Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Polygenic Inheritance”.

1. What kinds of traits were described by Mendel?
a) Contrasting traits
b) Alternative forms
c) Mixed forms
d) Opposite and recessive forms
Answer: a
Clarification: Through the experiments of pea conducted by Mendel, he described distinct contrasting traits such as flower colour which are either purple or white.

2. What are polygenic traits?
a) Traits controlled by a single gene
b) Traits not controlled by any genes
c) Traits controlled by two genes
d) Traits controlled by three or more genes
Answer: d
Clarification: Traits are the feature of a character by which we can distinguish organisms. Traits which are generally controlled by three or more genes are known as polygenic traits.

3. Which of the following is a classic example of polygenic inheritance?
a) Skin colour in humans
b) Blood groups
c) Flower colour in peas
d) Stem height in peas
Answer: a
Clarification: Skin colour in humans is a classic example of polygenic inheritance as this trait is controlled by three or more genes and we can see that this trait is not so distinct amongst the human population and is spread across a gradient.

4. In humans, only tall and short people exist.
a) True
b) False
Answer: b
Clarification: Height of humans is a polygenic trait and is therefore not limited to only tall and short people. Instead of two distinct alternative traits, a range of all the possible heights is present in a human population.

5. What are polygenes?
a) Genes involved in quantitative inheritance
b) Genes involved in the qualitative inheritance
c) Genes involved in multiple allelism
d) Multiple genes for a single trait
Answer: a
Clarification: Genes which are involved in quantitative inheritance are called as polygenes. In quantitative inheritance, each dominant allele expresses itself as a part of functional polypeptide and the full trait is shown when all the dominant alleles are present in an organism.

6. Which of the following scientists demonstrated the quantitative traits in wheat?
a) Ernst Haeckel
b) H. Nilsson-Ehle
c) West
d) Paul Vincent
Answer: b
Clarification: H. Nilsson-Ehle in 1908 and East in 1910 demonstrated the segregation and assortment of genes that controlled the quantitative traits, e.g., Kernel colour in wheat and corolla length in tobacco.

7. Which two varieties of wheat were crossed by H. Nilsson to study the kernel colour in wheat?
a) Red and black kernelled variety
b) Red and white kernelled variety
c) White and black kernelled variety
d) Black and blue kernelled variety
Answer: b
Clarification: In order to study the kernel colour of wheat, H. Nilsson crossed red kernelled variety with a white kernelled variety of wheat. He found out that the kernel colour in wheat is determined by AA and BB genes.

8. What was the ratio of F2 generation when red and white kernelled variety of wheat were crossed?
a) 1: 2: 1
b) 9: 3: 3: 1
c) 1: 4: 6: 4: 1
d) 3: 1
Answer: c
Clarification: The ratio of F2 generation when red and white kernelled wheat varieties were crossed was obtained as-1: 4: 6: 4: 1. Also, five different phenotypic classes were obtained.

9. Which of the following is not a phenotypic class of the F2 generation in wheat?
a) Extreme red
b) Deep red
c) Black
d) White
Answer: c
Clarification: The five phenotypic classes obtained while crossing red and white kernelled wheat variety are: the extreme red, deep red, intermediate red, light red and white.

10. On which of the following factor, the degree of redness of progenies depend?
a) Number of dominant alleles
b) Number of recessive alleles
c) Number of contrasting traits
d) Number of phenotypic characters
Answer: a
Clarification: When we crossed a red and white kernelled variety of wheat, we saw that all the red kernels do not exhibit the same shade of redness. The degree of redness was found to depend upon the number of dominant alleles.

11. On how many loci the genes responsible for skin colour are present?
a) Two
b) Three
c) Four
d) Five
Answer: b
Clarification: The three pair of genes which determine the skin colour in humans are present at three different loci and each dominant allele of that gene is responsible for the amount of melanin pigment in the skin.

12. On which of the following factors, the amount of melanin produced depends?
a) Number of recessive alleles
b) Number of chromosomes present in an individual
c) Number of dominant genes
d) Number of loci present in DNA
Answer: c
Clarification: The amount of melanin produced in the skin of humans is always proportional to the number of dominant genes. The effect of all the genes that are responsible for the skin colour is additive.

13. Davenport showed that six pairs of genes are involved in controlling the skin colour in humans.
a) True
b) False
Answer: b
Clarification: Davenport was a scientist who demonstrated that six genes are involved in controlling the skin colour in human beings. He also showed that skin colour can only be studied in a population.

14. Which of the following curves can be a representation of the skin colour in a population?
a) Sigmoid curve
b) An ellipse
c) Histogram
d) J-shaped curve
Answer: c
Clarification: We can study the frequency distribution of skin colour in the form of a bell-shaped normal distribution curve which is also represented by a Histogram.

15. Which of the following conclusions can be made by studying a histogram?
a) Extreme phenotypes are common
b) Intermediate phenotypes are more frequent
c) Intermediate phenotypes are rare
d) All phenotypes are present in equal amounts
Answer: b
Clarification: We can draw two conclusions by studying a histogram. These are that in a polygenic inheritance, the extreme phenotypes are rare and the intermediate ones are more frequent.

16. Which of the following is not an example of quantitative trait?
a) Cob length in maize
b) Height in humans
c) Human intelligence
d) Blood groups in humans
Answer: d
Clarification: Cob length in maize, height in humans, human intelligence, milk and meat production, height in humans and size, shape and number of seeds and fruits in plants are some of the common examples of quantitative traits.

Biology Multiple Choice Questions on “Evolution of Life Forms-A Theory”.

1. Which of the following was not included in theory of special creation?
a) All the living organisms that see today were created as such
b) The diversity was always the same since creation and will be the same in future
c) The earth is about 4000 years old
d) The solar system came from a massive body
Answer: d
Clarification: Theory of special creation said that life has not changed a bit since its origin. Our solar system was formed from Big bang and not from a massive body. The remaining options are the connotations of theory of special creation.

2. Who supported the theory of special creation?
a) Father Suarez
b) Father Darwin
c) Lamarck
d) Abbe Lemaitre
Answer: a
Clarification: Father Suarez was the greatest supporter of theory of special creation. Abbe Lemaitre proposed the Big-bang theory whereas the use and disuse of organs theory was put forward by Lamarck.

3. _______ was the name of the ship in which Darwin sailed around the world.
a) H.S.S Beagle
b) H.M.S Beagle
c) H.P.S Beagle
d) H.M.S Eagle
Answer: b
Clarification: Charles Darwin had set voyage around the world in a ship named H.M.S Beagle. He traveled to different islands to research about evolution. He found out that the existing living organisms had many similarities with life forms that existed millions of years ago.

4. ________ fitness was the fitness referred by Darwin for natural selection?
a) Reproductive
b) Health
c) Survival
d) Physical
Answer: a
Clarification: According to Darwin, reproductive fitness was the fitness required to survive in nature. It is the ability to adapt and get selected by nature. They will produce more off springs than other species, and have better chance for survival.

5. The scientist who divided the whole world into six major biogeographical regions called realms is _______
a) Hugo de Vries
b) Charles Darwin
c) Alfred Russel Wallace
d) Mathew Morgan
Answer: c
Clarification: On the basis of flora and fauna, Alfred Wallace divided the world into six major biogeographical regions called realms. This was based on biogeographical distribution. He worked and researched in Malay Archipelago.

6. Darwin found his finches in Galapagos Island.
a) True
b) False
Answer: a
Clarification: Darwin in his journey around the world, visited Galapagos island, where he discovered finches. He noticed the change in the modification of beaks of these finches and proposed adaptive radiation.

7. Evolution is a ______ process.
a) quick
b) stochastic
c) slow
d) fast
Answer: b
Clarification: Evolution is a stochastic process, which means that it is focusing on chance mutations. Based on determinism, evolution is not a direct process. It is also based on events that occurs in a chance.

8. It is said to believe that all the continents were present in the form of a single land mass called as ______
a) Pangaea
b) Globe
c) Echidna
d) Prion
Answer: b
Clarification: Millions of years ago, all the continents were present in the form of a single mass called Pangaea. It was due to a phenomenon called continental drift; the whole land mass split into seven respective continents.

9. Survival of fittest was the original idea of ________
a) Charles Darwin
b) Lamarck
c) Gregor Mendel
d) Herbert Spencer
Answer: d
Clarification: Herbert Spencer gave the original idea of survival of the fittest. But according to Darwin, fitness refers mainly only to reproductive fitness. Lamarck proposed use and disuse theory of organs. Mendel did experiments on genetics.

