CBSE Class 12 Biology Human Health And Diseases Worksheet Set C

 

MULTIPLE CHOICE QUESTIONS

Question. Malignant tertain malaria is caused by 
(a) P. vivax
(b) P. malariae
(c) P. ovale
(d) P. falciparum
Answer. D

Question. Which of the following disease is due to an allergic reaction ? 
(a) Goitre
(b) Hay fever
(c) Skin cancer
(d) Rheumatic fever
Answer. B

Question. Influenza is caused by 
(a) virus
(b) bacteria
(c) alga
(d) fungus
Answer. A

Question. HIV has a protein coat and genetic material
(a) ss RNA
(b) ds RNA
(c) ss DNA
(d) ds DNA
Answer. A

Question. Which type of cancer is found in lymph nodes and spleen?
(a) Carcinoma
(b) Sarcoma
(c) Lymphoma
(d) Leukemia
Answer. C

Question. Amoebiasis is caused by
(a) Entamoeba histolytica
(b) Taenia solium
(c) Plasmodium vivax
(d) E. coli
Answer. A

Question. The antigen-binding site are present where on the antibody molecule 
(a) on light chain as well as on heavy chain.
(b) on light chain only.
(c) on variable region and constant region of light chain.
(d) on heavy chain only.
Answer. A

Question. Which one of the following antimicrobial drugs is suitable for treatment of both tuberculosis and leprosy? 
(a) Isoniazid
(b) R-aminosalicylic acid
(c) Streptomycin
(d) Rifampicin
Answer. D

Question. Which of the following is a pentameric immunoglobulin and is produced first in a primary response to an antigen? 
(a) Ig G
(b) Ig M
(c) IgA
(d) Ig E
Answer. B

Question. Cattle fed with spoilt hay to sweet clover which contains dicumarol
(a) are healthier due to a good diet
(b) catch infections easily
(c) may suffer vitamin K deficiency and prolonged bleeding
(d) may suffer from beri-beri due to deficiency of vitamin-B
Answer. C

Question. Gambusia fish has been introduced in lakes and ponds of India to control a deadly disease. It feeds on larva of 
(a) nepenthes
(b) anopheles
(c) dragon fly
(d) house-fly
Answer. B

Question. Anti-viral substance is 
(a) antigen
(b) antibody
(c) interferon
(d) antibiotic
Answer. C

Question. Inflammatory response, in allergy is caused by the release of 
(a) antigen
(b) histones
(c) histamines
(d) antibodies
Answer. C

ASSERTION REASON QUESTIONS

Directions : These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following five responses.
(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.
(e) If the Assertion is incorrect but the Reason is correct.

Question. Assertion: There is no chance of malaria to a man on the bite of male Anopheles mosquito.
Reason: It carries a non-virulant strain of Plasmodium.
Answer. C

Question. Assertion : Rabies is an infection of mammals, it involves central nervous system which may result in paralysis and finally death.
Reason : This is caused by neurotropic bacteria in saliva of rabies animal. 
Answer. C

Question. Assertion : Plasmodium vivax is responsible for malaria.
Reason : Malaria is caused by polluted water.
Answer. B

Question. Assertion: Histamine is related with allergic and inflammatory reactions.
Reason: Histamine is a vasodilator.
Answer. A

Question. Assertion : Organ transplantation patients are given immunosuppressive drugs.
Reason : Transplanted tissue has antigens which stimulate the specific immune response of the recipient.
Answer. A

Question. Assertion: LSD and marijuana are clinically used as a analgesics.
Reason: Both these drugs suppress brain function.
Answer. C

Question. Assertion : A person who has received a cut and is bleeding needs to be given anti-tetanus treatment. 
Reason : Anti-tetanus injection provides immunity by producing antibodies for tetanus.
Answer. C

Question. Assertion (A) : Antigen can be easily recognized because it has antigenic determinants.
Reason (R) : The recognition ability is innate.
Answer. B

Long Answer Questions

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. 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) The disease is AIDS.
(b) The causative organism is Human Immunodeficiency Virus.
(c) It affects or destroys helper T-cells.

Question. What is cancer? How is a cancer cell different from normal cell? How do normal cells attain cancerous nature? 
Answer. An abnormal and uncontrolled division of cells is termed as cancer.

