The book contrasts China, near the one-child norm, with India, still striving for the two-child norm.

The orthodox preference for at least one son must be modified by education. The legal marriage age — 18 for girls, 21 for boys — must be followed strictly. Couples should delay the first child, space the second with a sufficient interval, and stop the third. People should adopt family planning methods: condoms such as Nirodh, intrauterine devices such as Copper-T, and oral pills such as Mala-D.

Family welfare is the broader frame. The inverted red triangle is the popular sign in India, displayed at family welfare centres where help and advice are free. Family welfare has three aspects. First, family planning for a small family. Second, the total welfare of that family, including the diet and nutrition of the child and the pregnant mother. Third, subsequent care of the children, such as immunisation and oral rehydration therapy.

12.13 METHODS OF CONTRACEPTION

The chapter ends with five methods of contraception. Hormonal methods — contraceptive pills — prevent the release of the egg from the ovary.

Barrier methods work physically. A condom such as Nirodh is a latex sheath used by men; it prevents sperms from being deposited in the vagina. Diaphragms are round latex caps fitted on the cervix that block sperm entry into the uterus. Spermicidal agents are chemicals placed near the cervix that kill sperms.

Intra-uterine devices — Lippe’s Loop and Copper-T — are fitted inside the uterus. They do not stop fertilisation; they prevent implantation of the blastocyst (embryo).

Surgical methods are permanent. Tubectomy, for females, opens the abdomen and cuts or ligates the fallopian tubes. Vasectomy, for males, ligates the vas deferens and removes a small piece between the ligatures. It is easier, quicker and safer, so the book recommends the husband be the one operated on. It has no effect on manliness or libido.

Induced abortion, or Medical Termination of Pregnancy (MTP), is a last step, not a contraceptive method. It is legal only within 5 months of pregnancy, must be done by a trained doctor at a hospital, is free at government hospitals, and does not need the husband’s consent.

Two traps appear in the progress check. An IUD does not prevent implantation in the vagina — implantation happens in the uterus. And tubectomy is not a male procedure. These methods build on the reproductive system chapter, which covers the organs involved.

What to practise from Population Class 10 ICSE

The chapter contains five PROGRESS CHECK blocks, and these are the ones to work through for your population class 10 ICSE notes.

• PROGRESS CHECK after section 12.3 — 3 questions on the cultural revolutions and medical science
• PROGRESS CHECK after section 12.9 — 2 questions on resources, true/false and fill in the blanks
• PROGRESS CHECK after section 12.11 — 2 questions on the technical terms and consequences of high population density
• PROGRESS CHECK after section 12.12 — 3 questions on large families, marriage age and family welfare
• Final PROGRESS CHECK — 25 questions, the chapter exercise covering multiple choice, very short answer, short answer, long answer, and structured/application/skill type questions

Within the 25-question block, practise the definitions — birth rate, death rate, growth rate, population density and exhaustible resource — the true/false statements on contraception, and the structured question comparing countries A and B using the given population figures.

Watch three common traps. Birth rate is not growth rate: growth rate subtracts deaths. IUDs block implantation, not fertilisation. And MTP is a last step, not a contraceptive method.

The official CISCE website publishes the current Class 10 Biology syllabus and board announcements.

Population Class 10 ICSE frequently asked questions

Where can I get population class 10 ICSE notes for Chapter 12?

This page explains every section of Selina Biology Chapter 12 in book order, with the definitions, formulas and worked examples. The chapter PDF is available on this page. Use the practice list above to find each exercise block with its question count.

What is the difference between birth rate and growth rate of population?

Birth rate, or natality, is the number of live births per 1000 people per year. Growth rate is the difference between birth rate and death rate. The common mistake is treating them as the same: birth rate counts births, while growth rate is the net result after deaths are subtracted.

What is population density in class 10 ICSE biology?

Population density is the number of individuals per square kilometre at any given time. Towns and larger cities have a greater density than rural areas. In 2016, India had about 392 persons per square kilometre.

How do IUDs prevent pregnancy — do they stop fertilisation?

No. Intra-uterine devices such as Lippe’s Loop and Copper-T are fitted inside the uterus. They do not stop fertilisation; they prevent implantation of the blastocyst. The common trap is writing ‘vagina’ — implantation happens in the uterus, not the vagina.

What is the difference between tubectomy and vasectomy?

Tubectomy is the female operation: the abdomen is opened and the fallopian tubes are cut or ligated. Vasectomy is the male operation: the vas deferens is ligated and a small piece removed. Vasectomy is easier, quicker and safer, and has no effect on manliness or libido.

Reference: ICSE Class 10 Biology textbook material, chapter 12: Population — CISCE-aligned.

More from this book

• Chapter 2: Structure of Chromosomes Cell Cycle and Cell Division
• Chapter 3: Genetics Some Basic Fundamentals
• Chapter 4: Absorption By Roots the Processes Involved
• Chapter 5: Transpiration
• Chapter 6: Photosynthesis
• Chapter 7: The Circulatory System
• Chapter 8: The Excretory System
• Chapter 9: The Nervous System
• Chapter 10: Endocrine Glands
• Chapter 11: The Reproductive System
• Chapter 13: Aids to Health
• Chapter 14: Health Organisations
• Chapter 15: Pollution