Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease Textbook Questions and Answers, Additional Important Questions, Notes.

BSEB Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Bihar Board Class 12 Biology Human Health and Disease Text Book Questions and Answers

Question 1.
What are the various public health measures, which you would suggest as safeguard against infectious diseases?
Answer:
Preventive measures are precautionary steps taken to check the transmission of infectious disceases. Common preventive measures include education, isolation, vaccination, sanitation, eradication of vectors and sterilization.
(i) Education: People should be educated about the communicable diseases so that they may protect themselves against infection.

(ii) Isolation: A person suffering from an infectious disease should be segregated so that others do not catch infection from him.

(iii) Vaccination: People should get vaccination to avoid infection, particularly during epidemic. Vaccination is available against cholera, typhoid, tuberculosis and many other diseases.

(iv) Sanitation: Garbage heaps, polluted water, foods exposed to dust and flies are the chief sources of disease-causing organisms. Sanitary surroundings can prevent spread of diseases.

(v) Eradication of vectors: The breeding places of the vectors should be destroyed and adult vectors killed by suitable methods.

(vi) Sterilization: Patient’s surroundings and articles of use should be sterilized. Soap, phenyl, Dettol and antiseptic lotion may be used wherever necessary.

Question 2.
In which way the study of biology has helped us to control infect,iou§ diseases?
Answer:
Infectious diseases or communicable diseases are caused by pathogens such as virus, bacteria, fungi, protozoans and worms etc. These diseases readily spread from the infectious person to the healthy persons. Biological research and tools has helped a lot to control and eradicate communicable diseases. It helps

  • to know the nature of the disease e.g. the causative agent and its life cycle,
  • to find out the mode of transmission of the disease (how the causative agent enters human body),
  • to provide treatment and cure to the infected person by medicines,
  • to provide vaccines and immunization treatments for preventing further spread of the disease,
  • to devise protective measures against the attack of the causative agent of the disease.

Question 3.
How does the transmission of each of the following diseases takes place?
(a) Amoebiasis, (b) Malaria, (c) Ascariasis, (d) Pneumonia.
Answer:
(a) Amoebiasis is caused by Entamoeba histolytic. It is a dimorphic protozoan, occurs in two forms viz., minute form and magna form. The tetranuclear cysts are ingested with contaminated food and water. Human, infection is direct and oral.

(b) Malaria is caused by protozoan parasite Plasmodium falciparum. It enters human body through the bite of an infected female anopheles mosquito. The parasite completes its life cycle in human body. The mosquito acquires the parasite by biting an infected human being.

(c) Ascariasis is caused by helminth Ascaris lumbricoides. It is a roundworm parasite in man. A healthy person get infection from water, vegetables and fruits etc. contaminated with the eggs of the parasite. The eggs are excreted with faeces from infected person and contaminate soil, water and plants etc.

(d) Pneumonia is caused by Streptococcus pneumonia and Haemophilus influenza. The bacteria from infected person are released out as droplets or aerosols. These are inhaled from healthy person who gets the infection. It is also spread by sharing glasses, cloth and utensils with the infected person.

Question 4.
What measure would you take to prevent water-borne diseases?
Answer:
Waterborne diseases can be prevented by two ways :
(i) Some diseases such as typhoid, amoebiasis and ascariasis spread through consuming contaminated
water, so proper hygienic are should be taken to use clean drinking water. Only boiled or filtered water should be used for cooking and drinking.

(ii) Some diseases such as malaria and filariasis are transmitted through insect vectors which use water reservoir as their breeding place, so its important (i) to periodically clean and disinfect the water reservoirs, pools, cesspools and tanks, (ii) avoiding stagnation of . water in and around residential areas,

(iii) regular cleaning of household coolers,
(iv) spraying insecticides in ditches, drainage areas and swamps etc.
(v) introducing fishes which feed on mosquito larvae in ponds
(vi) using sleeping nets and wire mesh to prevent mosquito entry.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 5.
Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
Answer:
DNA vaccination is a proposed experimental technique for protecting an organism against disease by injecting it with Nacked DNA to produce an immunological response. In DNA vaccination a single suitable gene is copied artificially from a pathogen and multiplied (in conventional vaccination practices a damaged or destroyed pathogen is administered).

