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NCERT Exemplar Class 12 Biology Solutions Chapter 8 Human Health and Disease

NCERT Exemplar Class 12 Biology Solutions Chapter 8 Human Health and Disease

Edited By Priyanka kumari | Updated on Aug 26, 2022 12:19 PM IST | #CBSE Class 12th

NCERT exemplar Class 12 Biology solutions chapter 8 are the complete study materials for any student preparing for board exams. The NCERT exemplar Class 12 Biology chapter 8 solutions provide the extra edge as well as the right guidance to the students. In addition to the board exams, the Class 12 Biology NCERT exemplar solutions chapter 8 will help students to prepare for upcoming competitive exams such as NEET as well. The questions are designed by professional experts with immense knowledge and in accordance with the CCE guidelines.

Introduction of NCERT Exemplar Class 12 Biology Solutions Chapter 8:

Multiple Choice Questions:

Question:1

The term 'Health' is defined in many ways. The most accurate definition of 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 a symbol of economic prosperity.

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Answer:

The answer is the option (c) health is a state of complete physical, mental, and social well-being
Explanation: To lead a quality life, physical fitness alone is not sufficient. Mental and Social well-being hold equal importance

Question:2

The organisms which cause diseases in plants and animals are called:
a. Pathogens
b. Vectors
c. Insects
d. Worms

Answer:

The answer is the option (a) Pathogens
Explanation: Only some insects and worms cause diseases. Vectors are just carriers of disease causing organisms.

Question:3

The clinical test that is used for the diagnosis of typhoid is:
a. ELISA
b. ESR
c. PCR
d. Widal

Answer:

The answer is the option (d) Widal-Test
Explanation: ELISA is used to diagnose AIDS. PCR amplifies gene copies to obtain a particular gene sequence. ESR test determines the sedimentation rate of RBCs and is used as a diagnostic tool for inflammation. Widal test is used to diagnose typhoid.

Question:4

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

Answer:

The answer is the option (d) (ii) and (iv)
Explanation: Cancer and allergy are non-infectious diseases.

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 answer is the option (d) intestine of mosquito
Explanation: intestine of mosquito

Question:6

The disease chikungunya is transmitted by:
a. house fly
b. Aedes mosquito
c. cockroach
d. female Anopheles

Answer:

The answer is the option (b) Aedes mosquitoes

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:

The answer is the option (a) Difficulty in respiration, fever, chills, cough, headache
Explanation: Symptoms in 'b' and'd' are related to digestive system. Symptoms in 'c' are related to common cold.

Question:8

Cancer-causing genes are called:
a. structural genes
b. expressed genes
c. oncogenes
d. regulatory genes

Answer:

The answer is the option (c) oncogenes
Explanation: The term 'onco' is related to cancer

Question:9

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:
a. metagenesis
b. metastasis
c. teratogenesis
d. mitosis

Answer:

The answer is the option (b) metastasis
Explanation: Metagenesis is related to alternation of generation. Teratogenesis is related to congenital deformities. And mitosis is a type of cell division.

Question:10

When a 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 an interest in sports

Answer:

The answer is the option (c) the patient shows behavioural and social maladjustment
Explanation: Option a, b and d cannot indicate a disease when taken in isolation.

Question:11

Which of the following is the reason(s) for Rheumatoid arthritis? Choose the correct option.
i. The ability to differentiate pathogens or foreign molecules from self cells increases.
ii. The 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:

The answer is the option (b) (ii) and (iv)
Explanation: (b) (ii) and (iv)

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 person
d. Sexual contact with infected persons

Answer:

The answer is the option (c) Shaking hands with infected persons
Explanation: HIV can only transmit through the exchange of body fluids

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 Erythroxylum coca

Answer:

The answer is the option (a) latex of Papaver somniferum
Explanation: (a) latex of Papaver somniferum

Question:14

The substance produced by a cell in a viral infection that can protect other cells from further infection are:
a. serotonin
b. colostrum
c. interferon
d. histamine

Answer:

The answer is the option (c) interferon
Explanation: Interferon is a protein which prevents a healthy cell from being infected by a virus.

