CBSE Class 12 Biology Human Health And Diseases Worksheet Set A

Question. Cancer cells are more easily damaged by radiation than normal cells because they are
(a) starved of mutation
(b) undergoing rapid division
(c) different in structure
(d) non-dividing
Answer : B

Question. Treatment and detection of cancer can be done by
(a) radiography
(b) chemotherapy
(c) surgery
(d) All of these
Answer : D

Question. Coca alkaloid or cocaine is obtained from 
(a) Papaver sonmiferum
(b) Atropa belladonna
(c) Erythoxylum coca
(d) Datura
Answer : C

Question. Cocaine is commonly called as
(a) coke
(b) crack
(c) Both (a) and (b)
(d) smack
Answer : C

Question. Traditional anesthesia is obtained from JIPMER 2019
(a) Datura
(b) poppy
(c) Cannabis
(d) Erythoxylum
Answer : D

Question. Which is the particular type of drug that is obtained from the plant whose one flowering branch is shown below?  (Image 148)
(a) Hallucinogen
(b) Depressant
(c) Stimulant
(d) Pain killer
Answer : A

Question. Drugs, that are normally used as medicines to help the patients cope with mental illness are
(a) barbiturates
(b) amphetamines
(c) benzodiazepines
(d) All of these
Answer : D

Question. LSD is derived from
(a) Claviceps purpurea
(b) Pseudomonas putida
(c) Cannabis indica
(d) Cannabis sativa
Answer : A

Question. Which one of the following is a correct matching pair of a drug and its category?
(a) Amphetamines — Stimulant
(b) Lysergic acid diethylamide — Narcotic
(c) Heroin — Psychotropic drug
(d) Benzodiazepies — Pain killer
Answer : A

Question. In malignant tumours, the cells proliferate, grow rapidly and move to other parts of the body to form new tumours. This stage of disease is called
(a) metagenesis
(b) metastasis
(c) teratogenesis
(d) mitosis
Answer : B

Question. ‘Smack’ is a drug obtained from the
(a) latex of Papaver somniferum
(b) leaves of Cannabis sativa
(c) flowers of Datura pinata
(d) fruits of Erythroxylum coca
Answer : A

Question. Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be
(a) nicotine
(b) tannic acid
(c) curcumin
(d) catechin
Answer : A

Question. Which one of the following fungi contains hallucinogens? 
(a) Morchella esculenta
(b) Amanita muscaria
(c) Neurospora sp.
(d) Ustilago sp.
Answer : B

Question. Those who take drugs intravenously develop a risk of
(a) AIDS
(b) hepatitis-B
(c) Both (a) and (b)
(d) malaria
Answer : C

Question. Cirrhosis of liver is caused by the chronic intake of
(a) opium
(b) alcohol
(c) tobacco (chewing)
(d) cocaine
Answer : B

Question. 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 : C

Question. 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 persons
(d) Sexual contact with infected persons
Answer : C

Question. Fill up the blanks.
I. The period between ....A....years of age maybe thought of as adolescence period.
II. Adolescence is a bridge linking ....B.... and ....C....
III. The chronic use of drug and alcohol damages ...D.... and ...E...
IV. Alcoholism during ....F.... adversely affects the foetus.
(a) A–12-18, B–childhood, C–adulthood, D–nervous system, E–liver, F–pregnancy
(b) A–10-15, B–adulthood, C–childhood, D–heart, E–stomach, F–adulthood
(c) A–15-20, B–adulthood, C–childhood, D–liver, E–kidney, F–pregnancy
(d) A–20-28, B–adulthood, C– childhood, D–liver, E–nervous system, F–pregnancy
Answer : A

Question. Which one of the following is a stimulant?
(a) LSD
(b) Cocaine
(c) Opium
(d) Heroin
Answer : B

Question. Plants with hallucinogenic properties are
(a) Atropa belladonna
(b) Datura
(c) Both (a) and (b)
(d) Papaver
Answer : C

Case-based MCQs

Attempt any four sub-parts from each question.

Each sub-part carries 1 mark.

