CBSE Class 12 Biology Human Health And Diseases Question Bank

MULTIPLE CHOICE QUESTIONS

Question. Which malarial parasite has longest incubation period?
(a) Plasmodium vivax
(b) Plasmodium falciparum
(c) Plasmodium malariae
(d) Plasmodium ovale
Answer. C

Question. The type of antibodies present in colostrum secreted from mammary gland is 
(a) IgM
(b) IgD
(c) IgE
(d) IgA
Answer. D

Question. Sporogony of malarial parasite occurs in
(a) liver of man
(b) RBCs of man
(c) stomach wall of mosquito
(d) salivary glands of mosquito
Answer. D

Question. Cyclosporine is used 
(a) For allergy
(b) As immunodepressent
(c) Prophylactic for virus
(d) None of the above
Answer. B

Question. Lysis of foreign cell is mediated through 
(a) IgM
(b) IgA
(c) IgE
(d) IgM & IgG
Answer. C

Question. The treatment of snake-bite by antivenom is an example of 
(a) artificially acquired active immunity
(b) artificially acquired passive immunity
(c) naturally acquired passive immunity
(d) specific natural immunity
Answer. B

Question. Electron beam therapy is a kind of radiation therapy to treat 
(a) enlarged prostate gland
(b) gall bladder stones by breaking them
(c) certain types of cancer
(d) kidney stones
Answer. C

Question. A young drug addict used to show symptoms of depressed brain activity, feeling of calmness, relaxation and drowsiness. Possibly he was taking
(a) Amphetamine
(b) Marijuana
(c) Pethadine
(d) Valium
Answer. D

Question. When children play bare footed in pools of dirty water and flood water, they may suffer from diseases like 
(a) leptospirosis and bilharizia
(b) malaria, amoebic dysentery and leptospirosis
(c) bilharizia, infective hepatitis and diarrhoea
(d) guinea worm infection, elephantiasis and amoebic dysentery
Answer. A

Question. Which one of the following is not a matching pair of a drug and its category ? 
(a) Amphetamines - stimulant
(b) Lysergic acid - narcotic dimethyl amide
(c) Heroin - psychotropic
(d) Benzodiazepam - pain killer
Answer. D

Question. An insect bite may result in inflammation of that spot. This is triggered by the alarm chemicals such as 
(a) histamine and dopamine
(b) histamine and kinins
(c) interferons and opsonin
(d) interferons and histones
Answer. B

Question. Antigen binding site in an antibody is found between 
(a) two light chains
(b) two heavy chains
(c) one heavy and one light chain
(d) either between two light chains or between one heavy and one light chain depending upon the nature of antigen
Answer. C

Question. Antigen is a substance which 
(a) lowers body temperature
(b) destroys harmful bacteria
(c) triggers the immune system
(d) is used as an antidote to poison
Answer. C

Question. Opium is obtained from 
(a) Oryza sativa
(b) Coffea arabica
(c) Thea sinensis
(d) Papaver somniferum
Answer. D

Question. Match the following bacteria with the diseases
Column-I                       Column-II
A. Treponema pallidum     I. Plague
B. Yersinia pestis             II. Anthrax
C. Bacillus anthracis        III. Syphilis
D. Vibrio                         IV. Cholera
(a) A – III; B – I; C – II; D – IV
(b) A – IV; B – I; C – II; D – III
(c) A – III; B – II; C – I; D – IV
(d) A – I; B – III; C – II; D – IV
Answer. A

Question. Which one of the following is a correct match?
(a) Bhang – Analgesic
(b) Cocaine – Opiate narcotics
(c) Morphine – Hallucinogen
(d) Barbiturate – Tranquiliser
Answer. D

Question. Which of the following is an autoimmune disorder? 
(a) Myasthenia gravis
(b) Osteoporosis
(c) Muscular dystrophy
(d) Gout
Answer. A

Question. Which of the following is based upon the principle of antigen-antibody interaction?
(a) PCR
(b) ELISA
(c) r-DNA technology
(d) RNA
Answer. B

Question. Identify the molecules (A) and (B) shown below and select the right option giving their source and use.