Question:15

Transplantation of tissues/organs to save certain patients often fails due to the 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 answer is the option (d) cell-mediated immune response

Question:16

Antibodies present in colostrum which protect the newborn from certain diseases are of
a. IgG type
b. Ig A type
c. Ig D type
d. Ig E type

Answer:

The answer is the option (b) IgA type

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:

The answer is the option (a) Nicotine

Question:18

Antivenom against snake poison contains:
a. Antigens
b. Antigen-antibody complexes
c. Antibodies
d. Enzymes

Answer:

The answer is the option (c) Antibodies

Question:19

Which of the following is not a lymphoid tissue?
b. Tonsils
c. Pancreas
d. Thymus

Answer:

The answer is the option (c) Pancreas

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 answer is the option (c) Thymus

Question:21

Haemozoin is a:
a. precursor of haemoglobin
b. the toxin released from Streptococcus infected cells
c. the toxin released from Plasmodium-infected cells
d. the toxin released from Haemophilus infected cells

Answer:

The answer is the option (c) toxin released from Plasmodium infected cells
Explanation: Haemozoin is responsible for episode of chills and fevers in a malaria patient.

Question:22

Which of the following is not the causal organism for ringworm?
a. Microsporum
b. Trichophyton
c. Epidermophyton
d. Microsporum

Answer:

The answer is the option (d) Macrosporum

Question: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

Answer:

The answer is the option (c) less prone to malaria
Explanation: Due to the different shape of RBCs, people suffering from sickle cell anaemia show higher resistance to malaria.

Very Short Answer Type Questions:

Question:1

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

Answer:

Yes, some pathogens are tissue/organ-specific. For instance, Rhinovirus only infects the nasal passage and respiratory tract only but not the lungs. Ringworm causing fungi only infect the skin.

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 the body are affected by the pathogen?

Answer:

(a) AIDS
(b) Human Immuno Deficiency Virus
(c) T-lymphocytes

Question:3

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

Answer:

B-cells are formed in the bone marrow and are responsible for the production of antibodies. T-cells are formed in the thymus, and they help B-cells in the production of antibodies.

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

cold

b. Salmonella

Typhoid

c. Microsporum

Filariasis

d. Plasmodium

malaria


Answer:

c) Microsporum causes ringworm and not filariasis.

Question:5

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

Answer:

Thymus is responsible for maturation of lymphocytes and is one of the primary lymphoid organs. As enough T-cells are generated during the foetal stage (pre-birth), their removal does not impact immunity significantly. However, if thymus is removed during infancy, there may be some effect on the individual's immunity

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:

Most microbial pathogens are eliminated due to mucus secreted by the inner lining of the alimentary canal. Pathogens which survive it, are killed in the stomach due to the acidic pH.

Question:7

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

Answer:

For a few days after birth, the mother's milk is rich in antibodies (IgA) which protects the infant against many diseases.

Question:8

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

Answer:

Interferon is a protein secreted by virus-infected cells, which act like cytokinine barriers and protects other cells from infection.

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:

Four withdrawal symptoms that an addicted person shows are:

  1. Anxiety

  2. Shakiness

  3. Nausea

  4. Sweating

Question:11

Why is it that during changing weather, one is advised to avoid close, crowded and air-conditioned places like cinema halls etc.?

Answer:

Germs, which can cause infectious diseases to float in the air during changing weather. Their presence is especially high in closed, crowded, and air-conditioned places. This is why we should avoid such places during changing weather.


Question:12

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

Answer:

People suffering from sickle cell anaemia are less prone to malaria. According to a report from the CDC, in areas with a higher number of cases of malaria, cases of sickle cell anaemia is also higher.

Question:13

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

Answer:

Microbes and antigens, which make their way into lymph and tissue field are trapped by lymph nodes. These trapped antigens, in turn, activate lymphocytes triggering the immune response.

Question:14

Why is an antibody molecule represented as H2L2 ?

Answer:

An antibody molecule is represented as H2L2 because they have four peptide chains -
a. Light Chains - These two chains are small
b.Heavy Chains -These two chains are long

Question:15

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

Answer:

Our body gains immunity against certain pathogens after they attack the body the first time. This is called the primary response and is characterised by low intensity.
However, when the same pathogens make their way in again, our immune system responds with higher intensity due to 'memory'. This more intense response is called a secondary response.

Question:16

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

Answer:

If a patient is advised Anti-Retroviral Therapy, he is likely to suffer from AIDS. Human Immunodeficiency Virus (HIV) is the causative organism.

Short Answer Type Questions:

Question:1

Differentiate between active immunity and passive immunity.

Answer:

Active Immunity

Passive Immunity

The body prepares antibodies in response to a pathogen or foreign material.

