NCERT Solutions for Class 12 Science Biology Chapter 8 Human Health And Diseases are provided here with simple step-by-step explanations. These solutions for Human Health And Diseases are extremely popular among Class 12 Science students for Biology Human Health And Diseases Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the NCERT Book of Class 12 Science Biology Chapter 8 are provided here for you for free. You will also love the ad-free experience on Meritnation’s NCERT Solutions. All NCERT Solutions for class Class 12 Science Biology are prepared by experts and are 100% accurate.
Page No 51:
Question 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.
Answer:
Health is defined as the state of complete physical, mental and social well-being of a person.
Hence, the correct answer is option C.
Page No 51:
Question 2:
The organisms which cause diseases in plants and animals are called:
a. Pathogens
b. Vectors
c. Insects
d. Worms
Answer:
Pathogens are infectious organisms that cause diseases in plants and animals.
Hence, the correct answer is option A.
Page No 51:
Question 3:
The clinical test that is used for diagnosis of typhoid is:
a. ELISA
b. ESR
c. PCR
d. Widal
Answer:
Widal test is used for the confirmation of typhoid fever.
Hence, the correct answer is option D.
Page No 51:
Question 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
Answer:
Infectious diseases are easily transmissible from an infected person to a healthy person. Influenza and Small pox are infectious diseases. Both Influenza and small pox are caused due to viral infection.
Hence, the correct answer is option D.
Page No 51:
Question 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. gut of mosquito
Answer:
The sporozoites that cause infection when a female Anopheles mosquito bites a person that are produced in the intestine of the mosquito.
Hence, the correct answer is option D.
Page No 52:
Question 6:
The disease chikunguniya is transmitted by:
a. house fly
b. Aedes mosquito
c. cockroach
d. female Anopheles
Answer:
Chikunguniya disease is transmitted by the bite of Aedes mosquito.
Hence, the correct answer is option B.
Page No 52:
Question 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
Answer:
Pneumonia is caused by the infection of bacteria such as Streptococcus pneumoniae and Haemophilus influenzae. The symptoms for this disease are difficulty in respiration, fever, chills, cough and headache.
Hence, the correct answer is option A.
Page No 52:
Question 8:
Cancer causing genes are called:
a. structural genes
b. expressor genes
c. oncogenes
d. regulatory genes
Answer:
Oncogenes are called the cancer causing genes. Such genes cause the growth of cancer cells. The proto-oncogenes are identified in normal cells and these cells are aeltiuated under certain conditions that lead to oncogenic transformation of the cells.
Hence, the correct answer is option C.
Page No 52:
Question 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
Answer:
The malignant tumors are a mass of proliferating cells called neoplastic or tumor cells. Such cells grow very rapidlly, invading and also causes damages to the normal surrounding tissues. Metastasis is the most feared property of malignant tumors as in this, the cells travel from these tumors and reach at distant sites through blood and starts forming a tumor.
Hence, the correct answer is option B.
Page No 52:
Question 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
Answer:
When an apparently healthy person is diagnosed as unhealthy by a psychiatrist, this occurs when the patient shows behavioural and social maladjustment.
Hence, the correct answer is option C.
Page No 52:
Question 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
Answer:
Rheumatoid arthritis is an auto immune disease caused due to some genetic or other unknown reasons. In this disease, the immune system lost the ability to differentiate between self and foreign cells. In this case, the body attacks self cells.
Hence, the correct answer is option B.
Page No 53:
Question 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
Answer:
AIDS (Acquired Immuno Deficiency Syndrome) is caused due to HIV virus. This disease can be transmitted by sharing injection needles with an infected person, blood transfusion with an infected person, unprotected sexual contact with an infected person and from an infected mother to her foetus.
Hence, the correct answer is option C.
Page No 53:
Question 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
Answer:
Heroin is commonly called smack. It is obtained by the acetylation of morphine. It is extracted from the latex of poppy plant Papaver Somniferum.
Hence, the correct answer is option A.
Page No 53:
Question 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
Answer:
Interferon are proteins produced by the viral-infected cells to protect non-infected cells from further viral infection.
Hence, the correct answer is option C.
Page No 53:
Question 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
Answer:
The body have ability to differentiate between self and non-self. The cell-mediated immunity is responsible for the graft rejection.
Hence, the correct answer is option D.
