CBSE Class 12 Biology Human Health And Diseases Worksheet

Important Questions for NCERT Class 12 Biology Human Health and Diseases

Ques. The infectious stage of Plasmodium that enters the human body is
(a) Trophozoites
(b) Sporozoites
(c) Female gametocytes
(d) Male gametocytes

Answer: B

Ques. Match the following diseases with the causative organism and select the correct option.
  Column-I                     Column-II
A. Typhoid               (i) Wuchereria
B. Pneumonia         (ii) Plasmodium
C. Filariasis             (iii) Salmonella
D. Malaria               (iv) Haemophilus
      A    B   C   D
(a) (i) (iii) (ii) (iv)
(b) (iii) (iv) (i) (ii)
(c) (ii) (i) (iii) (iv)
(d) (iv) (i) (ii) (iii) 

Answer: B

Ques. Identify the correct pair representing the causative agent of typhoid fever and the confirmatory test for typhoid.
(a) Salmonella typhi / Widal test
(b) Plasmodium vivax / UTI test
(c) Streptococcus pneumoniae / Widal test
(d) Salmonella typhi / Anthrone test

Answer: A

Ques. In which disease does mosquito transmitted pathogen cause chronic inflammation of lymphatic vessels?
(a) Elephantiasis
(b) Ascariasis
(c) Ringworm disease
(d) Amoebiasis

Answer: A

Ques. Which of the following sets of diseases is caused by bacteria?
(a) Cholera and tetanus
(b) Typhoid and smallpox
(c) Tetanus and mumps
(d) Herpes and influenza 

Answer: A

Ques. Which of the following diseases is caused by a protozoan?
(a) Babesiosis
(b) Blastomycosis
(c) Syphilis
(d) Influenza 

Answer: A

Ques. Match each disease with its correct type of vaccine.
       Column I                 Column II
A. Tuberculosis           (i) Harmless virus
B. Whooping cough    (ii) Inactivated toxin
C. Diphtheria               (iii) Killed bacteria
D. Polio                       (iv) Harmless bacteria
(a) A-(iv), B-(iii), C-(ii), D-(i)
(b) A-(i), B-(ii), C-(iv), D-(iii)
(c) A-(ii), B-(i), C-(iii), D-(iv)
(d) A-(iii), B-(ii), C-(iv), D-(i) 

Answer: A

Ques. The active form of Entamoeba histolytica feeds upon
(a) food in intestine
(b) blood only
(c) erythrocytes, mucosa and submucosa of colon
(d) mucosa and submucosa of colon only.

Answer: C

Ques. Infection of Ascaris usually occurs by
(a) Tse-tse fly
(b) mosquito bite
(c) drinking water containing eggs of Ascaris
(d) eating imperfectly cooked pork.

Answer: C

Ques. Identify the site where Wuchereria bancrofti is normally found in human body.
(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

Ques. Motile zygote of Plasmodium occurs in
(a) gut of female Anopheles
(b) salivary glands of Anopheles
(c) human RBCs
(d) human liver. 

Answer: A

Ques. Widal test is carried out to test
(a) malaria
(b) diabetes mellitus
(c) HIV/AIDS
(d) typhoid fever. 

Answer: D

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

Answer: D

Ques. Where will you look for the sporozoites of the malarial parasite?
(a) Saliva of infected female Anopheles mosquito
(b) Red blood corpuscles of human suffering from malaria
(c) Spleen of infected humans
(d) Salivary glands of freshy moulted female Anopheles mosquito 

Answer: A

Ques. Which one of the following options gives the correct match of a disease with its causative organism and mode of infection?
  Disease                      Causative                          Mode of infection
(a) Typhoid              Salmonella typhi                     With inspiredair
(b) Pneumonia        Streptococcus pneumoniae    Droplet infection
(c) Elephantiasis      Wuchereria bancrofti             With infected water and food
(d) Malaria                 Plasmodium vivax               Bite of male Anopheles mosquito

Answer: B

Ques. Common cold is not cured by antibiotics because it is
(a) caused by a virus
(b) caused by a Gram-positive bacterium
(c) caused by a Gram-negative bacterium
(d) not an infectious disease. 