Antibodies are deliberately put into the body by artificial means.

It is slow and takes time to respond.

It is fast and responds quickly.

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Question:2

Differentiate between a benign tumour and malignant tumour.

Answer:

Benign Tumour

Malignant Tumour

They usually do not spread to other parts of the body and remain confined to their original location

They spread to other parts of the body as well

They can't start a new tumour at a new place

They may start a new tumour at a new place

They cause little damage

They cause severe damage


Question:3

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

Answer:

Although active smokers are at more risk of smoking-related diseases, passive smoking is still more dangerous than active smoking. It is because the person is not intentionally doing it, but is forced by his/her situation to inhale the smoke, while an active smoker is aware of the danger, they are in.

Question:4

"Prevention is better than cure". Comment.

Answer:

Prevention is better than cure as the cure entails various costs - physical, emotional, and monetary. It adds a huge financial burden to the individual's family. Prevention generally costs a fraction of the cure and also prevents loss in economic productivity.

Question:5

Explain any three preventive measures to control microbial infections.

Answer:

Three preventive measures to control microbial infections are:
(a) Avoiding contaminated food and water: Many infections spread through contaminated food and water and can be easily prevented by avoiding contaminated food and water.
(b) Preventing vectors: Some diseases spread through vectors like a mosquito. These diseases can be prevented by putting a check on the breeding grounds for these vectors.
(c) Maintaining hygiene: Many diseases like Coronavirus are transmitted through water droplets that come out of our nose and mouth. Maintaining personal hygiene is the best way to avoid contracting such diseases

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 the virus called retrovirus?
c. Can the infected cell survive while viruses are being replicated and released?

Answer:

  1. 1: viral DNA is produced; 2: Viral RNA is produced by the host cell

  2. A virus which has an envelope enclosing RNA genome is called a retrovirus.

  3. Yes.

Question:7

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

Answer:

Maintaining personal hygiene ensures the non-transmission of many infectious diseases to a great extent. Especially diseases which transmit through air, droplets, and skin infections.
Lack of public hygiene is the biggest contributor to the spread of many diseases like cholera, typhoid, malaria and many more. Ensuring cleanliness of your surrounding can lead to a drastic reduction in incidences of many such diseases.

Question:8

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


Name of the diease

Causative organism

Symptoms

(i)

Ascariasis

Ascaris

_______

(ii)

_______

Trichophyton

Appearance of dry,scaly lesions on various parts of body

(iii)

Typhoid

Salmonella typhi

High fever,weakness,headache, stomach pain,constipation

(iv)

Pneumonia

Streptococcus pneumoniae

_______

(v)

_______

Rhino viruses

Nasal congestion and discharge, sore throat,cough, headache

(vi)

Filarisis

_______

Inflamation in lower limbs


Answer:

Name of diseases

Causative Organism

Symptoms

Ascariasis

Ascaris

Internal bleeding, muscular pain, anaemia, fever, blockage of intestinal passage

Ringworm

Trichophyton

Appearance of dry, scaly lesions on various parts of the body

Typhoid

Salmonella Typhi

High fever, weakness, headache, stomach pain, constipation

Pneumonia

Streptococcus pneumoniae

Fluid in lungs, fever, difficulty in breathing

Common cold

Rhinoviruses

Nasal congestion and discharge, sore throat, cough, headache

Filariasis

Wuchereria

Inflammation in lower limbs


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:

  1. Cannabinoids

  2. Inhalation and oral ingestion

  3. Cardiovascular system

Question:10

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

Answer:

CT

MRI

It stands for Computed Tomography

It stands for Magnetic Resonance Imaging

It uses X-ray for imaging

It uses a magnetic field and non-ionising radiations

It generates a 3-D image of the internals of an object

It detects pathological and physiological changes in living tissues


Question:11

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

Answer:

Drugs like morphine and codeine (opium) have strong medical applications where morphine is a very strong painkiller, and codeine is effective in suppressing cough. Unfortunately, the flip-side to both these medicines is that they are highly intoxicating and thus are misused for this purpose. Such drug abuse makes a person hallucinogenic.

Question:12

Why are cannabinoids banned in sports and games?

Answer:

Cannabinoids are used as a performance enhancer in sports as they reduce the sensation of pain and thus increases the endurance of the athlete.

Question:13

What is secondary metabolism?

