Assertion Reason Biology Chapter 7 Human Health and Disease

Questions of Assertion Reason Human Health and Disease biology CBSE Class 12 are very simple to understand as this chapter deals with Human Health and Disease. To solve assertion reason type questions of biology, deeper understanding of concept about Human Health and Disease is required. In order to help the student in solving Assertion Reason type of questions, detailed process is explained.

How to solve Assertion Reason Type Questions?
In Assertion-Reason type of question, two statements are given, first is Assertion and second is called Reason. Student must have to think critically about both the statements in Assertion Reason Questions, since it combines multiple choice questions and true/false type of questions which requires a higher level of understanding.

How many types are there of Assertion Reason Type Questions?
Assertion-Reason type of questions can be asked either with four MCQ options or with five MCQ options. First four options are same in both the cases only one more options is being provided i.e. last one. One extra option increases the difficulty level of the questions.

In assertion reason type of questions, all 4 or 5 options are same for each question, which are as:

(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.

Then a question haunts in every student’s mind, which option is correct and when?
This can be understood clearly with the following table:

Assertion (A)Reason (R)MCQ Options (Fixed for all questions)
If TrueTrue(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
If TrueTrue(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
If TrueFalse(c) Assertion (A) is true but reason (R) is false.
If FalseTrue(d) Assertion (A) is false but reason (R) is true.
If FalseFalse(e) Both Assertion and Reason are false.

Now, lets practice some Assertion Reason Questions of Biology : Chapter 7 Human Health and Disease.

Read instructions carefully before answering the questions.

For question given below, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.

Assertion: Streptococcus pneumoniae and Haemophilus influenzae are responsible for causing infectious diseases in human beings.
Reason: A healthy person acquires the infection by inhailing the droplets / aerosols released by an infected person.

Ans.1. (b)
A healthy person acquires the infection by inhaling the droplets/aerosols released by an infected person or even by sharing glasses and utensils with an infected person.

Assertion: Paroxysms are regular and daily in Quotidian malaria.
Reason: Recurrence of fever is after 48 hours if the infection is caused by Plasmodium malaria.

Ans.2. (d)
Paroxyms a sudden attack or outburst of a particular emotion or activity. Quotidian malaria in which the febrile paroxysms occur daily. In P. malaria infection, the relapses occur once every 72 hours and it is called Quartan malaria.

Assertion: There is no chance of malaria to a man on the bite of male Anopheles mosquito.
Reason: It carries a non-virulant strain of Plasmodium.

Ans.3. (c)
Male Anopheles mosquito do not have piercing and sucking type of mouth parts. So, they can not inject malarial parasite into man.

Assertion: Plasmodium vivax is responsible for malaria.
Reason: Malaria is caused by polluted water.

Ans.4. (b)
Malaria is caused by Plasmodium whose sexual phase occurs in the mosquito Anopheles. When female Anopheles feed on blood, they can serve as vector host for malarial parasite.

Assertion: Escherichia coli, Shigella sp. and Salmonella sp. are all responsible for diarrhoeal diseases.
Reason: Dehydration is common to all types of diarrhoeal diseases and adequate supply of fluids and electrolytes should be ensured.

Ans.5. (b)
Diarrhoeal disease conditions include frequent and excessive discharge of watery material from the bowel. Such diseases mostly result from ingestion of harmful germs with food and water. E. coli, Shigella sp. & salmonella sp. causes diarrhoea. Diarrhoea caused by virus, bacteria or parasites possesses two characteristics- firstly, the offending organisms colonise the intestine and as a consequence cause inflammation of the intestine or enteritis; and secondly, they upset the balance of intestinal fluid absorption and secretion mechanism, often enhancing the latter very considerably, which is then manifested as watery stool discharged frequently in large volumes. Shigella sp, Salmonella sp. are quite closely related genera that are responsible for diarrhoeal diseases. Dehydration is common to all types of diarrhoeal diseases & adequate supply of fluids & electrolytes that provides ions, should be ensured.

Assertion: Rabies is an infection of mammals, it involves central nervous system which may result in paralysis and finally death.
Reason: This is caused by neurotropic bacteria in saliva of rabies animal.

Ans.6. (c)
Rabies (hydrophobia) is caused by rabies virus. Its vectors are raboid animals especially dogs. It leads to encephalitis, fear of water (hydrophobia), high fever, severe headache, spasm of throat & chest, leading to death.

Assertion: Pork should be properly cooked to avoid Taenia infection.
Reason: It contains hexacanth and cysticeric larvae.

Ans.7. (c)
Human infection is direct and oral. It occurs by eating raw or under-cooked measly pork (Pig muscle with cysticerus larvae of Taenia). Infection in vegetarians occurs through improperly washed vegetable. So proper cooking of pork and properly washed vegetable to avoid Taenia infection.

Assertion: Tapeworm, roundworm and pinworm are endoparasites of human intestine.
Reason: Improperly cooked food is the source of all intestinal infections.

Ans.8. (a)
Endoparasite lives inside its host. Bovine endoparasites may be divided into three categories: nematodes, or roundworms; cestodes, or tapeworms; and trematodes, or flukes.

Assertion: Stool test is done to detect giardiasis.
Reason: Giardia is enteric flagellate protozoan.

Ans.9. (a)
If a giardia infection is present, the parasite or its cysts can be seen when the stool is looked at under a microscope. If giardiasis is suspected, an antigen test may be done on the stool or a sample of the fluid from the small intestine (duodenal contents). Giardia is a genus of anaerobic flagellated protozoan parasites of the phylum Sarcomastigophora that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis.

Assertion: Severe Acute Respiratory syndromes is common in China.
Reason: China is the most populated country of the world.

Ans.10. (b)
On November 16, 2002, an outbreak of what is believed to be severe acute respiratory syndrome (SARS), began in the Guangdong province of China, which borders on Hong Kong. China is the most populated country in the World.

Assertion: β-cells work chiefly by secreting substances called antibodies into the body fluids.
Reason: Antibodies ambush foreign antigen circulating in the blood stream.

Ans.11. (a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Assertion: Interferons help in the elimination of viral infections.
Reason: Interferons released by infected cells, reach nearby unaffected cells and make them resistant to viral infection.

Ans.12. (a)
Virus infected cells secrete proteins called interferons, which protect non-infected cells from further viral infection.

Assertion: An antibody is represented by H_{2}L_{2} .
Reason: Each antibody is made of four peptide chains.

Ans.13. (a)
Immunoglobulins, also known as antibodies, are glycoprotein molecules produced by plasma cells (white blood cells). The Ig monomer is a “Y”-shaped molecule that consists of four polypeptide chains; two identical heavy chains and two identical light chains connected by disulfide bonds.

Assertion: Innate immunity is non-specific defence.
Reason: It consists of four types of barriers.

Ans.14. (b)
Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body. Four barriers are physical, physiological, cellular and cytokine barriers.

Assertion: T-lymphocytes mediate CMI response.
Reason: The above response makes it easy to transplant organs.

Ans.15. (c)
Cell-mediated immunity (CMI) is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic Tlymphocytes, and the release of various cytokines in response to an antigen. The immune response to a transplanted organ consists of both cellular(lymphocyte mediated) and humoral (antibody mediated) mechanisms. Although other cell types are also involved, the T cells are central in the rejection of grafts.

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