Assignments Class 12 Biology Human Health and Diseases

Assignments for Class 12

Please refer to Assignments Class 12 Biology Human Health and Diseases Chapter 8 with solved questions and answers. We have provided Class 12 Biology Assignments for all chapters on our website. These problems and solutions for Chapter 8 Human Health and Diseases Class 12 Biology have been prepared as per the latest syllabus and books issued for the current academic year. Learn these solved important questions to get more marks in your class tests and examinations.

Human Health and Diseases Assignments Class 12 Biology

Question. The factor which has effect on health is :-
(a) Genetic disorders
(b) Infections
(c) Life style
(d) All of the above

Answer

D

Question. Which is required for maintenance of good health ?
(a) Balanced diet
(b) Personal hygiene
(c) Regular exercise
(d) All of the above

Answer

D

Question. Which is necessary for achieving good health?
(1) Awareness about diseases
(2) Proper disposal of wastes
(3) Control of vectors
(4) Maintenance of hygienic food and water
(a) 1
(b) 1 and 3
(c) 2 and 3
(d) 1, 2, 3 and 4

Answer

D

Question. Which is related with ringworm ?
(1) Microsporum
(2) Trichophyton
(3) Epidermophyton
(a) 1
(b) 1, 2
(c) 1, 3
(d) 1,2,3

Answer

D

Question. (a) Salmonella is pathogenic bacterium
(b) Sustained high fever (39°C to 40°C)
(c) Intestinal perforation in severe cases
(d) Confirmed by “widal test”
(e) “Marry Mallon” was a carrier Above statements are true for :-
(1) Plague
(2) Diphtheria
(3) Typhoid
(4) Dysentery

Answer

C

Question. Find the odd one out with regards to secondary immune response :-
(a) Booster
(b) Anamnestic
(c) Low intensified
(d) Develops after subsequent contact of same antigen

Answer

A

Question. Which immune response / immunity is mainly responsible for graft rejection ?
(a) Cell-mediated
(b) Humoral
(c) Antibody mediated
(d) All of the above

Answer

A

Question. The period between ____of age may be thought of as adolescence period
(a) 18-21 yrs.
(b) 12-21 yrs.
(c) 12-18 yrs.
(d) 18-25 yrs.

Answer

C

Question. Antibodies are found in :-
(a) Blood
(b) Pathogen
(c) Antigen
(d) Neurons

Answer

A

Question. The drugs, which are commonly abused are opioid,cannabinoids and coca alkaloid. Majority of these are obtained from_____, while some are obtained from _____.
(a) Fungi, non-flowering plants
(b) Flowering plants, fungi
(c) Fungi, flowering plants
(d) Non flowering plants, fungi

Answer

B

Question. Above statements/informations are correct for:-
(A) Smack 
(B) Diacetylmorphine
(C) White
(D) Odourless
(E) Bitter crystalline compound 
(F) Extracted from latex of poppy plant
(a) Morphine
(b) Heroin
(c) Cocain
(d) Barbiturates

Answer

B

Question. ATS provides :-
(a) Natural active innate immunity
(b) Natural passive innate immunity
(c) Artificial active acquired immunity
(d) Artificial passive acquired immunity

Answer

D

Question. Which cell acts as factory of HIV ?
(a) Macrophage
(b) TH cells
(c) TK cells
(d) N.K. cells

Answer

A

Question. In full blown AIDS, opportunistic infections are especially caused by :-
(a) Mycobacterium
(b) Toxoplasma
(c) Viruses and fungi
(d) All of the above

Answer

D

Question. ELISA is diagnostic test for :-
(a) Bacteria
(b) Viruses
(c) AIDS
(d) Dreaded diseases only

Answer

C

Question. “Don’t die of ignorance” slogan is used to create awareness for :-
(a) AIDS
(b) Cancer
(c) Typhoid
(d) Rabies

Answer

A

Question. H2L2 represents _____ molecule :-
(a) Antibody
(b) Antigen
(c) Pathogen
(d) Both (1) and (2)

Answer

A

Question. Which is a safe technique to detect cancer ?
(a) Radiography
(b) CT (Computed tomography) Scanning
(c) MRI (Magnetic Resonance Imaging)
(d) Biopsy

