Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Inheritance and Variation Principles – Mutation”.

1. Which of the following is incorrect with respect to mutation?
a) Sudden
b) Continuous
c) Change in chromosomes and genes
d) Leads to variation in DNA
Answer: b
Clarification: Mutations are not continuous. Instead, mutations are discontinuous variations in the genotype and phenotype of an organism. This is due to the changes in chromosomes and DNA. Mutations are sudden and they are a cause of the variation in DNA.

2. Which of the following is not a type of mutation?
a) Gene mutation
b) Chromosomal aberrations
c) Genomatic mutations
d) Colourful mutations
Answer: d
Clarification: Mutations are of three different types depending upon their cause and environment. The three types are:
i. Gene mutation
ii. Chromosomal aberrations
iii. Genomatic mutations

3. Which of the following is a classic example of point mutation?
a) Phenylketonuria
b) Sickle cell anaemia
c) Haemophilia
d) Thalassemia
Answer: b
Clarification: Sickle cell anaemia is a classic example of point mutation. Point mutation generally means that when a single base pair of DNA changes, a gene mutation occurs that causes the alternation of DNA.

4. Which of the following is also known as the removal of one or more bases from the nucleotide chain?
a) Deletion
b) Insertion
c) Transition
d) Transversion
Answer: a
Clarification: The removal of one or more bases from the nucleotide chain is also known as deletion. Deletion is a type of frame-shift mutation. If we add one or more bases in a nucleotide chain, then it is called insertion.

5. What is the substitution of a purine base with a pyrimidine base known as?
a) Deletion
b) Transition
c) Addition
d) Transversion
Answer: d
Clarification: The substitution of a purine base with a pyrimidine base or vice versa is known as transversion. This refers to the substitution mutation which is the replacement of one base by another.

6. Change in more than one nucleotide pair is known as a spontaneous mutation.
a) True
b) False
Answer: b
Clarification: No, change in more than one nucleotide pair is not called a spontaneous mutation, instead it is known as gross mutation. When gene mutations occur naturally and automatically due to any internal reasons, then it is called as spontaneous mutations.

7. Which of the following is not responsible for the formation of chromosomes?
a) DNA
b) Proteins
c) RNA
d) Endoplasmic reticulum
Answer: d
Clarification: The endoplasmic reticulum is not responsible for the formation of chromosomes. Chromosomes are made up of proteins, DNA, and RNA. The loss or gain of a segment of DNA often causes the alternation of chromosomes.

8. Intercalary aberrations are a part of which of the following?
a) Deletion
b) Addition
c) Inversion
d) Translocation
Answer: a
Clarification: Intercalary aberrations are a type of deletions where there is a loss of an intercalary segment of a chromosome due to its double break. Deletions result in the loss of some segments of chromosomes which further leads to mutation.

9. What does the given type of aberrations in the figure represent?

a) Deletions
b) Duplications
c) Translocation
d) Inversion
Answer: b
Clarification: The given figure represents the duplication aberrations where a part of the chromosome gets added so that a gene or a set of genes is duplicated or is represented twice.

10. How does deletion occur?
a) When a part of a chromosome is duplicated
b) When a part of a chromosome is left out
c) When a part of a chromosome is lost
d) When a part of a chromosome is translocated
Answer: c
Clarification: Deletions are a type of chromosomal aberrations where a part of a chromosome is lost. It is of two types-terminal and intercalary deletions. When the terminal segment of the chromosome is lost then it is known as terminal deletions and when an intercalary segment is lost then it is known as intercalary deletions.

11. What is translocation?
a) Shifting of part of chromosomes to the outside wall of nucleus
b) Shifting of a chromosome to another chromosome
c) Shifting of a part of a chromosome to another homologous chromosome
d) Shifting of a part of a chromosome to another non-homologous chromosome
Answer: d
Clarification: Translocation is the shifting of a part of a chromosome to another non-homologous chromosome. It results in the formation of new recombinant chromosomes as this induces faulty pairing of chromosomes during meiosis.