Answer: A

Ques. Ringworm in humans is caused by
(a) bacteria
(b) fungi
(c) nematodes
(d) viruses. 

Answer: B

Ques. Widal test is used for the diagnosis of
(a) malaria
(b) pneumonia
(c) tuberculosis
(d) typhoid. 

Answer: D

Ques. 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 the stage to enter fresh RBCs
(d) the microgametocytes and megagametocytes are being destroyed by the WBCs.

Answer: C

Ques. Which of the following is a pair of viral diseases?
(a) Common cold, AIDS
(b) Dysentery, common cold
(c) Typhoid, tuberculosis
(d) Ringworm, AIDS

Answer: A

Ques. Match the disease in column I with the appropriate items (pathogen / prevention / treatment) in column II.
     Column I                Column II
A. Amoebiasis         (i) Treponema pallidum
B. Diphtheria          (ii) Use only sterilised food and water
C. Cholera              (iii) DPT vaccine
D. Syphilis              (iv) Use oral rehydration therapy
(a) A – (ii), B – (i), C – (iii), D – (iv)
(b) A – (ii), B – (iii), C – (iv), D – (i)
(c) A – (i), B – (ii), C – (iii), D – (iv)
(d) A – (ii), B – (iv), C – (i), D – (iii) 

Answer: B

Long Answer Questions

Question. Mention the name of the causal organism, symptoms and the mode of transmission of the disease amoebiasis. 
                                             OR
(a) Name the protozoan parasite that causes amoebic dysentery in humans.
(b) Mention two diagnostic symptoms of the disease.
(c) How is this disease transmitted to others?
                                OR
(a) Name the agent that causes amoebiasis and the human body organ that it infects.
(b) Write the symptoms and the mode of transmission of the disease. 
Answer. Amoebic dysentery (Amoebiasis)
• It is caused by a protozoan endoparasite, Entamoeba histolytica, found in large intestine of humans.
• Housefly acts as mechanical carrier and transmits the parasite from faeces of infected person to the food.
• Infection takes place through food and water contaminated by faecal matter.

Question. A doctor prescribed morphine as a sedative and pain killer to your cousin who had undergone surgery. Even after recovery, he craved for the prescribed medicine. What do you conclude about his condition, had he continued with the same medication? After appraising yourself, what measures will you suggest to him to overcome this problem? Briefly explain any two.
Answer. His condition is drug dependence. It is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs is abruptly discontinued. Because of perceived benefits, drugs are frequently used repeatedly from which the person may not be able to get out.
Following measures can be taken to overcome this problem:
(i) Education and counseling to face problems and stresses and to channelise the energy into healthy pursuits like reading, music, yoga and other extracurricular activities.
(ii) Seeking help from parents to guide the person appropriately and immediately.
(iii) Seeking professional and medical help to the person to get rid of the problem completely with sufficient efforts and will power a(ny two).

Question. Name the form of Plasmodium that gains entry into the human body. Explain the different stages of its life cycle in the human body. 
Answer. Plasmodium vivax gains entry into the human body.
Malaria
• It is caused by a protozoan Plasmodium (P. vivax, P. malaria and P. falciparum).
• P. falciparum causes the most serious and fatal malignant malaria.
• The vector of Plasmodium is female Anopheles mosquito which transfers the sporozoites (infectious form).
• Treatment is by antimalarial drugs like quinine, chloroquin.
• Malaria can be prevented by killing mosquitoes by spraying DDT, BHC, etc., and using insect repellents, mosquito nets, etc.

Question. Malarial parasite ‘Plasmodium’ completes its life cycle in two hosts. Draw its complete life cycle and explain various stages it follows throughout its life. 
Answer. Stages:
(a) The stage in which the parasite enters in the body of humans through saliva of mosquito—sporozoite stage.
(b) Asexual reproduction of sporozoites in liver cells, resulting into bursting of those cells and releasing outside into the blood.
(c) Sporozoites infect RBCs, cause them to get burst and represented by repeated cycles of fever.
Released parasites also infect other RBCs.
(d) Parasites then follow sexual stage in RBCs which is called as ring signet stage and appears as a ring inside the RBCs under microscope. Usually presence of malarial parasite in humans is identified by pathologists by this stage.
(e) Female mosquito takes up gametocytes with the blood of host. Fertilisation and development takes place in the intestine of mosquito.
(f) From intestine, parasite comes to the salivary glands from where it reaches to human body and that is how the cycle continues.