Answer:

There are some pathways and small molecule products of metabolism, which are not essential for the survival of the organism. These are known as secondary or specialised metabolism.

Question:14

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

Answer:

Drugs and alcohol are intoxicating, and people use them to get 'high' but have serious long term repercussions. Ex- Liver cirrhosis (a life-threatening ailment) is common among long term alcohol addicts.

Question:15

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

Answer:

It is tough to maintain public hygiene in overcrowded places. Consider for example - Shared washrooms are common in overcrowded places. Compared to an individual's washroom, such washrooms will be highly unhygienic. Moreover, being densely populated, even simple diseases like common cold spread to many people very quickly.

Question:16

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

Answer:

Cannabinoids are obtained from Cannabis sativa. Marijuana and hashish are examples of cannabinoids. They affect the cardiovascular system.

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:

Many children are protected from the external environment early in their life because of which their immunity is low against hazardous environmental factors, especially in metropolitan areas. This is the main cause of allergic reactions in children.Some symptoms of an allergic reaction are; coughing, sneezing, breathlessness, etc.

Question:18

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

Answer:

Vaccination works on the principle of 'memory' of the immune system. Vaccines help the immune system to fight future attacks from a pathogen. Antibodies are created by the body in response to the vaccine, and these antibodies jump into action when the pathogen attacks again. Yeast is used to producing the Hepatitis B vaccine.

Question:19

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

Uncontrolled cell division which leads to the formation of a tumour is called cancer. Unlike a normal cell, which loses its ability to divide in a few iterations, cancer cells continue to divide endlessly. Generally, the normal cell stops diving when it comes in contact with other cells. This ability is known as contact inhibition, and cancerous cells are abnormal as they do not possess this ability.

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:

This condition is called allergy. Such a reaction is caused by mast cells; and basophils (white blood cells). To prevent such allergic reactions, one should avoid the substances to which they are allergic. Allergies against pollen are very common, and an allergic person should avoid going near such flowers.

Question:21

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

Answer:

Immune system always tries to reject any foreign substance. Unfortunately, this may lead to tissue rejection in Organ transplant. However, most of the tissues are identical in identical twins, and this reduces the chances of tissue rejection.

Question:22

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

Answer:

Lifestyle diseases occur because of faulty lifestyle. Overeating and sedentary lifestyle are the major causes of such diseases.Ex-Diabetes and hypercholesterolemia.

Question:23

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

Answer:

Compared to DNA, RNA replication is more susceptible to errors, and thus are more susceptible to mutations.


Long Answer Type Questions:

Question:1

Represent schematically the life cycle of a malarial parasite.

Answer:



Question:2

Compare the lifestyle of people living in urban areas with those of rural areas and briefly describe how lifestyle affects their health.

Answer:

People in Urban Areas

People in Rural Areas

Most of the people do jobs which involve sitting for long hours.

Most of people do jobs which involve manual work

Have a sedentary lifestyle

Have an active lifestyle

Can easily avail processed food

Primarily eat unprocessed and homemade

Environmental pollution is high

Environmental pollution is low

High risk of Diabetes and cardiovascular

Low risk of Diabetes and cardiovascular

Can receive quality medical attention

May not receive quality medical attention


Question:3

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

Answer:

Many adolescents who start taking drugs do so because of their curiosity and adventure-seeking nature. Moreover, under peer pressure, many adolescents end up taking drugs to experiment, and continued use leads to addiction.

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 overcome the problem.

Answer:

A person addicted to alcohol may avoid socialising, may become easily irritable and suffers from spells of rage and depression. Some people even resort to petty crimes if they are unable to afford the money to buy alcohol.
To address the situation:

  • A qualified counsellor should be pressed into service.

  • People closest to them should spend more time with the person

  • The person must get help to reduce or totally withdraw from any alcohol consumption

Question:5

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

Answer:

Following are the methods of cancer detection:
Biopsy: A small fragment of the concerning tissue is extracted and then goes through histopathological study.
Blood Test and Bone Marrow Test: Increased levels of cell count can be gauged from this test.
Imagery Technique: Internal organs can be diagnosed by X-ray, CT scan and MRI.
Apart from the above mentioned techniques, antibodies against cancer-specific antigens and molecular biotechnology are also used in certain cases.
Common approaches of treatment involve surgery, radiotherapy, and immunotherapy:

  1. Surgery: It can be used to remove the tumour.

  2. Radiotherapy: Radioactive rays can be utilised to destroy cancerous cells, with minimal impact to normal cells

  3. Immunotherapy: Chemotherapeutic drugs are used to destroy cancer cells. It involves the use of Interferon alfa, which helps the body's immune system to respond to cancer.