12. What is the full form of CML?
a) Chronic myopia lens
b) Chronic myelogenous leukaemia
c) Chronic muscle leukaemia
d) Cystic muscle leukaemia
Answer: b
Clarification: CML stands for Chronic myelogenous leukaemia. CML occurs due to the translocation of a segment of the long arm from chromosome 22 to chromosome 9. Chromosome 22 is also known as the Philadelphia chromosome.

13. Paracentric is a type of inversion involving centromere.
a) True
b) False
Answer: b
Clarification: Paracentric is not a type of inversion involving centromere. Instead, it is an inversion without involving centromere. Pericentric is a type of inversion which involves centromere.

14. Segmental changes of chromosome having an evolutionary significance, is of which of the following?
a) Deletion
b) Translocation
c) Inversion
d) Addition
Answer: b
Clarification: An important class of translocation having evolutionary significance is known as segmental changes or reciprocal translocation. It involves the mutual exchange of chromosome segments between two non-homologous chromosomes.

15. In which of the following organisms, an inversion occurs frequently?
a) Drosophila
b) Moth
c) Honey bees
d) Butterflies
Answer: a
Clarification: Inversion occurs frequently in Drosophila as a result of X-ray radiation. Inversion is technically a type of chromosomal aberration where the linear order of genes changes by 180° through the rotation.

16. Genomatic mutation is of how many types?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: Genomatic mutations are of two types-
i. Aneuploidy
ii. Euploidy
This kind of mutation involves the change in chromosome number that bring about visible threats on the phenotype.

Biology Multiple Choice Questions on “Biological Evolution – 1”.

1. _________ is the evolution from coacervates to simple cell structure.
a) Chemical evolution
b) Biological evolution
c) Organic evolution
d) Inorganic evolution
Answer: b
Clarification: The evolution starting from coacervates to the formation of a simple cell structure is known as Biological evolution. It is also called as Biogemy. This shows how cells originated during evolution.

2. Which of the following is related to protobionts?
a) Large colloidal drop like structures
b) Formed from micro molecules
c) Do not absorb molecules from the atmosphere
d) Does not contain proteins, nucleic acids, etc.
Answer: a
Clarification: Macromolecules synthesized in primitive oceans came together to form large colloidal drop like structures called protobionts. They grew up by absorbing molecules from the atmosphere. They also contained proteins, nucleic acids, lipids, etc.

3. Protobiont was formed by a cluster of ______
a) micro molecules
b) nucleic acids
c) lipids
d) macro molecules
Answer: d
Clarification: Each and every protobiont was formed by a cluster of macromolecules. The basic building blocks of protobionts is macromolecules. These molecules were synthesized abiotically in the primitive ocean.

4. Protobionts were unable to reproduce.
a) True
b) False
Answer: a
Clarification: It is true that protobionts were unable to reproduce. It is because many chemical reactions such as decomposition of glucose took place inside the protobionts. This totally disallowed them to reproduce which was one of the drawbacks.

5. What were the first sole living molecules according to Oparin?
a) Diploid
b) Coacervates
c) Mycoplasma
d) Bacteria
Answer: b
Clarification: The first sole living organisms were Coacervates. According to Oparin, these coacervates gave rise to a cell. Oparin’s coacervates had the ability to grow and exhibit a simple form of metabolism. But a lipid membrane and reproduction were absent.

6. Who discovered proteinoid microspheres with a primitive membrane?
a) Oparin
b) Haldane
c) Fox
d) Thomas
Answer: c
Clarification: A scientist named Fox in 1957 discovered proteinoid microspheres which had a primitive membrane. In his research, he heated a mixture of amino acids at temperature 130 – 180°C and poured it into cold water with lipids. He found out that the microsphere got separated.

7. Who among the scientist did not prove that RNA molecules have enzymatic activity?
a) Zaug
b) Thomas Cech
c) Altman
d) Oparin
Answer: d
Clarification: Zaug, Thomas Cech and Altman proved that RNA molecules have enzymatic activity. Ribozymes also called as RNA enzymes were able to replicate or produce primordial RNA. It was also believed that earth was an ‘RNA world’ about 4 billion years ago.