Answer

C

Question. Find out the incorrect matching with regards to innate immunity :-
(a) Physical barriers = Skin, mucosa
(b) Cytokine barriers = Interferons
(c) Cellular barriers = PMNL, neutrophils
(d) Physiological barriers = Epithelial lining

Answer

C

Question. Which type of radiations can cause DNA damage leading to neoplastic transformation ?
(A) Ionising radiations
(B) X-rays
(C) Non-ionising radiations
(D) UV-rays
(a) A and C
(b) B and D
(c) A and B
(d) A, B, C and D

Answer

D

Question. Which interferon is a biological response modifiers, that activates immune system for destroying tumor ?
(a) 1
(b) 2
(c) 3
(d) Both (b) and (c)

Answer

A

Question. AIDS don’t spread due to :-
(a) Mere touch
(b) Physical contact
(c) Body fluids
(d) Both (1) and (2)

Answer

D

Question. Incubation period for AIDS is usually :-
(a) 5-10 month
(b) 5-10 years
(c) 2-12 month
(d) 2-12 weeks

Answer

B

Question. Which disorder is not related with smoking?
(A) Lung cancer
(B) Bronchitis
(C) Emphysema
(D) Coronary heart disease
(E) Gastric ulcer
(F) Urinary bladder cancer
(G) Throat cancer
(a) A, B, E, G
(b) A, B, C, F, G
(c) C, D, F
(d) All are related

Answer

D

Question. Withdrawal syndrome is characterised by:-
(A) Anxiety
(B) Shakiness
(C) Nausea
(D) Sweating
(a) A, C
(b) B, C
(c) A, C, D
(d) A, B, C and D

Answer

D

Question. Which measure would be particularly useful for prevention and control of alcohol and drug abuse among adolescents ?
(A) Avoid undue peer pressure
(B) Seeking professional and medical help
(C) Looking for danger sign
(D) Education and counselling
(E) Seeking help from parents and peers
(a) A, B, D
(b) A, C, D, E
(c) C, E
(d) A, B, C, D, E

Answer

D

Question. Most of cancers are treated by combination of:-
(A) Surgery
(B) Radiotherapy
(C) Chemotherapy
(a) A and B
(b) A and C
(c) B and C
(d) A, B and C

Answer

D

Question. Cancer detection is based on :-
(A) Biopsy
(B) Histopathological study of tissues
(C) Blood test
(D) Bone marrow test
(a) A, B
(b) A, C & D
(c) A, B & C
(d) A, B, C & D

Answer

D

Question. Which is the particular type of drug that is obtained from the plant whose one flowering branch is shown here?

Assignments Class 12 Biology Human Health and Diseases

(a) Hallucinogen
(b) Depressant
(c) Stimulant
(d) Painkiller

Answer

A

Question. A doctor identifies symptoms of nasal congestion, headache, sore throat, hoarseness, cough in a patient. The conclusion is that, the patient is infected by a pathogen
(a) Plasmodium
(b) Adenovirus
(c) Salmonella
(d) Rhinovirus.

Answer

D

Question. Which of the following diseases is caused by a protozoan?
(a) Amoebiasis
(b) Ascariasis
(c) Syphilis
(d) Influenza

Answer

A

Question. Which of the following is an opioid drug ?
(a) Heroin
(b) Cocaine
(c) Marijuana
(d) Hashish

Answer

A

Question. The mature infective stages of malarial parasite which are transferred from mosquito to man are
(a) trophozoites
(b) sporozoites
(c) gametocytes
(d) merozoites.

Answer

B

Question. Which of the following body parts is majorly affected in the disease A?

Assignments Class 12 Biology Human Health and Diseases

(a) Muscles of the legs
(b) Blood vessels of the thigh region
(c) Skin between the fingers
(d) Lymphatic vessels of the lower limbs

Answer

D

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

Assignments Class 12 Biology Human Health and Diseases
Assignments Class 12 Biology Human Health and Diseases
Answer

D

Question. A person suffering from a disease caused by Plasmodium, experiences recurring chill and
fever at the time when

(a) the sporozoites released from RBCs are being rapidly killed and broken down inside spleen
(b) the trophozoites reach maximum growth and give out certain toxins
(c) the parasite after its rapid multiplication inside RBCs ruptures them, releasing haemozoin.
(d) the microgametocytes and megagametocytes are being destroyed by the WBCs.

