CBSE Class 12 Biology Human Health and Disease Assignment Set D

Assertion Reason Type Questions

Answer these questions selecting the appropriate option given below: –
A. Both A & R are True and R is the correct explanation of A.
B. Both A & R are True and R is not the correct explanation of A.
C. A is True but R is False.
D. A is False but R is True.

Question. Assertion (A) – Genetic disorders are infectious.
Reason (R) – Genetic disorders are inherited from parents to their children.
Answer: D

Question. Assertion (A) – Pneumonia causes severe respiratory problems.
Reason (R) – Due to infection, alveoli of lungs get filled with fluid.
Answer: A

Question. Assertion (A) – Female Anopheles mosquito is the pathogen for Malaria.
Reason (R) – Mosquito can transmit plasmodium.
Answer: D

Question.Assertion (A) – Asexual reproduction of plasmodium takes place in the Gut of Mosquito.
Reason (R) – Sporozoites are formed in the Gut of Mosquito.
Answer: D

Question. Assertion (A) – Virus infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.
Reason (R) – It is a case of physiological barriers.
Answer: C

Question. Assertion (A) – Anamnestic responses are highly intensified.
Reason (R) – Secondary response are due to memory of the first encounter.
Answer: A

Question. Assertion (A) – Colostrum is secreted by mother during the initial days of lactation.
Reason (R) – Colostrum provides active immunity.
Answer: C

Question. Assertion (A) – Many children in metro cities of India suffer from allergies.
Reason (R) – This could be because of the protected environment provided early in the life.
Answer: A

Question. Assertion (A) – Small children have more immunity 
Reason (R) – Thymus is quite large at the time of birth.
Answer: A

Question. Assertion (A) – In host cell, viral DNA is produced by reverse transcription. 
Reason (R) – Retrovirus has DNA genome.
Answer: C

Question. Assertion (A) – C-onc are cells that can cause cancer. 
Reason (R) – C-onc are cellular organisms.
Answer: D

Question. Assertion (A) – Heroin is an opioid. 
Reason (R) – Heroin is obtained from poppy plant.
Answer: B

Question. Assertion (A) – Cannabinoids can affect cardiovascular system of body. 
Reason (R) – Ganja is a cannabinoid.
Answer: B

Question. Assertion (A) – Smoking causes raise in blood pressure and increases heart rate. 
Reason (R) – Nicotine stimulates adrenal gland to release adrenaline and nor-adrenaline.
Answer: A

Question. Assertion (A) – Peer pressure is necessary for better performance.
Reason (R) – Undue pressure can lead to consumption of alcohol and drugs.
Answer: D

Question. Assertion (A) – AIDS and Hepatitis-B are viral diseases. 
Reason (R) – These diseases are transferred from one person to another by sharing of infected needles and syringes.
Answer: B

Question. Assertion (A) – Using morphine for medical purpose is a case of drug abuse.
Reason (R) – Morphine is a very effective sedative and painkiller.
Answer: D

Question. Assertion (A) – α-interferon is a biological response modifier. 
Reason (R) – α-interferon activates immune system and helps in destroying the tumor.
Answer: A

Question. Assertion (A) – Excessive dosage of cocaine causes hallucinations. 
Reason (R) – Atropa belladona and Datura have hallucinogenic properties.
Answer: B

Question. Assertion (A) – Rheumatoid arthritis is an auto-immune disease. 
Reason (R) – Here, body attacks self-cells.
Answer: A

Short Answer Type Questions

Question. (i) What is an ‘‘allergic reaction’’ ?
(ii) Name any two drugs used to quickly reduce the symptoms of allergy.
(iii) Why do more and more children in metro cities of India suffer from allergies and asthma?
Answer: (i) The exaggerated response of the immune system to certain antigens present in the environment is called allergic reaction. 
(ii) Anti-histamine, adrenalin, steroids.
(iii) Due to deteriorating air quality, sensitivity to the environment, allergens, lowering of immunity due to modern day life style (which could be due to the protected environment provided largely in life). 

Question. Write the causative agent of filariasis in human.
Mention its mode of transmission and symptoms of the disease.
Answer: Wuchereria bancrofti 
Transmitted to a healthy person through the bite of female mosquito vector. 
Inflammation of lymphatic vessels of the lower limbs or genital organs, leading to gross deformities. 

