NCERT Exemplar solutions for Biology [English] Class 12 chapter 8 - Human Health and Diseases [Latest edition]

The term ' health' is defined in many ways. The most accurate definition of health would be

The organisms which cause diseases in plants and animals are called ______.

The clinical test that is used for diagnosis of typhoid is ______.

Diseases are broadly grouped into infectious and non-infectious diseases. In the list given below, identify the infectious diseases.

1. Cancer
2. Influenza
3. Allergy
4. Small pox

The sporozoites that cause infection when a female Anopheles mosquito bites a person, are formed in ______.

The disease chikunguniya is transmitted by ______.

Many diseases can be diagnosed by observing the symptoms in the patient. Which group of symptoms are indicative of pneumonia?

Cancer causing genes are called ______.

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 ______.

When an apparently healthy person is diagnosed as unhealthy by a psychiatrist, the reason could be that ______.  

Which of the following are the reason(s) for Rheumatoid arthritis? Choose the correct option.

1. The ability to differentiate pathogens or foreign molecules from self-cells increases.
2. Body attacks self cells
3. More antibodies are produced in the body
4. The ability to differentiate pathogens or foreign molecules from self-cells is lost

AIDS is caused by HIV. Among the following, which one is not a mode of transmission of HIV?

'Smack' is a drug obtained from the ______.

The substance produced by a cell in viral infection that can protect other cells from further infection is ______.

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?

Antibodies present in colostrum which protect the new born from certain diseases is of ______.

Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be ______.

Antivenom against snake poison contains ______.

Which of the following is not a lymphoid tissue?

Which of the following glands is large-sized at birth but reduces in size with ageing?  

Haemozoin is ____________.

Which of the following is not the causal organism for ringworm?

A person with sickle cell anemia is ______.

Certain pathogens are tissue/organ specific. Justify the statement with suitable examples.

The immune system of a person is suppressed. In the ELISA test, he was found positive to a pathogen.

1. Name the disease the patient is suffering from.
2. What is the causative organism?
3. Which cells of body are affected by the pathogen?

Where are B-cells and T-cells formed? How do they differ from each other?

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

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

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?

Why is mother's milk considered the most appropriate food for a new born infant?

What are interferons? How do interferons check infection of new cells?

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.

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.

Why is it that during changing weather, one is advised to avoid closed, crowded and airconditioned places like cinema halls etc.?

The harmful allele of sickle cell anemia has not been eliminated from human population. Such afflicted people derive some other benefit. Discuss.

Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.

Why is an antibody molecule represented as H₂L₂?

What does the term `memory' of the Immune system mean?

If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.

Differentiate between active immunity and passive immunity.

Differentiate between a benign tumor and a malignant tumor.

Do you consider passive smoking is more dangerous than active smoking? Why?

“Prevention is better than cure”. Comment.

Explain any three preventive measures to control microbial infections.

In the given flow diagram, the replication of retrovirus in a host is shown. Observe and answer the following questions.

Fill in (1) and (2)

Why is the virus called retrovirus?

Can the infected cell survive while viruses are being replicated and released?

“Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify the statement giving suitable examples.

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

The outline structure of a drug is given below.

1. Which group of drugs does this represent?
2. What are the modes of consumption of these drugs?
3. Name the organ of the body which is affected by consumption of these drugs.

Give the full form of CT and MRI. How are they different from each other? Where are they used?

Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.

Why cannabinoids are banned in sports and games?

What is secondary metabolism?

Drugs and alcohol give short-term 'high' and long-term ‘damages’, Discuss.

Diseases like dysentery, cholera, typhoid etc., are more common in overcrowded human settlements. Why?

From which plant cannabiniods are obtained? Name any two cannabinoids. Which part of the body is effected by consuming these substances?

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.

What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis B vaccine is produced.

What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?

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.

For an organ transplant, it is an advantage to have an identical twin. Why?

What are lifestyle diseases? How are they caused? Name any two such diseases.

If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And Why?

Represent schematically the life cycle of a malarial parasite.

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.

Why do some adolescents start taking drugs. How can this be avoided?

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.

What are the methods of cancer detection? Describe the common approaches for treatment of cancer.

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.

What is Pulse Polio Programme of Government of India? What is OPV? Why is it that India is yet to eradicate Polio?

What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.