In This Post we are providing Chapter- 8 HUMAN HEALTH AND DISEASE NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERT MOST IMPORTANT QUESTIONS ON HUMAN HEALTH AND DISEASE
1.Describe the ill – effects of drug abuse in males & females. Also mention the preventive measures that is to be taken to reduce such effects.
Ans.1) ILL – DEFECTS IN MALES :- acne, increased aggressiveness , mood swing depression reduction of size of testicles, decreased Sperm production, kidney & liver dysfunction, premature baldness.
2) ILL – EFFECTS IN FEMALES :-masculinisation, increased aggressiveness, mood swings, depression abnormal menstrual cycle, excessive hair growth on face & body & deepening of voice.
The following measures are need to be taken to prevent such problems :-
- EDUCATION & COUNSELLING :- to face problem or stress, to accept failure as part of life & to channelize child’s energy to some health promoting activities.
- AVOID UNDUE PEER PRESSURE :- to pressurize a child to perform beyond his capabilities
- SEEKING HELP FROM PARENTS &PEERS :- to share the feeling of anxiety & guilty.
- SEEKING PROFESSIONAL FOR MEDICAL HELP :- help available in the form of highly qualified psychiatrist, psychologist etc.
2.What is vaccination? What type of immunity is provided by vaccination?
Ans.Vaccination is a process of development of immunity with administration of vaccines in the body, here weakened pathogen are infected into the body to produce immunity against a particular pathogen. This pathogen stimulates the body to produce antibodies. The antibodies produced against these antigens would neutralize the pathogenic agent. The vaccine also generates memory B – and T – cells that recognize pathogen quickly on subsequent exposure & overwhelm the invaders with massive production of antibodies.
The type of immunity is ACTIVE IMMUNITY.
However, if a person is infected with some deadly microbe to which quick immune response is required, we need to directly injected to patient’s body, This type of immunization is called PASSSIVE IMMUNISATION.
3. (i) Differentiate between communicable & non – communicable diseases?
(ii) Name the body part & the host in which following events takes place in life cycle of plasmodium.
(a) fertilization
(b) Development of Gametophyte :-
(c) Release of sporozoites :-
(d) Asexual Reproduction.
Ans. (i) Communicable diseases are caused lay biological agents & can spread from one person to another or one place to another through air, water, physical contact etc.
Non – communicable diseases are confined to a person & do not easily spread from one person to another.
(ii) (a) in the gut of female anopheles.
(b) in RBCS of Human beings.
(c) Salivary gland of female anopheles.
(d) liver cells of human beings.
4. Answer the following with respect to Caner.
(a) How does a cancerous cell differ from a normal cell?
(b) Benign tumor is less dangerous than malignant tumor. Why
(c) Describe causes of cancer.
(d) mention two methods of treatment of the disease.
Ans. (a) In normal cells, growth and differentiation is highly controlled and regulated (contact inhibition). The cancerous cells have lost the property of contact inhibition, hence continue to divide giving rise to masses of cells (tumors).
(b) The benign tumor remains confined in the organ affected as it is enclosed in a connective tissue sheath and does not enter the metastatic stage.
(c) Cancer may be caused due to carcinogens which are physical (radiations), chemicals (Nicotine, Aflatoxin, Cadmium oxide, Asbestos) and biological (viral oncogens).
(d) Surgery, radiotherapy, Chemotherapy
5. The pathogen of a disease depends on RBCs of human for grwoth and reproduction. The person with this pathogen suffers with chill and high fever.
(a) Identify the disease.
(b) Name the pathogen.
(c) What is the cause of fever?
(d) Represent the life cycle of the pathogen diagrammatically.
Ans. (a) Malaria
(b) Different species of Plasmodium viz P. vivax, P. Malariae and P. falciparum.
(c) Malaria is caused by the toxins (haemozoin) produced in the human body by the malarial parasite. This toxin is released by the rupturing of RBCs.
(d) Life cycle of Plasmodium : Fig. 8.1 Page 148, NCERT book, Biology – XII
6. The immune system of a person is supressed. He was found positive for a pathogen in the diagnostic test ELISA.
(a) Name the disease, the patient is suffering from.
(b) Which pathogen is identified by ELISA test?
(c) Which cells of the body are attacked by the pathogen?
(d) Suggest preventive measure of the infection.
Ans. (i) AIDS (Acquired Immuno Deficiency Syndrome)
(ii) HIV (Human Immunodeficiency Virus)
(iii) Helper T-cells, macrophages, B-lymphocytes.
