Human Health and Diseases Questions Class 12 Biology

ICSE Class 12 Biology

Health and Related Aspects, Common Human Diseases and Immunity

Very Short Answer Type Question

Question. Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes.
Answer : Dengue, Chikungunya//Yellow Fever / Eastern
Equine Encephalitis / West Nile Fever / Zika / Zika Viral Disease.

Question. How do cytokinin barriers provide innate immunity in humans?
How do cytokine barriers help in evading viral infections ?
Answer : Interferon (proteins), secreted by virus infected cells (protect non-infected cells from further viral infection).

Question. Thymus of a new born child was degenerating right from birth due to a genetic disorder. Predict its two impacts on the health of the child. 
Answer : Thymus provides micro-environment for the development and maturation of T-lymphocytes, its degeneration will weaken the immune system so the child will be prone to frequent infections.

Question. Why is colostrum a boon to the newborn baby ?
Answer : Colostrum (Mother’s first milk) contains good amount of antibodies like IgA, which provide passive immunity to the new born and protects it from various infections. 

Question. Retroviruses have no DNA. However the DNA of the infected host cell does possess the viral DNA. How is it possible?
Answer : After infecting the host cell, the viral RNA undergoes reverse transcription in the presence of an enzyme reverse transcriptase as a result of which viral DNA is formed. This DNA then gets incorporated into infected host DNA. 

Question. What is an autoimmune disease ?
What is an autoimmune disease ? Give an example.
Answer : Autoimmune disease is a condition of the body in which the immune system of the body attacks self cells e.g. rheumatoid arthritis. 

Question. How do monocytes act as a cellular barrier in humans to provide innate immunity ?
In what way is monocyte a cellular barrier with reference to immunity ?
Answer : Phagocytosis of microbes / destroy microbes.

Question. Name two types of cells which act as ‘cellular barriers’ to provide innate immunity in humAnswer :
Answer : (i) Polymorpho nuclear leucocytes (neutrophils).
(ii) Monocytes–A kind of lymphocyte.

Question. Why is Gambusia introduced into drains and ponds ?
Answer : Gambusia is a type of fish that preys upon the larvae of mosquitoes. It is therefore introduced into drains and ponds to feed on mosquito larvae / to eliminate the vectors responsible for causing malaria. It thus helps in controlling malaria.

Question. How does haemozoin affect the human body when released in blood during malarial infection ?
Answer : Hemozoin is a toxic substance released by rupturing of RBCs in to blood during malarial infection. It causes chill and high fever, recurring every 3 – 4 days / in cyclic manner.

Question. Why is secondary immune response more intense than the primary immune response in humans ? 
Answer : Body will have memory B cells of the first encounter / presence of antibodies developed during primary immune response.

Question. Name the two intermediate hosts which the human liver fluke depends on to complete its life cycle so as to facilitate parasitization of its primary host.
Answer : Terrestrial snail and fish are two intermediate hosts on which the human liver fluke depends to complete its life cycle so as to facilitate parasitization of its primary host. 

Question. State two different roles of spleen in the human body. 
Answer : Spleen is the secondary lymphoid organ that stores lymphocytes, it filters blood by trapping blood borne microbes by phagocytes and lymphocytes. It also acts as a large reservoir to store erythrocytes. 

Question. How does malaria differ from chikungunya with reference to their vectors.
Answer : The vector of malaria is Anopheles mosquito while that of chikungunya is Aedes mosquito.

Question. Name the category of disease in which ‘Rheumatoid arthritis‘ in human is put under.
Answer : Auto-immune disease.  

Question. Name the condition in vertebrates where the body attacks self-cells.
Answer : Auto immune disorder or auto-immune disease.

Question. A patient is down with Amoebiasis. List the symptoms that confirm this infection. Name the causative pathogen.
Answer : Constipation, abdominal pain, stools with mucous, blood clot. Entamoeba histolytica. 

Question. Name two intermediate hosts which the human liver fluke depends on to complete its life cycle so as to facilitate parasitization of its primary host.
Answer : (i) Snail (ii) Fish.

Question. Name the stage of Plasmodium that gains entry into the human when bitten by an infected female Anopheles.
Answer : Sporozoites.

Question. Trace the route of Sporozoite of Plasmodium when it enters the human body through the bite of infected female Anopheles mosquito till its entry into the R.B.C.
Answer : Sporozoites attack liver cells. Sporozoites reproduce asexually in liver cells bursting them and then reach RBC. 

Question. Some allergens trigger sneezing and wheezing in human beings. What causes this type of response by the body ?
Answer : Such type of response by the body is due to the exaggerated action of its immune system to certain antigens or allergen present in the environment.