Answer

D

Question. Identify the wrongly matched pair.
(a) Ringworm – Trichophyton
(b) Plague – Varicella zoster virus
(c) Malignant malaria – Plasmodium falciparum
(d) Common cold – Rhinovirus

Answer

B

Question. Which immunoglobulin can pass through placenta?
(a) IgA
(b) IgD
(c) IgG
(d) IgE

Answer

C

Question. In higher vertebrates, the immune system can distinguish self-cells and non-self. If this property is lost due to genetic abnormality and it attacks self-cells, then it leads to
(a) autoimmune disease
(b) active immunity
(c) allergic response
(d) graft rejection.

Answer

A

Question. Which one of the following statements is correct with respect to AIDS?
(a) The HIV can be transmitted through eating food together with an infected person
(b) Drug addicts are least susceptible to HIV infection
(c) AIDS patients are fully cured with proper care and nutrition
(d) The causative HIV retrovirus enters helper T-lymphocytes thus reducing their numbers.

Answer

D

Question. At which stage of HIV infection does one usually show symptoms of AIDS?
(a) Within 15 days of sexual contact with an infected person.
(b) When the infected retrovirus enters host cells.
(c) When HIV damages large number of helper T – Lymphocytes.
(d) When the viral DNA is produced by reverse transcriptase.

Answer

C


Question. Select incorrect option regarding the lymphoid organs labelled as P, Q, R and S in the diagram of human lymphatic system.

Assignments Class 12 Biology Human Health and Diseases

(a) T cells mature in Q.
(b) B and T cells undergo maturation in R.
(c) B and T cells undergo proliferation and differentiation in P.
(d) B cells mature in S.

Answer

B

Question. Which of the following is correct regarding AIDS causative agent HIV?
(a) HIV is an enveloped virus containing one molecule of single-stranded RNA and one molecule of reverse transcriptase.
(b) HIV is an enveloped virus that contains two identical molecules of single-stranded RNA and two molecules of reverse transcriptase.
(c) HIV is an unenveloped retrovirus.
(d) HIV is an enveloped virus containing two identical molecules of single stranded RNA and one molecule of reverse transcriptase.

Answer

B

Question. The figure given below shows mode of action of AIDS virus. Which step shows formation of viral DNA from RNA by reverse transcription?


(a) P
(b) Q
(c) R and S
(d) T

Answer

B

Question. In which one of the following options the two examples are correctly matched with their particular type of immunity?
Examples  ->Type of immunity
(a) Polymorphonuclear leukocytes and monocytes  -> Cellular barriers
(b) Anti-tetanus and anti-snake bite injections->Active immunity
(c) Saliva in mouth and tears in eyes->Physical barriers
(d) Mucus coating of epithelium lining the urinogenital tract and the HCI in stomach-> Physiological barriers

Answer

A

Question. Find out the wrong match.
(a) Eosinophils – Allergic response
(b) Basophils – Secrete histamine and serotonin
(c) Neutrophils – Phagocytic and destroy foreign organisms
(d) Monocytes – Secrete heparin

Answer

D

Question. Consider the following four statements (i – iv) regarding kidney transplant and select the two correct ones out of these.
(i) Even if a kidney transplant is proper, the recipient may need to take immuno-suppresants for a long time.
(ii) The cell-mediated immune response is responsible for the graft rejection.
(iii) The B-lymphocytes are responsible for rejection of the graft.
(iv) The acceptance or rejection of a kidney transplant depends on specific interferons.
The two correct statements are
(a) (ii) and (iii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (i) and (ii)

Answer

D

Question. Which of the following disease is confirmed by ‘widal test’?
(a) Tuberculosis
(b) Typhoid
(c) Plague
(d) Tetanus

Answer

B

Question. Malignant malaria is caused by the which of the following species of Plasmodium ?
(a) vivax
(b) malariae
(d) ovale
(d) falciparum