Question. (i) State what happens in the human body when malarial parasites infected RBCs burst to release the parasites in the blood.
(ii) Mention the specific sites in the host body where production of :
(a) Sporozoites and
(b) Gametocytes take place in the life cycle of the malarial parasites.
Answer: (i) The rupture of RBCs results in releasing toxic substance hemozoin, which is responsible for chill and high fever (recurring every 3-4 days).
(ii) (a) Intestine of mosquito.
(b) RBCs of human. 
Detailed Answer :
(i) When malarial parasite RBC burst they release a toxin called haemozoin. This causes chill and high fever which reoccur every third or fourth day.
(ii) (a) Production of sporozoites takes place in the oocyst on the surface of intestine of the female Anopheles mosquito.
(b) Production of gametocyte occurs in the RBCs of human host.

Question. (i) Differentiate between benign and malignant tumours.
(ii) Why is colostrum a boon to the new born baby ?
Answer: (i) Benign tumour remains confined to original location / does not spread to other part of the body / not cancerous.
Malignant tumour is mass of proliferating (neoplastic) cells that invade and damage surrounding tissue / cancerous tumour / tumour showing property of metastasis.
(ii) Colostrum contains antibodies / that provides resistance (immunity) to new born babies.

Question. (i) Name and explain giving reasons the type of immunity provided to the new born by colostrum and vaccinations.
(ii) Name the type of antibody
(a) Present in colostrum
(b) Produced in response to allergens in human body 
Answer: (i) Passive immunity, when ready made antibodies are directly given to protect the body against foreign agents.
Active immunity, when a host is exposed to antigens which may be in form of living or dead microbes or other proteins. Antibodies are produced in the host body. 
(ii) (a) IgA 
(b) IgE

Question. (i) Write the scientific names of the two species of filarial worms causing filariasis.
(ii) How do they affect the body of infected person (s)?
(iii) How does the disease spread ?
Answer: (i) Wuchereria bancrofti, Wuchereria malayi.
(ii) Inflammation of the lymphatic vessels of the lower limbs / inflammation of the genital organs / gross deformity of the lower limbs / deformity of the genital organs. (Any two)
(iii) Through the bite of female (Culex) mosquito.

Question. (i) Name the causative agent of typhoid in humans.
(ii) Name the test administered to confirm the disease.
(iii) How does the pathogen gain entry into the human body ? Write the diagnostic symptoms and mention the body organ that gets affected in severe cases.
Answer: (i) Salmonella typhi is a pathogenic bacterium that causes typhoid fever in human beings.
(ii) Typhoid fever could be confirmed by Widal test.
(iii) The pathogens generally enter the small intestine through food and water contaminated with them and migrate to other organs through blood.
Symptoms : Sustained high fever (39°– 40°C), weakness, stomach pain, constipation, headache and loss of appetite are some of the common symptoms of this disease. Intestinal perforation and death may occur in severe cases. Mainly this disease attacks the alimentary canal and brain. 

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: The type of immunity that is present at the time of birth in humans is innate immunity. The two ways by it can be accomplished are :
(i) Certain types of leucocytes (WBCs) like neutrophils, monocytes and natural killer (lymphocytes) in the blood and marcophages in tissues can engulf microbes, viruses and cellular debris etc.
(ii) Mucus secreted by mucous membrane traps the microorganisms and immobilize them. The skin is the physical barrier of the body. Its outer tough layer prevents the entry of bacteria and viruses. 

Question. Name the causative organism of the disease amoebiasis. List three symptoms of the disease.
Answer: Amoebiasis is caused by Entamoeba histolytica. 
The symptoms of the disease include :
(i) Stools with mucus and blood.
(ii) Diarrhoea, pain and stomach cramps.
(iii) Constipation. 

Question. A young boy when brought a pet dog home started to complain of watery eyes and running nose. The symptoms disappeared when the boy was kept away from the pet.
(i) Name the type of antibody and chemicals responsible for such a response in the boy.
(ii) Mention the name of any one drug that could be given to the boy for immediate relief from such a response. 
Answer: (i) Antibody : lgE.
Chemicals : Histamine & serotonin. The antibody (lgE) cause the release of these chemicals from mast cells.
(ii) Drugs : Antihistamine (citrazen, Avil-25/50),
Adrenalin and steroids, quickly reduce such symptoms of allergy.