This gene is then injected into a muscle. The muscle cells are tend to take this gene and use it as one of their own gene, making proteins according to the gene. The immune system will recognise these proteins as foreign and remember it, just like it does in the ‘classic’ vaccination.

Advantages of this technique are : (i) The gene is made artificially in lab, so its much more pure than a damaged pathogen which may sometimes cause adverse effects, (ii) It is only one of the many genes necessary for the pathogen to reproduce, but it is enough for the immune system to recognize as energy, but not enough to become a danger to the body.

Question 6.
Name the primary and secondary lymphoid organs.
Answer:
Primary lymphoid organs are bone marrow and thymus. Lymphocytes are produced in bone marrow. It provides the suitable environment for the development and maturation of B-lymphocytes. Thymus provides microenvironment for the development and maturation of T-lymphocytes. Thymus is quite large at the time of birth but reduces with age and by puberty, it becomes very small. At primary lymphoid organs, the immature lymphocytes differentiate into antigen sensitive lymphocytes.

Secondary lymphoid organs are spleen, lymph nodes, tonsils, appendix and Peyer’s patches of small intestine. These organs provides the interaction sites for antigen and lymphocytes.

Question 7.
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 is Mucosal-Associated Lymphoid Tissue. It is located in the living of respiratory, digestive and urogenital tracts.
(b) CMI – Cell-Mediated Immune system
(c) AIDS – Acquired Immuno Deficiency Syndrome
(d) NACO is National AIDS Control Organisation.
(e) HIV is Human Immunodeficiency Virus which causes AIDS.

Question 8.
Differentiate the following and give examples of each :
(a) Innate and acquired immunity
(b) Active and passive immunity.
Answer:
(a) Innate and acquired immunity :

Innate immunity Acquired immunity
(1) It is present from the birth. (1) It is developed after the birth during one’s own life.
(2) It is inheritable immunity. (2) It is not inheritable.
(3) It is not acquired from the previous attack of disease, e.g. against distemper disease. (3) It is acquired in response to a disease or vaccine, e.g. against smallpox, polio, tetanus etc.

(b) Active and passive immunity :

Character Active Immunity Passive immunity
(1) Source It is developed by an individual’s own cells in response to an infection or a vaccine. It is developed when readymade antibodies are inoculated from outside.
(2) Side effects It has no side effects. It may cause reaction.
(3) Period of relief It provides relief only after long period. It provides immediate relief.
(4) Period of effectivity It is long-lasting. It is short-lived.

Question 9.
Draw a well-labelled diagram of an antibody molecule.
Answer:
Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease 1

Question 10.
What are the various routes by which transmission of human immunodeficiency virus takes place?
Answer:
AIDS spread through following ways :

  • Unprotected (without condom) sexual intercourse with an infected partner if there is tissue injury to permit blood contact.
  • Use of contaminated needles and syringes to inject drugs or vaccines.
  • Use of contaminated razors for shaving.
  • Transfusion of infected blood or blood products.
  • Organ transplant.
  • Artificial insemination.
  • Parturition from mother to baby due to rupturing of blood vessels.

The sexual route of transmission accounts for over 75% of infections. It does not spread through simple contact. It is not a contagious disease.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 11.
What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
Answer:
AIDS virus is known as HIV, its a reverse transcriptase virus It has a single-stranded linear RNA as genetic material. Its diploid i.e. contains two copies of RNA molecule. (Diagram is already shown in introduction)
The virus binds specifically to a surface receptor on a helper T- cell and introduces its RNA and reverse transcriptase enzyme into the cells.