Page No 53:
Question 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
Answer:
Ig A antibody is present in colostrum that provides passive immunity to developing infant. Colostrum is the yellowish fluid secreted during the initial days of lactation.
Hence, the correct answer is option B.
Page No 54:
Question 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
Answer:
Tobacco contains a large amount of a chemical substances called nicotine. It is an alkaloid and this stimulates adrenal gland to release adrenaline and nor-adrenalilne into the blood circulation. This raises blood pressure and increases heart rate.
Hence, the correct answer is option A.
Page No 54:
Question 18:
Antivenom against snake poison contains:
a. Antigens
b. Antigen-antibody complexes
c. Antibodies
d. Enzymes
Answer:
In case of snakebites, anti-venom infection are given to the patient that contain preformed antibodies against the snake venom.
Hence, the correct answer is option C.
Page No 54:
Question 19:
Which of the following is not a lymphoid tissue?
a. Spleen
b. Tonsils
c. Pancreas
d. Thymus
Answer:
The primary and secondary lymphoid organs are:-
Bone marrow, thymus, spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix.
Hence, the correct answer is option C.
Page No 54:
Question 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
Answer:
The thymus is a lobed organ and is present near the heart and beneath the breast bone. The size of the thymus is large at the time of birth but its size decreases with increasing age. At the time of puberty, it is reduces to a very small size.
Hence, the correct answer is option C.
Page No 54:
Question 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
Answer:
Haemozoin is a toxin released due to multiplication of Plasmodium in the liver cells then attack the RBCs during malaria infection. This toxic substance is responsible for the chill and high fever recurring every three to four days.
Hence, the correct answer is option C.
Page No 54:
Question 22:
Which of the following is not the causal organism for ringworm?
a. Microsporum
b. Trichophyton
c. Epidermophyton
d. Macrosporum
Answer:
Ringworm is an most common infections disease in man. It is caused by the fungi Microsporum, Trichophyton and Epidermophyton.
Hence, the correct answer is option D.
Page No 55:
Question 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
Answer:
A person with sickle cell anemia is less prone to malaria because of sickle like shape of RBCs due to low oxygen tension.
Hence, the correct answer is option C.
Page No 55:
Question 1:
Certain pathogens are tissue/organ specific. Justify the statement with suitable examples.
Answer:
Certain pathogens are tissue/organ specific because they are adapted to overcome the resistance mechanisms of various tissues or organs.
When the pathogen enter in the gut they have the ability to survive in the stomach at low pH and is resistant to digestive enzymes produced by the stomach.
For example:- In case of pneumonia, the bacteria Streptococcus pneumoniae and Haemophilus influenzae only infects the alveoli of the lungs.
Page No 55:
Question 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?
Answer:
a. AIDS (Acquired Immuno Deficiency Syndrome)
b. HIV (Human Immuno Deficiency Virus)
c. The virus affects the helper T-cells (TH) of the body. Due to decrease in the number of helper T-cells (TH), the person starts suffering from infection.
Page No 55:
Question 3:
Where are B-cells and T-cells formed? How do they differ from each other?
Answer:
Both B and T lymphocytes are formed in bone marrow. But maturation of B-cell occurs in the bone marrow cells while maturation of T-cells takes place in the thymus.
B-cell produce antibodies (IgA, IgG, IgM, IgD, IgE) in response to antigens. These are responsible for humoral immunity.
T-cell stimultes the B-cells to produce antibodies. These are responsible for cell-mediated immunity.
Page No 55:
Question 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?
(a) Virus common cold
(b) Salmonella typhoid
(c) Microsporum filariasis
(d) Plasmodium malaria
Answer:
ans
Page No 55:
Question 5:
What would happen to immune system, if thymus gland is removed from the body of a person?
Answer:
ans
Page No 55:
Question 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?
Answer:
ans
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Question 7:
Why is mother's milk considered the most appropriate food for a new born infant?
Answer:
ans
Page No 55:
Question 8:
What are interferons? How do interferons check infection of new cells?
Answer:
ans
Page No 56:
Question 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.
Answer:
ans
Page No 56:
Question 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.
Answer:
ans
Page No 56:
Question 11:
Why is it that during changing weather, one is advised to avoid closed, crowded and airconditioned places like cinema halls etc.?
Answer:
ans
Page No 56:
Question 12:
The harmful allele of sickle cell anemia has not been eliminated from human population. Such afflicted people derive some other benefit. Discuss.
