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Q1. Name the type and give the effect of the following drugs in human. (i) LSD  (ii) Morphine (iii) Barbiturates.

Solution

(i) Lysergic Acid diethylamide is a hallucinogen. It affects the cerebrum and sense organs, changing the feeling, thoughts and perceptions of an individual. (ii) Morphine is an opiate narcotic. It suppresses the normal function of brain and relieves intense pain but temporarily. (iii) Barbiturates are sedative drugs and tranquilizers. It suppresses brain’s activity and creates a feeling of relaxation, drowsiness and sleepiness.

Q2. Define proto-oncogenes.

Solution

Inactive cancer causing genes are called proto-oncogenes.

Q3. Why do sports persons often fall a victim to cocaine addiction? 

Solution

Cocaine has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy. Therefore, certain sports persons misuse it to enhance their performance.

Q4. (i)What are allergens? How do human beings respond to them? (ii)What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis B vaccine is produced. 

Solution

(i) Allergens are substances which act as weak antigens and cause inappropriate and excessive immune response. Allergens initiates harmful antibody formation which in turn binds to the receptors on the mast cell. The mast cell releases chemicals sucha as histamines, which in turn causes inflammation of the mucous membranes. (ii) Principle of vaccination is based on the property of memory of immune system. In vaccination, a preparation of antigenic proteins of pathogens but weakened pathogens is introduced into the body. The antigens generate primary immune response by producing antibodies along with B-cells and T-cells. When the vaccinated person is attacked by the same pathogens, the existing memory B- cells and T-cells recognize the antigen and put a strong effect on the invaders with massive production of lymphocytes and antibodies. Hepatitis B vaccine is produced from yeast. 

Q5. (i)Why is using tobacco in any form injurious to the health? Explain. (ii)What are hallucinogens? Give their two examples. Mention their clinical use, if any. 

Solution

(i)Tobacco in any form is injurious to health because- (a) Smoking of tobacco is associated with cancers of lung, urinary bladder, coronary heart disease, gastric ulcer etc. (b) Smoking increases carbon monoxide content in blood and reduces the concentration of haem-bound oxygen, causing oxygen-deficiency in the body. (c) Oral cancer is due to chewing of tobacco etc. (d) Nicotine, the main content of tobacco stimulates adrenal gland to release adrenaline and nor-adrenaline into blood which raises the blood pressure and increases heart beat. (ii) Hallucinogens are a class of psychedelic drugs which affect cerebrum and sense organs to alter thought, feeling and perception. Two examples are lysergic acid diethyl amides (LSD) and methylenedioxy methamphetamine (MDMA). Clinically, they are used to treat depression and insomnia.

Q6. Name the type of cells the AIDS virus enters into after getting in the human body.

Solution

HIV enters into Helper T- cells reducing the number in the body of the infected person.

Q7. Name the type of cells the AIDS virus first enters into after getting inside the human body. Explain the sequence of events that the virus undergoes within these cells to increase their progeny. 

Solution

HIV inside the human body first attacks Helper T-cells of immune system. RNA and reverse transcriptase enter inside the Helper T-cells. RNA synthesizes the DNA by reverse transcription. DNA copy of HIV binds host cell’s DNA to form prophage and transcribes a large number of RNA molecules, each of which gets surrounded by protein coat to form HIV virus.

Q8. What is humoral immunity?  

Solution

Humoral immunity is the immunity involving antibodies that are secreted by B-cells and circulate as soluble proteins in blood. 

Q9. Recently chikungunya cases were reported from various parts of the country. Name the vector responsible.

Solution

Chikungunya is spread through Aedes mosquitoes which is a vector-borne disease.

Q10. (i)Why does a doctor administer tetanus antitoxin and not a tetanus vaccine to a child injured in a roadside accident with a bleeding wound? Explain. (ii)Describe the role of lymph nodes in providing immunity. 

Solution

(i) Tetanus is caused by a microbe which has a deadly and fast action. Action of vaccine is slow which becomes fatal. Therefore, antitoxins are administered which neutralize the effect of the bacterial toxin. (ii) Lymph nodes trap microorganisms. These trapped antigens activate lymphocytes present in the lymph and cause an immune response.

Q11. High fever, loss of appetite, stomach pain and constipation are some of the symptoms seen in a patient. How would the doctor confirm that the patient is suffering from typhoid and not amoebiasis? 

Solution

By performing Widal test, the doctor can confirm that the patient is suffering from typhoid and not amoebiasis.