S.No.	Cancer cell	Normal cell
(i)	Cancer cells divide in an uncontrolled manner.	Normal cells divide in a controlled manner.
(ii)	These cells do not show contact inhibition.	These cells show contact inhibition.
(iii)	Lifespan is indefinite.	Lifespan is definite.

In our body, the growth and differentiation of cells is highly controlled and regulated. The normal cells show a property called contact inhibition. The surrounding cell inhibits uncontrolled growth and division of a cell. The normal cells when lose this property, become cancerous, giving rise to masses of cells called tumours. Transformation of normal cells into cancerous cells is induced by some physical, chemical or biological agents (carcinogens).

Question. Explain the following in context of cancer:
(a) Benign tumour (b) Malignant tumour
(c) Oncogens/Carcinogens (d) Oncogenes
(e) Contact inhibition
Answer. (a) Benign tumours are the masses of cells which remain confined to their original location and do not spread to other parts of the body and cause little damage.
(b) Malignant tumours are the masses of proliferating cells called neoplastic or tumour cells.
These grow very rapidly, invading and damaging the surrounding normal tissues.
(c) Transformation of normal cells into cancerous, neoplastic cells may be induced by physical, chemical or biological agents. These agents are called carcinogens. For example X-rays, gamma rays, UV radiations and some chemicals like EtBr.
(d) The genes which may lead to oncogenic transformations of the cells are called oncogenes.
(e) Contact inhibition—Whenever normal cells come in contact with each other, after a definitetime they inhibit each others’ excess growth and multiplication. This property of normal cells is called contact inhibition which maintains the normal shape and size of the body. But cancer cells appear to have lost this property which results in their uncontrolled growth and multiplication.

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. 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. Name the cells HIV (Human Immunodeficiency Virus) gains entry into after infecting the human body. Explain the events that occur in these cells. 
Answer. HIV virus gains entry into Macrophages and (Helper) T-lymphocytes after getting into the human body.
Events that occur in the cells are:
(i) Viral RNA forms DNA by reverse transcription using the enzymes reverse transcriptase and directs the infected cells to produce viral particles.
(ii) Macrophages continue to produce viral particles and function as HIV factories.
(iii) The viral particles simultaneously enters into helper T-lymphocytes, replicates and produce viral progenies.
(iv) The number of T-lymphocytes progressively decreases in the body of the infected person.
(v) During this person suffers from bouts of fever, weight loss. Also decrease in the number of cells leads to weakening of immune system.

Question. (a) Name and explain any four lymphoid organs present in humans.
(b) Categorise the named lymphoid organs as primary or secondary lymphoid organs, giving reasons. 
Answer. Components of immune system:
• Lymphoid organs
• Immune cells
• Soluble molecules like antibodies
• Lymphoid tissues

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)

S.No.	Innate immunity	Acquired immunity
(i)	It is present from birth and is inherited from parents.	It is not present from the birth.
(ii)	It is non-specific.	It is pathogen specific.
(iii)	The various physical, physiological, cellular,cytokine barriers are the basis of innate immunity.	The memory cells formed by B and T-cells are the basis of acquired immunity.
(iv)	The innate immunity remains throughout life.	The acquired immunity can be short-lived or life long.

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.

Question. You have attended a birthday party hosted by one of your classmates. You found some guests at the party sitting in a corner making a lot of noise and consuming ‘something’. After a while one of the boys from the group started screaming, behaving abnormally and sweating profusely. On enquiry you found that the group members were taking drugs.
(a) Would you inform your parents/school authorities? Yes/No. Give reasons is support of your answer.
(b) Prepare a note to be circulated amongst the schoolmates about the sources and dangers of any two drugs.
(c) Write any two ways that you will suggest to your school principal so as to promote awareness amongst the youth against the use of these drugs. 
Answer. (a) Yes, so that it does not become a habit by repeated use. Consumption of drugs may cause harmful effects.
(b)

Drug	Source	Danger
Cocaine	Erythroxylum coca	Affects central nervous system and interferes with transport of dopamine.
Opioids/Heroin/Smack	Latex of Papaver somniferum (poppy plant)	Slows down body functions.
Cannabinoids	Cannabis sativa	Affects cardiovascular system

(c) Awareness can be promoted by organising poster making competitions, street plays, talks by experts and interviews of experts.