I. Read the following text and answer the following questions on the basis of the same :
Health is defined as a state of complete physical, mental and social well being. Balanced diet, personal hygiene and regular exercise are very important to maintain good health. Any disturbance of structure or function of the body may be regarded as disease. Diseases can broadly be categorized into infectious (communicable) and non-infectious (non-communicable). A wide range of organisms belonging to bacteria, viruses, fungi, protozoans etc., could cause diseases in man.

Question. DPT vaccine is used for the immunization of :
(A) Cholera
(B) Bubonic plague
(C) Typhoid fever
(D) Diptheria.
Answer : D

Question. Which of the following diseases are communicable ?
(A) Infectious diseases
(B) Deficiency diseases
(C) Allergies
(D) Degenerative diseases.
Answer : A

 

Question. The nature of the spread of communicable diseases is known as _______ .
(A) Parasitology
(B) Immunology
(C) Epidemiology
(D) None of these.
Answer : C

Question.Which among the following is a set of bacterial diseases ?
(A) Cholera, typhoid and mumps
(B) Malaria, mumps and poliomyelitis
(C) Diphtheria, leprosy and plague
(d) Tetanus, Tuberculosis and measles.
Answer : C

Question. Assertion (A) : Diphtheria is caused by Corynebacterium diphtheriae.
Reason (R) : Corynebacterium diphtheriae produce a potent exotoxin that inhibits protein synthesis in epithelial cells.
Answer : A

Very Short Answer Questions

Question. Why is Gambusia introduced into drains and ponds? 
Answer. To feed on mosquito larvae so as to eliminate the vectors responsible for causing malaria.

Question. Why do pollen grains of some flowers trigger ‘sneezing’ in some people? 
Answer. Pollen grains trigger sneezing by causing allergic reaction.

Question. Name the category of the disease: Rheumatoid arthritis. 
Answer. Auto-immune disease.

Question. Explain what is meant by metastasis.
Answer. Metastasis is the spread of cancerous cells through migration from one tissue to other tissue and organs resulting in formation of secondary tumour. Malignant tumour is a mass of proliferating cells called neoplastic cells. They grow rapidly and invade surrounding unaffected normal cells or tissues. Cells get sloughed off from such tumour and migrate to distant sites through blood.
A new place of infection is thus established and a new tumour is formed. This property is called metastasis.

Question. Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
Answer. The repeated use of alcohol or drugs increases the tolerance level of the receptors present in our body. Therefore, the receptors respond only to higher doses of alcohol or drugs. This leads to greater intake and addiction. Addiction drives the people to consume more knowing that their use makes them destructive. Hence, it is difficult to get rid of this habit.

Question. Discuss with your teacher what does ‘a suitable gene’ mean, in the context of DNA vaccines.
Answer. The term ‘suitable gene’ refers to that specific segment of DNA which forms immunogenic protein.
Such genes can be cloned and then integrated with vector for introducing into an individual to be immunised for certain disorder producing a particular vaccine against the pathogen.

Question. What measures would you take to prevent water-borne diseases?
Answer. Measures to prevent water-borne diseases are:
(i) Use clean drinking water.
(ii) Periodic cleaning and disinfection of water reservoirs, pools and tanks.
(iii) Proper sanitary conditions.
(iv) Prevention of passage of garbage and sewage into water reservoirs.

Question. Write the biological (binomial) names of causal organisms of the following diseases:
(a) Elephantiatis (Filariasis) (b) Amoebiasis
Answer. (a) Wuchereria bancrofti and Wuchereria malayi
(b) Entamoeba histolytica

Short Answer Questions

Question. Why is tobacco smoking associated with rise in blood pressure and emphysema (oxygen deficiency in the body)? Explain. 
Answer. Tobacco has nicotine that stimulates the release of adrenaline and noradrenaline which raise blood pressure. Smoking tobacco releases carbon monoxide which reduces the concentration of haem-bound oxygen. This causes emphysema.

Question. How does smoking tobacco in human lead to oxygen deficiency in their body?
Answer. Smoking increases the carbon monoxide (CO) content in the blood which has greater affinity to haemoglobin than oxygen. CO forms a stable bond with haemoglobin and does not allow binding of oxygen. Smoking also damages alveolar walls, which reduces respiratory surface (emphysema).

