Population: The Increasing Numbers and Rising Problems — ICSE Class 10 Biology Important Questions

Answer: (b) Birth rate.

Birth rate (natality) is expressed as the number of live births per 1000 individuals of the population per year.

Answer: (b) Demography.

Demography is the study of the size, growth, distribution and structure of human populations using statistics such as birth rate and death rate.

Answer: (b) 18.

Growth rate $=$= birth rate $-$- death rate $= 30 - 12 = 18$= 30 - 12 = 18 per 1000 per year.

Answer: (b) Growing rapidly with many young people.

A broad base shows a large number of children and young people who will soon reproduce, so such a population is expanding rapidly; a narrow top shows few elderly people.

Answer: (a) Because the death rate has dropped far more steeply than the birth rate, the gap between them (the growth rate) remains large, so the population keeps rising; R correctly explains A.

(i) Death rate (mortality) is the number of deaths per 1000 individuals of a population in one year.

(ii) Growth rate (natural increase) is the rate at which a population increases, given by birth rate minus death rate (excluding migration); it is expressed per 1000 persons per year.

Two factors that have lowered India's death rate are:

1. Better medical and health care — control of epidemics, vaccination, antibiotics and modern hospitals reduce deaths from disease.
2. Improved food supply and sanitation — a more assured food supply, clean drinking water and better sanitation reduce deaths from famine and infection.

Three major problems created by over-population are:

1. Unemployment and poverty: too many people compete for too few jobs, lowering per-capita income and spreading poverty.
2. Shortage of resources: demand outruns the supply of food, water, housing, schools and hospitals, so basic needs are not met.
3. Environmental damage: more people means more waste, more felling of forests and greater air, water and land pollution, degrading the environment.

(Other valid problems include pressure on land and increased slums.)

(i) Migration: immigration (people moving in) increases a local population, while emigration (people moving out) decreases it; migration changes population without changing birth or death rate.

(ii) Age of marriage: early marriage lengthens the reproductive period and tends to raise the birth rate, so a population grows faster; a later age of marriage lowers the birth rate.

(iii) Medical facilities: good medical care lowers the death rate (especially infant deaths) and increases life span, so the population grows even if the birth rate is unchanged.

Three measures to control population, apart from contraceptives, are:

1. Spread of education, especially of girls: educated people marry later, understand the value of small families and adopt family planning, which lowers the birth rate.
2. Raising the legal age of marriage: delaying marriage shortens the reproductive span and gives fewer child-bearing years, reducing births.
3. Improving the standard of living and providing social security: when parents are confident of jobs, health care and support in old age, they no longer rely on many children, so the birth rate falls.

(Incentives for small families and empowerment of women are also effective.)

A population pyramid (age-sex pyramid) is a bar diagram that shows the number or percentage of males and females in each age group of a population, with the youngest at the bottom and the oldest at the top, males on one side and females on the other.

Interpreting the shape:

• A broad base narrowing quickly to the top (as shown) means many children and young people; the population is growing rapidly (typical of developing countries like India).
• A pyramid with nearly straight sides (base and middle similar) means births balance deaths; the population is stable.
• A pyramid with a narrow base and wider middle/top means fewer children are being born; the population is declining or ageing.

Thus the shape of the pyramid at a glance reveals the growth trend of the population.

A rapidly rising population puts heavy pressure on a country in several ways:

1. Natural resources: demand for food, fresh water, fuel and land rises faster than supply. Forests are cleared for farming and housing, groundwater is over-drawn, and non-renewable resources are used up quickly, leading to shortages.

2. Employment: the number of job-seekers grows faster than the number of new jobs, causing widespread unemployment and under-employment, low wages and rising poverty.

3. Environment: more people generate more sewage, garbage and vehicle and industrial emissions, so air, water and land pollution increase; deforestation and loss of wildlife habitats also rise.

4. Health and education services: hospitals, doctors, schools and teachers become too few for the numbers, so services are overstretched, quality falls and many people remain without proper health care or education.

Overall, rapid population growth lowers the per-capita share of resources and the general standard of living, which is why population control is essential.

(i) Growth rate $=$= birth rate $-$- death rate $= 26 - 8 = \mathbf{18}$= 26 - 8 = 18 per 1000 per year.

(ii) The population is growing, because the birth rate (26) is greater than the death rate (8), giving a positive growth rate of 18 per 1000.

(iii) One factor that could reduce the birth rate is the spread of female education (or raising the age of marriage), which encourages smaller families.

(iv) A government measure is the family planning (family welfare) programme, which promotes small families and provides contraceptive advice and services.