Question. What is cancer? How is a cancer cell different from normal cell? How do normal cells attain cancerous nature? 
Answer. An abnormal and uncontrolled division of cells is termed as cancer.

S.No.	Cancer cell	Normal cell
(i)	Cancer cells divide in an uncontrolled manner.	Normal cells divide in a controlled manner.
(ii)	These cells do not show contact inhibition.	These cells show contact inhibition.
(iii)	Lifespan is indefinite.	Lifespan is definite.

In our body, the growth and differentiation of cells is highly controlled and regulated. The normal cells show a property called contact inhibition. The surrounding cell inhibits uncontrolled growth and division of a cell. The normal cells when lose this property, become cancerous, giving rise to masses of cells called tumours. Transformation of normal cells into cancerous cells is induced by some physical, chemical or biological agents (carcinogens).

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. Explain the following in context of cancer:
(a) Benign tumour
(b) Malignant tumour
(c) Oncogens/Carcinogens
(d) Oncogenes
(e) Contact inhibition
Answer. (a) Benign tumours are the masses of cells which remain confined to their original location and do not spread to other parts of the body and cause little damage.
(b) Malignant tumours are the masses of proliferating cells called neoplastic or tumour cells.
These grow very rapidly, invading and damaging the surrounding normal tissues.
(c) Transformation of normal cells into cancerous, neoplastic cells may be induced by physical, chemical or biological agents. These agents are called carcinogens. For example X-rays,
gamma rays, UV radiations and some chemicals like EtBr.
(d) The genes which may lead to oncogenic transformations of the cells are called oncogenes.
(e) Contact inhibition—Whenever normal cells come in contact with each other, after a definitetime they inhibit each others’ excess growth and multiplication. This property of normal cells is called contact inhibition which maintains the normal shape and size of the body. But cancer cells appear to have lost this property which results in their uncontrolled growth and multiplication.

Question. In an auto immune disorder, a person produces antibodies that mimic the action of TSH. Name the disorder, which results due to this situation. Give its symptoms. 
Answer. A patient with Grave’s disease produces auto- antibodies that bind with the receptor for thyroid stimulating hormone (TSH) and mimic the normal action of TSH, activating adenylate cyclase and resulting in production of thyroid hormones. Unlike TSH, auto-antibodies are not regulated, and consequently they overstimulate the thyroid.

Question. A youth in his twenties met with an accident and succumbed to the injuries. His parents agreed to donate his organs. List any two essential clinical steps to be undertaken before any organ transplant. Why is the transplant rejected sometimes? What views would you share with your health club members to promote organ donation?
Answer. Organ transplantation involves the removal of damaged/injured tissues or organs from the body of a person and their substitution by similar tissues/organs from a donor. Tissue matching, blood group matching are essential clinical steps before undertaking any graft/ transplant. Transplantation may result in the rejection of transplanted organs as the immune system recognises the protein in the transplanted tissue or organs as foreign and initiates cellular immunity.
We should raise and promote awareness about organ donation, about need of organ and tissue donors. There are lakhs of people waiting for organ donation and many people die daily while waiting for transplant. Organs and tissues from one donor can save upto 40-50 lives. So, we should encourage and get registered for organ donation to save many lives.

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. The given table shows differences between active and passive immunity:

Active immunity	Passive immunity
It is developed when the person’s own cells produce antibodies in response to infection or vaccine.	It is developed when antibodies produced in other organisms are injected into a person to counter act antigen such as snake venom.
It provides relief only after long period.	It provides immediate relief.
It has no side effects. It is long lasting.	It may cause reaction. It is not long lasting.
E.g., MMR vaccine for measles, mumps, rubella.	E.g., Colostrum rich in IgA antibodies provides immunity to newborn.