Question. When does a human body elicit an anamnestic response ?
Answer : Anamnestic response is the secondary response which is elicited when our body encounters with the same antigen to which the body has previously encountered.

Question. Why sharing of injection needles between two individuals is not recommended ?
Answer : Sharing of injection needles is not recommended so as to avoid the transmission of STDs like AIDS and Hepatitis from the diseased person to the healthy person

Question. It was diagnosed by a specialist that the immune system of the body of a patient has been suppressed. Name the disease the patient is suffering and its causative agent.
Answer : The name of such a disease is AIDS (Acquired Immunodeficiency Syndrome) and it is caused by HIV (Human Immunodeficiency Virus).

Question. State the function of mast cells in allergy response. 
Answer : The chemicals like histamine and serotonin are released from mast cells. These chemicals cause exaggerated response of immune system called allergy response. 

Question. Suggest a method to ensure an anamnestic response in humAnswer :
Answer : Vaccination or Immunization (Active / passive) or weakened or inactive microbes or pathogens or proteins or antibodies introduced into the host body.

Short Answer Type Question – l

Question. Name the cells HIV (Human Immunodeficiency Virus) gains entry into after infecting the human body. Explain the events that occur in these cells.
Answer : HIV (Human immune deficiency virus) enters into macrophages after getting in human body.
HIV multiplies first in macrophages and then in helper T cells or lymphocytes.
Events that occur in the human host after the entry of HIV :
(i) After entering the human body, the HIV virus attacks and enters the macrophages.
(ii) Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse transcriptase and give rise to viral DNA.
(iii) Then, this viral DNA incorporates into the host cell DNA, uses raw materials and infected cell machinery and directs the synthesis of virus particles.
(iv) At the same time, HIV enters the helper T-lymphocytes, replicates and produce progenies.
(v) As a result, T-lymphocytes start decreasing in number and immune response of the person becomes weak.

Question. (i) Name any two helminths which are known to be pathogenic to human.
(ii) List two symptoms of the diseases caused by any one of them
Answer : (i) Ascaris, Wuchereria
(ii) Symptoms-internal bleeding, muscular pain, fever, anaemia, blockage of the internal passage (any two) / chronic inflammation of the organs, deformities in genital organs

Question. Name the type of immunity the colostrum provides to a newborn baby. Write giving an example where this type of immunity should be provided to a person.
Answer : Passive Immunity
In case of infection by deadly microbes (tetanus) or snake bite where quick immune response is required 

Question. How are oncogenic viruses different from protooncogenes?
Answer : Oncogenic viruses are cancer causing viruses / external cancer causing factor.
Proto-oncogenes: Identified in normal cells which when activated (under certain condition) could lead to oncogenic transformation of cells / internal cancer causing factor. 

Question. Name any two secondary lymphoid organs in a human body and state the function of any of them.
Answer : Spleen, lymph nodes, tonsils, Peyer’s patches of small intestine, vermiform appendix.
They act as sites for interaction of lymphocytes with the antigen and cause immune response.
Function : Spleen : Trap blood-borne microorganisms and worn out RBCs, thus filters blood.
Lymph nodes : Trap the microorganisms / antigens (which happen to get into the lymph and tissue fluid). The trapped antigens activate lymphocytes and cause immune response.

Question. (i) Which organ of the human body is initially affected when bitten by an infected female Anopheles? Name the stage of the parasite that infects this organ.
(ii) Explain the events that are responsible for chill and high fever in the patient.
Answer : (i) Liver cells, sporozoites. 
(ii) Parasites reproduce asexually in RBC / multiply, Rupture of RBCs is associated with release of toxic substance called as hemozoin.

Question. List the symptoms of Ascariasis. How does a healthy person acquire this infection ?
Answer :
 Ascariasis is a helminthic disease caused by common round worm – Ascaris lumbricoides. The main symptoms of ascariasis are muscular internal bleeding, muscular pain, anaemia, blockage of intestinal passage.
By intake of water, vegetables, fruits, foods contaminated with the eggs of parasite excreted along with faeces of infected person.

Very Short Answer Type Question

Question. How are morphine & heroin related ? Mention their effects on human body.
Answer :
 Both are obtained from a plant ‘Papaver somniferum’.
Heroin is related to morphine as it is obtained by acetylation of the later. Morphine is a sedative while heroin is a depressant.

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. It reduces concentration of haem bound oxygen and causes oxygen  deficiency in the body. Smoking also damages alveolar walls, which reduces respiratory surface (emphysema).

Question. Mention the useful as well as harmful drug obtained from latex of poppy plant.
Answer : 

Question. Name one plant & the addictive drug extracted from its latex. How does this affect the human body ?
Answer : 
Morphine & Heroin are the addictive drug obtained from a plant called Papaver somniferum. Morphine is used as sedative but harmful when used as opioids.
Heroin is a depressant and slows down body functions.