8. Life originated millions of years ago as ________
a) protobionts
b) eobionts
c) coacervates
d) bacteria
Answer: b
Clarification: It was estimated about 3.9 billion years ago that, life originated as Eobionts (protocell). They evolved during the Precambrian era. They were anaerobic as well as heterotrophic in nature.

9. What was the mode of respiration for the prokaryotes during biological evolution?
a) Aerobic
b) Anaerobic
c) Cellular
d) External
Answer: b
Clarification: These prokaryotes were single-celled and consisted of naked DNA. They were chemoheterotrophs. Dependent on surrounding materials for food and energy.

10. The organisms that perform chemosynthesis for survival are called _____
a) Chemoautotrophs
b) Chemoheterotrophs
c) Chemical organisms
d) Photoautotrophs
Answer: a
Clarification: Chemoautotrophs are the organisms that perform chemosynthesis for food and survival. They produce organic molecules from inorganic molecules. They are anaerobic in nature.

11. What was utilized by photoautotrophs during photosynthesis when H₂O was absent?
a) HF
b) HCl
c) H₂S
d) H₂N₂
Answer: c
Clarification: Photoautotrophs were anaerobic and utilized hydrogen from sources other than H₂O like H₂S. So, no oxygen was produced and the atmosphere was kept reducing. This type of photosynthesis was mainly done by planktonic sulfur bacteria.

Biology Multiple Choice Questions on “Viral Diseases in Humans-1”.

1. Which virus causes Small Pox disease?
a) Variola virus
b) Varicella zoster
c) Rubeola virus
d) Rhabdo virus
Answer: a
Clarification: Variola virus causes Small Pox disease. Varicella zoster, Rubeola and Rhabdo viruses cause Chicken Pox, Measles and Rabies respectively.

2. Variola virus has ________ as genetic material.
a) Single stranded RNA
b) Double stranded RNA
c) Single stranded DNA
d) Double stranded DNA
Answer: d
Clarification: Variola virus has double stranded DNA as genetic material. Plant viruses generally have Single stranded RNA as a genetic material. Animal viruses have Single stranded or Double stranded RNA or Double stranded DNA as genetic material. Bacteriophages have Double stranded DNA as genetic material.

3. Small Pox vaccine is which kind of vaccine?
a) Attenuated Vaccine
b) Inactivated Vaccine
c) Second Generation Vaccine
d) Third Generation Vaccine
Answer: a
Clarification: Small Pox vaccine is an Attenuated Vaccine. Attenuated Vaccines are made by weakening the virulent properties of the pathogen. These vaccines provide Artificial Active Immunity and vaccination is the best preventive remedy for Small Pox.

4. Who is known as the Father of Immunology?
a) Dmitry Ivanovsky
b) Edward Jenner
c) Erik Acharius
d) Francesco Redi
Answer: b
Clarification: Edward Jenner is the Father of Immunology. He discovered the Small Pox vaccine in 1796. Dmitry Ivanovsky is known as the Father of Virology. Erik Acharius is the Father of Lichenology. Francesco Redi is the Father of Parasitology.

5. When was Small Pox eradicated from the world?
a) 1971
b) 1977
c) 1967
d) 1980
Answer: d
Clarification: The last known case of Small Pox was in 1977. However, the world was declared Small Pox free in 1980 by the World Health Organisation.

6. In Chicken Pox, rashes first appear on the body and then on the face.
a) True
b) False
Answer: a
Clarification: Rashes first appear on the body and then on the face in Chicken Pox disease. The rash comes out in crop and with each fresh crop, there may be slight fever again. Rashes change into Papules-vesicles without fluid and then into pustules and finally into a dark brown scab which falls off leaving no scar.