Then it produces DNA copy of itself by reverse transcription. DNA copy gets incorporated into the host cell genome. This is provirus form, which directs the viral genome for the production of new virus particles. Formation and release of daughter virus cells destroys the host cell. AIDS occurs when the number of helper T-cells falls too low to fight the disease.

Question 12.
How is a cancerous cell different from a normal cell?
Answer:
Cancerous cell is different from normal cell in following ways :
1. Cancers show uncontrolled mitotic divisions of cells causing unorganized growth. The rate of cell division is much faster than that of normal cells (e.g., gut lining cells divide after 36 hours; skin cells after every few days, red blood cells after every’ few weeks). The cells undergoing abnormal and uncontrolled growth are called paraneoplastic cells.

2. Cancer ceils lose the normal feedback controls that prevent excessive growth, so these cells grow much more than the normal cells.

3. Due to uncontrolled growth and division of cells, a tumour (also called neoplasm which literally means new growth) is generally formed. However, all tumours are not cancerous. Further, no tumour is formed in leukaemia (blood cancer).

4. These cells have less survival capability than the normal cells.
5. Cancer cells are far less adhesive than the normal cells so these generally wander through the tissues to cause cancerous growth in different parts of the body.
6. Most of these produce angiogenic factors which stimulate the growth of blood vessels to supply more nutrients required for cancer growth.
7. Cancer cells do not undergo differentiation.
8. Cancer cells do not show contact inhibition.
9. These cells have high invasiveness.
10. ln cancer cells, cytoskeletal structures like microtubules and microfilaments tend to be disorganized.

Question 13.
Explain what is meant by metastasis.
Answer:
In case of malignant tumour, the latent or first stage is very slow and unnoticeable. Later on, the tumour grows rapidly and competes with the normal cells for nutrients and kill them. This causes overcrowding and disruption of normal cells. Then it extends to the neighbouring tissue.

In the last stage, small pieces of primary tumour break off and are carried by blood or lymph to other parts of body and form secondary tumours. This process is called as metastasis. It is characteristic of malignant tumours and causes death of the victim due to increasing interference with the body’s life processes.

Question 14.
List the various harmful effects which alcohol/drug abuse.
Answer:
Drug abuse and alcohol intake is harmful in following ways :
(i) Effect on nervous system: These have sedative, analgesic and anaesthetic effects. These reduces the
efficiency of every tissue of the body. Prolonged use can cause various mental and physical symptoms.

(ii) Effect on heart: These drugs and alcohol dilates the blood vessels. Due to constant dilation, the arterial walls soon become brittle and rigid. This severly affects the working of heart.

(iii) Effect on stomach: These effect the living of the stomach and cause inflammation.

(iv) Effect on liver: Alcohol causes fatty liver syndrome and degeneration of liver called cirrhosis.

(v) Effect on kidneys: Kidneys overwork to eliminate harmful wastes from the body.

(vi) Effect on immunity: The users loose resistance to infections, alcoholics are mal-nutritioned and susceptible to diseases like pneumonia. Prolonged use of drugs may cause impotertcy, chromosomal abnormalities and defective offsprings. ‘

(vi) Effect on the family: These abuses directly or indirectly affect the family and community life. The addicts are psychologically maladjusted and suffer from insecurity.

(vii) Effect on society: These habits are invariably associated with social crimes and dissolution of moral and cultural inhibition. Drugs are illegally obtained and encourage smuggling and stealing money. These abuses can cause traffic and industrial accidents and commit crimes.

Question 15.
Do you think that friends can influence one to take alcohol/ drugs? If yes, how may one protect himself/herself from such an influence?
Answer:
Adolescence is a period and a process when a child becomes mature in attitude and beliefs for effective participation in society. Adolescence is a bridge linking childhood and adulthood. It is accompanied by several biological and psychological changes. The pressure to excel in academics, unstable or unsupportive family, movies and media all play a significant role to lure the adolescents to these malpractices. Further frequent appreciation of the drug experience by friends allures others to experiment the drugs and alcohol.

Thus friends play a pivotal role in introducing one to drugs and alcohol, but one should understand that every child has his/her own personality and stamina. He/she should not be pushed unduly to perform beyond their threshold limits. They should seek help from parents. They should be provided proper education and conselling accept disappointments and failure as part of life.

Question 16.
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:
Once a person depends on drugs it is difficult to get rid of this habit due to psychological and physical or physiological reasons. The person believes that the normal state of well being can be attained only with the drug’s action or alcohol. Sometimes the intake of a drug or alcohol becomes essential to maintain physiological equilibrium. In such situations, the nervous system functions normally in the presence of the drug/alcohol only. It seems almost impossible to sustain life without drug/alcohol.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 17.
In your view, what motivates the youngsters to take to alcohol or drugs and how can this be avoided?
Answer:
There are many factors which motivates the youngsters to take alcohol or drugs. Some of these are :
(i) Curiosity: Frequent references to drugs/alcohol by public media create curiosity for having a personal experience of these things.

(ii) Peer’s pressure: Appreciation of such things by friends allures others to start their use.

(iii) Pleasure: Sometimes youngsters take drugs/alcohol for fun and pleasure.

(iv) Frustration and depression: Some youngsters take drugs/ alcohol to get rid of frustration and depression.

(v) Sometimes students take drugs to keep awake the whole night for exams.

(vi) A wrong notion is that drugs/alcohol open up a new vyorld tempts some youngsters to start using these things.

(vii) Easily availability of drugs/alcohols also a cause to start their use. ‘
To avoid addiction, one should try to understand oneself fully and to accept oneself as one is. At times of stress and strain, one should face the problem rather than forget them by taking alcohol or drugs. It is better to talk about the problems to family members, friends, teachers or other mature persons in the community. A sympathiser can always be found and all problems have solutions.

Bihar Board Class 12 Biology Human Health and Disease Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Name two contagious diseases.
Answer:
Pneumonia, common cold, chickenpox.

Question 2.
Give two forms of cancers on the basis of their spread.
Answer:
Benign cancer and malignant cancer.

Question 3.
What is full form of DPT?
Answer:
Diphtheria, pertussis and tetanus.

Question 4.
Name two congenital diseases.
Answer:
Haemophilia and alkaptonuria.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 5.
What is a carrier?
Answer:
A person that harbours living germs which do not cause the disease.

Question 6.
What is incubation period?
Answer:
Interval between infection and appearance of disease.

Question 7.
Give the source of opium.
Answer:
Capsules of white poppy plant, Papaver somniferum.

Question 8.
What are stimulant?
Answer:
Drugs that increase the activities of central nervous system.

Question 9.
What is the source of cocaine?
Answer:
Leaves and young shoots of coca plant.

Question 10.
Give the role of anabolic steroids.
Answer:
Increase in muscle mass.

Question 11.
How do non-specific defence mechanisms resist infection?
Answer:
by blocking the entry of pathogens into the body or by destroying the microbes without antibody generation.

Question 12.
List the fluids which contain lysozyme.
Answer:
Sweat, saliva, tears, nasal secretion.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 13.
What do the abbreviations AMIS and CMIS denote?
Answer:
Antibody-Mediated Immune System and Cell-Mediated Immune System.

Question 14.
What is the role of complement system?
Answer:
To assist defence mechanism of the body.

Question 15.
What is the role of suppressor cells?
Answer:
To prevent immune system from attacking body’s own cells.

Question 16.
What is diapedesis?
Answer:
Escape of WBCs from capillaries.

Question 17.
Name the two major group of cells required in attaining specific immunity.
Answer:
B-cells and T-cells.

Question 18.
Mention the role of large intestine in natural defence of body?
Answer:
Normal microorganism of large intestine secrete antibiotics that kill many pathogenic bacteria.

Question 19.
Who was the father of Immunology?
Answer:
Emil von Behring.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 20.
What is the life span of B-cells and T-cells?
Answer:
B-cells live for few days and T-cells live for 4-5 years or more.