Short Answer Type Question – l

Question. What happens to an individual when a regular dose of drugs/alcohol is abruptly discontinued? What characteristics, manifest in the individual under such a situation ?
Answer : Withdrawal syndrome.
Manifestation of unpleasant characteristics and feelings.
Anxiety, shakiness, nausea and sweating.

Question. Why are adolescents especially advised not to smoke ? How does smoking affect the functioning of the body ?
Answer : Because smoking paves the way to hard drugs, increased chances of cancer particularly of lungs, cause oxygen deficiency in the body
Nicotine (in cigarette) stimulates adrenal gland,
which raises blood pressure / increases heart rate. It increases carbon monoxide (CO) in blood and reduces oxyhaemoglobin. This causes O2 deficiency in the body. Therefore, the adolescents are advised not to smoke.

Question. What is “withdrawal syndrome” ? List any two symptoms, it is characterized by.
Answer : Manifestation of unpleasant characteristic when a regular dose of drugs / alcohol is abruptly discontinued or reduced.
Unpleasant feeling, Anxiety, shakiness, nausea, sweating.

Question. Name two drugs obtained from poppy plant.
“These drugs are medically useful but are often abused“. Taking the mentioned examples justify by giving reasons.
Answer : Heroin / smack, morphine; morphine obtained from latex of unripe capsules of poppy plant
(Papaver somniferum) is an effective pain killer and sedative, heroin (a derivative of morphine) is used as drug. If these drugs are taken for the purpose other than medicinal or taken in larger doses that may impair the physical and mental state of a person. Then it is said to be abused.

Question. (a) Name the source plant of heroin drug. How is it obtained from the plant?
(b) Write the effects of heroin on the human body.
Name the plant source of the drug popularly called “smack”. How does it affect the body of the abuser ?
Name an opioid drug and its source plant. How does the drug affect the human body ?
Answer : (a) Papaver somniferum / Poppy plant.
Extracted from latex of the plant / acetylation of morphine (obtained from the latex of plant).
(b) Depressant, slows down body function.

Question. Name the plant source of ganja. How does it affect the body of the abuser ?
Answer : Ganja is obtained from Cannabis sativa / hemp plant.
It is hallucinogenic, alters perception, causes illusion and damages cardio vascular system.

Question. Name and state the effect of a drug that is often medically prescribed, but its over use leads to drug dependence and drug abuse.
Answer : Morphine, barbiturate, amphetamines, benzodiazepines, lysergic acid diethyl amides (LSD)
Affects the central nervous system, acts as a pain killer, acts as a sedative, treats depression, treats insomnia, creates hallucinogenic effect.

Short Answer Type Question – ll

Question. (i) HIV and Hepatitis-B are STDs. Mention the two other ways by which they can be transmitted to a healthy person.
(ii) Why is early detection of STD essential ? What can it lead to otherwise ? Explain
Answer : (i) HIV can also be transmitted to a healthy person by :
(a) Sharing of infected needles and surgical instruments.
(b) From infected mother to the foetus.
(c) Transfusion of infected Blood.
(ii) Leads to complication in life later; pelvic inflammatory disease (P/D) / abortion / infertility / cancer of reproductive tract, still birth, ectopic pregnancies. STDs are curable if detected early and treated properly otherwise they may lead to death. 

Question. A group of youth were having a ‘rave party‘ in an isolated area and was raided by police. Packets of ‘smack‘ and syringes with needles were found littered around.
(i) Why is taking ‘smack‘ considered an abuse ?
(ii) Write the chemical name of ‘smack‘ and the name of its source plant.
(iii) Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why ?
Answer : (i) Because an addictive substance causes drug dependence and affects nervous system / used in amounts or frequencies that impairs ones physical and physiological or psychological functions.
(ii) Diacetyl-morphine Papaver somniferum / poppy plant / opium poppy.
(iii) They can acquire serious infections i.e. transmission of HIV infections or AIDS or Hepatitis.

Question. Prior to a sports events blood and urine samples of sports persons are collected for drug tests.
(i) Why is there a need to conduct such tests ?
(ii) Name the drugs the authorities usually look for.
(iii) Write the generic names of two plants from which these drugs are obtained.
Answer : (i) To detect drug abuse / use of banned drugs / use of cannabinoids / anabolic steroids / narcotic analgesic diuretics / hormones / drugs used to accelerate performance / increase muscle strength / bulk / promote aggressiveness / to ensure fair game.
(ii) Cannabinoids / cocaine / coca alkaloid / coke / crack / hashish / charas / ganja / hemp plant extract.
(iii) Cannabis / Atropa / Erythroxylum / Datura.