Answer

D

Question. Identify the site where Wuchereria bancrofti is normally found on human body.
(a) Lymphatic vessels of the lower limbs
(b) Muscles of the legs
(c) Blood vessels of the thigh region
(d) Skin between the fingers

Answer

A

Question. Amoebiasis is caused by
(a) Plasmodium vivax
(b) Entamoeba gingivalis
(c) Trypanosoma gambiense
(d) Entamoeba histolytica

Answer

D

Question. Which of the following set includes bacterial diseases ?
(a) Tetanus, typhoid, tuberculosis
(b) Small pox, influenza, tetanus
(c) Meningitis, measles, syphilis
(d) None of the above.

Answer

A

Question. Black water fever is a severe complication of
(a) Plasmodium falciparum
(b) P. vivax
(c) P. malariae
(d) all of the above

Answer

A

Question. Which of the following disease is not transmitted through contaminated water ?
(a) Typhoid
(b) Diphtheria
(c) Amoebiasis
(d) Hepatitis A

Answer

B

Question. Which of the following is the most accurate definition of infection?
(a) The presence of microorganism in a particular location.
(b) The disruption of normal host functions by microorganisms.
(c) The survival and reproduction of microorganisms in a host.
(d) The appearance of symptoms in a host, caused by microorganisms.

Answer

C

Question. The cells affected in leukaemia are
(a) plasma cells
(b) erythrocytes
(c) thrombocytes
(d) leucocytes

Answer

D

Question. Which one of the following acts as a physiological barrier to the entry of micro organisms in human body?
(a) Skin
(b) Epithelium of urogenital tract
(c) Tears
(d) monocytes

Answer

C

Question. Antigens are present
(a) inside the nucleus.
(b) on cell surface.
(c) inside the cytoplasm.
(d) on the nuclear membrane.

Answer

B

Question. The cytotoxic cells are produced by
(a) T-Cells
(b) B-Cells
(c) memory Cells
(d) mast Cells

Answer

A

Question. The exaggerated response of the immune system to certain antigens is called
(a) primary response
(b) secondary response
(c) immune suppression response
(d) allergy

Answer

D

Question. When body cannot differentiate between its own and foreign matter it is referred to as
(a) passive immunity
(b) active Immunity
(c) autoimmunity
(d) immunodeficiency

Answer

C

Question. Organ transplant rejection may be prevented by using
(a) antibodies
(b) new T cells
(c) immunosuppressive drug
(d) immunostimulatory drug

Answer

C

Question. Inflammatory response in allergy is caused by
(a) histamines
(b) antigen
(c) prothrombin
(c) antibodes

Answer

A

Question. The principle of vaccination is based upon which property of immune system ?
(a) Memory
(b) Diversity
(c) Specificity
(d) All of these

Answer

A

Question. The foetus gets immunized after receiving antibodies from mother through placenta. This type of immunization is called
(a) active immunity
(b) innate immunity
(c) passive immunity
(d) humoral immunity

Answer

C

Question. Which of the following vaccine has been produced from yeast by recombinant DNA technology ?
(a) Hepatitis A
(b) Hepatitis B
(c) Hib
(d) Oral polio

Answer

B

Question. Which of the following lymphoid organ provides the site for the interaction of lymphocytes with the antigen ?
(a) Bone marrow
(b) Thymus
(c) Spleen
(d) All of these

Answer

C

Question. Which of the following is an autoimmune disease ?
(a) Asthma
(b) Rheumatoid arthritis
(c) Cirrhosis
(d) AIDS

Answer

B

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 is not immunity related disease ?
(a) AIDS
(b) Polio
(c) Cancer
(d) Small pox

Answer

C

Question. AIDS is due to
(a) reduction in number of helper T cells
(b) lack of interferon
(c) reduction in number of killer T cells
(d) autoimmunity

Answer

A

Question. Cancer cells are more easily damaged by radiation than normal cells because they are
(a) non-dividing
(b) starved of mutation
(c) different in structure
(d) undergoing rapid division

Answer

D

Question. Techniques like radiography (use of X-rays), CT scanning and MRI are very useful to detect
(a) autoimmune disorders.
(b) disease caused by viral infection.
(c) disease caused by bacterial infection.
(d) disease caused by an uncontrolled division of abnormal cells of internal organs.

