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CNMS ICSE - 7 Std
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Answer key

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Chapter: 08. Allergy

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SECTION A: MULTIPLE CHOICE QUESTIONS

(b) Clemens Von Pirquet
(b) Casein
© Indoor allergy to pet dander
(d) IgE antibodies
© Anaphylaxis
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SECTION B: FILL IN THE BLANKS

other work
rhinitis (or Hay Fever)
skin
intradermally
Histamines
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SECTION C: TRUE OR FALSE

False. Correct Statement: The first exposure of an allergic person to an allergen does not cause allergy (it causes sensitisation).
True.
False. Correct Statement: Allergic asthma causes the narrowing of the bronchi (or bronchospasm), leading to difficulty in breathing.
True.
False. Correct Statement: Contact dermatitis is a skin allergy caused by direct contact with substances.
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SECTION D: EXPLANATION OF TERMS

Allergens: The substances in the environment that trigger an exaggerated or abnormal reaction in the immune system of a sensitive person.
Sensitisation: The process during the first exposure to an allergen where the immune system of an allergic person develops a primary immune response, causing B-cells to produce IgE antibodies and histamines.
Urticaria: Also known as hives, it is a skin allergy characterized by an outbreak of swollen, pale-red bumps or patches on the skin.
Immunity: The ability of the body to defend itself against infections, foreign substances, and develop resistance to infectious diseases.
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SECTION E: DIFFERENTIATE BETWEEN THE CONCEPTS

Seasonal Allergy vs. Perennial Allergy:
Seasonal Allergy: Occurs only during specific seasons of the year and goes away when the season ends. Example: Spring allergies caused by pollen, or Hay fever.
Perennial Allergy: Can appear at any time year-round. Example: Allergies to dust mites, pet dander, or food items.
T-cells vs. B-cells (in normal individuals):
T-cells: In normal individuals, T-cells recognize antigens/allergens as harmless and prevent B-cells from launching an attack.
B-cells: In normal individuals, B-cells remain inactive toward harmless allergens. (In allergic individuals, B-cells escape this regulation and produce IgE antibodies/histamines on sensitisation).
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SECTION F: SHORT ANSWER QUESTIONS

The three entry routes of allergens into the human body are:
Nose (Breathing): e.g., Pollen, dust mites, mould spores.
Mouth (Eating): e.g., Eggs, milk, nuts, wheat, medicines.
Skin (Contact): e.g., