NCERT Exemplar: Human Health & Diseases - 1 | Biology Class 12 - NEET PDF Download

MULTIPLE-CHOICE QUESTIONS 

Q.1. The term 'Health' is defined in many ways. The most accurate definition of the health would be:
(a) Health is the state of body and mind in a balanced condition
(b) Health is the reflection of a smiling face
(c) Health is a state of complete physical, mental and social well-being
(d) Health is the symbol of economic prosperity.
Ans. (c)
Solution.
Health is not just the absence of disease. It is a state of complete physical, mental, social and psychological well-being.

Q.2. The organisms which cause diseases in plants and animals are called:
(a) Pathogens
(b) Vectors
(c) Insects
(d) Worms
Ans. (a)
Solution.
A wide range of organisms belonging to bacteria, viruses, fungi protozoans, helminthes, etc., could cause diseases in man. Such disease causing organisms are called pathogens.

Q.3. The clinical test that is used for diagnosis of typhoid is:
(a) ELISA
(b) ESR
(c) PCR
(d) Widal
Ans. (d)
Solution.
The chemical test that is used for diagnosis of typhoid is Widal-Test.

Q.4. Diseases are broadly grouped into infectious and non-infectious diseases.
In the list given below, identify the infectious diseases.
i. Cancer
ii. Influenza
iii. Allergy
iv. Small pox
(a) i and ii
(b) ii and iii
(c) iii and iv
(d) ii and iv
Ans. (d)
Solution.

Q.5. The sporozoites that cause infection when a female Anopheles mosquito bites a person, are formed in:
(a) liver of the person
(b) RBCs of mosquito
(c) salivary glands of mosquito
(d) Intestine of mosquito
Ans. (d)
Solution.
The sporozoites that cause infection, when a female Anopheles mosquito bites a person being are formed in intestine of mosquito.

Q.6. The disease chikunguniya is transmitted by:
(a) House fly
(b) Aedes mosquito
(c) Cockroach
(d) Female Anopheles
Ans. (b)
Solution.
Dengue and chikunguniya are transmitted by Aedes mosquitoes.

Q.7. Many diseases can be diagnosed by observing the symptoms in the patient. Which group of symptoms are indicative of pneumonia?
(a) Difficulty in respiration, fever, chills, cough, headache
(b) Constipation, abdominal pain, cramps, blood clots
(c) Nasal congestion and discharge, cough, constipation, headache
(d) High fever, weakness, stomach pain, loss of appetite and constipation
Ans. (a)
Solution.

• Difficulty in respiration, fever, chills, cough, headache: Pneumonia
• Constipation, abdominal pain, cramps, blood clots: Amoebiasis
• Nasal congestion and discharge, cough, sorethroat, headache: Common cold
• High fever, weakness, stomach pain, loss of appetite and constipation: Typhoid

Q.8. Cancer causing genes are called:
(a) Structural genes
(b) Expressor genes
(c) Oncogenes
(d) Regulatory genes
Ans. (c)
Solution.
Oncogenes are the cancer causing genes.

Q.9. In malignant tumors, the cells proliferate, grow rapidly and move to other parts of the body to form new tumors. This stage of disease is called:
(a) Metagenesis
(b) Metastasis
(c) Teratogenesis
(d) Mitosis
Ans. (b)
Solution.
In malignant tumors, the cells proliferate, grow rapidly and move to other parts of the body to form new tumors. This stage of disease is called metastasis.

Q.10. When an apparently healthy person is diagnosed as unhealthy by a psychiatrist, the reason could be that:
(a) The patient was not efficient at his work
(b) The patient was not economically prosperous
(c) The patient shows behavioural and social maladjustment
(d) He does not take interest in sports
Ans. (c)
Solution.
When an apparently healthy person- is diagnosed as unhealthy by a psychiatrist, the reason could be that the patient shows behavioural and social maladjustment.