10. The drawback of Darwinism was that it couldn’t explain _______
a) Variations
b) Large rate of production
c) Struggle for existence
d) Reproductive fitness
Answer: a
Clarification: Darwin couldn’t explain why a few species develop useful variation and others have harmful variations. Also, he was not able to tell the difference in between somatic and germinal variations.

Biology Multiple Choice Questions on “Human Health and Diseases”.

1. Who is the Father of Medicine?
a) Aristotle
b) Hippocrates
c) Antoine van Leeuwenhoek
d) Antoine Lavoisier
Answer: b
Clarification: The Father of Medicine is Hippocrates. Aristotle is the Father of Biology, Antoine van Leeuwenhoek is the Father of Microbiology and Antoine Lavoisier is the Father of Chemistry.

2. Health is not defined by ________
a) physical well being
b) mental well being
c) social well being
d) genetic Disorders
Answer: d
Clarification: Health is defined as a state of complete physical, mental and social well-being. While genetic disorders are the deficiencies or defects which the child inherits from parents from birth, which affect the health of an individual.

3. Who discovered blood circulation in the human body?
a) William Harvey
b) Robert Hooke
c) Karl Landsteiner
d) Robert Brown
Answer: a
Clarification: William Harvey first discovered blood circulation in the human body. Robert Hooke discovered cell, Karl Landsteiner discovered blood groups and Robert Brown discovered nucleus in a cell.

4. Which of the following is the most fatal non-infectious disease?
a) AIDS
b) Cancer
c) Diabetes
d) Obesity
Answer: b
Clarification: Cancer is the most fatal non-infectious disease. In 2017, 9.6 million people are estimated to have died from various forms of cancer. While AIDS is the most fatal infectious disease affecting nearly 36.9 million people worldwide. Diabetes and Obesity are also non-infectious diseases but not the most fatal.

5. Diseases can be broadly grouped into infectious and non-infectious diseases.
a) True
b) False
Answer: a
Clarification: Diseases can be grouped into infectious and non-infectious diseases. Those diseases which can be transmitted by blood, serum or any other body fluid are called infectious diseases and those diseases which cannot be transmitted from patients to other people are called as non-infectious diseases.

6. Which of the following is not a biological agent that causes disease?
a) Mycoplasma
b) Virus
c) Radiations
d) Fungi
Answer: c
Clarification: Radiations are physical agents that cause disease along with electricity, pressure, heat, cold, etc. Mycoplasma, virus and fungi are biological agents or pathogens that cause various diseases.

7. How are Infectious Diseases transmitted?
a) Droplet Infection
b) They are inherited
c) By seeing patients
d) Eating an unhealthy diet
Answer: a
Clarification: Infectious diseases are transmitted from one person to another by droplet infection, direct contact with infected persons, animal bite, contact with soil or by transplacental transmission.

8. Which of the following is a Congenital Disease?
a) Kwashiorkor
b) Sickle-cell anaemia
c) Goitre
d) Rheumatoid Arthritis
Answer: b
Clarification: Sickle-cell anaemia is a congenital disease. Congenital diseases are contracted before birth due to chromosomal abnormalities or gene mutations or defect in development. Goitre and Kwashiorkor are caused due to deficiency of an essential element while Rheumatoid Arthritis is an autoimmune disease.

9. Which property is not exhibited by a disease-causing pathogen?
a) Invasiveness
b) Toxigenicity
c) Virulence
d) Co-operation
Answer: d
Clarification: Co-operation is a property not exhibited by a pathogen. Invasiveness of a pathogen is its ability to gain entry into a host and grow. Virulence is the ability of a pathogen to produce disease. Toxigenicity is the power of a pathogen to form toxins capable of damaging host cells.

10. Excess or deficiency of chromosomes, mutations, harmful alleles are the mechanical agents which cause diseases.
a) True
b) False
Answer: b
Clarification: Excess or deficiency of chromosomes, mutations, harmful alleles are the genetic agents which cause diseases. These agents cause diseases like colour blindness, albinism, haemophilia, Turner’s syndrome etc.

11. Which of the following is not a Degenerative disease?
a) Hypertension
b) Atherosclerosis
c) Obesity
d) Alzheimer’s disease
Answer: c
Clarification: Degenerative diseases are those diseases which are caused by ageing resulting in malfunctioning or decreased deficiency. For example-Hypertension, Atherosclerosis, Alzheimer’s disease etc.