Molecule Source Uses
(a) (A) Cocaine          Erythroxylum coca      Accelerates the transport of dopamine
(b) (B) Heroin            Cannabis sativa         Depressant and slows down body functions
(c) (B) Cannabinoid    Atropa belladona        Produces  hallucinations
(d) (A) Morphine       Papaver somniferum    Sedative and pain killer
Answer. D

Question. Pasteurella/Yersinia pestis (causal agent of Bubonic Plague) is transmitted by 
(a) Cimex
(b) Xenopsylla
(c) Pediculus
(d) Aedes
Answer. B

Question. Which of the following pairs is not correctly matched ? 
(a) Cholera – Vibrio cholerae
(b) German measles – Rubella virus
(c) Whooping cough – Bordetella pertussis
(d) Tetanus – Pasteurella pestis
Answer. D

Question. Human immuno deficiency virus (HIV) has a protein coat and a genetic material which is
(a) Single stranded DNA.
(b) Single stranded RNA.
(c) Double stranded RNA.
(d) Double stranded DNA.
Answer. B

Question. Which one of the following pairs of diseases is viral as well as transmitted by mosquitoes?
(a) Elephantiasis and dengue
(b) Yellow fever and sleeping sickness
(c) Encephalitis and sleeping sickness
(d) Yellow fever and dengue
Answer. D

ASSERTION REASON QUESTIONS 

Directions : Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

Question. Assertion : Escherichia coli, Shigella sp. and Salmonella sp. are all responsible for diarrhoeal diseases.
Reason : Dehydration is common to all types of diarrhoeal diseases and adequate supply of fluids and electrolytes should be ensured.
Answer. B

Question. Assertion : Dope test is used to estimate the level of blood alcohol by analyzing the breath of persons drinking alcohol.
Reason : A drunken person usually feels tense and less talkative. 
Answer. D

Question. Assertion : Interferons are a type of'antibodies produced by body cells infected by bacteria.
Reason : Interferons stimulate inflammation at the site of injury.
Answer. D

Question. Assertion : Mast cells in the human body release excessive amounts of inflammatory chemicals, which cause allergic reactions.
Reason : Allergens in the environment on reaching human body stimulate mast cells in certain individuals.
Answer. A

Question. Assertion : Cannabis sativa is a powerful anti-depressant.
Reason : Hashish and Marijuana are derived from it.
Answer. D

Question. Assertion: Epstein– Barr virus is an oncovirus.
Reason: It stimulates the growth of cancer.
Answer. A

Question. Assertion: HIV infected person are prone to oppurtunistic diseases.
Reason: Immune system weakens during HIV infection. 
Answer. A

Question. Assertion : Histamine is involved in allergic and inflammatory reactions.
Reason : Histamine is a vasodilator. 
Answer. A

Question. Assertion : The antibodies separted from serum are homogenous.
Reason : Monoclonal antibodies are homogenous immunological reagents. 
Answer. D

Question. Assertion : Interferons are effective against viruses.
Reason : Proteins which can be synthesized only by genetic engineering are effective against viruses. 
Answer. C

Question. Assertion : Cancer cells are virtually immortal until the body in which they reside dies.
Reason : Cancer is caused by damage to genes regulating the cell division cycle.
Answer. B

Question. Assertion : Cocaine has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy.
Reason : Injecting the microbes intentionally during immunisation or infectious organisms gaining access into body during natural infection induces active immunity. 
Answer. C

Question. Assertion: Artificially acquired passive immunity results when antibodies or lymphocytes produced outside the host are introduced into a host.
Reason: A bone marrow transplant given to a patient with genetic immunodeficiency is an example of artificially acquired passive immunity.
Answer. B

Very Short Answer Questions

Question. Millions of chickens were killed in West Bengal, Orissa and Maharashtra recently. What was the reason? 
Answer. Millions of chickens were killed (culled) in West Bengal, Orissa and Maharashtra because they were found to be infected with H5N1 virus, the causal organism of Bird Flu.