Short Answer Type Questions

Question 1.
Explain why scientists have failed to produce vaccines against AIDS.
Answer:
AIDS spread through HIV virus. It is a retrovirus with RNA as genome. Chances of mutation are very high in RNA. The virus every time mutates in its reverse transcription and replication cycle. Most HIV particles produced in an infected person differ in surface receptors at least slightly from those on the original infecting virus.

Question 2.
What is cancer? What are three main types of cancer?
Answer:
Cancer is characterized by uncontrolled growth and division of certain body tissues thus forming a tumour. Such cells are called paraneoplastic cells. Cancer cells do not undergo differentiation and have high invasiveness. Depending on the basis of location cancerous tumours are of three types –

  1. Cacinomas: Cancer which are located in epithelial tissues e.g. breast, stomach, lung, skin and pancreas cancer.
  2. Sarcomas: Cancer of connective tissue and muscular tissue derived from mesoderm e.g. bone, lymph nodes and muscle cancer.
  3. Leukaemia or Blood cancers: It affects children below 15 years. WBC count in blood increases due to increased formation of WBCs in bone marrow, which decreases erythropoiesis and RBCs count.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 3.
What is meant by reservoirs of infection.
Answer:
Reservoirs of infection are those sites which are occupied by pathogens, when they are not inside the human body. There are different for different pathogens. They are of following type :

(a) Carriers or vectors: Those living organisms which spread the pathogens from an infected person to healthy person. Themselves they do not suffer from the disease, e.g. for plasmodium (pathogen) the carrier host is female Anopheles mosquito.

(b) Soil is the reservoir of infection of Clostridium tetani (tetanus bacteria).

(c) Air is reservoir of bacterial cysts of tuberculosis and diphtheria and many others.

(d) Food and water: They serve reservoirs for cholera, typhoid, polio, Entamoeba histolytica etc.

Question 4.
Write down the effects of Nicotine on human body?
Answer:
Nicotine stimulates passage ot nerve impulses, causes muscles to relax and causes the release of adrenalin, increases both blood pressure and rate of heartbeat. The increased blood pressure caused by %ircutating red blood copies, smoking leads to increased Middle-During the smoking, starts narrowing, risk of heart diseases. Right-Ending with complete local obstruction.
Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease 2

Question 5.
Briefly write the functions of macrophages.
Answer:
Macrophages have following functions :

  • Defence: Wandering macrophages dispose of microbes in the connective tissue. They are known as histiocytes. Fixed macrophages destroy microbes in the blood and lymph.
  • Scavenging: Macrophages also dispose of dead tissue cells and noncellular foreign matter.
  • Antigen display: Macrophages carry the antigens on their surface and display them to lymphocytes.
  • Many macrophages may fuse to form a large multinucleate giant cell to capture a big size foreign body.

Question 6.
Explain why secondary immune response is very quick and intense?
Answer:
Secondary immune response is very quick and intense because the memory B-cells persisting from the primary immune reaction quickly form antibodies to deal with microbes.

Question 7.
Why skin is called a self-disinfecting organ?
Answer:
Skin is called a self-disinfecting organ because sweat and sebum, which are secreted by sudoriferous glands and sebaceous glands contain lactic acid and fatty acids which check microbial growth on the skin. Sweat also contains lysozyme which kills bacteria.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 8.
What is passive immunity?
Answer:
Immunity is called passive when antibodies produced in other organism are injected into a person who already has a potential antigen in his body. For example, passive immunity is developed to counteract snake venom and rabbies.

Question 9.
In case of infectious disease, having fever is beneficial for the body?
Answer:
In case of severe infection, body temperature rises, causing fever. Mild fever strengthens the defence mechanism by activating the phagocytes and inhibiting the growth of the microbes.