Answer:
ans
Page No 56:
Question 13:
Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.
Answer:
ans
Page No 56:
Question 14:
Why is an antibody molecule represented as H2L2?
Answer:
ans
Page No 56:
Question 15:
What does the term `memory' of the Immune system mean?
Answer:
ans
Page No 56:
Question 16:
If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.
Answer:
ans
Page No 57:
Question 1:
Differentiate between active immunity and passive immunity.
Answer:
ans
Page No 57:
Question 2:
Differentiate between benign tumor and malignant tumor.
Answer:
ans
Page No 57:
Question 3:
Do you consider passive smoking is more dangerous than active smoking? Why?
Answer:
ans
Page No 57:
Question 4:
“Prevention is better than cure”. Comment.
Answer:
ans
Page No 57:
Question 5:
Explain any three preventive measures to control microbial infections.
Answer:
ans
Page No 57:
Question 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?
Answer:
ans
Page No 58:
Question 7:
“Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify the statement giving suitable examples.
Answer:
ans
Page No 58:
Question 8:
The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.
_________________________________________________________________________________________________________
Name the of Disease Causative organism Symptoms
_________________________________________________________________________________________________________
(i) Ascariasis Ascaris ____
(ii) ____ Trichophyton Appearance of dry, scaly lesions on various parts of the body
(iii) Typhoid ____ High fever, weakness, headache, stomach pain, constipation.
(iv) pneumoniae Streptococcus Pneumonia ____
(v) ____ Rhino viruses Nasal congestion and discharge, sorethroat, cough, headache
(vi) Filariasis ____ Inflammation in lower limbs
__________________________________________________________________________________________________________
Answer:
ans
Page No 58:
Question 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 the consumption of these drugs.
Answer:
ans
Page No 58:
Question 10:
Give the full form of CT and MRI. How are they different from each other? Where are they used?
Answer:
ans
Page No 58:
Question 11:
Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.
Answer:
ans
Page No 59:
Question 12:
Why cannabinoids are banned in sports and games?
Answer:
ans
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Question 13:
What is secondary metabolism?
Answer:
ans
Page No 59:
Question 14:
Drugs and alcohol give short-term 'high' and long-term ‘damages’, Discuss.
Answer:
ans
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Question 15:
Diseases like dysentery, cholera, typhoid etc., are more common in over crowded human settlements. Why?
Answer:
ans
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Question 16:
From which plant cannabiniods are obtained? Name any two cannabinoids. Which part of the body is effected by consuming these substances?
Answer:
ans
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Question 17:
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:
ans
Page No 59:
Question 18:
What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis B Vaccine is produced.
Answer:
ans
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Question 19:
What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
Answer:
ans
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Question 20:
A person shows strong unusual hypersensitive reactions when exposed to certain substances present in the air. Identify the condition. Name the cells responsible for such reactions. What precaution should be taken to avoid such reactions.
Answer:
ans
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Question 21:
For an organ transplant, it is an advantage to have an identical twin. Why?
Answer:
ans
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Question 22:
What are lifestyle diseases? How are they caused? Name any two such diseases.
Answer:
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Page No 59:
Question 23:
If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And Why?
Answer:
ans
Page No 59:
Question 1:
Represent schematically the life cycle of a malarial parasite.
Answer:
ans
Page No 59:
Question 2:
Compare the life style of people living in the urban areas with those of rural areas and briefly describe how the life style affects their health.
Answer:
ans
Page No 59:
Question 3:
Why do some adolescents start taking drugs. How can this be avoided?
Answer:
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Page No 59:
Question 4:
In your locality, if a person is addicted to alcohol, what kind of behavioural changes do you observe in that person? Suggest measures to over come the problem.
Answer:
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Page No 60:
Question 5:
What are the methods of cancer detection? Describe the common approaches for treatment of cancer.
Answer:
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Page No 60:
Question 6:
Drugs like LSD, barbiturates, amphetamines, etc., are used as medicines to help patients with mental illness. However, excessive doses and abusive usage are harmful. Enumerate the major adverse effects of such drugs in humans.
Answer:
ans
Page No 60:
Question 7:
What is Pulse Polio Programme of Government of India? What is OPV? Why is it that India is yet to eradicate Polio?
Answer:
ans
Page No 60:
Question 8:
What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.
Answer:
ans
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