Question. What is colostrum? Why is it important to be given to the newborn infants?
Answer. The milk that comes out of the mammary glands during initial days of lactation is called colostrum.
It contains several antibodies (IgA most abundantly), absolutely essential for developing resistance in the new-born babies.

Question. Name the plant source of the drug popularly called “smack’. How does it affect the body of the abuser? 
Answer. Plant source of ‘smack’ is Papaver somniferum or poppy.
Smack is a depressant and slows down body functions.

Question. Name the plant source of ganja. How does it affect the body of the abuser? 
OR
From which plant are cannabinoids obtained? Name any two cannabinoids. Which part of the body is affected by consuming these substances? 
Answer. Cannabinoids are obtained from the inflorescence of the plant Cannabis sativa. Marijuana, hashish, charas, ganja are some cannabinoids. These chemicals interact with cannabinoid receptors of the body, mainly present in the brain. Cardiovascular system is affected adversely.

Question. The following are some well-known abbreviations, which have been used in this chapter.
Expand each one to its full form:
(a) MALT (b) CMI (c) AIDS (d) NACO (e) HIV
Answer. (a) MALT—Mucosal associated lymphoid tissues.
(b) CMI—Cell-mediated immunity.
(c) AIDS—Acquired immunodeficiency syndrome.
(d) NACO—National AIDS Control Organisation.
(e) HIV—Human Immunodeficiency Virus

Question. What are the various public health measures which you would suggest as safeguard against infectious disease?
Answer. The common preventive measures are as follows:
(i) Education: People should be educated about communicable diseases to protect themselves from such diseases.
(ii) Isolation: The infected person should be isolated to minimise the spread of infection.
(iii) Vaccination: People should get vaccination on time to avoid infection.
(iv) Sanitation: The sanitation condition should be improved to avoid infection from polluted water, contaminated food, etc.
(v) Eradication of vectors: The breeding places of vectors should be destroyed and adult vectors should be killed by suitable methods.
(vi) Sterilisation: The patient’s surroundings and articles of use should be completely sterilised so as to reduce the chances of infection.

Question. In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
Answer. Reasons for alcohol abuse in children:
(i) Social pressure.
(ii) Curiosity and need for adventure, excitement and experiments.
(iii) To overcome hardships of daily life.
(iv) In order to escape from stress, depression and frustration.
(v) Unsupportive family structure.
Alcohol and drugs can be avoided by following ways:
(i) Avoiding undue peer pressure.
(ii) Educating and counselling problems and stresses to avoid disappointments and failure in life.
(iii) Seeking help from parents and peers.
(iv) Seeking professional and medical help whenever required.

Question. How does the transmission of each of following diseases take place?
(a) Amoebiasis
(b) Malaria
(c) Ascariasis
(d) Pneumonia.
Answer. (a) Amoebiosis
Caused by Entamoeba histolytica (Protozoan parasite).
Transmission:
(i) By ingesting cysts with food and water.
(ii) The cysts are carried by flies from faeces to food and drinks.
(b) Malaria
Caused by Plasmodium sps.
Transmission:
(i) Transmitted by female Anopheles mosquito.
(ii) Female Anopheles injects sporozoites along with saliva while sucking blood.
(c) Ascariasis
Caused by Ascaris lumbricoides. Is transmitted through contaminated food and water with Ascaris eggs.
(d) Pneumonia
Caused by Streptococcus pneumoniae. Transmission is through sputum, droplets or aerosols of the patient.

Question. Name the blank spaces a, b, c and d in the table given below:

S.No.	Name of the drug	Plant source	Organ system affected
(i)	a	Poppy plant	b
(ii)	Marijuana	c	d

Answer. (a) Morphine
(b) Central nervous system
(c) Cannabis sativa
(d) Cardiovascular system.

Question. List the harmful effects caused by alcohol/drug abuse.
Answer. The following are the harmful effects caused by alcohol/drug abuse:
(i) It affects the nervous system resulting in loss of judgement, will power and self-control,visual problem, etc.
(ii) It may cause peptic ulcer, gastric carcinoma, etc.
(iii) It may affect liver by causing hepatitis, liver failure, liver cell carcinoma, etc.
(iv) Reckless behaviour, vandalism and violence, isolation, depression, fatigue, aggressive, fluctuations in weight, appetite, etc.
(v) Those who take drugs intravenously are much more likely to acquire serious infections like AIDS and hepatitis-B.
(vi) Damages nervous system and may cause liver cirrhosis.