Question. Categorise the named lymphoid organs as primary or secondary lymphoid organs, giving reasons. 
Answer. (a) Four lymphoid organs are :
(i) Bone marrow : It is the main lymphoid organ where all blood cells including lymphocytes are formed. Maturation of B-lymphocytes occurs here. (ii) Thymus : It is the site of T lymphocyte maturation. Thymus is situated near the heart and is quite large in size at the time of birth but keeps reducing with age.
(iii) Lymph nodes: These are small solid structures found at intervals along the lymphatic system. They are composed of lymphoid tissue and act as filters for the lymph, preventing foreign particles from entering the bloodstream. Lymph nodes also produce lymphocytes and plasma cells.
(iv) Spleen: It is a bean shaped organ which is the largest single mass of lymphoid tissue in the body. In foetus the spleen produces all types of blood cells but in adult it only produces lymphocytes. Macrophages of spleen are phagocytic.
(b) Lymphoid organs are those organs where the maturation and proliferation of lymphocytes takes place. There are two types of lymphoid organs : primary and secondary.
Primary lymphoid organs are those where T lymphocytes and B lymphocytes mature and acquire their antigen-specific receptors. Bone marrow and thymus are primary lymphoid organs. B-lymphocytes mature in bone marrow and T-lymphocytes mature in thymus.
Secondary lymphoid organs are those where B lymphocytes and T lymphocytes undergo proliferation and differentiation. They acquire immune response in these organs and become effector cells. Lymph nodes and spleen are secondary lymphoid organs.

Question. Name the type of cells the AIDS virus enters into after getting in the human body.
Answer. AIDS virus, HIV enters into macrophages after entering into human body.

Question. Name the two types of cells in which the HIV multiplies after gaining entry into human body.
Answer. Macrophages and helper T cells.

Question. (a) Name the group of viruses responsible for causing AIDS in humans. Why are these viruses so named?
(b) List any two ways of transmission of HIV infection in humans, other than sexual contact.
Answer. (a) AIDS is caused by human immunodeficiency virus (HIV), a member of a group of viruses called retroviruses. These viruses are called retroviruses because they have RNA as their genome, enclosed within an envelope.
(b) Other than sexual contact, transmission of HIV
infection in humans could also occur by
(i) Transfusion of contaminated blood and blood products.
(ii) From infected mother to her child through placenta.

Question. Name the cells that act as HIV factory in humans when infected by HIV. Explain the events that occur in the infected cell.
Answer. Macrophages act as HIV factory in humans. Events that occur in infected cells are:
(i) After the entrance of the virus into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of reverse transcriptase enzyme. (ii) Viral DNA gets incorporated into the host cell’s DNA and directs the infected cells to produce viruses.
(iii) Simultaneously HIV virus enters into helper T lymphocytes where it replicates and produces more viruses. This is repeated so that the number of helper T lymphocytes decreases in the body of the infected person.
(iv) Due to decrease in the number of helper T lymphocytes in the body, the person starts suffering from infections and gets immune deficiency and he/ she is unable to protect himself/herself against these infections.

Question. A person in your colony has recently been diagnosed with AIDS. People/residents in the colony want him to leave the colony for the fear of spread of AIDS.
(a) Write your view on the situation, giving reasons.
(b) List the possible preventive measures that you would suggest to the residents of your locality in a meeting organised by you so that they understand the situation.
(c) Write the symptoms and the causative agent of AIDS. 
Answer. (a) An AIDS patient should not be forced to leave the society because AIDS cannot be transmitted by following methods :
(i) insect bites, (ii) crowded transport, (iii) shaking hands, (iv) sharing towels, (v) coughing and sneezing, (vi) kissing and embracing, (vii) sharing utilities and telephone, (viii) swimming pools and toilets.
(b) I would try to educate the residents about the cause of spread of AIDS emphasising that it is caused by sexual contact with infected person, through infected needles and blood transfusion. Therefore, the preventive measures would be to avoid multiple sexual partners, use disposable needles and condoms.
(c) The symptoms of HIV infection include fever,
lethargy, pharyngitis, nausea, headache, rashes, swollen lymph nodes etc. The causative agent of AIDS is human immunodeficiency virus (HIV).

Question. Indiscriminate diagnostic practices using X-rays etc., should be avoided. Give one reason.
Answer. Indiscriminate use of X-rays can cause DNA
damage leading to neoplastic transformation

Question. (a) Explain the property that prevents normal cells from becoming cancerous.
(b) All normal cells have inherent characteristic of becoming cancerous. Explain.
 Answer. (a) Contact inhibition is the property that prevents normal cells from becoming cancerous. Due to this property they contact with other cells which inhibits their uncontrolled growth, thus prevent them from becoming cancerous.
(b) Cancerous growth of normal cells is due to loss of contact inhibition and programmed cell death, which keep their number constant. Due to loss of these properties, normal cells become cancerous.

