Class 12 Biology Chapter 8 Human Health and Disease

Class 12 Biology Chapter 8 Human Health and Disease The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 8 Human Health and Disease Question Answer.

Class 12 Biology Chapter 8 Human Health and Disease

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Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 12 Biology Chapter 8 Human Health and Disease Solutions for All Subjects, You can practice these here.

(E). Short Answer Questions (3 Marks) : 

Q.1. Discuss the three criteria which affect the health, causing diseases.

Ans : The three criteria which effect health are : 

(i) Genetic disorder. 

(ii) Infections. and 

(iii) Life style including food and water we take rest and exercise we give to our bodies and habits that we have or lack. 

Q.2. What are the different species that cause malaria in man? 

Ans : The three species of protozoa that cause Melaria in man are : Plasmodium vivax, Plasmodium malaria and Plasmodium falciparum. 

Q.3. Diagramatically explain the life cycle of malarial parasite. 

Ans : Malaria parasite requires two hosts to complete its life cycle-human and mosquitoes. Female Anopheles mosquito is the vector of this disease. 

The life cycle of malaria parasite is given in the figure below:

Q.4. Name the causative organism of amoebiasis. State the symptoms of the disease. 

Ans : Entamoeba histolytica, a protozoa parasite causes amoebiasis. Symptoms of the disease include constipation abdominal pain and cramps, stools with excess mucous and blood clots. 

Q.5. Describe the structure of antibody molecule. 

Ans : The B-lymphocytes produce an army of proteins in response to pathogens into the blood to fight with them which are known as antibodies. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Hence, an antibody is represented as H₂L₂. Different types of antibodies are produced in our body. Among these IgA, IgM, IgE and IgG are some of them. 

Q.6. What is immunization? How recombinant DNA technology helps in mass immunization? 

Ans : Immunization is a preparation of antigenic proteins of pathogen or inactivated or weakened Pathogen (vaccine) are introduced into the body. Vaccines produced using recombinant DNA technology allow large scale production and hence greater availability for immunization. eg-hepatitis B vaccine produced from yeast.

Q.7. Write a note on prevention of AIDS. 

Ans : AIDS can be prevented by adopting the following methods: 

(a) Blood should be properly tested before transfusion. 

(b) Disposable needles should be used for injection purpose.

(c) Condom should be used at the time of sexual relation with unknown mate.

(d) Mother/Father suffering from AIDS should avoid to conceive. 

Q.8. Discuss the causes of cancer. 

Ans : Transformation of normal cells into cancerous neoplastic cells may be induced by physical chemical or biological agents which are known as carcinogens ionising radiations like X-rays and gamma rays and non-ionising radiations like uv cause DNA damage leading to neoplastic transformation. The chemical present in the tobacco also helps in this process. 

Q.9. How cancerous growth occurs? 

Ans : The neoplastic cells grow very rapidly, invading and damaging the surrounding the normal cells by competing for vital nutrients. Cells sloughed from much tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor. 

Q.10. From which plant cocaine is obtained? Why sportspersons abuse this drug? State the effect of excessive dosage of cocaine. 

Ans : Sport persons abuse this drug because it has a potent stimulating action on central nervous system, producing a sense of euphorbia and increased energy for which one can be more active. 

Excessive dosage of cocaine causes hallucinations. 

Q.11. Write notes on 

(a) Opioids.

(b) Cannabinoids.

(c) Cocaine.

Ans : (a) Opioids : They are depressant and analgesic so commonly called pain killers. An opium addict leses weight, interest in work, fertility and working efficiency. In severe cases, it may block the respiration and cause death. 

(b) Cannabinoids : These are those psychedelic chemical compounds which interact with the receptors present principally in brain. These include drugs derived from the inflorescence of the hemp (cannabis) plants. These dilate the pupil, increased urination and high sugar level. The chemical structure is – 

(c) Cocaine : It is derived from the leaves and young branches of South American plant, Erythroxylon coca found in Bolivia and Peru. It interferes the transport of the neurotransmitter dopamine. It is generally sniffed or smoked. It is also strong stimulant but its overdose may cane severe headache, convulsions hallucination and death due to cardiovascular or respiratory failure. 

(F).Long Answer Questions : (5 Marks) 

Q.1. What is the infective stage of malarial parasite? Describe the life cycle of malarial parasite in brief. 

Ans : The infective stage of malarial parasite is sporozoite. the life cycle of malarial parasite requires two hosts-human and mosquito. The female Anopheles mosquito is the vector of this disease too. A tiny protozoa – Plasmodium is responsible for this disease. There are three species of Plasmodium. Plasmodium enters the human body as sporozoites through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCS) resulting in their rupture. 

The rupture of RBCS is associated with release of a tonic substance, haemozoin, which is responsible for the chill and high fever. recurring every three to four days. When this mosquito bites an infected person, these parasite enters the mosquitoes body and undergo further development. The parasites multiply within them to form sporozoites that are stored in their salivary glands. When these mosquitoes bites a healthy person, the sporozoites are introduced to their body causing malaria. 

Q.2. How a healthy person acquires pneumonia? State the symptoms of pneumonia. 

Ans : Pneumonia is caused by bacteria Streptococcus pneumoniae. A healthy person acquires the infection by inhaling the droplets or aerosols released by an infected person or even by sharing glasses and utensils with an infected person. 

The symptoms of pneumonia include fever, chills, cough and headache. In severe cases, the lips and finger nails may turn grey to bluish in colour. 

Q.3. Discuss the immune system of the body with neat labelled diagram.

Ans : The human immune system consists of lymphoid organs, tissues, cells and soluble molecules like antibodies. It recognises foreign antigens, responds to these and remembers them. It also plays an important role in allergic reaction, auto immune disease and organ transplantation. 