7. Which of the following is the most common late complication of Chicken Pox?
a) Fever
b) Shingles
c) Small Pox
d) Mumps
Answer: b
Clarification: The most common late complication of Chicken Pox is Shingles which is caused by the reactivation of Varicella zoster virus. Shingles cause the appearance of painful rashes which appear as a stripe of blisters on the trunk or the back.

8. What is the full form of MMR vaccine?
a) Mumps Measles Rabies
b) Malignant Melanoma Rheumatism
c) Measles Mumps Rubella
d) Malignant-Malaria Rheumatoid
Answer: c
Clarification: MMR Vaccine is a combined vaccine given to babies within 12-15 months of their birth for the protection against Measles, Mumps and Rubella viruses.

9. What is the incubation period of Rhabdo virus?
a) 1 day-2 weeks
b) 10-20 days
c) 2-4 weeks
d) 10 days-1 year
Answer: d
Clarification: Rhabdo virus is introduced in the body by the bite of rabid or mad dogs usually. It can also be injected by the bite of cats, wolves etc. The incubation period of this virus is from 10 days to one year.

10. Which is the most important characteristic symptom of Rabies?
a) Fear of Height
b) Fear of Water
c) Fear of Cats
d) Fear of Fire
Answer: b
Clarification: Rabies is commonly called as hydrophobia which means Fear of Water. Therefore, Fear of Water is the most important characteristic symptom of Rabies. Other symptoms include excess salivation, severe headache, alternating phases of excitement and depression.

11. What is the mortality rate of humans if they contract rabies?
a) 50% fatal
b) 100% fatal
c) No effects
d) 33% fatal
Answer: b
Clarification: Rabies is 100% fatal if neurological symptoms have developed like violent movements, uncontrolled excitement, inability to move the parts of the body, confusion and loss of consciousness. Once these symptoms appear, the result is always death.

12. What is the earliest sign of contracting Polio?
a) Paralysis
b) Inflammation of the body
c) Inability to bend the head forward
d) Inability to walk
Answer: c
Clarification: The earliest sign of Polio is the inability to bend the head forward. However, the attack of paralysis begins with high fever, headache, chills, vomiting and pain all over the body. Within 2-3 days the paralysis reaches its maximum.

13. Which of the following options is incorrect regarding the contraction of Polio?
a) It spreads through intestinal discharges
b) It spreads through contaminated food and water
c) It spreads by flies
d) It spreads through mosquito bites
Answer: d
Clarification: Polio disease mainly spreads through intestinal discharges like the faeces. It may also spread through contaminated food or water and by flies or other insects which contaminate food or drink. Poliovirus usually enters the body through the alimentary canal where it multiplies and then reaches the nervous system via bloodstream.

14. What is the full form of OPV?
a) Oral Polio Vaccine
b) Oesophagus Polio Vaccine
c) Oral Plague Vaccine
d) Oesophagus Plague Vaccine
Answer: a
Clarification: The full form of OPV is the Oral Polio Vaccine. The Oral Polio Vaccine was developed by Albert Sabin and came into commercial use in 1961.

Biology Multiple Choice Questions on “Human Health and Disease – Immune System in the Body”.

1. What is the life span of the memory B-cells of the immune system?
a) A few days
b) A few hours
c) A few years
d) A few years to whole life
Answer: d
Clarification: The life span of the memory B-cells of the immune system is a few years to whole life. These memory cells do not produce antibodies but when the same pathogen attacks for the second time, that differentiate into effector cells.

2. Which of the following is introduced during smallpox vaccination?
a) Antibodies
b) Antigens
c) Attenuated virus
d) WBCs
Answer: c
Clarification: Small Pox vaccination is a first-generation vaccine where an attenuated form of the virus is injected into the body of the patient. The first vaccination was developed by Edward Jenner against smallpox.

3. Primary response of the body to an antigen is much stronger and intense that the Secondary response.
a) True
b) False
Answer: b
Clarification: Primary immune response is the first immune response developed during the first encounter with the antigen. It is feeble but relatively longer. The secondary immune response is a quick heightened immune response against a subsequent encounter with the same antigen. It is due to the presence of memory cells against that antigen. Hence, the secondary response is more intense than the primary response.

