Increased IMR and decreased MMR in a population will: (a) Cause rapid increase in growth rate (b) Result in decline in growth rate (c) Not cause significant change in growth rate (d) Result in an explosive population

> [!TLDR] > An increase in Infant Mortality Rate (IMR) generally leads to a higher overall death rate, which is likely to outweigh the positive impact of a decreased Maternal Mortality Rate (MMR), resulting in a decline in the population growth rate. To understand how changes in Infant Mortality Rate (IMR) and Maternal Mortality Rate (MMR) affect population growth, we first need to grasp the concept of population growth rate itself. Population growth rate is primarily determined by the difference between the birth rate (natality) and the death rate (mortality), along with migration (immigration and emigration). For this question, we will focus on the birth and death rates. ### Infant Mortality Rate (IMR) The Infant Mortality Rate (IMR) is defined as the number of deaths of infants under one year of age per 1,000 live births. It is a crucial indicator of the overall health and socio-economic conditions of a region. * **Impact of Increased IMR:** When the IMR increases, it means that a greater number of infants are dying before reaching their first birthday. This directly contributes to a higher overall death rate in the population. A higher death rate, all else being equal, tends to slow down or reduce population growth. ### Maternal Mortality Rate (MMR) The Maternal Mortality Rate (MMR) is defined as the number of deaths of women due to pregnancy or childbirth complications per 100,000 live births. It reflects the quality of maternal healthcare services available. * **Impact of Decreased MMR:** When the MMR decreases, it means fewer mothers are dying during pregnancy or childbirth. This directly contributes to a lower overall death rate, particularly among women of reproductive age. A lower death rate, all else being equal, tends to increase population growth. Furthermore, fewer maternal deaths mean more women survive to potentially have more children, which can indirectly support a higher birth rate or at least maintain the reproductive potential of the

Increased IMR and decreased MMR in a population will: (a) Cause rapid increase in growth rate (b) Result in de

NCERT Exemplar · Q2

Q. Increased IMR and decreased MMR in a population will:

(a) Cause rapid increase in growth rate

(b) Result in decline in growth rate

(d) Result in an explosive population

Uttar Pradesh UpmspMCQ· 1mImportance★★★★★

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Concept understanding — Population Growth Factors

Population Growth Factors: A First Look

Think about a village, a city, or even your own family. Why do some families grow larger over time, while others stay the same size or shrink? Why do some cities burst with new people while others seem to lose residents? The answer lies in population growth factors — the forces that determine whether a population increases, decreases, or stays stable.

The Core Idea

At its simplest, a population changes because of two things: people being added and people being taken away. But what adds people? Only one thing: births. What takes people away? Only one thing: deaths. That is the natural rhythm of any population.

But there is a third force that matters enormously for a country, state, or city: migration. People move in (immigration) and people move out (emigration). So the real equation — though we are not using numbers here — is:

Births + Immigration = Additions

Deaths + Emigration = Subtractions

When additions are greater than subtractions, the population grows. When subtractions are greater, it shrinks. When they are equal, it stays the same.

The Three Main Factors

The NCERT textbook identifies three broad categories of factors that influence these additions and subtractions:

1. Fertility (the birth side)

Fertility is not just about biology — it is deeply shaped by society. Why do people in some regions have many children, while in others they have few? The factors include:

Age at marriage: Earlier marriage generally means a longer childbearing period.
Education and employment of women: Educated women who work tend to have fewer children and have them later.
Economic conditions: In agricultural societies, children are often seen as economic assets (help on the farm). In urban industrial societies, children are more of an expense.
Cultural and religious norms: Some communities encourage large families; others do not.
Government policies: Think of China's former one-child policy or India's family planning programmes.

2. Mortality (the death side)

Why do people die earlier in some places than in others? The key factors are:

Healthcare infrastructure: Access to hospitals, vaccines, and medicines.
Nutrition and sanitation: Malnutrition and unclean water kill millions.
Disease patterns: Epidemics like malaria, tuberculosis, or HIV/AIDS.
Natural disasters and conflicts: Famines, wars, earthquakes.
Age structure: A population with many elderly people will naturally have more deaths.

Important

The most dramatic change in human history came from a decline in mortality — not a rise in fertility. Better medicine, sanitation, and food supply caused death rates to fall sharply, especially in the 20th century. This is why the world's population exploded.

3. Migration (the movement side)

People move for reasons that pull them towards a place or push them away from another.

Push factors (reasons to leave):

Unemployment or low wages
Political instability or persecution
Natural disasters or environmental degradation
Lack of educational opportunities

Pull factors (reasons to come):

Better job prospects and higher incomes
Peace and security
Better schools and universities
Family reunification

Migration can be internal (within a country, like rural-to-urban movement) or international (across borders).