12. Which of the following does not affect health?
a) Genetic disorders
b) Infections
c) Life Style
d) Health Insurance
Answer: d
Clarification: Genetic Disorders are the deficiencies or the defects with which a child is born or inherits them from parents. Infections are also a disease caused by the invasion of microorganisms. Life Style includes how much exercise we do daily and how much healthy do we eat every day. So Genetic Disorders, Infections and Lifestyle affect our health.

Biology Multiple Choice Questions on “Human Health and Disease – Vaccination and Immunisation”.

1. Who discovered the technique of preparing vaccine from attenuated pathogen and in which year?
a) Edward Jenner, 1796
b) Louis Pasteur, 1879
c) Robert Downey, 1856
d) Von Behring, 1950
Answer: b
Clarification: Louis Pasteur discovered the technique of preparing vaccine from an attenuated pathogen in 1879. This was the first true vaccine consisting of weakened micro-organisms against the disease chicken cholera.

2. The term vaccine was introduced by ________
a) Edward Jenner
b) Robert Koch
c) Louis Pasteur
d) Von Behring
Answer: a
Clarification: The term vaccine was coined by Edward Jenner. A vaccine is a suspension or extract of weakened pathogens which when injected into a healthy person provides active acquired immunity to the disease.

3. Jenner prepared the vaccine of smallpox by using _______
a) The attenuated pathogen of smallpox
b) The killed pathogen of smallpox
c) The attenuated pathogen of Cowpox
d) Pathogens from Cowpox pustule
Answer: d
Clarification: Edward Jenner prepared his first vaccine of smallpox by using pathogens from cow pustule. He injected fluid from the sore of milkmaid suffering from cowpox into the body of a healthy boy which did not later catch smallpox.

4. Why are the vaccines produced through genetic engineering considered as safe?
a) They have only the coat of pathogen
b) They are attenuated form of a pathogen
c) They have killed form of pathogens
d) They have all the genes of pathogens
Answer: a
Clarification: The vaccines produced through genetic engineering are considered safe because they contain antigen only from the coat of pathogen which is almost harmless.

5. What is the basic principle of immunisation and vaccination?
a) It is based on the number of B and T lymphocytes
b) It is based on the property of memory of the immune system
c) It is based on antigen-antibody interactions
d) It is based upon the number of white blood cells
Answer: b
Clarification: The basic principle of immunisation or vaccination is based on the property of memory of the immune system. When an immunised person is attacked by the pathogen, the existing bodies immediately attack the antigen while the memory T and B cells give rise to a massive crop of lymphocytes and antibodies.

6. Toxoids are toxins usually inactivated by formalin which retain their antigenic property.
a) True
b) False
Answer: a
Clarification: Toxoids are toxins usually inactivated by formalin which retain their antigenic property. A toxoid stimulates the antitoxin formation and protects the body from exotoxins= producing organisms.

7. ATS inoculation soon after injury that brings contact with soiled objects give protection against the possible attack of __________
a) Poliomyelitis
b) AIDS
c) Tetanus
d) Influenza
Answer: c
Clarification: ATS inoculation soon after injury that brings contact with soiled objects give protection against the possible attack of tetanus. Wounds and cutes or surgical instruments coming in contact with the road dust may cause the entry of spores into the body. Injection of ATS within 24 hours of injury gives passive immunity to the individual.

8. A disease against which vaccination is resorted only during epidemics is ___________
a) Diarrhoea
b) Tuberculosis
c) AIDS
d) Cholera
Answer: d
Clarification: A disease against which vaccination resorts only during epidemics is Cholera. Vaccination against cholera gives immunity for only a few months. It is useful, especially during epidemics. Chlorination or ozone treatment of water, boiled water, disinfected food are measures essential for prevention.

9. On which of the following discoveries, Von Behring was awarded the noble prize?
a) For discovering passive immunity
b) For discovering active immunity
c) For discovering and making the first true vaccine
d) For discovering methods to protect people from smallpox
Answer: a
Clarification: Von Behring was awarded the noble prize for his work on passive immunity. He is also regarded as the Father of Passive immunity.