Q12. (i)What is a vaccine? Give an example of a vaccine produced by recombinant DNA technology. (ii)Name the disease against which DPT vaccine develops immunity? 

Solution

(i)An inoculation stimulating the production of antibodies in the body is called vaccine. An example of vaccine produced by recombinant DNA technology is Hepatitis B that was produced from yeast. (ii) DPT vaccine develops immunity against diphtheria, pertusis and tetanus.

Q13. How does smoking cause oxygen deficiency in body?

Solution

Carbon monoxide present in tobacco smoke binds haemoglobin of RBCs faster than oxygen thus decreasing the oxygen- carrying capacity of haemoglobin.

Q14. Name and explain the two types of immune responses in humans. 

Solution

The two types of immunity are active immunity and passive immunity. The immunity developed in the host body due to production of antibodies in response to antigens is active immunity.   When ready-made antibodies are directly given to protect the body against foreign antigens is passive immunity.

Q15. It was diagnosed by a specialist that the immune mechanism of the body of a patient has been suppressed. Name the disease the patient has been suffering from and the microbe responsible for it. Which part of the immune system does it affect and in what manner?

Solution

The patient is suffering from Acquired Immuno Deficiency Syndrome (AIDS). The causal organism is Human Immunodeficiency Virus (HIV). HIV infects Helper T-cells. HIV enters Helper T-cells where it replicates and produces progeny viruses. The progenies liberated by lysis of host T-cells attack other Helper T-cells. Repeated attacks result in progressive decrease in the number of T-cells and thus reducing immunity.

Q16. (i) Why is tobacco smoking associated with rise in blood pressure and emphysema (oxygen deficiency in the body)? Explain. (ii) How does the moderate and high dosage of cocaine affect the human body?  

Solution

(i) Tobacco has nicotine that stimulates the release of adrenaline and nor-adrenaline, which raise blood pressure. Smoking tobacco releases carbon monoxide, which reduces the concentration of haem-bound oxygen. This causes emphysema. (ii) Cocaine has a potent stimulating action on central nervous system producing a sense of euphoria and increased energy. Excessive dosage of cocaine causes hallucinations.

Q17. What bad effect has tobacco on respiratory system? Name two toxic substances present in tobacco.

Solution

Tobacco smoke causes inflammation of bronchi called bronchitis and inflammation of lung alveoli called emphysema. Two toxic substances present in tobacco are nicotine and carbon monoxide.

Q18. State two different roles of spleen in the human body. 

Solution

Spleen is the secondary lymphoid organ that stores lymphocytes and act as reservoir to store erythrocytes.

Q19. Name an opioid drug and its source plant. How does the drug affect the human body? 

Solution

Heroin is an opioid drug derived from latex of poppy plant, Papaver somniferum. Heroin acts as depressant and it causes drowsiness and lethargy decreasing the body functions.

Q20. (i)What would happen to immune system, if thymus gland is removed from the body of a person?   (ii)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. 

Solution

(i) Thymus is the primary lymphoid organ. Immature lymphocytes differentiate into antigen-sensitive lymphocytes. If thymus gland is removed from the body of a person, his immune system becomes weak as a result the person’s body becomes prone to infectious diseases. (ii) Unusual hypersensitive reactions form a condition called allergy. The cells responsible for such reactions are mast cells.

Q21. A boy of ten years had chicken pox. He is not expected to have the same disease for the rest of his life. Mention how it is possible.

Solution

The boy produces antibodies when he encounters for the first time that result in memory of the first encounter to protect the body in future.

Q22. Generally lung cancer patients are heavy smokers. Why?

Solution

Benzopyrene and Nitrosodimethylene present in tobacco are carcinogenic in nature and cause lung cancer.

Q23. Name the group of viruses responsible for causing AIDS in humans. Why are these viruses so named?

Solution

AIDS is caused by HIV which belongs to retroviruses. These are so called as they can cause reverse transcription in the presence of enzyme reverse transcriptase.

Q24. Write the source and the effect on the human body of the following drugs: morphine, cocaine, marijuana.

Solution

(i) Morphine is obtained from poppy plant Papaver somniferum. It binds to specific opioid receptors present in central nervous system and gastrointestinal tract. (ii) Cocaine is obtained from coca plant Erythroxylum coca. It interferes with the transmit of the neurotransmitter, dopamine. (iii) Marijuana is obtained from Cannabis sativa. It affects the cardiovascular system of the body.

Q25. What is contact inhibition in the normal cells of the body? What are the consequences when this property is lost by these cells? 