Question. (i) Why is there a fear amongst the guardians that their adolescent wards may get trapped in drug/ alcohol abuse ?
(ii) Explain ‘addiction‘ and ‘dependence‘ in respect of drug / alcohol abuse in youth.
Answer : (i) Adolescents are easily affected by (Vulnerable to) peer pressure, adventure, curiosity, excitement, experimentation and media. 
(ii) Addiction : Psychological attachment to certain effects such as Euphoria or temporary feeling of well – being.
Dependence : Tendency of the body to show withdrawal syndrome or symptoms if regular doses of drug or alcohol is abruptly discontinued.

Question. A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.
(i) Will you report to the authorities ? Why ?
(ii) Name a plant from which such chemicals are obtained.
(ii) Write the effect of these chemicals on human body.
Answer : (i) Yes May be abused by sports persons.
(ii) Cannabis sativa / any other relevant plant.
(iii) Effects cardio vascular system of the body.
(ii) Cannabinoids can be obtained from a plant called Cannabis sativa.
(iii) Although these chemicals increase athletic performance of the sports persons but they have many harmful side effects. The cannabinoids bind to cannabinoid receptors present in the brain and affect the cardiovascular system.

Question. A doctor prescribed morphine as a sedative and pain killer to your cousin who had undergone surgery. Even after recovery, he craved for the prescribed medicine. What do you conclude about his condition, had he continued with the same medication? After appraising yourself, what measures will you suggest to him to overcome this problem? Briefly explain any two. 
Answer : Drug dependence is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome. If regular dose of drugs is abruptly discontinued / because of perceived benefits, drugs are frequently used repeatedly from which the person may not be able to rid off.
Measures :
(i) Education and counselling-to face problems and stresses / to channelize the energy into healthy pursuits like reading, music, yoga and other extracurricular activities.
(ii) Seeking help from parents-to guide the person appropriately and immediately.
(iii) Seeking professional and medical help-to help the person to get rid of the problem completely with sufficient efforts and will power. 

Question. Explain the following with reference to drug/ alcohol abuse : (i) Addiction, (ii) dependence and (iii) withdrawal symptoms.
Answer : (i) Addiction – Frequent use of drugs or alcohol leads to increase in the level of tolerance of receptors present in our body, thus making these receptors respond to only higher doses of drugs and alcohol. +
Psychological attachment to certain effects such as euphoria and temporary feeling of well being associated with drugs and alcohol. 
(ii) Dependence – Due to inherent addictive nature and its psychological attachment to drugs or alcohol and are unable to live without them. 
(iii) Withdrawal syndrome – When a person is taking drugs / alcohol regularly and the intake of drugs is abruptly discontinued it leads to various characteristics symptoms (nausea, anxiety, shakiness, sweating etc.).

Question. (i) Name the drug used
(a) As an effective sedative & pain killer.
(b) For helping patients to cope with mental illness like depression but often misused.
(ii) How does the moderate & high doses of cocaine affect human body?
Answer : (i) (a) Morphine.
(b) LSD (Lysergic acid dimethylamide) or Barbiturates.
(ii) Moderate dose of cocaine have stimulating action on central nervous system. It produces a sense of euphoria and increased energy. High dosage of cocaine causes hallucinations.

Question. Why is tobacco smoking associated with rise in blood pressure and emphysema (Oxygen deficiency in the body) ? Explain.
Answer : Tobacco stimulates the release of adrenaline hormone due to the presence of nicotine in it. This raises the blood pressure. Smoking releases carbon mono-oxide. This reduces the haem bound oxygen concentration and causes the oxygen deficiency in the body.

Question. Write the source and the effect on the human body of the following drugs :
(i) Morphine
(ii) Cocaine
(iii) Marijuana 
Answer : (i) Morphine : poppy plant / Papaver somniferum, depressant.
(ii) Cocaine : Erythroxylum coca, stimulates CNS / causes euphoria / hallucination.
(iii) Marijuana : Cannabis sativa, affects cardiovascular system of the body.

Question. ‘Prevention is better than cure’ is an apt slogan to safeguard adolescents from drug abuse. List any six steps that could be taken in this regard.
Answer : Six steps that can be taken for prevention and control of drug abuse among adolescents are :
(i) A regular monitoring of the activities of adolescents by parents.
(ii) Avoiding undue peer pressure as every child has his own stamina and personality.
(iii) Educating and counselling about the dangers of drug abuse.
(iv) Channelizing the child’s energy into healthy pursuits like sports and other extra-curricular activities.
(v) Seeking professional and medical help for those who have unfortunately got in the quagmire of drug.
(vi) Identifying the motivations for alcohol and drug abuse in children.