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:

Adverse Effects of LSD: Most common side-effect of LSD is depression. Other side-effects include Schizophrenia or sever uterine contractions (in female)
Adverse Effects of Barbiturates: Side-effects of Barbiturates include -

  • Tolerance - Person needs higher doses as time passes

  • Dependence - Person cannot live without this drug.

Adverse Effects of Amphetamines: Mental depression and bouts of hallucinations are common side effects.

Question:7

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

Answer:

Pulse Polio: Launched in 1995-96, it is a mass immunisation programme aimed at eradicating the poliomyelitis virus from India. This programme has been undertaken with active cooperation from government agencies, NGOs, UNICEF, and CDC.
Key Objectives of Pulse Polio:

  • Not a single child should be missed.

  • High level of surveillance.

  • Reporting of any new case within 14 days.

To cover all the children below age 5, Polio booths are established throughout the country and volunteers are hired to administer the polio vaccine.
OPV (Oral Polio Vaccine): OPV is an attenuated vaccine, which is produced at a sub-physiological temperature by the passage of the virus through non-human cells. This produces spontaneous mutation in the viral genome. A single vial of OPV usually contains 10-20 doses.
India was declared a Polio free nation on 27th March 2014 as there were no new cases in the previous three years.

Question:8

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

Answer:

In recombinant DNA vaccine, only one or two antigen is inserted into the DNA of a suitable host. Recombinant DNA technology enables to make vaccines on a larger scale with least chances of contamination. These are cheaper. Examples include Hepatitis B and HPV Vaccine
Cell culture is used to do large scale production. A suitable animal (ex - horse) is injected with strains of pathogen and antigens are produced in the horse's cells. Antigens are then extracted from horse's serum. However, there are many shortcomings to this method –

  • Due to the possibility of contamination, there are chances of contracting other diseases

  • The method is challenged by Animal Rights Activists.

Recombinant DNA technology can address these issues as yeast is required to produce the vaccine, and large scale production can be done at a lower cost.

Health is an important part of our existence. In fact, the term health is frequently used in all fields of life. But what does Health really mean? As explained in the NCERT exemplar solutions for Class 12 Biology chapter 8, health is not simply the absence of disease or physical fitness. When people are healthy, they are more efficient, active, and productive. Health is defined as complete physical, mental and social well-being of the body.

In NCERT exemplar Class 12 Biology solutions chapter 8, the various aspects related to health be it the influence of different diseases, the immunity of the organism and fatal diseases like AIDS and Cancer are well explained.

Major Subtopics in NCERT Exemplar Class 12 Biology Chapter 8 Solutions Human Health And Disease

  • Common Diseases in Humans
  • Immunity
  • Innate Immunity
  • Acquired Immunity
  • Active and Passive Immunity
  • Vaccination and Immunity
  • Allergies
  • Auto Immunity
  • Immune system in the Body
  • AIDS
  • Cancer
  • Drugs and Alcohol Abuse
  • Adolescence and Drug/Alcohol Abuse
  • Addiction and Dependence
  • Effects of Drug/Alcohol Abuse
  • Prevention and Control
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NCERT Exemplar Class 12 Biology Solutions Chapter 8 Human Health And Disease - Learning Outcome

  • In NCERT exemplar Class 12 Biology chapter 8 solutions, the students will learn about different aspects of health as an important factor. Awareness about diseases and their effects on various body functions along with the precautions and cure are detailed in this chapter of NCERT Class 12 Biology Solutions.

  • Besides being highly informative the NCERT exemplar solutions for Class 12 Biology chapter 8 is fun and interesting as it talks about various vital topics like vaccinations, fatal disease like Cancer and AIDS, their diagnosis, cure and prevention.

  • The chapter also explain the importance of avoiding drugs as well as their impacts on adolescence.

  • NCERT exemplar Class 12 Biology solutions chapter 8 can be a student’s best companion in the stressful time of exams as it helps the students to overcome fear before the exam with practice, improves their management skills and develops accuracy.

NCERT Exemplar Class 12 Biology Chapter Wise Links:

Important Topics NCERT Exemplar Class 12 Biology Solutions Chapter 8

  • The impact of various environmental factors like vectors, diet, drugs on the health of living organisms are explained in the class 12 Biology NCERT exemplar solutions chapter 8.