Long Answer Type Questions

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.
(i) Write what the doctor injected into the patient’s body.
(ii) How do you think this injection would protect the patient against the disease ?
(iii) Name the disease against which this injection was given and the kind of immunity it provides.
Answer: (i) Tetanus antitoxins/Tetanus toxoid. 
(ii) The preformed antibody injected, act on the pathogen immediately to provide protection.
(iii) Tetanus, passive acquired immunity.
Detailed Answer :
(i) In the patient’s body, the doctor has injected antiserum containing preformed antibodies against the causative organisms or toxin produced by it.
(ii) The solution injected by the doctor had antibodies. Hence, the injection would protect the patient against the diseases and provide him humoral immunity.
(iii) The disease against which this injection was given is tetanus caused by Clostridium tetani, which usually exists in environment as spores and may gain access to the body through wound.
The type of immunity that the injection containing antiserum provides is a passive acquired immunity as preformed antibodies are used because fast action is required in this emergency case. 

Question. (i) What makes some viruses cause cancer in humans ?
(ii) How do benign tumours turn malignant ?
How do the latter harm the human body ?
Answer: (i) Cancer-causing viruses are called oncogenic viruses or oncoviruses. They have genes called viral oncogenes. The normal protooncogenes present in normal cells get activated into oncogenes by some viruses and lead to oncogenic transformation of normal cells into cancerous cells causing cancer.
(ii) A benign tumour may turn malignant if it is not removed as soon as it is noticed. The benign tumour cells are sometimes carried by blood or lymph to other parts of the body where they spread, continue to divide and start new tumour there. Such tumour cells are called as malignant cells and the tumour as malignant tumour. The malignant tumours are called as cancer. A malignant tumour is not self-limited in its growth, is capable of invading into adjacent tissues and may be capable of spreading to distant tissues. A benign tumour has none of these properties.
The malignant tumours cells compete with the normal cells for vital nutrients and disrupt their normal metabolism and damage the normal cells. 

Question. Explain the process of replication of a retrovirus after it gains entry into the human body.
Answer: After getting into the body of the person, the virus enters into macrophages, where RNA genome of the virus replicates to form viral DNA with the help of the 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 particles and acts like a HIV factory. Simultaneously, HIV enters into helper T-lymphocytes (TH), replicates and produce progeny viruses. The progeny viruses released in the blood attack other helper T-lymphocytes.
This is repeated leading to a progressive decrease in the number of helper T-lymphocytes in the body of the infected person. During this period, the person suffers from bouts of fever, diarrhea and weight loss. Due to decrease in the number of helper T-lymphocytes, the person starts suffering from infections that could have been otherwise overcome, such as those due to bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma. The patient becomes so immunodeficient that he / she is unable to protect himself / herself against infections.

Question. (i) Cancer is one of the most dreaded diseases of humans. Explain ‘Contact inhibition’ and ‘Metastasis’ with respect to the disease.
(ii) Name the groups of genes which have been identified in normal cells that could lead to cancer and how they do so ?
(iii) Name any two techniques which are useful to detect cancers of internal organs.
(iv) Why are cancer patients often given α-interferon as part of the treatment ?
Answer: (i) Contact with other cells inhibits their uncontrolled growth. 
Tumour cells reach distant sites, through blood. 
(ii) Proto oncogenes. 
When activated under certain condition could lead to oncogenic transformation of the cells.
(iii) Biopsy / radiography / CT / MRI (Any two)
(iv) It activates immune system, destroys tumour.
Detailed Answer :
(i) Contact inhibition : Normal cells have the property of contact inhibition i.e. their growth is stopped after coming in contact with other cells. But the cancer cells do not have this property of contact inhibition. They unlike normal cells divide continuously (uncontrolled cell division) and give rise to a mass of cells called tumour.
Metastasis : It is the property exhibited by the cancerous cells. In this process, the cancerous
cells spread to different parts of the body.
Same cells get sloughed off from the tumour and move to distant sites through body fluids and initiate the formation of new tumours by dividing actively.
(ii) Many genes called as proto oncogenes or cellular oncogenes have been identified in normal cells which when activated under certain conditions lead to the oncogenic transformation of normal cells causing cancer.
(iii) X Rays (Radiography), CT (computerized tomography), MRI and biopsy are useful in detecting cancers of internal organs.
(iv) The cancer patients are often given α-interferons as a part of treatment because it activates their immune system and helps in destroying tumour.