(iv) Preventive measures :
(a) People should be educated about AIDS transmission.
(b) Disposable needles and syringes should be used
(c) Sexual habits should be changed immediately
(d) High-risk groups should be discouraged from donating blood.
(e) Routine screening may be done.
7.Discuss the role of lymphoid organs in the immune response. Explain the different types of lymphoid organs giving two examples of each type in humans.
Ans.Lymphoid organs are organs where origin or maturation & proliferation of lymphocytes occurs. These lymphoid organs are of two types:-
1.PRIMARY LYMPHOID ORGAN: – where immature lymphocytes differentiate into antigen – sensitive lymphocytes. It includes :-
(a)BONEMARROW :– It is the main lymphoid organ present in the thigh region where all types of blood cells including lymphocytes are formed. It provides micro – environment for the development & maturation of B – cells.
(b)THYMUS :- It is located beneath the chest bone near heart. It provides microenvironment for the development & maturation of T – lymphocytes.
2.SECONDAR LYMPHOID ORGAN :- They provide the site for interaction of lymphocytes with antigen which then proliferate to become effector cells. It includes.
(a)SPLEEN :- It is large bean shaped organ & contains mainly lymphocytes & phagocytes. It acts as a filter of blood by trapping blood – bound micro – organism.
(b)LYMPHNODE :- They are small – solid structure located at different points along lymphatic system. It serves to trap antigen which happens to get into lymph & tissue fluid. Antigen trapped in lymph nodes are responsible for activation of lymphocytes,
8.With the help of a well – labelled diagram, Describe the life cycle of malarial parasite.
Ans.Malaria is caused by plasmodium vivax. It has two hosts – female anopheles is the vector of plasmodium while the primary host is man where the parasite maintains an amoeboid stage in RBCS & later produces gametophyte.
Life cycle of plasmodium involves following steps:-
- The sporozoites enters the human body, reach the liver through blood & multiply within the liver cells such liver cells burst & release the parasites into blood.
- They attack RBCS, multiply & cause their rupture.
The rupturing of RBCS is associated with the release of a toxin called haemozoin, which is responsible for recurring fever & the chill / shivering.
- Gametophytes are developed in RBCS.
- When a female anopheles mosquito bites an infected person, these parasites enter the mosquito’s body & undergo further development. These parasites multiply within then in the stomach & develop a cyst.
- The cyst produces sporozoites which reach salivary gland of mosquito. When such infected Anopheles sucks blood of a healthy person, it transfers. Sporozoites to repeat amoeboid stage again.
9. What do you mean by “Out – breeding”. What are the different methods employed for out breeding.
Ans.Breeding between the unrelated ale & female animals is called Outbreeding. It can be done in following ways:-
- OUT CROSS :- The mating of animals within the same breed but do not have any common ancestor on either side of their pedigree for 4-6 generation is called an out cross. It is the best method of breeding of animals that are below average in milk production, growth rate of beef cattle etc.
- CROSS–BREEDING :- It is a cross between superior males of one breed & Superior females of another breed. It allows the desirable qualities of two different breeds to be combined & are used for commercial production eg .Hisardale, a new breed of sheep is developed by crossing bikaneri ewes & Marino rams.
- INTERSPECIFIC HYBRIDISATION :- male & female animals of two different related species are mated so, that progeny may combine desirable features of both parents eg. mule is produced by crossly donkey & a female house.
10. What is somatic hybridization – Explain the steps involved in the production of somatic hybrids?
Ans.Somatic hybridization is the process of fusing protoplasts of somatic cells derived from two different varieties or species of a plant on a suitable nutrient culture medium under sterile condition. One example of somatic hybrid is topato produced by fusion of protoplast of tomato & potato.
Somatic hybridization involves the following steps:-
- Isolation of protoplast from two different varieties of plants – each having a desirable character,
- Fusion of cytoplasm of two protoplast results in coalescence of cytoplasm. The nuclei of two protoplasts may or may not fuse together even after fusion of cytoplasm, fusion of protoplast requires a suitable agent called fusogeneg. PEG or polyethylene glycol.
- Under favourable conditions, hybrid protoplast synthesise new cell wall around it. Hybrid cell functions as a single cell & then undergo sustained division to form callus.
- The regenerated callus is transferred to a new culture plates containing suitable culture media.Here callus divide & form root & shoot after organogenesis.
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