  • Different diseases that threaten the well-being of humankind, their causes, symptoms and prevention are explained in this chapter which helps students to grasp the concepts well.

  • Also, the immunity that protects a living and helps them fight back the disease is also mentioned in NCERT exemplar solutions for Class 12 Biology chapter 8.

NCERT Exemplar Class 12 Solutions Subject Wise:

Check NCERT solutions for questions given in the book:

Also, Read NCERT Solution subject wise

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Also Check NCERT Books and NCERT Syllabus here

Frequently Asked Question (FAQs)

1. Are these Solutions useful for competitive exams?

Yes, the NCERT exemplar Class 12 Biology solutions chapter 8 are useful for competitive exams as well. The exemplar is prepared in accordance with the NCERT, which is also followed in the competitive exams like NEET.

2. Are these Biology solutions chapter 8 based on the NCERT book?

The Class 12 Biology NCERT exemplar solutions chapter 8 are prepared by the experts according to the CCE guidelines and are completely based on NCERT books.

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One can download the solutions in PDF format by using the webpage to PDF tools available online.

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Questions related to CBSE Class 12th

Have a question related to CBSE Class 12th ?

Hello student,

If you are planning to appear again for class 12th board exam with PCMB as a private candidate here is the right information you need:

  • No school admission needed! Register directly with CBSE. (But if you want to attend the school then you can take admission in any private school of your choice but it will be waste of money)
  • You have to appear for the 2025 12th board exams.
  • Registration for class 12th board exam starts around September 2024 (check CBSE website for exact dates).
  • Aim to register before late October to avoid extra fees.
  • Schools might not offer classes for private students, so focus on self-study or coaching.

Remember , these are tentative dates based on last year. Keep an eye on the CBSE website ( https://www.cbse.gov.in/ ) for the accurate and official announcement.

I hope this answer helps you. If you have more queries then feel free to share your questions with us, we will be happy to help you.

Good luck with your studies!

There is a good chance that Jadavpur University will accept your NIOS improvement exam marksheet for Maths, but there could be a few factors to consider:

The university might have specific guidelines regarding accepting improvement exams from NIOS or other open schooling boards.

Look for the admission brochure or information on the university website related to eligibility criteria for admission. This might mention the acceptability of improvement exams.

Contact the Jadavpur University admissions office directly and explain your situation. Inquire whether they accept improvement exams from NIOS for Maths and if there are any specific requirements or procedures to follow.

Many universities in India accept improvement exams from NIOS or other recognized boards as long as it improves your overall score and meets the eligibility criteria for the program you are applying to.

Getting clarification directly from Jadavpur University is the most reliable way to ensure your NIOS improvement exam marksheet will be accepted for admission purposes. This proactive approach will help you avoid any last-minute surprises during the application process.

https://university.careers360.com/articles/jadavpur-university-application-form

I hope it helps!

I understand you're feeling stressed and scared about your CBSE Class 12th Chemistry compartment exam

The CBSE usually conducts compartment exams only once a year in July. There isn't an official provision to skip the first attempt and appear for a later one.

You seem eligible for the compartment exam this year since you have an "RT" (Repeater with Theory) in Chemistry.

Since you have applied, it's best to focus your energy on preparing well for the compartment exam happening in July 2024. Utilize this time effectively for revision and practice.

Hello,


Yes, you can give improvement exams for 2-3 subjects in CBSE (Central Board of Secondary Education). CBSE allows students who have appeared for their Class 12 board exams to improve their scores by re-appearing for exams in up to five subjects the following year.


Hope this helps,


Thank you

You most likely will still be considered for passing based on the information you provided.

The CHSE Odisha board requires a minimum of 33% marks in each subject (including theory and practical) and an overall aggregate of 33% to pass class 12 exams.Since your failure is in the optional subject, and assuming all other subjects meet the minimum marks (33%), you should be okay.

You need 33% marks in each subject (5 main subjects + 1 optional). If you have 33% or above in all your main subjects, even if you failed the optional subject, your overall aggregate should likely be above 33% (considering the marks of all 6 subjects).

However , to be absolutely certain, it's best to confirm this directly with the CHSE Odisha board or the college you are applying to.

https://school.careers360.com/exams/odisha-chse

I hope it helps!

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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