Lymphoid organs are the organs where origin and maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus where immature lymphocyte differentiate into antigen- sensitive lymphocytes. After maturation these migrate to secondary lymphoid organs, like spleen, lymph nodes, tonsils, peyer’s patches of small intestine and appendix, which provide the sites for interaction of lymphocytes with the antigen. 

The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced. With this the thymus provide micro environments for the development and maturation of T-lymphocytes. Spleen also has a large reservoir of Erythrocytes. Moreover it also has lymphocytes and phagocytes. 

The lymph nodes are small solid structures located at different points along the lymphatic system which serve to trap the microorganism or other antigens. 

The diagrammatic representation of the lymph nodes are given below:

Q.4. Name the causative organisms of AIDS. 

Ans : The causative organism of AIDS is Human Immuno Deficiency Virus (HIV) which is belonging to retrovirus. 

Q.5. Describe the mechanism of HIV infection. 

Ans : AlDS is caused human immuno deficiency virus (HIV). After getting into the body of the person, the HIV virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help’of enzyme reverse transcriptase. This viral DNA gets incorporated into host cell’s DNA and directs the infected cells to produce virus particles. The macrophages continue to produce virus. The HIV enters into helper T-lymphocytes, replicates and produce progeny viruses which is released in the blood attack other helper T-lymphocytes leading to a progressive decrease in the helper T-lymphocytes in the body of the infected person. During this period, the person suffers from bouts of fever, diarrhoea and weight loss and also starts suffering from infections that have been otherwise overcome. The patient become so immune deficient that they are unable to protect themselves against these infections. This can be diagnosed by ELISA test. 

Q.6. How cancer can be diagnosed? Discuss the treatments of cancer. 

Ans : Cancer detection is based on biopsy and histopathological studies of the tissue. 

Blood and bone marrow tests for increased cell counts in the case of leukemias. 

In biopsy, a piece of the suspected tissue cut in then sections is stained and examined under microscope by a pathologist. Techniques like radiography, CT and MRT are very useful to detect. Antibodies against cancer specific antigens are also used for detection of certain cancers. The common approaches for treatment of cancer are surgery, radiation therapy and immunotherapy. Several chemotherapeutic drugs are used to kill cancerous cells. The patients are given substance called biological response modifiers which activates their immune system and helps in tumor destroying. 

Q.7. What is adolescence? Write an essay on adolescence and abuse of drugs/alcohol. 

Ans : Adolescence means the period and the process during which a child become mature in terms of his or her attitudes and beliefs for effective participation in the society. The period between 12-18 years of age may be thought of as adolescence period which is the bridge linking childhood and adulthood. 

Adolescence is accompanied by several biological and behavioural changes for which it is a vulnerable phase of mental and psychological development of an individual. Curiosity, need for adventure and experimentation constitute common causes, which motivate youngsters towards drug and alcohol use. This is complicated further by effects that might be perceived as benefits of alcohol or drug use. Thus, the first use of drug or alcohol may be out of curiosity or experimentation, but later the child starts using these to escape facing problems and this turns to abuse of drug or alcohol. 

Q.8. State the effects of drug/alcohol abuse. 

Ans : The immediate adverse effects of drug and alcohol abuse are manifested in the form of reckless behaviour, vandalism and violence. Excessive doses of drugs may lead to coma and death lead to respiratory failure, heart failure or cerebral hemorrhage. A combination of drug in take along with alcohol generally results in overdosing and even deaths. The most common warning signs of drug and alcohol abuse among youth include drop in academic performance, unexplained absence from school or college, lack of interest in personal hygiene, depression, fatigue, aggressive, rebellious behaviour, deteriorating relationships with family and friends, loss of interest in hobbies, change in sleeping and eating habits fluctuations in might, appetite etc. 

There may even be some for reaching implications of drug alcohol abuse. Ifa abuser is unable to get money to buy drugs and alcohol, they may turn to stealing. 

Q.9. Discuss the various means of prevention and control of drug and alcohol abuse. 

Ans : Prevention is better than cure. So it is best to identify the situations that may push and adolescent towards use of drugs or alcohol and to take remedial measures well in time. Some measures for prevention and control of alcohol and drugs abuse are given below: 

(i) To Avoid Reduce Peer Pressure : The choice and personality of childs should be respected and nurtured.

(ii) Education and Counselling : It is necessary to face problems and stresses and thus learn to accept disappointments and failures as a part of life. 

(iii) Seeking help from Parents and Peers : To guide appropriately. 

(iv) Looking for danger signs. 

(v) Seeking professional and medical help. 

Q.10. State the causes of cancer. 

Ans : Causes of cancers are: 

(i) Ionising radiations like X-ray, gamma ray and particulate radiation may cause the rupture of DNA strands which may lead to formation of cancer. 

(ii) Physical irritants like certain food, which causes abrasion of the linings of the intestinal tract are also carcinogenic. Kashmiris usc kangri to keep themselves warm but is know to cause abdominal skin cancer due to constant heat exposure. 

(iii) Chemical agents like caffein, polycyclic hydrocarbons, heavy metal ions, hormones like testosterone, estrogen (are also causes cancer of prostate and breast respectively). Cigarette smoking causing binopyrine poisoning, chewing betel nut causes mouth cancer by tenine poisoning in are body. 

(iv) Biological agent like oncovirus causes cervix cancer etc. 

(G). Special Question : (1 Mark) 

Q.1. Disease causing organisms. 

Ans : Pathogens. 

Q.2. Causative organism of malignant malaria. 

Ans : Plasmodium falciparum.

Q.3. The yellowish fluid secreted by mother during initial days of lactation. 

Ans : Colostrum. 

Q.4. A group of symptoms of a disease. 

Ans : Syndrome.

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