Why This Matters

Population growth factors are not just academic. They shape everything:

Economic planning: A rapidly growing population needs more schools, hospitals, jobs, and housing. A shrinking population faces labour shortages and an ageing society.
Resource use: More people mean more demand for water, food, energy, and land.
Environmental impact: Population growth is one driver of climate change, deforestation, and pollution.
Social stability: Uneven growth between regions can cause tension, especially when migration is involved.

Note

The NCERT textbook emphasises that population growth is not inherently good or bad. It depends on the context. A young, growing population can be a demographic dividend if there are enough jobs. But if growth outpaces resources, it becomes a burden.

A Final Intuition

Imagine a bucket with a tap pouring water in (births + immigration) and a hole letting water out (deaths + emigration). The water level is the population size. Population growth factors are everything that makes the tap flow faster or slower, and everything that makes the hole bigger or smaller. Some factors you can control (like family planning policies), others you cannot (like a pandemic or a drought).

Understanding these factors helps you see why some countries are young and crowded, others are old and shrinking, and why people move across the world in search of a better life. It is the story of humanity, told through numbers — but driven by choices, circumstances, and chance.

This topic shows up often in student searches, usually phrased as "Population Growth Factors: Definition, Diagram & Examples", "Population Growth Factors NEET questions", or "Population Growth Factors diagram and explanation". This concept is directly part of the Organisms and Populations chapter in the NCERT/CBSE Class 12 Biology syllabus, and it is also an important topic for NEET and state medical/CET entrance exams, making it worth mastering for both board and competitive-exam preparation.

An increase in Infant Mortality Rate (IMR) generally leads to a higher overall death rate, which is likely to outweigh the positive impact of a decreased Maternal Mortality Rate (MMR), resulting in a decline in the population growth rate.

To understand how changes in Infant Mortality Rate (IMR) and Maternal Mortality Rate (MMR) affect population growth, we first need to grasp the concept of population growth rate itself. Population growth rate is primarily determined by the difference between the birth rate (natality) and the death rate (mortality), along with migration (immigration and emigration). For this question, we will focus on the birth and death rates.

Infant Mortality Rate (IMR)

The Infant Mortality Rate (IMR) is defined as the number of deaths of infants under one year of age per 1,000 live births. It is a crucial indicator of the overall health and socio-economic conditions of a region.

Impact of Increased IMR: When the IMR increases, it means that a greater number of infants are dying before reaching their first birthday. This directly contributes to a higher overall death rate in the population. A higher death rate, all else being equal, tends to slow down or reduce population growth.

Maternal Mortality Rate (MMR)

The Maternal Mortality Rate (MMR) is defined as the number of deaths of women due to pregnancy or childbirth complications per 100,000 live births. It reflects the quality of maternal healthcare services available.

Impact of Decreased MMR: When the MMR decreases, it means fewer mothers are dying during pregnancy or childbirth. This directly contributes to a lower overall death rate, particularly among women of reproductive age. A lower death rate, all else being equal, tends to increase population growth. Furthermore, fewer maternal deaths mean more women survive to potentially have more children, which can indirectly support a higher birth rate or at least maintain the reproductive potential of the population.

Combined Effect on Population Growth Rate

Now, let's consider the combined effect of an increased IMR and a decreased MMR. These two factors have opposing influences on the overall death rate:

Increased IMR pushes the overall death rate up.
Decreased MMR pushes the overall death rate down.

To determine the net effect, we need to consider the relative magnitudes of these changes. In many populations, especially those with poor health infrastructure or socio-economic challenges, the number of infant deaths can be substantially higher than the number of maternal deaths. An increase in IMR often signifies a broader deterioration of health conditions, such as widespread disease, malnutrition, or lack of basic sanitation and healthcare, which can lead to a significant rise in overall mortality.

While a decrease in MMR is a positive development, the increase in deaths due to a rising IMR is often more substantial in terms of absolute numbers and its impact on the overall death rate. If a significant number of infants are dying, this adds considerably to the total deaths in a population. Therefore, the increase in the death rate caused by a rising IMR is likely to outweigh the decrease in the death rate brought about by a falling MMR.

Important

An increase in the overall death rate, assuming the birth rate does not increase dramatically to compensate, will lead to a decline in the population growth rate.

✓Final answer

Increased IMR and decreased MMR in a population will result in a decline in the growth rate, as the rise in infant deaths typically contributes more significantly to the overall death rate than the reduction in maternal deaths.

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Q.Increased IMR and decreased MMR in a population will:

Infant Mortality Rate (IMR)

Maternal Mortality Rate (MMR)

Combined Effect on Population Growth Rate

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