Class 12 Biology Chapter 7 Exemplar Solutions
Multiple Choice Questions (MCQs)
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.
2. The organisms which cause diseases in plants and animals are called
(a) pathogens
(b) vectors
(c) insects
(d) worms
3. The chemical test that is used for diagnosis of typhoid is
(a) ELISA test
(b) ESR test
(c) PCR test
(d) Widal test
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. Smallpox
(a) I and II
(b) II and III
(c) III and IV
(d) II and IV
5. The sporozoites that cause infection when a female Anopheles mosquito bites a human being are formed in
(a) liver of human
(b) RBCs of mosquito
(c) salivary glands of mosquito
(d) intestine of human
6. The disease chikungunya is transmitted by
(a) house flies
(b) Aedes mosquitoes
(c) cockroach
(d) female Anopheles
7. Many disease 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 and headache
(b) Constipation, abdominal pain, cramps and blood clots
(c) Nasal congestion and discharge, cough, sore throat and headache
(d) High fever, weakness, stomach pain, loss of appetite and constipation.
8. The genes causing cancer are
(a) structural genes
(b) expressor genes
(c) oncogenes
(d) regulatory genes
9. In malignant tumours, the cells proliferate, grow rapidly and move to other parts of the body to form new tumours. This stage of disease is called
(a) metagenesis
(b) metastasis
(c) teratogenesis
(d) mitosis
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
11. Which of the following are the reasons (s) for rheumatoid arthritis? Choose the correct option.
I. Lymphocytes become more active
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
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
13. ‘Smack’ is a drug obtained from the
(a) latex of Papaver somniferum
(b) leaves of Cannabis sativa
(c) flowers of Dhatura pinata
(d) fruits of Erythroxylum coca
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
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
16. Antibodies present in colostrum, which protect the newborn from certain diseases, is of
(a) IgG type
(b) IgA type
(c) IgD type
(d) IgE type
17. Tobacco consumption is known to stimulate secretion of adrenaline and noradrenaline. The component causing this could be.
(a) nicotine
(b) tannic acid
(c) curaimin
(d) catechine
18. Anti-venom against snake poison contains
(a) antigens
(b) antigen-antibody complexes
(c) antibodies
(d) enzymes
19. Which of the following is not a lymphoid tissue?
(a) Spleen
(b) Tonsils
(c) Appendix
(d) Thymus
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
21. Haemozoin is
(a) precursor of haemoglobin
(b) toxin from Streptococcus
(c) toxin from Plasmodium species
(d) toxin from Haemophilus species
22. One of the following is not the causal organism for ringworm
(a) Microsporum
(b) Trichophyton
(c) Epidermophyton
(d) Macrosporum
23. A person with sickle–cell anaemia is
(a) more prone to malaria
(b) more prone to typhoid
(c) less prone to malaria
(d) less prone to typhoid
Very Short Answer Type Questions
1. Certain pathogens are tissue/organ specific. Justify the statement with suitable example.
2. The immune system of a person is suppressed. In the ELISA test, was found positive to a pathogen.
- (a) Name the diseases the patient is suffering from.
- (b) What are the causative organisms?
- (c) Which cells of body are affected by the pathogen?
3. Where are B-cells and T-cells formed? How do they differ from each other?
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) Microsporium | Filariasis |
| (d) Plasmodium | Malaria |
5. What would happen to immune system if thymus gland is removed from the body of a person?
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?
7. Why is mother’s milk considered the most appropriate food for a newborn infant?
8. What are interferons? How do interferons check infection of new cells?
9. In the figure, structure of an antibody molecule is shown. Name the parts A, B and C.
10. If a regular dose of drug or alcohol is not provided to an addicted person, he show some withdrawal symptoms. List any four such withdrawal symptoms.
11. Why is it that during changing weather, one is advised to avoid closed, crowded and air-conditioned places like cinema halls, etc?
12. The harmful allele of sickle-cell anaemia has not been eliminated from human population. Such afflicted people derive some other benefit. Discuss.
13. Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.
14. Why is an antibody molecule represented as H2L2?
15. What does the term ‘memory’ of the immune system mean?
16. If a patient is advised anti-retroviral therapy, which infection is he suffering from? Name the causative organism.
Short Answer Type Questions
1. Differentiate between active immunity and passive immunity.
2. Differentiate between benign tumour and malignant tumour.
3. Do you consider passive smoking is more dangerous than active smoking? Why?
4. ‘Prevention is better than cure’. Comment.
5. Explain any three preventive measures to control microbial infections.
6. In the given flow diagram, the replication of retrovirus in a host is shown. Observe and answer the following questions.
(a) Fill in (A) and (B)
(b) Why is the virus called retrovirus?
(c) Can the infected cell survive while viruses are being replicated and released?
7. ‘Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases. Justify the statement, giving suitable examples.
8. The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.
| Diseases | Causative organisms | Symptoms |
| Ascariasis | Ascaris | — |
| — | Trichophyton | Appearance of dry, scaly lesions on various parts of the body |
| Typhoid | — | High fever, weakness, headache, stomach pain and constipation. |
| Pneumonia | Streptococcus pneumoniae | — |
| — | Rhino viruses | Nasal congestion and discharge, sore throat, cough, headache |
| Filariasis | — | Inflammation in lower limbs |
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.
10. Give the full form of CT and MRI. How are they different from each other? Where are they used?
11. Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.
12. Why are cannabinoids banned in sports and games?
13. What is secondary metabolism?
14. Drugs and alcohol give short-term ‘high’ and long-term ‘damage’.
15. Diseases like dysentery, cholera, typhoid, etc., are more common in over crowded human settlements. Why?
16. From which plant are cannabinoids obtained? Name any two cannabinoids. Which part of the body is affected by consuming these substances?
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.
18. What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis B vaccine is produced.
19. What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
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 precautions should be taken to avoid such reactions?
21. For an organ transplant, it is an advantage to have an identical twin. Why?
22. What are lifestyle diseases? How are they caused? Name any two such diseases.
23. If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And why?
Long Answer Type Questions
1. Represent schematically the life-cycle of a malarial parasite.
2. Compare the lifestyle of people living in the urban areas with of those rural areas and briefly describe how the lifestyle affects their health.
3. Why do some adolescents start taking drugs? How can this be avoided?
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 overcome the problem.
5. What are the methods of cancer detection? Describe the common approaches for treatment of cancer.
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.
7. What is the Pulse Polio Programme of the Government of India? What is OPV? Why is it that India has yet to eradicate polio?
8. What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.
Class 12 Biology Chapter 7 Exemplar Solutions PDF
Download the CBSE Class 12 Biology Chapter 7 Exemplar Solutions PDF!
Additional Study Materials
- Human Health and Disease – Competency-Based Questions
- Human Reproduction – Exemplar Solutions
- Reproductive Health- Exemplar Solutions
- Principles of Inheritance and Variation- Exemplar Solutions
- Molecular Basis of Inheritance- Exemplar Solutions
- Evolution- Exemplar Solutions
Thankyou for sharing the information with us.