4. Formation of a large number of effector cells against a particular antigen is called ______
a) Mass replication
b) Clonal selection
c) Mass selection
d) Pure line selection
Answer: b
Clarification: Formation of a large number of effector cells against a particular antigen is called Clonal selection. It involves the formation of a clone of cells by each activated T-lymphocyte and antibody-producing plasma cells by activated B-lymphocyte, each exhibiting the specificity for the same antigen.

5. Which of the following immunoglobulins is also called secretory immunoglobulin?
a) IgG
b) IgA
c) IgM
d) IgE
Answer: b
Clarification: IgA immunoglobulins are also called secretory immunoglobulin because it is present in all the body secretions including colostrum and mother’s milk. It functions as the first line of defence against ingested and inhaled pathogens by activating alternative pathways of the complement system.

6. Which of the following is an immunosuppressant drug?
a) Antihistamine
b) Cyclosporin
c) Neomycin
d) Streptokinase
Answer: b
Clarification: Cyclosporin is an immunosuppressant drug. This drug prevents rejection of kidney, heart and liver transplants. It destroys T-cell mediated immune responses while spares humoral antibody responses.

7. Which one of the following people are given the highest priority in transplanting organs to a donor?
a) Identical twin
b) Sibling
c) Parent
d) Unrelated donor
Answer: a
Clarification: For organ or tissue transplantation, the preference order for the donor is Identical twin > Sibling > Parent > Unrelated Donor. As there are antigens which are likely to be attacked by recipient T-cells and antibodies, the recipients of organ or tissue transplants are always given immunosuppressants.

8. Immunosuppressants are chemicals which enhance the immune system of the body.
a) True
b) False
Answer: b
Clarification: Immunosuppressants are chemicals which suppress the immune reaction of the body so that the antigens of the patient’s body do not attack the transplanted organs or tissues.

9. What is the full form of SCID?
a) Severe Combined Immunodeficiency
b) Sarcolemma Infected Disease
c) Septic Infectious diseases
d) Seven Convoluted Immunity disorder
Answer: a
Clarification: SCID stands for Severe Combined Immunodeficiency where very few T-lymphocytes are formed. B-lymphocytes are also deficient. As a result, the patient dies of even minor infections.

10. Which of the following is not a cause of Immunodeficiency diseases?
a) Gene mutation
b) Infection
c) Accident
d) Shortage of water in the body
Answer: d
Clarification: Immunodeficiency diseases are disorders of the immune system where one or more components of innate or acquired immunity become defective due to gene mutations, Infections, Malnutrition or eve accidents.

11. Lymphoid Organs are not responsible for ___________
a) Proliferation of lymphocytes
b) Differentiation of lymphocytes
c) Destruction of lymphocytes
d) Maturation of lymphocytes
Answer: c
Clarification: Lymphoid organs are not responsible for the destruction of lymphocytes. Lymphoid organs are those organs having lymphatic tissues where maturation, proliferation and differentiation of lymphocytes occur.

12. In which of the following places MALT is not found?
a) Respiratory tract
b) Digestive tract
c) Urogenital tract
d) Eyes
Answer: d
Clarification: MALT is not found in the eyes. MALT is a lymphoid tissue which is located within the mucosal lining of the major tracts like respiratory, digestive and urogenital tracts.

13. MALT constitutes for about _______ percentage of the lymphoid tissue in the human body.
a) 30%
b) 40%
c) 50%
d) 60%
Answer: c
Clarification: MALT stands for Mucosal Associated Lymphoid Tissue. It constitutes about 50% of the lymphoid tissue in the human body.

14. Which of the following organs is also called as “Graveyard of RBCs”?
a) Spleen
b) Heart
c) Bone Marrow
d) Liver
Answer: a
Clarification: Spleen is also called as Graveyard of RBCs. It is a large bean-shaped organ which mainly contains lymphocytes, phagocytes and a large number of erythrocytes. It acts as a filter of blood by trapping blood-borne microorganisms.