Answer

D

Question. TB is cured by
(a) griseofulvin
(b) ubiquinone
(c) rifampin
(d) eucitol

Answer

C

Question. The drug “Belladonna” is obtained from
(a) Rauwolfia
(b) Atropa
(c) Capsicum
(d) Solanum

Answer

B

Question. Which of the following is a narcotic drug?
(a) Heroin
(b) Codeine
(c) Morphine
(d) All of these

Answer

D

Question. Opium is obtained from
(a) Papaver somniferum
(b) Rauwolfia serpentina
(c) Cannabis sativus
(d) Claviceps purpurea

Answer

A

Question. Narcotic drugs like charas, bhang and ganja are extracted from
(a) hemp plant
(b) coco plant
(c) poppy seeds
(d) hallucinogen

Answer A

Question. Opium is obtained from which part of the plant Papaver somniferum ?
(a) Inflorescence
(b) Male part (dried)
(c) Seed (unripe)
(d) Leave

Answer

C

Question. Cirrhosis of the liver is caused by
(a) cocaine
(b) LSD
(c) alcohol
(d) morphine

Answer

C

Question. LSD is obtained from
(a) bryophyte
(b) pleridophyte
(c) brown algae
(d) fungus

Answer

D

Statement Type Questions for Class 12 Biology Human Health and Diseases

Question. Which of the following statements regarding drugs are correct ?
(i) Heroin, commonly called smack, is obtained by acetylation of morphine.
(ii) Cocaine is obtained from the latex of Papaver somniferum.
(iii) Marijuana interferes with the transmission of dopamine.
(iv) Morphine is an effective sedative and pain killer.
(a) (i) and (ii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer

B

Question. Which of the following is the correct statement regarding the particular psychotropic drug specified?
(a) Barbiturates cause relaxation and temporary euphoria
(b) Hashish causes after thought perceptions and hallucinations.
(c) Opium stimulates nervous system and causes hallucinations.
(d) Morphine leads to delusions and disturbed emotions.

Answer

B

Question. The following four statements (i – iv) kidney transplant. Identify the two correct statements.
(i) Even if a kidney transplant is proper the recipient may need to take immunosuppresants for a long time.
(ii) The cell-mediated immune response is responsible for the graft rejection.
(iii) The B-lymphocytes are responsible for rejection of the graft.
(iv) The acceptance or rejection of a kidney transplant depends on the specific interferons.
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)

Answer

A

Question. Select the correct statement.
(a) Cocaine is given to patients after surgery as it stimulates recovery.
(b) Barbiturates when given to criminals make them tell the truth.
(c) Morphine is often given to persons who have undergone surgery as a pain killer.
(d) Chewing tobacco lowers blood pressure and heart rate.

Answer

C

Question. At which stage of HIV infection does one usually show symptoms of AIDS?
(a) Within 15 days of sexual contact with an infected person.
(b) When the infecting retrovirus enters host cells.
(c) When viral DNA is produced by reverse transcriptase.
(d) When HIV replicates rapidly in helper T-lymphocytes and damages large number of these.

Answer

D

Question. Common cold differs from pneumonia in that
(a) pneumonia is caused by a virus while the common cold is caused by the bacterium Haemophilus influenzae.
(b) pneumonia pathogen infects alveoli whereas the common cold affects nose and respiratory passage but not the lungs.
(c) pneumonia is a communicable disease whereas the common cold is a nutritional deficiency disease.
(d) pneumonia can be prevented by a live attenuated bacterial vaccine whereas the common cold has no effective vaccine.

Answer

B

Question. Which of the following statement is correct regarding the number of helper T cells and the viral concentration in the blood?
(a) As the number of HIV increase, so do the numbers of helper T cells.
(b) As the number of HIV increase, the number of helper T cells decreases.
(c) As the concentration of HIV decreases, the number of helper T cells increases.
(d) There is no relationship between the concentration of HIV and the number of helper T cells.