Solution

Normal cells show the property of contact inhibition which checks their uncontrolled growth and division; however, in cancer cells, this property of contact inhibition is lost and the cells undergo uncontrolled growth and division which leads to tumor formation.

Q26. In what different forms is the tobacco used? Name its addicting component. 

Solution

Tobacco is chewed, smoked or snuffed. Its addicting component is nicotine.

Q27.  Differentiate between benign tumor and malignant tumor.

Solution

 Benign Tumor Malignant Tumor (i) These remain confined in the organ affected. (i) These spread from one organ to other organs of the body. (ii) These are enclosed in a connective tissue sheath. (ii) These are not enclosed in a connective tissue sheath. (iii) These have less growth rate. (iii) These have rapid growth rate. (iv) Cancer cells are more adhesive. (iv) Cancer cells are less adhesive. (v) No metastasis occurs. (v) Metastasis is generally present.  

Q28. Why do the symptoms of malaria not appear immediately after the entry of sporozoites into the human body when bitten by female Anopheles? Explain. 

Solution

Malarial parasite attacks the RBCs resulting in their rupture. The ruptured RBCs release toxic substance called haemozoin which is responsible for chill and high fever. Therefore no symptoms appear between the parasite enters the body till RBCs release haemozoin.

Q29. Mention the useful as well as the harmful drug obtained from the latex of Poppy plant. 

Solution

Useful drug obtained from poppy plant is morphine and harmful drug obtained is heroin.

Q30. Alcohol is not a food. Comment on the statement.

Solution

The energy produced by oxidation of alcohol is not according to the body needs. Some energy of body is used to expel extra heat out of the body. In addition, the presence of alcohol in body tissues causes some ill effects.

Q31. (i)How do B-cells direct humoral immunity? (ii)Name the type of barrier of innate immunity system which involves macrophages. 

Solution

(i) B-cell specific antigens stimulate B-cell production and it multiplies to produce a clone of plasma cells. The cells differentiated into memory and effector cells due to clonal selection. They produce antibodies that circulate in body fluid and kill the pathogens. (ii)Cellular barrier or phagocytosis involves macrophages.

Q32. Name the two-special types of lymphocytes in humans. How do they differ in their roles in immune response? 

Solution

B-lymphocytes and T-lymphocytes are two types of lymphocytes in humans. B- lymphocytes produce antibodies that can produce response to pathogens. T- lymphocytes help the B-lymphocytes to produce antibodies.

Q33. Explain three methods of treatment of cancer. 

Solution

Three methods of treatment of cancer are- (i) Surgery- The tumor cells are removed with the help of surgery to check the spread of cancerous cells. (ii) Radiation therapy- A lethal irradiation of tumor cell is done, taking proper care of the normal tissues surrounding the tumor mass. (iii) Chemotherapy- Cancerous cells are killed by several chemotherapeutic drugs. These drugs exhibit side effects such as hair loss and anaemia.

Q34. What type of virus causes AIDS? Name its genetic material. 

Solution

Retrovirus causes AIDS and RNA is its genetic material.

Q35. What is cancer? How is a cancer cell different from normal cell? How do normal cells attain cancerous nature? 

Solution

An abnormal and uncontrolled division of cells is termed as cancer.  Cancer Cell  Normal Cell (i) Cancer cells divide in an uncontrolled manner. (i) Normal cells divide in a controlled manner. (ii) The cells do not show contact inhibition. (ii) These cells show contact inhibition. (iii) Lifespan is indefinite. (iii) There is a definite lifespan. 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 cells. The normal cells lose this property and become cancerous cell giving rise to masses of cells called tumors. Transformation of normal cells into cancerous cells is induced by physical, chemical and biological agents that are called carcinogens.

Q36. What are carcinogens? Name any two carcinogens. 

Solution

Carcinogens are physical, chemical or biological cancer causing agents. Two carcinogens are X-rays and aflatoxin.

Q37. Which test is employed to diagnose cervix cancer?  

Solution

Pap’s test is used to diagnose cervix cancer. 

Q38. List the specific symptoms of pneumonia. Name the causative organism. 

Solution

Specific symptoms of pneumonia are fever, cough, headache and chills. The causative organisms are Streptococcus pneumoniae and Haemophillus influenzae.

Q39. Write two examples of carcinogens. 

Solution

Ultra-violet rays and X-rays are two examples of carcinogens.

Q40. Give various methods of HIV transmission. 

Solution

Various methods of HIV transmission are sexual intercourse, use of contaminated needles and syringes, blood transfusion, artificial insemination, organ transplantation, breast feeding etc.