Question. Under polio prevention programme, infants in India were given polio vaccines on a large scale at regular intervals to eradicate polio from the country.
(a) What is a vaccine? Explain how does it impart immunity to the child against the disease.
(b) With the help of an example each, differentiate between active and passive immunity.
Answer. (a) Vaccination is the process of introduction of weakened or inactivated pathogens or proteins (vaccine) into a person to provide protection against a disease.
• Vaccines are weakened or inactivated pathogens or proteins introduced into a person to provide protection against a disease.
• Immunisation is the process by which the body produces antibodies against the vaccine (primary response) and develops the ability to neutralise pathogens during actual infection (secondary response).
• Vaccination provides immunisation after a time gap.
• Vaccination and immunisation are based on the property called ‘Memory’ of the immune system.
(b) Refer to Basic Concepts Point 9.

Question. To which category of cells do B-cells and T-cells belong? How do they differ from each other with reference to their formation and response to antigens?
Answer. B-cells and T-cells belong to the category of lymphocytes, i.e., leucocytes (WBC).
Differences between B-lymphocyte and T-lymphocyte

Question. Explain the process of replication of a retrovirus after it gains entry into the human body.
OR
(a) How does a Human Immunodeficiency Virus (HIV) replicate in a host?
(b) How does a HIV-infected patient lose immunity?
(c) List any two symptoms of this disease. 
Answer. (a)

(b) An HIV-infected patient loses immunity due to loss of T-lymphocytes.
(c) Symptoms are fever, diarrhoea, susceptibility to other diseases and prone to microbial infection. (Any two)

Question. Your school has been selected by the Department of Education to organise and host an interschool seminar on “Reproductive Health—Problems and Practices”. However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is “too embarrassing.”
Put forth four arguments with appropriate reasons and explanation to justify the topic to be very essential and timely. 
Answer. (i) The issue of puberty and adolescence need to be addressed effectively with the respective age group because many changes take place in the body during adolescence of which they are supposed to be aware of.
(ii) To bring in awareness about their reproductive health and its effect on their physical,emotional and social being.
(iii) To address the increase in sex abuse and sex crimes in our country.
(iv) Myths and misconceptions related to reproductive issues need to be cleared at the right time.

Question. Why do some adolescents start taking drugs? How can the situation be avoided?
Answer. The psychological attachment to certain effects such as euphoria and temporary feeling of well-being,associated with drugs and alcohol is called addiction.
• People take drugs/alcohol when not needed, but with repeated use, tolerance level of receptions in body increases; receptors thus respond to higher doses, leadinng to greater intake and addition.
For measures to avoid taking drug, Avoid undue pressure: Every child has his own choice and personality and hence should be respected and nurtured accordingly. They should not be forced to perform beyond their threshold limits, be in sports or studies, etc.
• Educating and counselling: Children should be educated and counselled to face problems, stresses,to accept disappointments and features as part of life. We shold put in efforts to channellise child’s energy into healthy pursuits like sports, reading, music, yoga etc.

Question. (a) Name and explain giving reasons, the type of immunity provided to the newborn by the colostrum and vaccinations.
(b) Name the type of antibody
(i) present in colostrum
(ii) produced in response to allergens in human body.
Answer. (a) Colostrum provides passive immunity, because the infant gets antibodies from the mother’s body directly for protection.Vaccinations provide active immunity because in this case microbes are injected into the body do develop immunity slowly.
(b) (i) IgA (ii) IgE

Question. What is the basic principle of vaccination? How do vaccines prevent microbial infections?
Name the organism from which hepatitis B vaccine is produced. 
Answer. Principle of vaccination is based on the property of ‘memory’ of immune system. In vaccination,a preparation of antigenic proteins of pathogens or inactivated/live but weakened pathogens is introduced into the body. The antigens generate primary immune response by producing antibodies along with forming memory B-cells and T-cells. When the vaccinated person is attacked by the same pathogens, second time/subsequent time the existing memory B-cells and T-cells recognise the antigen and overwhelm the invaders with massive production of lymphocytes and antibodies. Hepatitis B vaccine is produced from yeast.

