Class XII – Human Health and Diseases – PYQs

Ans. Lifestyle diseases are ailments that are primarily based on the day-to-day habits of people. Lifestyle diseases are caused by specific food habits, work related posture or exposure to harmful radiations or substances, lack of physical exercise, mental stress, etc. Two lifestyle diseases are

• Hypertension
• Heart disease

Ans. Sickle-cell anaemia still persists in the population despite being harmful because this mutation can also be beneficial in certain conditions. The mutant HbS type haemoglobin is found at high frequencies (upto 20% and above) in the tropical Africa.

It is known that heterozygotes (Hb^S /Hb^A), having both types of haemoglobin show resistance to malarial infection as the body targets the Plasmodium falciparum infected cell for destruction. In contrast, individuals homozygous for normal haemoglobin (Hb^A / Hb^A) suffer high mortality rates in early childhood due to malarial infection. Thus, the allele for sickle-cell has been maintained because heterozygotes have a higher reproductive success than either of the two possible homozygotes.

Ans. The disease with given characteristics is amoebiasis. Causative agent is a parasite, Entamoeba histolytica, which is found in the large intestine of human. The transmitting agent of the pathogen is housefly. Symptoms include constipation, abdominal pain, cramps and stools with excess mucus and blood clots.

Ans.

Ans. Comparison between the symptoms of ascariasis, amoebiasis and elephantiasis are as follows

Ans. To prevent water-borne diseases, water bodies, like ponds, water tanks, reservoirs in the city or village should be cleaned periodically. The proper disposal of domestic waste, excreta, sewage should be done. At personal level, boiling of water, using water purifier, washing hands before meals should be practiced.

Ans. Prevention is always better than cure because some diseases cause extensive damage to the body tissues or organs and have a

(i) negative effect on their capacity to function.

(ii) permanent or long term debilitating effect.

(iii) negative mental and psychological effect.

(iv) financial burden.

Hence, it is said that prevention is easier and effective than cure of a disease.

Ans. During changing weather, one is advised to avoid crowded places because changing seasons are the time when infectious agents are more active as moist conditions favours the growth of pathogens. Also, people are more vulnerable as their body system is busy in adapting to the changing environmental conditions of temperature, humidity, etc. Thus, this increases the chances of getting easily infected by various pathogens.

Ans. Slums are generally unauthorised and encroached colonies having no public facilities. Due to lack of public facilities and education, the living standards there are very low and people are always at risk. Thus, there is a need to organise visits to educate people of slum about sanitation and other health related issues.

Ans. Development of healthy life is a bidirectional process and needs the cooperation of both authorities and public of slum area. Interacting with people, understanding their needs, availability of funds, interaction with all concerned authorities, making a concrete plan of development are required to handle the situation of slums.

Ans. Preventive measures to control microbial infections are as follows

1. Personal hygiene Keeping the body clean, consumption of clean drinking water, food, vegetables, fruits, etc.

2. Public hygiene Proper disposal of waste and excreta, periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks and observing standard practices of hygiene in public catering.

3. For vector borne diseases such as malaria Eradication of vectors and destroying their breeding sites, e.g. using mosquito nets and repellents, avoiding stagnation of water, regular cleaning of coolers, etc., introducing fishes like Gambusia in ponds that feed on mosquito larvae, spraying of insecticides in ditches, drainage areas and swamps, etc.

Ans. (i) A–Physiological barriers, B–Acid in stomach.

(ii) C–Cellular barriers, D–Phagocytose and destroy microbes

(iii) E–Interferons, F–Prevention of viral infections

Ans. When the boy suffered from chickenpox, first time his body’s immune system exhibited primary response. Along with that, the memory of chickenpox virus was stored by the immune system. Now, whenever the same virus will attack this boy, the immune system will produce an intense response, preventing the body from getting chickenpox again. Thus, protecting the boy from getting infected by chickenpox ever again in life. It is known as acquired immunity.

Ans. Interferons are special kind of proteins secreted by virus infected cells. These protect the healthy cells from the virus attack.

Ans. Memory of the immune system is an unique feature, which helps in producing an intensive secondary/anamnestic response when the pathogen attacks the second time.

Ans. Types of acquired immune responses are

(i) Humoral immune response provided by B-lymphocytes.

(ii) Cell-mediated immune response provided by T-lymphocytes.

Ans. Functional differences between B and T-cells are as follows

Ans. Hepatitis-B vaccine is produced from surface antigens of transgenic yeast by rDNA technology. The antigens represent whole protein vaccine.

16. Why is mother’s milk considered the most appropriate food for a new-born infant?

OR

Why is colostrum a boon to the new-born baby?

Ans. Mother’s milk is considered most appropriate or a boon for a new-born infant as it provides immunity in the initial period of baby’s life. The yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant.

Ans. The basic principle of immunisation is based on the property of memory of the immune system. In vaccination, an antigen or antigenic protein or pathogen which is in inactive form is introduced in the body which induces very mild immune response. The vaccine thus, generates antibodies that neutralise pathogen during actual infection. It also generates memory B and T-cells that recognise the pathogen on subsequent exposure and elicit a massive immune response. Yeast cells help in production of hepatitis-B vaccine.