Question. In which way has the study of biology helped us to control infectious diseases?
Answer. Study of biology helps us to diagnose the pathogen in following ways:
(i) The life cycle of many pathogens is studied.
(ii) Alternate and reservoir hosts are known.
(iii) The mechanisms of transmission of disease is known.
(iv) The protective measures are suggested against disease and pathogen based on above studies.
(v) Suitable medicines against infectious diseases are suggested.
(vi) The preparation of vaccines against many pathogens also entitle the use of study of biology.

Very Short Answer

Question. What are infectious diseases?
Answer. S.L.Miller observed the formation of amino acids.

Question. What are pathogens?
Answer. Evolutionary biology is the study of history of life forms on the earth.

Question. Who initiated the collaboration with Norman Barlaug which culminated in the Green Revolution?
Answer. The units of life are called spores.

Question. Define health?
Answer. Oparin and Haldane proposed the first form of life from pre-existing non-living organic molecules.

Question. Who discovered the blood circulation?
Answer.  The original drifted population becomes founders and the effect is called founder effect.

 

Short Answer

Question. What do you mean by widal test?
Answer. Evolution of life means the gradual formation of complex organisms from simpler ones.Evolution occurs when there is change in the genetic material the chemical molecule,DNA which is inherited from the parents, and especially in the proportions of different genes in a population. Genes represent the segments of DNA that provide the chemical code for producing proteins.

Question. What is the use of vaccines, immunisation programs and antibiotics?
Answer. Embryology is the study and analysis of embryos. Evidence of an evolutionarycommon ancestor is seen in the similarity of embryos in markedly different species.

Question. How the health is affected?
Answer. Origin of life means the appearance of simplest primordial life from non- living matter.Organic molecules are the necessary building blocks for the evolution of life. The Origin of Life, Oparin argued that a primordial soup of organic molecules could be created in oxygen-less atmosphere through the action of sunlight.

Question. Why maintenance of personal and public hygiene is important?
Answer. Anatomy. Species may share similar physical features because the feature was present in a common ancestor (homologous structures). Molecular biology. DNA and the genetic code reflect the shared ancestry of life. Biogeography. Fossils. Direct observation.

Question. What kind of common disease in human cause by rhino viruses and how they infect?
Answer. Evidence of an evolutionary common ancestor is seen in the similarity of embryos in markedly different species. Darwin used the science of embryology to support his conclusions. Embryos and the development of embryos of various species within a class are similar even if their adult forms look nothing alike.

 

Long Answer

Question. Explain how can we prevent and control of alcohol and drugs abuse among the adolescents?
Answer. 
1. Convergent evolution is a process by which distantly related species develop similar structures as adaptations to the environment whereas divergent evolution is a process by which an interbreeding species diverges into two or more descendant species.
2. Convergent evolution occurs through developing analogous structures whereas divergent evolution occurs through developing homologous structures.
3. In Convergent evolution both species live within the same environment whereas in divergent evolution the two species live in different environments than their ancestor.
4. In convergent evolution unrelated organisms evolve similarities while adapting to a common environment whereas in divergent evolution the divergence of two different species results in two species becoming less like the common ancestor.
5. Ostriches, rheas, and emus are examples of convergent evolution whereas dinosaurs, Darwin’s finches, and forelimb structures of vertebrates are examples of divergent evolution.

Question. Explain the types of barriers of innate immunity?
Answer. Hardy- Weinberg principle stated that allele frequencies in a population are stable and is constant from generation. The gene pool and their alleles in a population remains a constant. Hardy-Weinberg principle stated it using an algebraic principle. Hardy- Weinberg law, an algebraic equation that describes the genetic equilibrium within a population. It was discovered independently in 1908 by Wilhelm Weinberg, a German physician, and Godfrey Harold Hardy, a British mathematician. There are five basic Hardy-Weinberg assumptions: no mutation, random mating, no gene flow, infinite population size, and no selection. Human populations do not meet all the conditions of Hardy-Weinberg principle exactly, and their allele frequencies will change from one generation to the next, so the population evolves. The Hardy-Weinberg Equilibrium can be used as a null hypothesis, compared to values from a real population, to describe statistically significant deviations from the Equilibrium. If the deviation is significant, then the gene frequencies are changing and thus, evolution is occurring. It is useful because it describes mathematically the genetic product of a population in which all individuals are equally likely to survive and to produce surviving offspring. Specifically, it calculates the genotype frequencies that will be observed in a population that is not evolving.