15. Which of the following organ is also called as “Throne of Immunity”?
a) Bone Marrow
b) Thymus
c) Brain
d) Heart
Answer: b
Clarification: Thymus is also called as Throne of Immunity or training school of T-lymphocytes. It is a lobed organ located near the heart and beneath the breast bone. It is the site where T-lymphocytes mature.

Biology Multiple Choice Questions on “Animal Breeding”.

1. Which of the following is not an aspect of animal breeding?
a) Improve desirable qualities of breeds
b) Increasing the yield
c) Making diseased organisms
d) Making disease resistance breeds
Answer: c
Clarification: Breeding of animals is an important aspect of animal husbandry. Animal breeding aims at increasing the yield of animals and improving the desirable qualities of their produce and making them disease resistant.

2. What is a breed?
a) Animals related by descent
b) Animals related by an ascent
c) Animals not related at all
d) Clone of animals
Answer: a
Clarification: A group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc., are said to belong to a breed.

3. Animals are selected for breeding on the basis of all of the following except ______
a) Mammary system and udder
b) ratio of yield to diet
c) Having long ears
d) Disease resistance
Answer: c
Clarification: Animals are selected for breeding on the basis of quality and quantity of yield, the ratio of yield to diet, duration of reproductive period and lactation, mammary system and udder and disease resistance.

4. What is inbreeding?
a) Mating of closely related species
b) Mating of unrelated species
c) Mating of clones
d) Mating of different breeds
Answer: a
Clarification: Inbreeding refers to the mating of more closely related individuals within the same breed for 4-6 generations. The breeding strategy is as follows-superior males and superior females of the same breed are identified and mated in pairs.

5. Crosses between different breeds are called inbreeding.
a) True
b) False
Answer: b
Clarification: When breeding is between animals of the same breed, it is called inbreeding, while crosses between different breeds are called outbreeding. Also, inbreeding is the mating of two related species while outbreeding is the mating of two unrelated species.

6. Which of the following is not associated with inbreeding?
a) Mating between animals of unrelated species
b) Elimination of undesirable characters
c) Increases homozygosity
d) Causes inbreeding depression
Answer: a
Clarification: Inbreeding is the mating between the animals of the same breed having common ancestors up to 4-6 generations. Inbreeding increases homozygosity. It is also responsible for the elimination of undesirable characters and it causes inbreeding depression.

7. Which of the following type of animals breeding is used to develop a pure line in any animal?
a) Outcrossing
b) Crossbreeding
c) Hybridisation
d) Inbreeding
Answer: d
Clarification: Inbreeding increases homozygosity, thus inbreeding is necessary if we want to evolve a pure line in any animal. Inbreeding also exposes harmful recessive genes that are eliminated by selection. It also helps in the accumulation of superior genes and the elimination of less desirable genes.

8. Which breeding is used to overcome inbreeding depression?
a) Out-crossing
b) Cross-breeding
c) Interspecific hybridisation
d) Inbreeding
Answer: a
Clarification: Continued inbreeding, especially close inbreeding, usually reduces fertility and even productivity. This is called inbreeding depression. Whenever this becomes a problem, selected animals of the breeding population should be mated with unrelated animals of the same breed. This is called as outcrossing and it often helps to overcome inbreeding depression.

9. Which of the following is the best breeding method for animals which are below average in productivity?
a) Out-breeding
b) Out-crossing
c) Inbreeding
d) Interspecific hybridisation
Answer: b
Clarification: Out-crossing is the practice of mating of animals within the same breed, but having no common ancestors on either side of their pedigree. The offspring of such a mating is known as an outcross. It is the best breeding method for animals that are below average in productivity in milk production, the growth rate in beef cattle, etc.