Answer

C

Case Based MCQs for Class 12 Biology Human Health and Diseases

Case I : Read the following passage and answer questions below:
X and Y are communicable diseases whereas W and Z are non-communicable diseases. X is transmitted through vectors whereas Y is transmitted through droplet infection. W is caused due to a hormone deficiency whereas Z is a degenerative disease.
Based on the above information, answer the following questions.

Question. Select the correct statement.
(a) If X is sleeping sickness then its vector is Leishmania.
(b) If Y is diphtheria then it is caused by Bacillus anthracis.
(c) If W is hypothyroidism then it is caused by deficiency of thyroxine hormone.
(d) If Z is myocardial infarction then patient develops acute rheumatic fever, joint pain and throat infection.

Answer

C

Question. If X and Y both are bacterial diseases then select the correct match from the following.
(a) X- Bubonic plague – Yersinia pestis
(b) Y – Gonorrhea – Neisseria gonorrhoeae
(c) X – Whooping cough – Bordetella pertussis
(d) Y – Botulism – Clostridium botulinum

Answer

A

Case II : Read the following passage and answer questions below:
In a study to test a new vaccine against a viral disease, mouse model testing is done. In this process, mice are vaccinated and their blood samples were tested. Mice developed mild disease symptom. After few days those mice were again infected with the virus. This time they do not show any disease symptoms. Their blood samples were tested. Two graphs show antibody concentration for the first and second infection in mice blood. 

Assignments Class 12 Biology Human Health and Diseases

Based on the above information, answer the following questions.

Question. P and Q in the given graphs indicate
(a) IgM and IgG respectively
(b) IgG and IgM respectively
(c) IgG and IgE respectively
(d) IgM and IgA respectively.

Answer

B

Question. Which of the following is incorrect for P?
(a) It is the most abundant class of Ig.
(b) It is found in blood, lymph and intestine.
(c) It is unable to cross the placental barrier.
(d) It is a monomer.

Answer

C

Question. Read the given statements and select the correct option.
Statement A : Mice do not show any disease symptoms during second exposure to the pathogenic virus.
Statement B : The antibody production is accelerated and more intense during secondary immune response.
(a) Both statements A and B are true.
(b) Statement A is false but statement B is true.
(c) Statement A is true but statement B is false.
(d) Both statements A and B are false.

Answer

A

Assertion & Reasoning Based MCQs for Class 12 Biology Human Health and Diseases

Two statements are given-one labelled Assertion and the other labelled Reason.
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.

Question. Assertion : Inflammatory response is produced in the body after some infections.
Reason : This is one of the ways of defence mechanism.

Answer

A

Question. Assertion : Spleen produces all type of blood cells in fetus but produces only lymphocytes in adults.
Reason : Macrophages of spleen are phagocytic.

Answer

B

Question. Assertion : Allergy is an autoimmune disorder.
Reason : Allergy involves IgE antibodies and chemicals like histamine and serotonin from mast cells.

Answer

B

Question. Assertion : Tranquilizers are used to treat schizophrenia.
Reason : Tranquilizers are psychedelic drugs.

Answer

C

Question. Assertion : Smoking causes oxygen deficiency in the body.
Reason : Carbon monoxide when inhaled while smoking, combines with haemoglobin to form chemically stable compound.

Answer

A

Question. Assertion : Cocaine has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy.
Reason : It interferes with the transport of the neurotransmitter acetylcholine.

Answer

B

Question. Assertion: Virus-infected cells secrete proteins known as interferons.
Reason: Interferons protect the non-infected cells from bacterial infection.

Answer

C

Question. Assertion: Antiretroviral drugs are very effective in treatment against AIDS.
Reason: AIDS virus is a retrovirus with ssDNA as genetic material.

Answer

D

Very Short Answer Type Questions for Class 12 Biology Human Health and Diseases

Question. How do neutrophils acts as a cellular barrier to pathogens in humans?
Answer : Cellular barrier is a type of innate immunity. Neutrophil is a type of leucocyte (WBC) in the blood which phagocytose and destroy microbes, thus act as cellular barrier to pathogens in human.

Question. A boy of ten years had chicken-pox. He is not expected to have the same disease for the rest of his life. Mention how it is possible.
Answer : A body when encounters a pathogen for first time produces antibodies, that result in memory of the first encounter to protect the body in future.