10. Emil Von Behring injected some toxoid serum into the patient suffering from AIDS to discover passive immunity.
a) True
b) False
Answer: b
Clarification: Emil Von Behring injected some toxoid serum into the patient suffering from Diphtheria. He withdrew some blood from an infected diphtheria sheep and the separated the serum by allowing it to clot. He injected this serum into the patient suffering from Diphtheria. Within a few hours, she began to recover dramatically.

11. Which of the following statements is incorrect regarding Vaccination and Immunisation?
a) Immunisation is the phenomena of increasing specific antibody production
b) Vaccination is the process of inoculation of harmless antigenic material into the healthy person
c) A single vaccination gives adequate immunity and lasts lifelong
d) Immunisation is carried out through vaccination and injection of antiserum
Answer: c
Clarification: A single vaccination gives adequate immunity and lasts lifelong is the incorrect statement. It may not give adequate immunity. Therefore, 2-3 booster doses of vaccine are administered later on at specific intervals.

Biology Multiple Choice Questions on “Food Production Strategies – Single Cell Protein”.

1. SCP stands for __________
a) Single Cell Protein
b) Stress Cultivated Plant
c) Somatic Cultivated Plantlet
d) Soma Clonal Plants
Answer: a
Clarification: SCP stands for Single Cell Protein. Single-cell protein is protein-rich cell biomass of unicellular or multicellular organisms which is used as food or feed.

2. How much per cent of the human population is suffering from hunger and malnutrition?
a) 75 per cent
b) 5 per cent
c) 25 per cent
d) 50 per cent
Answer: c
Clarification: More than 25 per cent of the human population is suffering from hunger and malnutrition. One of the alternate sources of proteins for animal and human nutrition is SCP.

3. Which of the following algae can be grown on wastewater?
a) Spirogyra
b) Volvox
c) Spirulina
d) Chlamydomonas
Answer: c
Clarification: Microbes are being grown on an industrial scale as a source of good protein. Blue-green algae like Spirulina can be grown easily on materials like wastewater from potato processing plants that contain starch.

4. On which of the following material, Spirulina cannot grow?
a) Straw
b) Molasses
c) Animal manure
d) Lava
Answer: d
Clarification: Spirulina can be easily grown on materials like straw, molasses, animal manure and even sewage, to produce large quantities and can serve as food rich in protein, minerals, fats and carbohydrates and vitamins. Incidentally, such utilisation also reduces environmental pollution.

5. Which of the following bacterial species is known for its high rate of biomass production?
a) Methylophilus methylotrophus
b) Xanthomonas
c) Clostridium
d) Rhizomonas
Answer: a
Clarification: Certain bacterial species like Methylophilus methylotrophus have a high rate of biomass production and growth and are known to produce 25 tonnes of protein.

6. The shift from grain to meat diets also creates more demand for cereals.
a) True
b) False
Answer: a
Clarification: The shift from grain to meat diets also creates more demand for cereals as it takes 3-10 kg of grain to produce 1 kg of meat by animal farming. For example, a 250 kg cow produces only 200 grams of protein per day while it eats 10-30 kg of food.

7. Which of the following is the most common source of SCP?
a) Multicellular yeast
b) Single-celled yeast
c) Unicellular algae
d) Unicellular bacteria
Answer: b
Clarification: The most common source of single-cell protein is single-celled yeasts (e.g., Candida utilis) and filamentous fungus-like Fusarium graminearum. Single-cell protein is rich in good quality protein.

8. Which of the following is not an organic matter on which microorganisms are raised for SCP?
a) Sawdust
b) Paddy straw
c) Acids
d) Whey
Answer: c
Clarification: Microbial biomass can be raised using low-cost organic matter like that of sawdust, paddy straw, paddy husk and industrial organic wastes and effluents like whey. However, care has to be taken to remove excess nucleic acids and heavy metals or toxins present in organic wastes.

9. Low protein and high fat are desirable features of human food.
a) True
b) False
Answer: b
Clarification: Single Cell Protein is rich in good quality protein but poor in fats because high protein and low-fat contents are desirable features of human food. Therefore, SCP can be used as food or feed.

10. Which of the following is not an advantage of SCP?
a) Used as a protein-rich diet
b) Reduce environmental pollution
c) Increase in supply of protein
d) Increases water pollution
Answer: d
Clarification: SCP can be used as a protein-rich supplement of human diet and can take off the pressure from the agricultural system for increasing the protein content of food articles. It also increases the protein supply and use of organic wastes and industrial effluents helps in reducing environmental pollution.