- Keneitsino Lydia
- June 10, 2026
Master Birth Rate and Death Rate Population MCQs Class 12 Biology: Powerful Practice Questions for Exam Success
Birth Rate and Death Rate Population MCQs Class 12 Biology is an important topic for aspirants who want to understand population ecology, population growth, natality, mortality, population density, and demographic changes in a clear and exam-focused way. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants revise how populations change over time due to births, deaths, immigration, and emigration. In ecology, a population means a group of individuals of the same species living in a particular area at a particular time. Birth Rate and Death Rate Population MCQs Class 12 Biology is useful for Class 12 board exams, NEET, nursing entrance exams, agriculture exams, and other biology-based competitive tests.
Birth Rate and Death Rate Population MCQs Class 12 Biology becomes easier when aspirants first understand birth rate. Birth rate, also called natality, refers to the number of new individuals added to a population by reproduction during a given period. Birth Rate and Death Rate Population MCQs Class 12 Biology explains that birth rate is usually expressed per individual per unit time or per thousand individuals per year. When the birth rate is high, the population tends to increase if other factors remain favorable. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants connect birth rate with reproduction, population growth, and biotic potential.
Birth Rate and Death Rate Population MCQs Class 12 Biology also explains death rate, also known as mortality. Death rate refers to the number of individuals removed from a population due to death during a particular period. Birth Rate and Death Rate Population MCQs Class 12 Biology teaches that death rate may increase due to disease, predation, competition, lack of food, unfavorable climate, pollution, or old age. If the death rate is higher than the birth rate, the population declines. If the birth rate is higher than the death rate, the population grows. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants understand this balance clearly.
Birth Rate and Death Rate Population MCQs Class 12 Biology is closely related to population density. Population density is the number of individuals present in a unit area or volume at a given time. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants remember that population density changes due to four main processes: natality, mortality, immigration, and emigration. Natality and immigration increase population size, while mortality and emigration decrease it. Birth Rate and Death Rate Population MCQs Class 12 Biology becomes easier when aspirants revise these four factors together because they are often asked in exams.
Birth Rate and Death Rate Population MCQs Class 12 Biology also includes population growth rate. Growth rate shows how fast a population increases or decreases over time. Birth Rate and Death Rate Population MCQs Class 12 Biology explains that when resources are unlimited, populations may show exponential growth. However, in nature, resources such as food, space, water, shelter, and mates are limited. Therefore, most populations show logistic growth, where the population grows slowly at first, then rapidly, and finally stabilizes near carrying capacity. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants connect birth rate and death rate with real ecological conditions.
Birth Rate and Death Rate Population MCQs Class 12 Biology should also be studied with carrying capacity and environmental resistance. Carrying capacity is the maximum population size that an environment can support. Birth Rate and Death Rate Population MCQs Class 12 Biology explains that environmental resistance includes all limiting factors that prevent unlimited population growth. These may include shortage of food, competition, predators, parasites, disease, and climatic stress. When environmental resistance increases, death rate may rise and birth rate may fall. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants understand why populations do not grow endlessly.
Birth Rate and Death Rate Population MCQs Class 12 Biology is also important for understanding human population studies. Human population growth depends on fertility, mortality, healthcare, sanitation, food availability, education, migration, and social conditions. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants revise how improvements in medicine and public health reduce death rate, while social and economic factors may influence birth rate. A rapidly growing population usually has high birth rate and low death rate. A stable population shows balance between birth rate and death rate. Birth Rate and Death Rate Population MCQs Class 12 Biology helps aspirants interpret age pyramids and demographic patterns.
For effective preparation, Birth Rate and Death Rate Population MCQs Class 12 Biology should be revised using formulas, examples, and short notes. Aspirants should understand terms such as natality, mortality, population density, biotic potential, environmental resistance, carrying capacity, exponential growth, logistic growth, immigration, and emigration. Birth Rate and Death Rate Population MCQs Class 12 Biology becomes easier when aspirants practice numerical concepts such as calculating birth rate per individual per year. Instead of memorising definitions only, aspirants should focus on how each factor affects population size. Birth Rate and Death Rate Population MCQs Class 12 Biology supports better accuracy in ecology-based questions.