Question. (a) What makes some viruses cause cancer in humans?
(b) How do benign tumors turn malignant? How does the latter harm the human body?
Answer. (a) Cancer causing viruses are called oncogenic viruses. The genes of oncogenic viruses are known as viral oncogenes which could lead to oncogenic transformation of cells, causing cancer.
(b) Abnormal increase in number of cells in a tissue or organ forms a clone of proliferative cells. This excessive proliferation gives rise to a mass of cells which is initially known as benign tumour. The benign tumour cells sometimes enter into the blood vessels and migrate to other sites in the body where these cells continue to divide and start a new tumour there, such tumour cells are known as malignant cells and tumours are called malignant tumours. The malignant tumours are designated as cancer. The malignant tumors damage normal cells and compete with them for vital nutrients and disrupt the normal metabolism.

Question. (a) Cancer is one of the most dreaded disease.
Explain ‘contact inhibition’ and ‘metastasis’ with respect to the disease.
(b) Name the group of genes that have been identified in normal cells that could lead to cancer. How do these genes cause cancer?
(c) Name any two techniques that are useful in detecting cancers of internal organs.
(d) Why are cancer patients often given a-interferon as part of the treatment?
Answer. (a) The normal cells are characterised by contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Metastasis is a property shown by cancerous cells in which these cells detach from the tumours and move to distant sites through body fluids and develop secondary tumours. Metastasis is fatal because the cancerous cells damage other normal cells, compete with them for vital nutrients and disrupt the normal metabolism.
(b) Several genes called cellular oncogenes (c-onc) or proto oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells (cancer).
(c) Radiography (X-rays) and CT (computerised tomography) are useful in detecting cancer of internal organs.
(d) The cancer patients are given substances called biological response modifiers such as -interferon which activate their immune system and helps in destroying the tumour.

Question. How does smoking tobacco in humans lead to oxygen deficiency in their body? 
Answer. Smoking tobacco increases carbon monoxide content in blood and reduces concentration of haembound oxygen, which causes oxygen deficiency in the body.

Question. What is ‘withdrawal syndrome’? List any two symptoms it is characterised by. 
Answer. Withdrawal syndrome is group of symptoms that occur in drug and alcohol addicted individuals who abruptly discontinue or reduce the use of drug of their choice. Withdrawl symptoms include anxiety and nausea.

Question. Write the scientific name of the source plant of the drugs, marijuana and hashish and mention their effect on the human body. 
Answer. Drugs, marijuana and hashish are obtained from Cannabis sativa. Being hallucinogenic, they give feeling of well being and happiness. Sometimes, marijuana causes uncontrolled laughter and dilation of pupil.

Question. Name the plant source of the drug popularly called ‘smack’. How does it affect the body o the abuser?
Answer. Smack is an opioid narcotic, obtained from poppy plant, Papaver somniferum. It is a powerful analgesic and relieves the pain by acting on central nervous system.

Question. Name the plant source of ganja. How does it affect the body of the abuser?
Answer. Ganja is obtained from Cannabis sativa. It is hallucinogenic. It alters thoughts, feelings and perceptions and causes illusions.

Question. Why is using tobacco in any form injurious to the health? Explain. 
Answer. Smoking of tobacco is associated with cancer of lungs, urinary bladder and throat, bronchitis, emphysema, coronary heart diseases, etc. Smoking also increases the CO content in blood and reduces the concentration of haembound oxygen, thus causing oxygen deficiency in the body. Chewing of tobacco causes cancer of oral cavity. Nicotine, an alkaloid present in tobacco, stimulates the adrenal glands to secrete adrenaline and nor- adrenaline, which increase the blood pressure and heart rate.

Question. Why do sports persons often fall a victim to cocaine addiction? 
Answer. Sportspersons often become addicted to cocaine, to enhance their performance. Cocaine is a stimulant that increases heart beat, blood pressure, body temperature and delays fatigue. Sportspersons take drugs to promote aggressiveness and to increase athletic performance.

