# RBSE Solutions For Class 12 Biology Chapter 38: Human Population | Textbook Important Questions & Answers

RBSE Class 12 Biology Chapter 38- Human Population. In this chapter, students can learn in detail about the population, types of population, population density, types of population density, determination of the population density, human population, population growth form, population in India, factors affecting the rate of population growth, age pyramid and factors to control the population. It also deals with the monospecific population, polyspecific population, formula for calculating population, crude density and ecological density, types of determination of the population density, S-shaped growth curve, J-shaped growth curve, birth rate, age distribution, family planning and mortality rate.

These important questions help students to perform exceptionally well in their exams. By practising these important questions, students can analyze their preparation, get a thorough knowledge about all the important terminologies and perform their best in the examinations.

RBSE Solutions for Class 12 are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.

## RBSE Class 12 Biology Chapter 38 Important Questions

### RBSE Biology Chapter 38: MCQ Type Questions

Q.1. The contribution of India in the total world population is _________.

(a) 12.4 %

(b) 17.85%

(c) 16.2%

(d) 15.1%

Sol: (b) 17.85%.

Q.2. The scientist who first proposed the theory or human population is _________.

(a) Malthus

(b) Lamark

(c) Darwin

Sol: (a) Malthus.

Q.3. The reason for a rapid population growth is _________.

(a) Increase in the birth rate

(b) Global warming

(c) Improvement of lifestyle

(d) Decreased Mortality

Sol: (d) Decreased Mortality.

Q.4. The shape of the population due to the maximum old aged people is_________.

(a) An increase in the future

(b) Will be stable

(c) A decrease in the future

(d) None of these

Sol: (c) A decrease in the future.

Q.5. Which one of the following is not a contraceptive?

(a) Condom

(b) Saheli tablet

(c) Vault

(d) Steroid Pill

Sol: (d) Steroid Pill.

Q.6. How many types of population density are there?

(a) Three

(b) Four

(c) Two

(d) Five

Sol: (c) Two.

Q.7. When is the World’s Population Day celebrated?

(a) 11th July

(b) 1st April

(c) 15th March

(d) None of the above.

Sol: (a) 11th July.

Q.8. Which of the factors affect population growth?

(a) Temperature

(b) Climate

(c) Birth rate

(d) None of the above

Sol: (c) Birth rate.

Q.9. From the population point of view, India is the _______ largest country in the world.

(a) Second

(b) Third

(c) Fifth

(d) Sixth

Sol: (a) Second.

Q.10. In ecology, the population density of organisms is usually calculated by _________.

(a) Direct Count Method

(b) Sampling method

(c) Marking and Recapture Method

(d) All of the above.

Sol: (d) All of the above.

### RBSE Biology Chapter 38: Short and Long Answer Type Questions.

Q.1.What is population growth?

Sol: Population growth in animals exhibits a fixed pattern, which can be exhibited by a population growth graph. The population growth graph is drawn between population size and time.

Q.2.What is the main factor for the decreased mortality in India?

Sol: The main factor for the decreased mortality in India is the advanced and excellent medical facilities and the time bond vaccinations.

Q.3. What is the population?

Sol: A group of animals of a species at a specific place and at a specific time is called a population.

Q.4. What will happen if the population of the natality and mortality rate will be equal?

Sol: If the natality and mortality rate will be equal then the size of the population of that species will be stationary.

Q.5. What is IUD in contraception devices?

Sol: The IUD stands for Intrauterine Device.

1. Intrauterine Device is a small T-shaped device, which is inserted into the uterus by doctors.
2. These devices promote phagocytosis of sperms to prevent fertilization.
3. They are used to delay pregnancy. Cut, Cu7 are the devices containing copper.
4. These devices release copper ions, which inhibits the motility of the sperms and fertilization.
5. These devices are considered as ideal contraceptives for females.
6. IUD hormones prevent implantation in the uterus after the birth of two children from a respective mother. This method is widely used in India and it is an ideal method.

Q.6. What is birth control?

Sol: The process which uses certain devices, drugs or surgical procedures in both males and females, to prevent conception is called birth control.

Q.7. What is a vasectomy?Â

Sol: Vasectomy is one of the surgical procedures for male sterilization, also called castration, This surgical procedure is used to control the population and is also called family planning. This method is used in all males. In this method, a small incision is made and vas deferens get tied. It is commonly known as “Male Nasbandi”

Q.8. What is tubectomy?Â

Sol: Tubectomy is one of the surgical methods, also called castration, which is used to control the population and is also called family planning. This method is used in all females. In tubectomy, a small part of the fallopian tube is either tied or removed via an incision.

This technique is more effective and can be reversed. This technique is commonly known as “Female Nasbandi”

Q.9. What are contraceptive pills?

Sol: Contraceptive pills are used as oral hormonal pills These pills contain small doses of estrogen or progesterone hormones. These oral hormonal pills should be taken for a period of 21 days.

After a gap of seven days, that is at the time of menstruation, these pills should be avoided. After this gap, pills should be continued in the same pattern until and unless a female desires conception or fertilization.

Progesterone or combination with estrogen hormones may also be given to females via injections. They work similarly to the orally taken pills.

Saheli tablets are a new oral contraceptive without any steroids hormone. It contains a chemical called centchroman. It is a highly effective contraceptive pill.