Birth Rate and Death Rate Population MCQs Class 12 Biology:
- What are the end products of fermentation?
A. Methanol and CO₂
B. Acetic acid and SO₂
C. Ethyl alcohol and CO₂
D. Formaldehyde and O₂
Answer: C. Ethyl alcohol and CO₂
Explanation: The common end products of alcoholic fermentation are ethyl alcohol and carbon dioxide. Other types of fermentation may produce lactic acid or organic acids.
- What chemical is produced by the host plant to protect itself against fungal infection?
A. Toxin
B. Phytoalexin
C. Phytotoxin
D. Hormone
Answer: B. Phytoalexin
Explanation: Phytoalexins are antimicrobial compounds produced by plants in response to fungal infection. They are toxic to fungi and help protect the plant.
- Which microbe is responsible for the production of citric acid through fermentation of cane molasses?
A. Penicillium notatum
B. Rhizopus spp.
C. Aspergillus niger
D. Mucor spp.
Answer: C. Aspergillus niger
Explanation: Citric acid is produced commercially by fermentation of sugars such as cane molasses using Aspergillus niger.
- Match the following bacteria/microbes of List I with their commercial products of List II.
List I:
- Lactobacillus
- Aspergillus niger
- Acetobacteraceae
- Clostridium butyricum
List II:
I. Butyric acid
II. Acetic acid
III. Lactic acid
IV. Citric acid
Options:
A. III, II, IV, I
B. I, IV, III, II
C. III, IV, II, I
D. III, IV, I, II
Answer: C. III, IV, II, I
Explanation: Lactobacillus produces lactic acid, Aspergillus niger produces citric acid, Acetobacteraceae produces acetic acid, and Clostridium butyricum produces butyric acid.
- Which term describes organisms that are able to generate heat energy within the body and also retain it?
A. Endothermic
B. Exothermic
C. Photothermic
D. Geothermic
Answer: A. Endothermic
Explanation: Endothermic organisms can generate heat energy within the body and retain it to maintain body temperature.
- What is the term for the inactive stage that animals undergo during winter, also known as winter sleep?
A. Aestivation
B. Hibernation
C. Adaptation
D. Acclimatization
Answer: B. Hibernation
Explanation: Hibernation is the inactive stage or dormancy during winter. It is also called winter sleep.
- What is the term for the maintenance of relatively constant internal conditions different from the surrounding environment?
A. Haemostasis
B. Osmoregulation
C. Homeostasis
D. Biogenesis
Answer: C. Homeostasis
Explanation: Homeostasis is the maintenance of relatively constant internal conditions despite changes in the external environment.
- Why is it easier for a small animal to run uphill than for a large animal?
A. The efficiency of muscles in large animals is less than in small animals
B. It is easier to carry a small body weight
C. Smaller animals have a higher metabolic rate
D. Small animals have a lower O₂ requirement
Answer: C. Smaller animals have a higher metabolic rate
Explanation: Smaller animals generally have a higher metabolic rate, which results in faster energy release and helps them run uphill more easily.
- Which two changes usually tend to occur in plain dwellers when they move to high altitudes of 3,500 m or more?
A. Increase in red blood cell production and increased breathing rate
B. Increased breathing rate and increase in thrombocyte count
C. Increase in red blood cell size and increase in thrombocyte count
D. Increase in red blood cell size and increase in red blood cell production
Answer: A. Increase in red blood cell production and increased breathing rate
Explanation: At high altitudes, oxygen availability is low. The body responds by increasing breathing rate and red blood cell production.
- What is the reason for the increase in red blood cells when there is little oxygen in the body?
A. To compensate for the lack of oxygen
B. To decrease breathing depth and rate
C. To decrease heart rate
D. To increase oxygen levels in the blood
Answer: A. To compensate for the lack of oxygen
Explanation: When oxygen levels are low, the body produces more red blood cells to improve oxygen transport.