Question 10.
What are interferons?
Answer:
Interferons are antiviral proteins secreted by virus-infected cells. It is released from the infected cells and makes the nearby uninfected cells more resistant to the viral infection.

Question 11.
With examples, define distilled and undistilled alcohols.
Answer:
Alcohol produced by mere fermentation of raw material is called undistilled alcohol, e.g. beer, champagne. Alcohol formed by distilling the fermented product of raw material is called distilled alcohol, e.g. whisky, brandy etc.

Question 12.
Write a note on cirrhosis.
Answer:
Liver converts alcohol into fat that is stored in liver cells. Excess fat reduces formation of glycogen, enzymes and structural proteins. The fatty liver then hardens and dries up as its cells are replaced by fibrous tissue’. The degeneration of liver is known as cirrhosis.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 13.
Name the two main classes of general drugs. Give their source and one example of each.
Answer:

  1. Natural drugs obtained from plants, e.g. quinine and morphine, from animals, e.g. heparin and liver extract, and microorganisms, e.g. penicillin and steptomycin;
  2. Synthetic drugs which are manufactured in the laboratory, e.g. aspirin, chloroquine etc.

Question 14.
What are endogenous and exogenous chemical agents of disease?
Answer
Endogenous chemical agents are those which are formed in the body itself. These may be hormones, urea etc. Exogenous chemical agents are those which enter the body from environment through water, air, food etc. for example fumes, spores etc.

Question 15.
How infection is different from infestation?
Answer:
Infection is the entry of a pathogen inside the host’s body, whereas infestation is the presence of pathogens, generally arthropods on the body surface or on the clothes, e.g. louse infestation.

Long Answer Type Questions

Question 1.
Differentiate between them :
(i) Antibodies and antigens
(ii) Interferons and antibodies
(iii) Benign tumour and Malignant tumour
(iv) B-cells and T-cells.
Answer:
(i) Antibodies and antigens :

Antibodies Antigens
(1) Antibody is a molecule synthesized by an animal to combat foreign material. (1) Antigen is usually a foreign material that elicits antibody formation.
(2) Each antibody is a protein molecule. (2) Antigen is a protein or polysaccharide molecule.
(3) Antibody occurs on the surface of a plasma cell and also in body fluids. (3) Antigen may occur on the surface of a microbe or as a free molecule.
(4) Antibody directly joins an antigen to destroy the latter. (4) Antigen binds to a macro-phage to reach a helper T-cell to initiate immune response.

(ii) Interferons and antibodies :

Interferons Antibodies
(1) Are produced by any microbe infected cell. (1) Are produced by plasma B-cells only.
(2) Leave the infected cell and enter a nearby healthy cell to dispose of the microbes. (2) Pass into the circulate in blood any lympth to dispose of antigens.
(3) Induce the healthy cell to synthesize antimicrobial proteins that check microbial (3) Selectively bind to antigens that are immobilised for easy attack by phagocytes.
(4) Are quick in action but give a temporary protection against microbes. (4) Are slow in action but give a long-lasting protection against antigens.
(5) Act inside the cells. (5) Act outside the cells.
(6) Form the body’s second line of defence. (6) Form the body’s third line of defence.

(iii) Benign tumour and Malignant tumour :

Benign tumour Malignant tumour
(1) These remain confined in the organ affected. (1) These spread from one organ to other organs of the body.
(2) These are enclosed in a connective tissue sheath. (2) These are not enclosed in connective tissue sheath.
(3) These have less growth rate. (3) These have rapid growth rate.
(4) Cancer cells are more adhesive. (4) Cancer cells are less adhesive.
(5) No metastasis. (5) Metastasis is generally present.