Question. List four reasons to justify the ban on intake of cannabinoids by sportspersons. 
Answer. The intake of cannabinoids by sportspersons should be banned due to following reasons: (i) They have a potent stimulating action on the central nervous system causing hallucinations.
(ii) They produce a sense of euphoria and increased energy and hence, sportspersons become addicted to them.
(iii) They delay fatigue.
(iv) They increase blood sugar level and frequency of urination.

Question. Prior to a sports event, blood and urine samples of sports persons are collected for drug tests.
(a) Why is there a need to conduct such tests?
(b) Name the drugs the authorities usually look for.
(c) Write the generic names of two plants from which these drugs are obtained.
Answer. (a) It is necessary to conduct such tests on sportspersons because they take various drugs like cocaine/coca alkaloids and cannabinoids to increase their muscle tone and performance in sports.
(b) Cocaine/coca alkaloids and cannabinoids.
(c) Cannabinoids are obtained from Cannabis sativa and cocaine is obtained from Erythroxylum coca.

Question. A team of students is preparing to participate in the interschool sports meet. During a practice session you and some vials with labels of certain cannabinoids.
(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, I will report to authorities because cannabinoids are drugs and drug abuse is an illegal practice.
(b) Cannabis sativa
(c) Cannabinoids alter thoughts, feelings and perceptions. These drugs cause illusions.

Question. (a) Name a drug used (i) as an effective sedative and pain killer (ii) for helping patients to cope with mental illnesses like depression, but often misused.
(b) How does the moderate and high dosage of cocaine affect the human body?
Answer. (a) (i) Morphine (ii) Barbiturates
(b) Cocaine taken in low dose induces sense of well being and pleasure and delays fatigue, but in high dosage, it causes hallucinations.

Question. You have attended a birthday party hosted by one of your classmates. You found some guests at the party sitting in a corner making a lot of noise and consuming ‘something’. After a while one of the boys from the group started screaming, behaving abnormally and sweating profusely. On enquiry you found that the group members were taking drugs.
(a) Would you inform your parents/school authorities? Yes/No. Give reasons in support of your answer.
(b) Prepare a note to be circulated amongst the schoolmates about the sources and dangers of any two drugs.
(c) Write any two ways you will suggest to your school principal so as to promote awareness amongst the youth against the use of these drugs. 
Answer.  (a) Yes, I would inform the parents/school authorities, as taking drugs is an illegal practice . Also, teachers and parents can educate and counsel them properly and can make them understand the illeffects of taking these drugs.
(b) 

Class of drugs	Source	Danger/ill-effects
Opioids	Papaver somniferum	(i) Morphine depresses respiratory centre, lowers blood pressure and heart beat. (ii) Heroin is a depressant and slows down body functions. Both of them affect the central nervous system.
Cannabinoids	Cannabis sativa	They are used in the form of hashish, ganja, charas and marijuana. They are hallucinogens and affect cardiovascular system, and increases blood sugar level.

(c) (i) The principal can arrange for counselling by psychiatrists, psychologists, etc. Professionals can address the students regarding drug addiction, its immediate and future consequences.
(ii) He can get posters showing ill effects of using drugs pasted on the walls of the school or can arrange for a play based on drug addiction to be shown to the students.

Question. An active member of an awareness group conducts regular programmes to sensitise public against alcoholism amongst youth-a serious health hazard in his locality.
Identify the values this member of the group is trying to propagate amongst the people in his locality.
Answer. He must be trying to make the people aware of the immediate ill-effects of alcoholism like reckless behavior and vandalism and how the excess dose can lead to cirrhosis, cerebral haemorrhage, heart failure, infertility and death due to respiratory failure. Alcoholism can lead to aggressive and rebellious behaviour, deteriorating relationship with family and friends, loss of interest in hobbies, weight loss/gain etc. The far-reaching implications are : (i) stealing, when the abuser is unable to get money to buy alcohol/drugs, (ii) causing mental and financial distress to his/her family, friends, etc.
To avoid all these and to motivate the youth to live a happy and healthy life must be the aim of his counselling.

Please click on below link to download CBSE Class 12 Biology Human Health And Diseases Worksheet Set C