Question. How do interferons protect us? 
Answer. Interferons protect non-infected cells from further viral infections, by creating cytokine barriers.

Question. What is an autoimmune disease? Give an example. 
Answer. It is an abnormal immune response in which the immune system of the body starts rejecting its own body cells or ‘self’ cells and molecules. For example, rheumatoid arthritis.

Question. Define the term ‘health’. Mention any two ways of maintaining it. 
Answer. Health is a state of complete physical, mental and social well-being.
Good health is maintained by balanced diet/personal hygiene/regular exercise. (Any two)

Question. Malaria, typhoid, pneumonia and amoebiasis are some of the human infectious diseases.
Which ones of these are transmitted through mechanical carriers?
Answer. Malaria and amoebiasis are transmitted through mechanical carriers.

Question. Draw a well labelled diagram of an antibody molecule.
Answer. 

Question. Name two STDs which can be transmitted through contaminated blood.
Answer. Hepatitis-B and AIDS are the two STDs which can be transmitted through contaminated blood.

Question. Trace the route of Sporozoite of Plasmodium when it enters the human body through the bite of infected female Anopheles mosquito till its entry into the R.B.C.
Answer. Sporozoites attack liver cells. ½ Sporozoites reproduce asexually in liver cells by bursting them and then reach RBC. 

Question. A patient is down with Amoebiasis. List the symptoms that confirm this infection. Name the causative pathogen.
Answer. Constipation, abdominal pain, stools with mucous, blood clot.
Causative pathogen : Entamoeba histolytica. 

Question. Suggest a method to ensure an anamnestic response in humans.
Answer. Vaccination or Immunization (Active / passive) or weakened or inactive microbes or pathogens or proteins or antibodies introduced into the host body.

Question. Name any two physiological barriers that provide innate immunity.
Answer. Acid in stomach/Saliva in mouth/tears in eyes.

Question. How drug abuse lead to stunted growth ?
Answer. It is due to premature closure of growth centres of the long bones. 

Question. Name the stage of Plasmodium that gains entry into the human when bitten by an infected female Anopheles Mosquito.
Answer. Sporozoites.

Question. Retroviruses have no DNA. However the DNA of the infected host cell does possess the viral DNA. How is it possible?
Answer. After infecting the host cell, the viral DNA undergoes reverse transcription in the presence of an enzyme reverse transcriptase as a result of
which viral DNA is formed. This DNA then gets incorporated into infected host DNA.

Question. Name three important disorders caused by alcohol.
Answer. Pancreatitis, alcoholic hepatitis and liver cirrhosis.

Question. What are interferons?
Answer. Virus infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.

Short Answer Questions

Question. Why does a doctor administer tetanus antitoxin and not a tetanus vaccine to a child injured in a roadside accident with a bleeding wound? Explain.
                                                                                            OR
Why is a person with cuts and bruises following an accident administered tetanus antitoxin? Give reasons. 
Answer. Tetanus is caused by a microbe which has a deadly and fast action. Action of vaccine is slow and this delay may become fatal. Therefore, antitoxins are administered which neutralise the effect of the bacterial toxin.

Question. How does spleen act as a lymphoid organ? Explain.
Answer. The spleen is a large bean-shaped organ. It mainly contains lymphocytes and phagocytes. It acts as a filter of the blood by trapping blood-borne microorganisms. Spleen also has a large reservoir of erythrocytes.

Question. (a) Name the source plant of heroin drug. How is it obtained from the plant?
(b) Write the effects of heroin on the human body. 
                         ​​​​​​​                       OR
Name an opioid drug and its source plant. How does the drug affect the human body?
Answer. (a) The source drug of heroin is poppy plant (Papaver somniferum).
It is derived by acetylation of morphine, which is obtained from the latex of the poppy plant.
(b) Heroin is a depressant and slows down the body functions.