Q.11. Which of the following are the reason(s) for Rheumatoid arthritis? Choose the correct option.
i. The ability to differentiate pathogens or foreign molecules from self cells increases.
ii. Body attacks self cells
iii. More antibodies are produced in the body
iv. The ability to differentiate pathogens or foreign molecules from self cells is lost
(a) i and ii
(b) ii and iv
(c) iii and iv
(d) i and iii
Ans. (b)
Solution.
Rheumatoid arthritis is an autoimmune diseases in which

• Body attacks self cells
• The ability to differentiate pathogens or foreign molecules from self cells is lost

Q.12. AIDS is caused by HIV. Among the following, which one is not a mode of transmission of HIV?
(a) Transfusion of contaminated blood
(b) Sharing the infected needles
(c) Shaking hands with infected persons
(d) Sexual contact with infected persons
Ans. (c)
Solution.

• Transfusion of contaminated blood
• Sharing the infected needles
• Sexual contact with infected persons

Q.13. 'Smack' is a drug obtained from the:
(a) Latex of Papaver somniferum
(b) Leaves of Cannabis sativa
(c) Flowers of Dhatura
(d) Fruits of Erythroxyl coca
Ans. (a)
Solution.

• Smack’ is a drug obtained from the latex of Papaver somniferum.
• Smack are brown sugar, the common name of Heroin.
• Heroin is obtained by acetylation of morphine.

Q.14. The substance produced by a cell in viral infection that can protect other cells from further infection is:
(a) Serotonin
(b) Colostrum
(c) Interferon
(d) Histamine
Ans. (c)
Solution.
The substance produced by a cell in viral infection that can protect other cells from further infection is interferon.

Q.15. Transplantation of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections?
(a) Auto-immune response
(b) Humoral immune response
(c) Physiological immune response
(d) Cell-mediated immune response
Ans. (d)
Solution.
Transplantation of tissues/organs to-save certain patients often fails due to rejection of such tissues/organs by the patient. Cell-mediated immune response is responsible for such rejections.

Q.16. Antibodies present in colostrum which protect the new born from certain diseases is of
(a) Ig G type
(b) Ig A type
(c) Ig D type
(d) Ig E type
Ans. (b)
Solution.
Antibodies present in colostrum which protect the new bom from certain diseases is of Ig A type.

Q.17. Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be:
(a) Nicotine
(b) Tannic acid
(c) Curamin
(d) Catechin
Ans. (a)
Solution.
Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be nicotine. Morphine, cocaine, codeine and nicotine are all alkaloids.

Q.18. Antivenom against snake poison contains:
(a) Antigens
(b) Antigen-antibody complexes
(c) Antibodies
(d) Enzymes
Ans. (c)
Solution.
Anti-venom against snake poison contains antibodies.

Q.19. Which of the following is not a lymphoid tissue?
(a) Spleen
(b) Tonsils
(c) Pancreas
(d) Thymus
Ans. (c)
Solution.
Spleen, Tonsils and Thymus are lymphoid tissue while pancreas is mixed gland.

Q.20. Which of the following glands is large sized at birth but reduces in size with ageing?
(a) Pineal
(b) Pituitary
(c) Thymus
(d) Thyroid
Ans. (c)
Solution.
Thymus glands is large sized at birth but reduces in size with ageing.

Q.21. Haemozoin is a:
(a) Precursor of hemoglobin
(b) Toxin released from Streptococcus infected cells
(c) Toxin released from Plasmodium infected cells
(d) Toxin released from Haemophilus infected cells
Ans. (c)
Solution.
Haemozoin is a toxin released from Plasmodium infected cells.

Q.22. Which of the following is not the causal organism for ringworm?
(a) Microsporum
(b) Trichophyton
(c) Epidermophyton
(d) Macrosporum
Ans. (d)
Solution.
Microsporum, Trichophyton and Epidermophyton are the causal organism for ringworm while Macrosporum is a brown alga.

Q.23. A person with sickle cell anemia is
(a) More prone to malaria
(b) More prone to typhoid
(c) Less prone to malaria
(d) Less prone to typhoid
Ans. (c)
Solution.
A person with sickle cell anemia is less prone to malaria.

VERY SHORT ANSWER TYPE QUESTIONS

Q.1. Certain pathogens are tissue/organ specific. Justify the statement with suitable examples.
Ans. Salmonella typhi causes typhoid and infects small intestine while intestinal endoparasite causes amoebic dysentery and infects large intestine.