Ans. Tetanus antitoxin is a preparation containing antibodies to the toxin. Produced by tetanus bacteria, Clostridium tetani.

Ans. The injured persons are immediately injected with tetanus antitoxin for preventing any infection and septic. Antitoxins neutralise the toxin produced by bacteria.

Ans. Tetanus antitoxin represents artificial passive immunisation where quick response is generated in the body.

Ans. In metropolitan cities, lifestyle is responsible for lowering of immunity and high sensitivity to allergens. The polluted environment of cities, which affect the respiratory system is the reason of allergy/asthma in children’s. Some symptoms of allergic reactions are sneezing, watery eyes, running nose and difficulty in breathing.

Ans. Thymus is a primary lymphoid organ. It is lobe-shaped and is known to be the site for the growth and differentiation of antigen sensitive T-lymphocytes.

Ans. Thymus releases T-lymphocytes, which are involved in cell-mediated immunity and also help B-lymphocytes to produce antibodies.

(i) MALT – Mucosal Associated Lymphoid Tissue

(ii) CMI – Cell-Mediated Immunity

(iii) AIDS – Acquired Immuno Deficiency Syndrome

(iv) NACO – National AIDS Control Organisation

(v) HIV – Human Immunodeficiency Virus

Ans. The patient is suffering from AIDS

Ans. AIDS is caused by Human Immunodeficiency Virus (HIV). It is a retrovirus containing RNA as genetic material.

Ans. Macrophages and helper T-cells are affected by the pathogen.

Ans. Repeated blood transfusion may result in contracting diseases like AIDS. The recipient must ensure that the donor’s blood is being screened for HIV and other pathogens.

Ans. In the absence of such measures, the patient can get infected by HIV (Human Immunodeficiency Virus) which causes AIDS. It is a threatening disorder that weakens the immune system by attacking helper T-cells in the body

Ans.

Ans. Differences between benign and malignant tumour are as follows

Ans. CT is Computed Tomography which uses X-rays to generate 3D images of internal organs.

MRI is Magnetic Resonance Imaging which uses strong magnetic fields and non-ionising radiations to detect pathological and physiological changes in the living tissue accurately.

Both are used in cancer detection.

Ans. Heroin is obtained from acetylation of morphine. They both affect the central nervous system and gastrointestine tract. Thus, both are related. Morphine, is as an effective sedative and painkiller while heroin acts as depressant and slows down body functions.

Ans. Both morphine and heroin are extracted from the latex of plant Papaver somniferum.

Morphine acts as an effective sedative and painkiller, while heroin acts as depressant and slows down body functions. When taken in excess amounts, these drugs alter the moods or induce sleep.

Ans. The scientific names of the source plant of drugs marijuana and hashish is Cannabis sativa. They usually effect the cardiovascular system of human body.

Ans. A–Cocaine, B–Central nervous system, C–Cannabis sativa, D–Cardiovascular system

Ans. Many secondary metabolites obtained from plants are used for their medicinal properties, e.g. opiates derived from poppy plant are used as drugs to relieve pain. The problem starts when these metabolites are misused for having pleasure and are taken in doses above the prescribed limit, e.g. opium addict loses weight, fertility and interest in work.

Ans. Passive smoking can be equally dangerous because it exposes the person to the same harmful effects of smoke. Passive smoking means being in the same room or place, where someone is smoking and getting exposed to smoke in the surrounding area.

Once inhaled, the smoke can trigger mucus release in the bronchioles that blocks the airways. This induces coughing. But prolonged exposure can lead to bronchitis, emphysema, respiratory tract infections and eventually lung cancer.

Ans. If the regular dose of drug or alcohol in an addicted person is discontinued abruptly, the body exhibits characteristic and unpleasant symptoms called ‘withdrawal syndrome’.

The ‘withdrawal syndrome’ is characterised by symptoms like anxiety, shakiness, nausea and excessive sweating.

Ans. Cannabinoids are banned in sports as athletes were misusing these drugs in order to enhance their performance. These can have a serious negative effect on their general health and in long term, can hamper the normal functioning of organ systems.

Hence, intake of cannabinoids should be banned.

Ans. Yes, the ‘dope test’ should be conducted on sports persons participating in prestigious athletic meet.

This is done to find out whether any participant had taken any kind of performance enhancing drugs.

The use of drugs in sports should be banned as

(i) they increase muscle strength.

(ii) promote aggressiveness.

(iii) increase athletic performance.

Because of above reasons, use of such drugs, e.g. steroids, analgesics, diuretics should be banned for participants as it would be unfair to the other participants (not consuming such drugs).

Ans. The age between 12-18 years of age is called adolescent period. There is always a fear amongst guardians that their adolescents may get trapped in drug/alcohol abuse due to following reasons

(a) Adolescence is accompanied by several biological and behavioural changes. It is a vulnerable phase of mental and psychological development of an individual in which an individual may get addicted to alcohol/drugs very easily.