Question. Explain some common diseases in humans?
Answer. 
1. Adaptive radiation is the diversification of a group of individuals into forms filling different ecological niches whereas divergent evolution is a process of developing two or more species from a common ancestor over time.
2. Adaptive radiation is a rapid process of evolution whereas divergent evolution is a slow process of evolution.
3. Adaptive radiation is a type of microevolution whereas divergent evolution is a type of macroevolution.
4. Adaptive radiation brings morphological and ecological changes to a particular population whereas divergent evolution generates a new species that is unable to interbreed with the original species.
5. Darwin’s finches, Australian marsupials, and cichlid fish are some examples of adaptive radiation whereas the forelimb structures of mammals are an example of divergent evolution.

Question. Difference between innate immunity and acquired immunity?
Answer. Evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. The theory of evolution is based on the idea that all species are related and gradually change over time. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules. Evolution in organisms occurs through changes in heritable traits the inherited characteristics of an organism. In humans, for example: eye colour is an inherited characteristic and an individual might inherit the brown-eye trait from one of their parents. Inherited traits are controlled by genes and the complete set of genes within an organism's genome (genetic material) is called its genotype.

Question. State the difference between infectious disease and non-infectious diseases?
Answer. 
1. Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring whereas artificial selection refers to the process by which animals and plants are chosen by the breeder to produce desirable and inheritable characters in the successive generations.
2. Natural selection produces a huge biological diversity whereas artificial selection produces organisms with selected traits.
3. Natural selection is a nature-made selection process whereas artificial selection is a man-made selection process.
4. Natural selection is a slow process whereas artificial selection is a rapid process.
5. Natural selection facilitates evolution through generating biological diversity whereas artificial selection does not facilitate evolution.        

Question. Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible? 
Answer. Retroviruses have RNA as their genome. RNA genome of virus replicates in host cell to form viral DNA with the help of reverse transcriptase enzyme.

Question. Why sharing of injection needles between two individuals is not recommended?
Answer. Sharing of injection needles between two individuals can transmit various diseases like AIDS and hepatitis B, as these diseases are transmitted via blood and semen.

Question. How does HIV differ from a bacteriophage?
Answer. HIV has single stranded RNA as genetic material, while bacteriophage has dsDNA.

Question. What type of virus causes AIDS? Name its genetic material. 
Answer. AIDS is caused by human immunodeficiency virus (HIV), a retrovirus. It has ssRNA as genetic material.

Question. Differentiate between benign and malignant tumors. 
Answer. Comparison between benign tumor and malignant tumor is as follows :

Benign tumor	Malignant tumor
It remains confined to the affected organ.	It spreads to other organs of the body.
Rate of growth is usually slow.	Rate of growth is usually rapid.
It causes limited damage to the body.	The cancer cells migrate to other sites of the body and start a new tumor there. This property is called metastasis.
It is non-cancerous.	It is cancerous.

 

Question. Why are the tumors cells dangerous?
Answer. Tumor cells are dangerous, as they have lost the property of contact inhibition and shows uncontrolled growth. Tumor cells invade and destroy the surrounding tissues.

Question. Why do normal cells not show cancerous growth? 
Answer. Normal cells have a limited life span. Their production is regulated in such a manner that number of given cell type remains nearly constant. These cells also show property of contact inhibition, which inhibit their uncontrolled growth.

Question. State the functions of primary and secondary lymphoid organs in humans. 
Answer. There are two types of lymphoid organs : primary lymphoid organs and secondary lymphoid organs. The primary lymphoid organs are those organs where T lymphocytes and B lymphocytes, mature and acquire their antigen-specific receptors. After maturation, the lymphocytes migrate to secondary lymphoid organs e.g., bone marrow and thymus where they undergo proliferation and differentiation. The acquired immune response to antigens usually develops in these organs and become effector cells.