Question. (a) Why is there a fear amongst the guardians that their adolescent wards may get trapped in drug/alcohol abuse?
(b) Explain ‘addiction’ and ‘dependence’ in respect of drugs/alcohol abuse in youth.
Answer. (a) Adolescents are easily affected by (or are vulnerable to) peer pressure. Curiosity, need for adventure and excitement, and experimentation constitute common causes for motivation. A child’s natural curiosity motivates him/her to experiment. Television, movies, newspapers, internet also promote drug use.
(b) Addiction is the psychological attachment to certain effects such as euphoria or temporary feeling of well-being.
Dependence is the tendency of the body to show withdrawal syndrome or symptoms if regular doses of drug/alcohol is abruptly discontinued.

Question. (a) Name the types of lymphoid organs, lymph nodes and thymus are. Explain the role played by them in causing immune response.
(b) Differentiate between innate immunity and acquired immunity. 
Answer. (a) Thymus is primary lymphoid organ and lymph nodes are secondary lymphoid organs.
Thymus provides the microenvironment for immature lymphocytes to differentiate into antigen-sensitive lymphocytes.
Lymph nodes serve to 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.
(b)

Question. A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabionoids.
(a) Will you report to the authorities? Why?
(b) Name a plant from which such chemicals are obtained.
(c) Write the effect of these chemicals on human body.
Answer. (a) Yes. Because these may be abused by sports person.
(b) Cannabis (sativa)
(c) Cannabinoids effect cardiovascular system of the body.

Question. (a) Name and explain giving reasons, the type of immunity provided to the newborn by the colostrum and vaccinations.
(b) Name the type of antibody
(i) present in colostrum
(ii) produced in response to allergens in human body.
Answer. (a) Colostrum provides passive immunity, because the infant gets antibodies from the mother’s body directly for protection.
Vaccinations provide active immunity because in this case microbes are injected into the body do develop immunity slowly.
(b) (i) IgA (ii) IgE

Question. (a) Cancer is one of the most dreaded diseases of humans. Explain ‘Contact inhibition’ and ‘Metastasis’ with respect to the disease.
(b) Name the group of genes which have been identified in normal cells that could lead to cancer and how they do so?
(c) Name any two techniques which are useful to detect cancers of internal organs.
(d) Why are cancer patients often given α-interferon as part of the treatment?
Answer. (a) Contact inhibition is the property of normal cells in which contact with other cells inhibits their uncontrolled growth.
Metastasis is the property in which tumour cells reach distant sites in the body, through blood.
(b) Proto oncogenes or Cellular oncogenes.
These genes when activated under certain condition could lead to oncogenic transformation of the cells.
(c) Biopsy/radiography/CT/MRI (Any two)
(d) α-interferon activates immune system and destroys the tumour.

ONE MARK QUESTION

1 What role do macrophages play in providing immunity to humans?

2 Recently chikungunya cases were reported from various parts of the country. Name the vector responsible.

3 How do neutrophils act as a cellular barrier to pathogens in humans?

4 Name the two types of cells in which the HIV multiplies after gaining entry into the human blood.

5 Given below are some human organs. Identify one primary and one secondary lymphoid organs: Liver,Thymus, Stomach,Thyroid, Tonsils

6 How does colostrums provide initial protection against diseases to new born infants? Give one reason.

7 Small allergens trigger sneezing and wheezing in human beings. What causes this type of response by the body?

8 A body of ten years had chicken pox. He is not exposed to have the same disease for the rest of his life. Mention how it is possible.

9 What type of virus causes AIDS? Name its genetic material.

10 Give the scientific name of the parasite that causes malignant malaria in humans.

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