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NCERT Exemplar · Class 12 · Biology

Chapter 8: Human Health and Diseases

Practice each question, then open the answer or worked solution.

Multiple Choice Questions

23 questions
Q1Multiple choice

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

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Correct option: C
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Ans: Correct option is c.

Health is defined as a state of complete social, mental, and physical well-being that is free of sickness. Nutrition, lifestyle, environmental factors, and genetics are thought to be the key pillars of health. A person's health may be jeopardised if any of these are compromised. A well-balanced nutrient diet keeps a person healthy by providing all of the essential nutrients that the body requires. Environmental influences have an impact on an individual's health.


Q2Multiple choice

The organisms which cause diseases in plants and animals are called:

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Correct option: A
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Ans: Correct option is a

Pathogens are organisms that cause disease in both plants and animals. There are several forms of pathogens:

1. Viruses: These are not cells, but rather DNA or RNA segments. They're the ones who infect you with viruses. Retroviruses, human immunodeficiency viruses, and other viruses are examples.

Bacteria are single-celled microorganisms that cause bacterial infections. Streptococcus pneumonia, for example.

3. Fungi are eukaryotic organisms like moulds and yeast. Fungal infections are spread by them. Trichophyton and Aspergillus, for example.

4. Protozoa: These organisms are unicellular and include algae, amoeba, and Euglena, among others. 

5. Worms, also known as Helminths, are parasitic creatures. Hookworm, threadworm, pinworm, flatworm, and roundworm are some of the types of worms.


Q3Multiple choice

The clinical test that is used for diagnosis of typhoid is:

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Correct option: D
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Ans: Correct option is d

ELISA is an Enzyme Linked Immunosorbent Assay which is used for many purposes including detection of many diseases, viruses and certain mutations.

ESR is Erythrocyte Sedimentation Rate which is used in diagnosis of various blood and systemic disorders.

PCR or Polymerase Chain Reaction is used in detection of various diseases at genetic level and for various other purposes.

Widal Test is used primarily for the diagnosis of typhoid in an individual with lesser fatal symptoms.


Q4Multiple choice

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

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Ans: Correct option is d.

Influenza is a viral infection caused by the influenza virus. The influenza virus is a highly contagious illness. It is spread through direct contact, the use of infected people's belongings, and droplets. High fever, runny nose, sore throat, muscle pains, headache, cough, sneezes, and exhaustion are all frequent symptoms.

Smallpox is caused by the Variola virus. It is a highly contagious disease with no known cure. Smallpox has been eradicated thanks to massive vaccination campaigns around the world.


Q5Multiple choice

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

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1. When a female Anopheles mosquito bites an infected person, the sporozoites that carry malarial plasmodium cells enter the mosquito's gut.

2. It begins to replicate here and is stored in the salivary glands of the mosquito.

3. When a mosquito bites an uninfected person, the sporozoites reach the liver and begin to proliferate, causing the RBC to rupture and release a toxin called hemozoin, which causes fever, chills, and scarring.


Q6Multiple choice

The disease chikungunya is transmitted by:

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Correct option: B
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Ans: Correct option is b

Chikungunya is transmitted to humans through infected mosquito bites. Chikungunya disease is caused by the chikungunya virus, which is spread by Aedes mosquitoes. The most common indicators of infection are fever and joint pain. Other symptoms may include a headache, muscular soreness, joint swelling, or a rash.


Q7Multiple choice

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

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Correct option: A
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Ans: Correct option is a.

Pneumonia is a respiratory disease primarily presenting with symptoms of fever, chills, cough, headaches and a difficulty in breathing.

Amoebiasis is a parasitic disease affecting human intestines producing symptoms like constipation, abdominal pain, blood clots and cramps.

Influenza is another respiratory disease which presents as nasal congestion, discharge, headache and cough.

Typhoid is a fatal disease which presents with high fever, stomach pain, weakness, appetite loss, constipation accompanied with weakness.


Q8Multiple choice

Cancer-causing genes are called:

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Ans: Correct option is c

Oncogenes are cells that can turn a healthy cell into a cancerous one. These genes usually have a component in them which can turn cancerous on exposure to a carcinogenic substance. 

Except for regulatory proteins, structural genes code for RNA and other proteins. Regulatory genes are the genes that control the expression of other genes.


Q9Multiple choice

In malignant tumours, the cells proliferate, grow rapidly and move to other parts of the body to form new tumours. This stage of the disease is called:

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Correct option: B
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Sr No

Tumours

Definition

1

Metagenesis

In an orgasim, the reproduction cycle alternates between sexual and asexual are known as metagenesis.

2

Metastasis

In malignant tumours, the cells proliferate, grow very fastly and move towards other parts of the body to form new tumours. 

3

Teratogenesis

It is the process by which congenital or birth defects take place in the foetus.

4

Mitosis

Cell division in which two daughter cells are formed having the same number of chromosomes.


Q10Multiple choice

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

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Ans: Correct option is c

If a seemingly healthy person is labelled as unwell by a psychiatrist, the cause could be that the patient exhibits behavioural and social maladjustment. Extreme thirst, dehydration, or hunger, weight loss without effort or abnormal weight loss, a want to binge eat excessively, a desire to vomit on purpose, or a desire to starve (not eat at all). A preoccupation with food and weight, as well as a distorted body image, are also present. When body temperature deviates from its typical range, it can be an indication of acute or chronic disease, as well as signal specific health issues. This will be the root of people who are physically unfit.