Question. List the two types of immunity a human baby is born with. Explain the differences between the two types. 
Answer. Two types of immunity with which human baby is born include-
(i) Innate immunity - It is inherited by an organism from the parents and protects it from birth throughout the life. It is not specific to particular pathogen and consists of four types of barriers - physical, physiological, cellular and cytokine.
(ii) Natural passive immunity - It is passively transferred from mother to foetus through placenta, as IgG antibodies can cross placental barrier to reach the foetus.

Question. 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.
Answer. A child injured in a roadside accident with a bleeding wound has chances of getting infected from tetanus so quick immune response is required, therefore, preformed antibodies, or antitoxin (a preparation containing antibodies to the toxin) is directly injected. In vaccination, a preparation of antigenic proteins of pathogen or inactivated/ weakened pathogen (vaccine) are introduced into the body. The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection. Therefore, vaccine administration would not have given quick relief and thus would not have been effective.

Question. Name and explain the type of immunity that is provided by injecting microbes deliberately during immunisation into the human body.
Answer. Artificial active immunity is the type of immunity that is provided by injecting microbes deliberately during immunisation into the human body. The microbes are injected through vaccines. Vaccine is a suspension of dead/weakened microbes of disease which when injected into healthy person provides artificial active immunity e.g., live BCG vaccine for tuberculosis, MMR vaccine for measles, mumps and rubella.

Question. (a) Name the lymphoid organ in humans where all the blood cells are produced.
(b) Where do the lymphocytes produced by the lymphoid organ mentioned above migrate and how do they affect immunity? 
Answer. a) Bone marrow.
(b) The lymphocytes produced migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix. The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells which then affect immunity.

Question. How does spleen act as a lymphoid organ? Explain. 
Answer. Spleen acts as secondary lymphoid organ where mature B and T lymphocytes undergo proliferation and differentiation. In spleen, lymphocytes develop acquired immune response to antigens and becomes effector cells.

Question. Name the type of immunity that is present at the time of birth in humans. Explain any two ways by which it is accomplished. 
Answer. Innate immunity is the resistance to infection, which an individual possesses by virtue of his genetic make up, that is it comprises all those defence elements with which an individual is born It is accomplished by certain barriers such as physical, physiological, cellular and cytokine barriers.

Question. Name and explain the type of barrier of innate immunity where some cells release interferons when infected.
Answer. The type of this barrier is called cytokine barrier. Cytokines are protein molecules, released by cells when activated by antigen, that are involved in cell-to-cell communication, acting as enhancing mediators for immune response through interaction with specific cell-surface receptors on leucocytes. Interferons are examples of cytokines. Interferons protect against viral infections of cells.

Question. What is the functional difference between B-cells and T-cells? 
Answer. Differences between B-Lymphocytes (B-cells) and T-Lymphocytes (T-cells)

B-Lymphocytes (B-cells)	T-Lymphocytes (T-cells)
B-cells form humoral or antibodymediated immune system.	T-cells form cellmediated immune system.
ey defend against viruses and bacteria that enter the blood and lymph.	They defend against pathogens including protists and fungi that enter the cells.
Plasma cells formed by division of B-cells produce antibodies and provide immunity against foreign substances.	T lymphocytes produce dierent types of T-cells, killer T-cells react against cancer cells, suppressor cells inhibit immune system.

 

Question. (a) Name and explain giving reasons, the type of immunity provided to the newborn by the colostrum and vaccinations.
(b) Name the type of antibody
(i) present in colostrum
(ii) produced in response to allergens in human body. 
Answer. a) Colostrum (mother’s first milk) rich in IgA antibodies provides natural passive immunity to new born. In passive immunity, ready-made antibodies are directly injected into a person to protect the body against foreign agents.
Through vaccination artificial active immunity, will be provided to the newborn in which his own cells will produce antibodies in response to vaccine. E.g., BCG vaccine for tuberculosis.
(b) (i) IgA (ii) IgE

Question. Do you support ‘Dope’ test being conducted on sportspersons participating in a prestigious athletic meet? Give three reasons in support of your answer. 
Answer. Yes, Dope test should be conducted on sportspersons participating in athletic meet because:
(i) Athletes intake cannabinoids to increase their muscle tone and to have better performance.
(ii) Intake of cocaine alters cardiovascular functions, increases heart beat and blood pressure. (iii) Cocaine delays fatigue and helps to enhance performance.