- What term is used to describe the property shown by reptiles and amphibians to change their body temperature according to the external environment?
A. Regulators
B. Conformers
C. Partial regulators
D. Thermophiles
Answer: B. Conformers
Explanation: Conformers cannot maintain a constant internal body temperature and change according to the external environment.
- What is the term used to describe the force opposite to the ability to reproduce at a given rate in the growth and development of a population?
A. Fecundity
B. Environmental resistance
C. Biotic control
D. Mortality
Answer: B. Environmental resistance
Explanation: Environmental resistance is the force that opposes the biotic potential or reproductive capacity of a population.
- What is the evolutionary force that reduces genetic variation by removing low frequency alleles?
A. Adaptive radiation
B. Gene flow
C. Genetic drift
D. Reproductive isolation
Answer: C. Genetic drift
Explanation: Genetic drift is a random change in allele frequency that may remove low frequency alleles and reduce genetic variation.
- Which of the following statements are correct about populations and communities?
I. Population is a group of organisms belonging to a species living in a particular area.
II. Population of different species in a given habitat, interacting with one another, constitute a community.
III. Population is a group of organisms belonging to different species.
Options:
A. I and III only
B. I and II only
C. II and III only
D. I, II and III
Answer: B. I and II only
Explanation: A population consists of organisms of the same species living in a particular area. A community consists of populations of different species interacting in a habitat.
- If there are 250 snails in a pond, and within a year their number increases to 2500 by reproduction, what is their birth rate per snail per year?
A. 25
B. 15
C. 10
D. 9
Answer: D. 9
Explanation: Birth rate = ΔN / N / Δt. Here, ΔN = 2500 – 250 = 2250, N = 250, and Δt = 1 year. Therefore, birth rate = 2250/250 = 9 per snail per year.
- According to the provided passage, what is the study of ecology of population called?
A. Autecology
B. Synecology
C. Ecotype
D. Demecology
Answer: D. Demecology
Explanation: Demecology is the branch of ecology that deals with the study of populations, including birth rate, death rate, population size, and growth.
- Match the microbial products listed under Column I with the related microbes given under Column II.
Column I:
A. Citric acid
B. Cyclosporin-A
C. Statin
D. Gobar gas
Column II:
p. Methanobacterium
q. Monascus purpureus
r. Aspergillus niger
s. Trichoderma polysporum
Options:
A. A-r, B-s, C-q, D-p
B. A-t, B-q, C-s, D-r
C. A-q, B-s, C-t, D-r
D. A-r, B-s, C-q, D-t
Answer: A. A-r, B-s, C-q, D-p
Explanation: Citric acid is produced by Aspergillus niger, Cyclosporin-A by Trichoderma polysporum, statins by Monascus purpureus, and gobar gas by Methanobacterium.
- Which one of the following microbes is the source for vitamin C?
A. Pseudomonas sp.
B. Acetobacter sp.
C. Aspergillus sp.
D. Chlorella
Answer: B. Acetobacter sp.
Explanation: Acetobacter is associated with vitamin C production and also helps in vinegar production.
- Match the following organisms with their products.
Organism:
a. Aspergillus niger
b. Acetobacter
c. Saccharomyces
d. Lactobacillus
Product:
i. Ethanol
ii. Butyric acid
iii. Acetic acid
iv. Citric acid
v. Lactic acid
Options:
A. a-ii, b-iii, c-v, d-iv
B. a-iv, b-iii, c-i, d-v
C. a-i, b-ii, c-iv, d-iii
D. a-iii, b-v, c-ii, d-i
Answer: B. a-iv, b-iii, c-i, d-v
Explanation: Aspergillus niger produces citric acid, Acetobacter produces acetic acid, Saccharomyces produces ethanol, and Lactobacillus produces lactic acid.
- Choose the incorrect statements from the following.