10. Which of the following is not included in out-breeding?
a) Out-crossing
b) Cross-breeding
c) Inbreeding
d) Interspecific hybridisation
Answer: c
Clarification: Out-breeding is the breeding of the unrelated animals which may be between individuals of the same breed but having no common ancestors for 4-6 generations (Out-crossing) or between different breeds (Cross-breeding) or different species (Interspecific hybridisation).

Biology Problems for MBBS Entrance Exams on “Plant Diseases caused by Fungi and Nematodes”.

1. Disease-causing fungi are of ____ types.
a) Two
b) Three
c) Four
d) Five
Answer: a
Clarification: Disease-causing fungi are of two types, obligate and non-obligate parasites. Obligate parasites can grow and multiply only in the association of their host plants. Non-obligate parasites become parasitic only when they come in contact with a suitable host.

2. Symptoms of fungal diseases may be localised or systemic.
a) True
b) False
Answer: a
Clarification: Symptoms of fungal diseases may be localised i.e. restricted to an area of infection or maybe systemic i.e. spreading throughout the plant body.

3. Which of the following is not a method of controlling fungal diseases?
a) Antibiotics
b) Fungicides
c) Resistant varieties
d) Use of pathogen-free seeds
Answer: a
Clarification: Fungal diseases can be controlled by roguing or removal of diseased parts, sanitation or destruction of plant debris, resistant varieties, use of pathogen-free seeds, bio pesticides if available and spraying with fungicides like Bordeaux mixture.

4. Witches’ broom is a characteristic symptom of diseases caused by ___________
a) Virus
b) Fungi
c) Bacteria
d) Nematodes
Answer: b
Clarification: Witches broom is a characteristic symptom of diseases caused by fungi. The various symptoms of the fungal disease include necrosis, leaf spots, cankers, scabs, pustules, dieback, damping off, blights, rots, stunting, leaf curls, overgrowths, warts, galls, witches’ broom, wilt, rust, smut and mildew.

5. The following diagram represents the infected leaf of ________

a) Early blight of potato
b) Late blight of potato
c) Black rust of wheat
d) Smut of Wheat
Answer: b
Clarification: The following diagram represents the infected leaf of Late blight of potato. It is caused by the fungus Phytophthora infestans. The disease kills the foliage, reducing the yield of tubers which are often are infected.

6. The following diagram represents the infected black stem of ___________

a) Rice
b) Wheat
c) Barley
d) Cocoa
Answer: b
Clarification: The above diagram represents the infected black stem rust of wheat. Rusts of Wheat are brownish to blackish spore rich pustules which develop on the leaves and stem surface of Wheat. Rusts are generally caused by Puccinia.

7. Which of the following statements is not related to Loose smut of Wheat?
a) Caused by Ustilago
b) Attacks barley
c) Caused by Puccinia
d) A disease common in humid areas
Answer: c
Clarification: Loose smut of wheat is a highly damaging smut disease that is more common in humid areas. The disease is caused by Ustilago. It also attacks Barley and a number of grasses.

8. Which of the following is a Non-characteristic symptom of Nematode disease?
a) Yellowing of Foliage
b) Distortion of leaves
c) Necrotic lesions
d) Blotches
Answer: a
Clarification: Non- characteristic above-ground symptoms of nematode disease include reduced growth, yellowing of foliage, wilting and low-quality yield of the plant.

9. Fungicides can be used to treat diseases caused by Nematodes.
a) True
b) False
Answer: b
Clarification: Measures used to control diseases caused by nematodes include disinfection of soil by steam, rotation of crops, fallowing, biological control agents, uncontaminated seeds, resistant varieties and spraying crops with nematicides.

10. Which of the following statement is not related to Root-Knot of Brinjal and Tomato?
a) Caused by Meloidogyne
b) The male worm is cylindrical
c) The female worm is circular
d) Site of infection produces gall
Answer: c
Clarification: Root-knot of Brinjal and Tomato is caused by nematode Meloidogyne incognita. The male worm is cylindrical and female worm is pear-shaped. Infected cells proliferate near the site of infection produces spherical to elliptical swellings called galls.

To practice Biology Problems for MBBS Entrance Exams,