Question. When you go for a trek/trip to any high altitude places, you are advised to take it easy and rest for the first two days. Comment, giving reasons. 
                         ​​​​​​​                         ​​​​​​​                         OR
Why do tribes who live in high altitude of Himalayas experience discomfort in respiration?
How do they get adapted to survive in such a situation? 
Answer. At high altitudes it is advised to take easy due to low oxygen availability. This may also cause altitude sickness. It is also advised to take rest because body compensates the low oxygen availability during rest by increasing RBC production and decreasing the binding capacity of haemoglobin, in turn increasing the breathing rate.

Question. Explain the relationship between B-lymphocytes and T-lymphocytes in developing an immune response. 
Answer. B-lymphocytes produce antibodies to fight pathogen.
T-lymphocytes do not produce antibodies but help B cells to produce them. They can also destroy pathogen directly.

Question. What would happen to immune system, if thymus gland is removed from the body of a person? 
Answer. Thymus is the primary lymphoid organ. In thymus gland, immature lymphocytes differentiate into antigen-sensitive lymphocytes. If thymus gland is removed from the body of a person, his immune system becomes weak. As a result the person’s body becomes prone to infectious diseases.

Question. How are auto-immune diseases different from immunodeficiency disease? Give one example of each in human.
Answer. 

Question. In the metropolitan cities of India, many children are suffering from allergy/asthma. What are the main causes of this problem? Give some symptoms of allergic reactions.
Answer. Allergy is the exaggerated response of the immune system to certain antigens present in the environment. In metropolitan cities lifestyle is responsible in lowering of immunity and sensitivity to allergens. More polluted environment increases the chances of allergy in children.
Some symptoms of allergic reactions are sneezing, watery eyes, running nose and difficulty in breathing.

Question. (a) Name the virus that causes AIDS in humans.
(b) Explain the sequence of events that follows when this virus attacks to cause immune deficiency in humans.
Answer. (a) Human Immunodeficiency Virus.
(b) (Life cycle of HIV).• It was first reported in U.S.A. in 1981 and in last 25 years, it has killed more than 25 million people.
• It is caused by the Human Immunodeficiency Virus (HIV).
• HIV belongs to the group retrovirus.
• It has RNA genome enclosed in an envelope.
• Transmission of HIV occurs through following ways:
(i) By sexual contact with the infected person.
(ii) By transfusion of contaminated blood and blood products.
(iii) By sharing infected needles.
(iv) From infected mother to her child through placenta. 
• It is not spread by more touch or physical contact. It only spreads through body fluids. Hence the infected persons should not be isolated from family and society.

Question. Name the two special types of lymphocytes in humans. How do they differ in their roles in immune response? 
Answer. B-lymphocytes and T-lymphocytes are the lymphocytes in humans.
B-cells produce pathogen specific antibodies and are responsible for humoral immune response.
T-cells help the B-cells to produce antibodies and are responsible for cell-mediated immunity.

Question. Name the cells that act as HIV factory in humans when infected by HIV. Explain the events that occur in the infected cell.
                         ​​​​​​​                         ​​​​​​​                         ​​​​​​​OR
Name the type of cells the AIDS virus first enters into after getting inside the human body.
Explain the sequence of events that the virus undergoes within these cells to increase their progeny.
Answer. Macrophages/Helper T-cells act as HIV factory.
The virus enters macrophages or helper T-cells where RNA genome of the virus forms viral DNA with the help of the enzyme reverse transcriptase. The viral DNA then gets incorporated into host cell’s DNA and directs infected cells to produce new virus particles.

Question. What is “withdrawal syndrome”? List any two symptoms it is characterised by. 
Answer. It is the state experienced by addicts when their regular dose of alcohol/drug is abruptly discontinued. It is often characterised by anxiety, shakiness, nausea and sweating.

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