(iv) B-cells and T-cells :

B-cells T-cells
(1) B-cells form humoral or anti-mediated immune system (AMIS). (1) T-cells form cell-mediated immune system (CMIS).
(2) They are differentiated in bone marrow. (2) They are differentiated in thymus gland.
(3) They defend against some viruses, encapsulated bacteria and toxins that enter the blood and lymph. (3) They’ defend against viruses, protists, fungi and some bacteria which enter the cells.
(4) They form by division plasma cells. (4) They form by division lymphoblasts of three types: killer, helper and suppressor cells.
(5) Plasma cells do not move to the site of infection. (5) Lymphoblasts move to the site of infection.
(6) Plasma cells secrete antibodies that pass into the blood and lympth and dis-pose of the antigens. (6) Killer cells on reaching the site of infection secrete perforin that kills microbes by puncturing their cell membrane.
(7) Plasma cells do not react against transplants and cancer cells (7) Killer cells react against transplants and cancer cells also.
(8) Plasma cells have no inhibitory role on immune system. (8) Suppressor cells inhibit the immune system from attacking body’s own cells.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

2.
(i) Give a schematic representation of events during inflammatory reaction.
(ii) Write down the role of lymphatic system.
(iii) What is the role of macrophages?
Answer:
Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease 3
(ii) Lymphatic system have following roles :
(a) It drains excess tissue fluid from the extracellular spaces back into the blood.

(b) Some of the fluid from the digestive tract is absorbed into the lumph. The lymphatic vessels store this fluid temporarily and release it gradually so that the kidneys do not face a sudden pressure of urine excretion.

(c) It carries carbon dioxide and nitrogenous waste materials that diffuse into the tissue fluid to the blood.

(d) It takes lymphocytes and antibodies from the lymphatic nodes to the blood.

(e) It transports fats digested and absorbed in the intestine to the blood in the form of chylomicron droplets.

(f) It destroys the invading microorganisms and foreign particles in the lymphatic nodes.

(g) It maintains the quality and quantity of the blood by restoring the fluid and solutes that leave it.

(h) It brings plasma protein macromolecules synthesized in the liver cells and hormones produced in the endocrine glands to the blood. These molecules cannot pass into the narrow blood capillaries but can diffuse into lymphatic capillaries.

(iii) Macrophages have following roles/functions :
(a) Defence: Wandering macrophages (also called histiocytes) dispose of microbes in the connective tissue. Fixed macrophages destroy microbes in the blood and lymph.

(b) Giant Cell Formation: Many macrophages may fuse to form a large multinucleate giant cell to capture a foreign body too big for a single macrophage to engulf.

(c) Scavenging: Macrophages also dispose of dead tissue cells and noncellular foreign matter.

(d) Antigen Display: Macrophages carry the antigens of the engulfed microbes on their surface to display them to the lymphocytes in the lymphatic nodes. This activates the immune system.

(e) Secretion of Endogenous Pyrogen: Macrophages secrete interleukin-1 (IL-l), also called endogenous pyrogen. It plays a role in inflammatory response, in causing fever, and inactivation of other phagocytic cells as well as the T-cells and B-cells to produce their effect.
Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease 4

One Word Type Questions

Question 1.
Name the process of making a person immune to a disease.
Answer:
Immunization;

Question 2.
Is the skin surface acidic or alkaline?
Answer:
Acidic

Question 3.
Can the skin be grown in a culture?
Answer:
Yes.

Question 4.
Mention the source of perforin.
Answer:
Killer T-cells.

Bihar Board Class 12 Biology Solutions Chapter 8 Human Health and Disease

Question 5.
Name the bacteria that normally inhabit vagina.
Answer:
Lactobacilli

Question 6.
Give an alternative term for wandering macrophages.
Answer:
Histiocytes

Question 7.
Which protein occurs in the stratum corveum of epidermis?
Answer:
Keratin (horn)

Question 8.
Which hallucinogen is extracted from a cactus?
Answer:
Mescaline

Question 9.
Name any stimulant.
Answer:
Amphetamines

Question 10.
Which hallucinogen is derived from a fungus?
Answer:
Psilocybin

Question 11.
Which disease is caused by dog bite?
Answer:
Rabies

Question 12.
Name two types of toxins.
Answer:
Exotoxins and endotoxins.