Q.2. The immune system of a person is suppressed. In the ELISA test, he was found positive to a pathogen.
(a) Name the disease the patient is suffering from.
(b) What is the causative organism?
(c) Which cells of body are affected by the pathogen?
Ans. (a) Acquired Immuno Deficiency Syndrome (AIDS)
(b) Human Immuno deficiency virus (HIV)
(c) Helper T-lymphocytes (T_H or T₄)

Q.3. Where are B-cells and T-cells formed? How do they differ from each other?
Ans. Both B-cells and T-cells are formed in bone marrow. B-cells matures in bone marrow while T-cells matures in thymus. B-cells provides humoral immunity and T-cells provides cell mediated immunity (CMI).

Q.4. Given below are the pairs of pathogens and the diseases caused by them. Which out of these is not a matching pair and why?

Ans. Pair is mismatched. Microsporum causes ringworm disease.

Q.5. What would happen to immune system, if thymus gland is removed from the body of a person?
Ans. 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,

Q.6. Many microbial pathogens enter the gut of humans along with food. What are the preventive barriers to protect the body from such pathogens? What type of immunity do you observe in this case?
Ans. (i) The mucus coating of the epithelium lining of the gut helps in trapping microbes entering the body.
(ii) Saliva in the mouth and hydrochloric acid in gastric juice secreted by stomach prevent microbial growth. This type of immunity is innate immunity.

Q.7. Why is mother's milk considered the most appropriate food for a new born infant?
Ans. Mother’s milk is considered as the most appropriate food for a new born infant because the yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant.

Q.8. What are interferons? How do interferons check infection of new cells?
Ans. Interferons are natural proteins produced by the cells of immune system in response to foreign agents such as viruses, tumor cells and parasites and protect non-infected cells from further infection. Interferons inhibit the viral replication within host cells, activate natural killer cells and macrophages, increases antigen presentation to lymphocytes, and induce the resistance of host cells to viral infection. When the antigen is presented to matching T-cells’ and B-cells, these cells multiply and remove the foreign substance.

Q.9. In the figure, structure of an antibody molecule is shown. Name the parts A, B and C.
Show A, B and C in the diagram.
Ans. A — Constant region of heavy chain,
B — Constant region of light chain,
C — Variable region of light and heavy chain

Q.10. If a regular dose of drug or alcohol is not provided to an addicted person, he shows some withdrawal symptoms. List any four such withdrawal symptoms.
Ans. The withdrawal symptoms are:
(a) Anxiety
(b) Shakiness
(c) Nausea
(d) Sweating

Q.11. Why is it that during changing weather, one is advised to avoid closed, crowded and air conditioned places like cinema halls etc.?
Ans. During changing weather, one is advised to avoid closed, crowded and air- conditioned placed like cinema halls, etc., because during this period the infectious agents are more humorous and prevalent to which we are more vulnerable.

Q.12. The harmful allele of sickle cell anemia has not been eliminated from human population. Such afflicted people derive some other benefit. Discuss.
Ans. The harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population because SCA is a harmful condition which is also a potential saviour from malaria.
Those with the benign sickle trait possess a resistance to malarial infection. The pathogen that causes the disease spends part of its cycle in the red blood cells and triggers an abnormal drop in oxygen levels in the cell. In carriers, this drop is sufficient to trigger the full sickle-cell reaction, which leads to infected cells being rapidly removed from circulation and strongly limiting the infection’s progress. These individuals have a great resistance to infection and have a greater chance of surviving outbreaks. This resistance to infection is the main reason the SCA allele and SCA disease still exist. It is found in greatest frequency in populations where malaria was and is still often a serious problem.

Q.13. Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.
Ans. Lymph nodes are small solid structures located at different points along the lymphatic system. Lymph nodes trap the microorganisms or other antigens, which happen to get into the lymph and tissue fluid. Antigens trapped in the lymph nodes are responsible for the activation of lymphocytes present there and cause the immune response.