(b) In this age, the first use of drugs or alcohol may be out of curiosity or experimentation, which later on turns to addiction.

(c) Adolescents usually take drugs due to social pressure, need of adventure, excitement, to avoid stress, depression and frustration.

Ans. Addiction. It is a psychological attachment to certain effects such as euphoria and temporary feeling of well-being associated with drugs and alcohol. It makes the person to take up drugs on regular basis, even when they are not needed or even when their use becomes self-destructive.

Dependence. It is the tendency of the body to show unpleasant and characteristic withdrawal syndrome, if the dose of alcohol or drug is discontinued abruptly. Dependency pushes the person away from social norms and leads to social adjustment problems.

Ans. Recombinant DNA vaccines are made up of a small circular DNA (plasmid) that has very tiny piece of pathogen DNA incorporated in it to produce one or two specific proteins of the pathogen.

This recombinant DNA is introduced into the bacteria or yeast cells, where it can use cell’s machinery to produce polypeptides of pathogen. These are used as vaccines to trigger a range of immune responses. Vaccines produced by using this approach allow large scale production, e.g.

(i) Hepatitis-B vaccine produced from yeast.

(ii) Bird flu DNA vaccine.

Advantages

(i) Recombinant DNA vaccines are advantageous over killed or attenuated vaccines, since they do not get virulent or mutated again as it is seen in case of attenuated vaccines.

(ii) Secondly these are highly pure, specific and elicit show strong immune response

Ans. The process by which retrovirus gains entry into human host body or the mechanism by which AIDS virus causes immunodeficiency is as follows

Ans. Contact inhibition: Normal cells have the property of contact inhibition (stoppage of growth on coming in contact with other cells), but cancer cells do not have this property. As a result, cancer cells divide continuously to give rise to a mass of cells (tumours).

Metastasis: This property is exhibited by malignant tumours. It is the pathological process of spreading of cancerous cells to different parts of the body. These cells divide uncontrollably, forming a mass of cells called tumour. From the tumour, some cells get sloughed off and enter the bloodstream. From the bloodstream, these cells reach nearby as well as distant parts of the body therefore, initiating the formation of new tumours by dividing actively.

Ans. There are cancer causing viruses called oncogenic viruses. They have genes called viral oncogenes. Certain other genes called cellular oncogenes (c-onc) or proto-oncogenes have been identified in normal cells, which when activated can lead to tumour formation.

Ans. Techniques that are useful in detecting cancers of internal organs are

(a) Computed Tomography (CT) is done to generate a 3-D image of internal tissue. It uses X-rays.

(b) Magnetic Resonance Imaging (MRI) involves the use of non-ionizing radiations and strong magnetic fields to detect pathological and physiological changes in a living tissue.

Ans. The biological response modifiers such as a-interferons are given to cancer patients as a part of their treatment because it activates patients’ immune system and helps in destroying the tumour.

Ans. Harmful effects of drugs like LSD, barbiturates, etc., are

(i) Anxiety, shakiness, nausea and sweating, loss of mind control.

(ii) Reckless behaviour, vandalism and violence.

(iii) Lack of interest in personal hygiene, fluctuations in weight and appetite.

(iv) Social adjustment problems.

(v) Withdrawal, isolation, depression, fatigue, aggressive behaviour.

(vi) Withdrawal symptoms can be severe and life threatening.

(vii) Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage.

Ans. Adolescents take drugs/alcohol due to following reasons

(i) Social and peer pressure.

(ii) Curiosity and need for adventure, excitement and experiment.

(iii) To avoid stress, depression and frustration.

(iv) To overcome hardships.

(v) Avoid unsupportive or unstable family structure.

(vi) Perception that it is cool or progressive. This perception is further promoted by TV, movies, newspapers and internet.

This can be avoided by

i) Avoid undue peer pressure: Parents must understand the abilities and personality type of the child. A child should not be pushed unduly for studies or sports or other activities. Pressure from parents and teacher beyond threshold is not healthy for children.

(ii) Education and counselling: Parents and teachers should educate and counsel the child to face difficult situations as part of life. Stress, disappointments and failure must be taken in a healthy way. Involvement in extracurricular activities is a good distraction from daily stress. It channelizes the child’s energy in right direction.

(iii) Seeking help from parents and peers: In case of any academic or emotional problem, advice and guidance should be sought out from parents or trusted friends. Besides solving problems, it also helps in venting out feelings of anxiety, fear and guilt.

(iv) Looking for danger signs: Danger signs must be brought in light and must be told to parents and teachers if they find someone using drugs or alcohol. There should be no hesitation in informing the same to the elders. This helps in preventing the person from drug abuse and initiating remedial steps.

(v) Seeking professional and medical help: Affected people have a lot of help available in the form of doctors, psychologists, psychiatrists and rehabilitation programmes. An addicted person can get completely rid of the problem and lead a perfectly normal and healthy life by getting help.