Emergency pills contain a chemical called levonorgestrel. This pill is to be taken after forced sex or unplanned sex within 72 hours. It prevents ovulation. It is also called a pill-72.

Q.10. What are the types of Intrauterine Devices (IUD)? Draw the structure of an Intrauterine Devices (IUD).

Sol: There are two types of Intrauterine Devices (IUD).

• Copper Intrauterine Devices – This device functions by releasing small amounts of copper in the uterus which prevents sperms from reaching the ovary.
• Hormonal Intrauterine Devices – This device functions by releasing progestin in the body which prevents the formulation of eggs.

Structure of an Intrauterine Devices

Q.11.What is mortality?

Sol: Mortality shows the number of deaths in a particular population. It is expressed as the number of deaths per 100 people per year. It is measured with the help of systems such as SAPS II and III, APACHE-II, Glasgow, Coma scale, etc.

Q.12. What is population density

Sol: The population density tells the size of a population. This attribute is the reflection of the condition of a habitat. More density indicates that the habitat provides more favourable living conditions.

Q.13. What are the surgical methods in birth control?

Sol: It is the type of birth control, which is achieved by surgical methods. This is a method in which both men and women are surgically operated to prevent fertilization.

For women, the process is called Tubal ligation.

In this process of the surgical method, the eggs are blocked either by cutting or sealing of the fallopian tube, so that eggs do not reach the uterus at all.

For men, the process is called Vasectomy.

Vasectomy involves the cutting and sealing of the vas deferens so that the sperms do not enter the ejaculation stream.

Q.14.What is tubectomy?

Sol: Tubectomy is also known as tubal sterilization. It is a permanent method of contraception in women. In tubectomy, a small part of the fallopian tube is removed via an incision or it is tied. These techniques are effective and have reversibility.

Q.15.What is human population growth?

Sol: Human population growth is the increase in the number of individuals in a particular area. Changes in public health and sanitation have led to a decrease in the death rate over the past 200 years. The invention of antibiotics and vaccines has decreased the chances of infections in humans. Urbanization and advancements in agriculture have also led to an increase in population.

Q.16. What is Natality?

Sol: Natality is also called fertility.

It determines the growth of any population. In a population, the ability to produce a newborn baby from an active reproducing organism is called fertility. In a growing population, natality is one of the important factors.

The birth rate is the number of births per 1000 individuals per year. It can be calculated by the following formula:

B = B/t

Where:

N is the natality or the birth rate

B is the birth of a child per 1000 individuals

It is the time period in a year.

Bodenheimer divided the human population into three groups:

1. Pre-reproductive population: Population below 18 years of age.
2. Reproduction population: Population between 18 to 45 years of age.
3. Post reproductive population: Population above 45 years of age.

An increase in population growth is indicated by the total number of the reproductive population. Similarly, the number of post-reproductive populations indicates a decrease in population growth.

Q.17. What is mortality?

Sol: Mortality is also called the death rate. It is the number of deaths per thousand persons in a year.

M = D/t

Where:

M is mortality.

D is the number of death in one thousand people.

t is the time in years.

In many countries, a decline in death rates is recorded which results in an increase in the population.

This could be because of the following reasons:

1. Levels of cleanliness have increased.
2. Availability of food and water is an insufficient amount.
3. Awareness towards personal health and cleanliness has increased.
4. Developed medical facilities including immunization vaccination.

Q.18. Explain the mortality and natality along with the graph.

Sol: Mortality and natality are the important factors which determine the population. In other words, using mortality and rate, population pattern of any country can be determined

• Crude Birth Rate

The crude birth rate is the rate of births among a population of 1000.

Crude Birth Rate = (Number of living birt in a year/population in half-year ) * 100

• Crude Death Rate

The crude death rate is the rate of death among a population of 1000.

Crude Death Rate = (Number of total death in a year/population in half-year ) * 100

• The annual rate of natural increase / Growth:
1. Difference between mortality and natality is called annual growth rate.
2. Annual growth rate = Natality or birth rate – mortality rate.3

If mortality and natality are equal. The population shape is stationary means the growth rate of the population will be zero. However, it occurs very rarely. It can be seen in some developed society.

Q.19. What are the population and population growth? What are the factors affecting the rate of population growth?

Sol: A group of species, living at a specific place and at a specific time is called a population. Population growth in living species exhibits a fixed pattern, which can be exhibited by a population growth graph. The population growth graph is drawn between population size and time. The population of any country is affected by four factors:

1. Natality â€“ It is the number of births in a given period of time in a population
2. Mortality â€“ It is defined as the number of deaths that takes place in a population at a given period of time.
3. Immigration â€“ It is defined as the number of individuals which come from another population and add to the population in consideration during a period of time.
4. Emigration â€“ It is defined as the number of individuals from a population who relocate the habitat and go to a different habitat at a given period of time.

Q.20. What is the difference between J and S-shaped Curves Of Population? Explain with the graphs.

Sol: The J-shaped and the S-shaped curves are different in the following ways:

 J-shaped Curve S-shaped Curve The exponential growth of population over time. The sigmoid or the logistic growth of population over time. It occurs when there are plenty of resources. It occurs when the resources are limited. It occurs in two phases- log and lag phase. It occurs in lag phase, log phase, deceleration phase and stationary phase. The stationary is not usually reached. The stationary phase is reached. It takes into account the carrying capacity. It does not take into account the carrying capacity.

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