Question. How does nicotine affect human body?
Answer : Nicotine stimulates the release of adrenaline leading to high blood pressure and heartbeat rate. 

Question. Name the drugs obtained from hemp plant.
Answer : Bhang, ganja, charas marijuana and datura.

Question. Which disease is associated with the following symptoms : Sudden onset of profuse watery stool followed by vomiting, rapid dehydration, and muscular cramps?
Answer : Cholera

Short Answer Type Questions for Class 12 Biology Human Health and Diseases

Question. What category of pathogens causes poliomyelitis? How is crippling caused in the victim of this disease? How this disease can be prevented?
Answer : Poliomyelitis is caused by poliovirus – one of a small group of RNA – containing viruses. They are included within the picornavirus group. It affects the central nervous system resulting in crippling. The disease can be prevented by avoiding contaminated food and water. Immunization using the Sabin vaccine (taken orally) or the Salk vaccine (injected) is highly effective.

Question. Why is using tobacco in any form injurious to health?
Answer :
 Tobacco is used for smoking, chewing and snuffing. Its main stimulating component is a poisonous, volatile alkaloid nicotine, which causes addiction. Besides the poisonous nicotine, it also contains carbon monoxide and polycyclic aromatic hydrocarbons. It leads to various diseases such as cancer, high and low blood pressure, smoker’s cough and bronchitis.

Question. (a) Name a drug used
(i) as an effective sedative and painkiller
(ii) for helping patients to cope with mental illnesses like depression, but often misused.
(b) How does the moderate and high dosage of cocaine affect the human body?
Answer :
  (a) (i) Morphine (ii) Barbiturates
(b) Cocaine taken in low dose induces sense of well being and pleasure and delays fatigue, but in high dosage, it causes hallucinations.

Question. What is meant by contact inhibition? How does this phenomenon operate in cancer cells?
Answer :
 The normal cells are characterised by contact inhibition i.e. they form monolayers. Further, they cannot move away from each other. However in cancer cells they form multilayer due to loss of contact inhibition. As a result, they freely move, and get deposited in any part of the body, a property referred to as metastasis.

Question. List the specific symptoms of typhoid. Name its causative agent.
Answer :
 Typhoid is caused by Salmonella typhii. Its specific symptoms are :
(i) constant high fever but low pulse rate
(ii) weakness and
(iii) abdominal pain and passes frequent stools.

Question. (a) Name the infective stage of Plasmodium which Anopheles mosquito takes in along with the blood meal from an infected human.
(b) Why does the infection cause fever in human?
(c) Give a flow chart of the part of the life cycle of this parasite passed in the insect.
Answer :
(a) The infective stage of Plasmodium which Anopheles mosquito takes in along with the blood meal from an infected human is gametocyte.
(b) Malaria is characterised by fever at intervals, sudden acute chillness (cold rigor stage) accompanied by shivering followed by rise in temperature. Peak fever (hot or febrile stage) is 41.1°C or 106°F which persists for 3-6 hours. After 2-4 hours of fever, there is profuse sweating (sweating or defervescence stage) which lowers the body temperature to near normal.
(c) Life cycle of Plasmodium vivax showing stages in insect

Question. Name the pathogen that causes amoebiasis in humans. Give the symptoms and the mode of transmission of the disease.
Answer : Amoebiasis is caused by monogenetic protozoan Entamoeba histolytica. It is characterised by abdominal pain, mild diarrhoea alternating with constipation, passing out of mucus, pieces of necrotic mucous membrane and blood in faeces, and faeces with cysts. The infection occurs by the cysts of Entamoeba present in the stool of infected person, cat, dog, monkey, rat, rabbit etc. through the agency of house flies, manure, air currents, a number of other physical contacts and unsafe drinking water.

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.
Answer : A child injured in a roadside accident with a bleeding wound has chances of getting infected from tetanus so quick immune response is required, therefore, preformed antibodies, or antitoxin (a preparation containing antibodies to the toxin) is directly injected. In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body. The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection.
Therefore, vaccine administration would not give quick relief and thus not considered effective.