Question. “Prevention is better than cure” is an apt slogan to safeguard adolescents from drug abuse. List any 6 steps that could be taken in this regard.
Answer. Yes, it is always better to prevent the adolescents from being getting addicted to harmful drugs, rather than cure them for addiction. Six steps that could be taken in this regard are: (i) A child should not be pushed unduly to perform beyond his/her threshold limits in studies, sports or any other activities.
(ii) Educating and counselling him/her to face problems and stresses and accept disappointments and failures as part of life.
(iii) Parents and teachers can identify the danger signs and take appropriate steps to diagnose the malady and underlying causes, so that proper remedial steps can be taken.
(iv) Help can/should be sought from qualified psychologists and psychiatrists.
(v) The individual can seek help from parents and teachers.
(vi) Help can also be sought from close and trusted friends; this would help to vent the feelings and anxiety and guilt.

Question. Write the source and the effect on the human body of the following drugs:
(a) Morphine
(b) Cocaine
(c) Marijuana 
Answer. (a) Morphine – It is obtained from Papaver somniferum. It is strong analgesic and has sedative and calming effect. It decreases blood pressure and depresses respiratory centre.
(b) Cocaine – It is obtained from Erythroxylum coca. It has vasoconstrictor properties and is powerful CNS stimulant. Its excessive dosage causes hallucinations.
(c) Marijuana – It is obtained from Cannabis sativa.
It is a hallucinogen and may cause psychosis.

Question. Why are lymph nodes and bone marrows called lymphoid organs? Explain the functions of each one.
Answer. Lymph nodes and bone marrow are called lymphoid organs as these are the sites for proliferation and maturation of lymphocytes respectively.
Lymph nodes are secondary lymphoid organs where mature B- and T-lymphocytes undergo proliferation and differentiation. Bone marrow is a primary lymphoid organ where B cells mature and acquire their antigen-specific receptors.

Question. (a) List any two situations when a medical doctor would recommend injection of preformed antibodies into the body of a patient.
Name this kind of immunisation and mention its advantages.
(b) Name the kind of immunity attained when instead of antibodies weakened antigens are introduced into the body.
Answer. (a) If a person is infected with some deadly microbes to which quick immune response is required as in tetanus, we need to directly inject the preformed antibodies or antitoxin. Even in the cases of snakes bites the injection which is given to the patients, contain preformed antibodies against the snake venom. This type of immunisation is called artificial passive immunisation. It provides immediate relief but may cause some problems.
(b) In vaccination, a preparation of inactivated/ weakened antigenic proteins of pathogens are introduced into the body. This produces immune response and the type of immunity is called artificial active immunity.

Question. (a) It is generally observed that the children who had suffered from chicken-pox in their childhood may not contract the same disease in their adulthood. Explain giving reasons the basis of such an immunity in an individual.
Name this kind of immunity.
(b) What are interferons? Mention their role.
Answer. (a) Children who had suffered from chicken- pox may not contract the same disease in their adulthood because of development of memory cells. These type of cells develop during first encounter with the pathogen. Memory cells are highly specific and may remain in body for decades. Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic response. This type of immunity is known as acquired natural active immunity.
(b) Interferons are the proteins produced by virus infected cells. They protect non-infected cells from further viral infection.

Question. A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.
(a) Write what did the doctor inject into the patient’s body.
(b) How do you think this injection would protect the patient against the disease?
(c) Name the disease against which this injection was given and the kind of immunity it provides. 
Answer. (a) Doctor injected anti-tetanus toxin into patient’s body.
(b) Injection containing preformed antibodies or antitoxin (preparation containing antibodies to toxin) would neutralise the pathogenic agents and would give quick relief.
(c) Injection was given against tetanus and it provides artificial passive immunity.

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