Q.14. Why is an antibody molecule represented as H₂L₂?
Ans. Each antibody molecule is made of the two heavy chains (H₂) and two light chains (L₂), hence represented as H₂ L₂.

Q.15. What does the term 'memory' of the Immune system mean?
Ans. When body encounters a pathogen for the first time produce a response called 1° response. 1° response is of low intensity. When body encounters the same pathogen subsequently then body elicits 2° response. 2° response is highly intensified. This is due to the fact that our body have memory of the first encounter.

Q.16. If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.
Ans. The patient is suffering from AIDS. The causative organism for AIDS is HIV (Human Immuno deficiency Virus).

SHORT ANSWER TYPE QUESTIONS

Q.1. Differentiate between active immunity and passive immunity.
Ans.

Q.2. Differentiate between benign tumor and malignant tumor.
Ans.

• Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage.
• Malignant tumors are a mass of proliferating cells called neoplastic or tumor cells. Neoplastic cells grow very rapidly, invading and damaging the surrounding normal tissues. As these cells actively divide and grow they also starve the normal cells by competing for vital nutrients.
• Cells sloughed from such tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property called metastasis is the most feared property of malignant tumors.

Q.3. Do you consider passive smoking is more dangerous than active smoking? Why?
Ans. Yes, passive smoking is also dangerous as the active smoking because the person is exposed to the same harmful effects of smoking like emphysema, bronchitis, lung cancer, urinary bladder cancer or even peptic ulcer.

Q.4. “Prevention is better than cure”. Comment
Ans. Prevention is better than cure is true as in same cases the disease is non- curable like AIDS and Hepatitis-B, and in some cases’ the treatment causes financial problems in the family.

Q.5. Explain any three preventive measures to control microbial infections.
Ans. (i) Maintenance of personal and public hygiene is very important for prevention and control of many infectious diseases. Measures for personal hygiene include keeping the body clean; consumption of clean drinking water, food, vegetables, fruits, etc. Public hygiene includes proper disposal of waste and excreta; periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks and observing standard practices of hygiene in public catering.
(ii) In cases of air-borne diseases such as pneumonia and common cold, in addition to the above measures, close contact with the infected persons or their belongings should be avoided.
(iii) For diseases such as malaria and filariasis that are transmitted through insect vectors, the most important measure is to control or eliminate the vectors and their breeding places. This can be achieved by avoiding stagnation of water in and around residential areas, regular cleaning of household coolers, use of mosquito nets, introducing fishes like Gambusia in ponds that feed on mosquito larvae, spraying of insecticides in ditches, drainage areas and swamps, etc. In addition, doors and windows should be provided with wire mesh to prevent the entry of mosquitoes.

Q.6. In the given flow diagram, the replication of retrovirus in a host is shown.
Observe and answer the following questions.
(a) Fill in (1) and (2)
(b) Why is the virus called retrovirus?
(c) Can the infected cell survive while viruses are being replicated and released?
Ans. (a) (i) Viral DNA is produced by reverse transcriptase.
(ii) New viral RNA is produced by infected cell.
(b) HIV is called retrovirus because it forms DNA from RNA by reverse transcription.
(c) Yes, infected cell can survive while viruses are being replicated and released.

Q.7. “Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify the statement giving suitable examples.
Ans. Measures for personal hygiene include keeping the body clean; consumption of clean drinking water, food, vegetables, fruits, etc. Public hygiene includes proper disposal of waste and excreta; periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks, and observing standard practices of hygiene in public catering. These measures are particularly essential where the infectious agents are transmitted through food and water such as typhoid, amoebiasis and ascariasis.

Q.8. The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.

Ans.

Q.9. The outline structure of a drug is given below.
(a) Which group of drugs does this represent?
(b) What are the modes of consumption of these drugs?
(c) Name the organ of the body which is affected by consumption of these drugs. 
Ans.
(a) Cannabinoids
(b) Generally taken by inhalation and oral ingestion
(c) Affect the cardiovascular system of the body

Q.10. Give the full form of CT and MRI. How are they different from each other? Where are they used?
Ans. 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 internals of an object. MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.