A. Aspergillus produces acetic acid.
B. Lactobacillus produces lactic acid.
C. Lipases are used in laundry.
D. Cyclosporin-A is used as blood cholesterol lowering agent.
Options:
A. A, B only
B. A, D only
C. B, C only
D. A, C only
Answer: B. A, D only
Explanation: Aspergillus niger produces citric acid, not acetic acid. Cyclosporin-A is an immunosuppressant used in organ transplantation, not a blood cholesterol lowering agent.
- Statins produced by this yeast have been commercialized as blood-cholesterol lowering agents.
A. Saccharomyces cerevisiae
B. Monascus purpureus
C. Candida utilis
D. Trichoderma
Answer: B. Monascus purpureus
Explanation: Statins produced by Monascus purpureus are used as blood cholesterol lowering agents by inhibiting cholesterol synthesis.
- Which one of the following pairs is wrongly matched?
A. Textile – Amylase
B. Detergents – Lipase
C. Alcohol – Nitrogenase
D. Fruit juice – Pectinase
Answer: C. Alcohol – Nitrogenase
Explanation: Alcohol is produced by fermentation of sugars with the help of yeast. Nitrogenase is involved in biological nitrogen fixation, not alcohol production.
- Which of the following is a commercial blood cholesterol lowering agent?
A. Statin
B. Streptokinase
C. Lipases
D. Cyclosporin-A
Answer: A. Statin
Explanation: Statins are commercial blood cholesterol lowering agents produced by Monascus purpureus.
- What is the reason for sewage water turning black?
A. H₂S
B. NH₃
C. CH₄
D. CO₂
Answer: A. H₂S
Explanation: Sewage water may turn black due to the presence of hydrogen sulphide and other decomposition products.
- What does a high amount of E. coli in water indicate?
A. Hardness of water
B. Industrial pollution
C. Sewage pollution
D. Presence of chlorine in water
Answer: C. Sewage pollution
Explanation: A high amount of E. coli in water indicates fecal contamination and sewage pollution.
- What are the sediments in the settling tanks of tertiary treatment in STP called?
A. Activated sludge
B. Contaminants
C. Effluents
D. Sewage
Answer: A. Activated sludge
Explanation: In sewage treatment, the sediment formed in settling tanks is commonly called activated sludge. It contains decomposer microbes that help in further treatment.
- What causes foul smell in water bodies of tanks and ponds?
A. Aerobiosis
B. Anaerobiosis
C. Psammophytes
D. Biological magnification
Answer: B. Anaerobiosis
Explanation: Foul smell in water bodies is caused by anaerobic decomposition of organic matter, which produces gases such as hydrogen sulphide.
- Which of the following is a biodegradable pollutant?
A. Sewage
B. Plastic
C. Polythene
D. DDT
Answer: A. Sewage
Explanation: Sewage contains organic waste and human excreta, so it is a biodegradable pollutant.
- What percentage of impurities in domestic sewage are in the form of suspended solids, colloidal material, and dissolved materials?
A. 0.1%
B. 2.1%
C. 5.0%
D. 10.0%
Answer: A. 0.1%
Explanation: Domestic sewage contains about 0.1% impurities in the form of suspended solids, colloidal matter, and dissolved substances.
- What is the sewage treatment process where a part of decomposer bacteria present in the waste is recycled into the starting of the process called?
A. Cyclic treatment
B. Activated sludge treatment
C. Primary treatment
D. Tertiary treatment
Answer: B. Activated sludge treatment
Explanation: Activated sludge treatment involves recycling a part of the decomposer bacteria-rich sludge back into the treatment process.
Conclusion on Birth Rate and Death Rate Population MCQs Class 12 Biology
In conclusion, Birth Rate and Death Rate Population MCQs Class 12 Biology is a valuable topic for aspirants preparing ecology and population biology. Birth Rate and Death Rate Population MCQs Class 12 Biology improves understanding of natality, mortality, population density, growth rate, carrying capacity, and environmental resistance. Birth Rate and Death Rate Population MCQs Class 12 Biology also helps aspirants connect theory with real examples such as human population growth, animal populations, disease effects, and resource limitation.