Question.

Assignments Class 12 Biology Human Health and Diseases


Identify P, Q and R in the schematic diagram of an antibody given above and answer the questions.
(a) Write the chemical nature of an antibody.
(b) Name the cells that produce antibodies in humans.
(c) Mention the type of immune response provided by an antibody.

Answer : In the given structure of an antibody molecule, ‘P’ is the antigen binding site, ‘Q’ is constant region of light chain and ‘R’ is constant region of heavy chain.
(a) Antibodies are immunoglobulins which are protein in nature.
(b) B-cells produce antibodies.
(c) Humoral immune response is an antibody mediated immune response.

Question. Describe the structure of immunoglobulin (Ig). Draw diagram showing the formation of antigen-antibody complex and label the parts.
Answer :Immunoglobulins are glycoproteins made up of four polypeptide chains (linked by disulphide bonds), two heavy and two light chains. Light and heavy chains are subdivided into variable and constant region. Variable portion is used for binding to antigen and a constant portion determines its adherence and diffusivity.

Assignments Class 12 Biology Human Health and Diseases

Question. Which pathogen causes diphtheria? Why is it dreaded as fatal disease? How can it be prevented?
Answer : Diphtheria is caused by Corynebacterium diphtheriae.
This disease is dreaded because at later stage, a soft grey membrane forms across the throat, constricting the air passage causing difficulty in breathing and swallowing.
Bacteria multiply at the site of infection and release a toxin into the bloodstream which damages heart and nerves. Death from heart failure or general collapse can follow within four days. The disease is spread by direct contact with a patient or carrier or by contaminated milk. It can be prevented by taking DPT vaccine.

Question. Differentiate between active immunity and passive immunity. Give any one example where passive immunisation is needed.
Answer :
The given table shows differences between active and passive immunity.

Assignments Class 12 Biology Human Health and Diseases

In case of snake bites, injection containing preformed antibodies against the snake venom is given to the patient.

Long Answer Type Questions for Class 12 Biology Human Health and Diseases


Question. (a) Name and explain any four lymphoid organs present in humans.
(b) Categorise the named lymphoid organs as primary or secondary lymphoid organs, giving reasons.
Answer : (a) Four lymphoid organs present in humans are :
(i) Bone marrow : It is the main lymphoid organ where all blood cells including lymphocytes are formed. Maturation of B-lymphocytes occurs here.
(ii) Thymus : It is the site of T-lymphocyte maturation.
Thymus is situated near the heart and is quite large in size at the time of birth but keeps reducing with age.
(iii) Lymph nodes: These are small solid structures found at intervals along the lymphatic system. They are composed of lymphoid tissue and act as filters for the lymph, preventing foreign particles from entering the bloodstream. Lymph nodes also produce lymphocytes and plasma cells.
(iv) Spleen: It is a bean shaped organ which is the largest single mass of lymphoid tissue in the body. In fetus the spleen produces all types of blood cells but in adult it only produces lymphocytes. Macrophages of spleen are phagocytic.
(b) Bone marrow and thymus are primary lymphoid organs where T-lymphocytes and B-lymphocytes mature and acquire their antigen-specific receptors. Lymph nodes and spleen are secondary lymphoid organs where B-lymphocytes and T-lymphocytes after maturation migrate via blood vascular and lymphatic system to the secondary lymphoid organs where they undergo poliferation and differentiation.

Question. (a) What happens to a normal cell in a body when oncogenes get activated under certain conditions?
(b) Which techniques are useful to detect cancer of internal organs?
(c) Why are cancer patients often given a-interferon during their treatment?
Answer : (a) When cellular oncogenes or proto-oncogenes are activated under certain conditions in normal cells in a body, they could lead to oncogenic transformation of the cells.
Transformation of normal cells into cancerous neoplastic cells may be induced by physical, chemical or biological agents also.
(b) Techniques like radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Computed tomography uses X-rays to generate a three-dimensional image of the internal organ. MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.
(c) Cancer patients are often given a-interferon during their treatment, because these biological response modifiers activate the immune system and help in destroying the tumour.

Assignments Class 12 Biology Human Health and Diseases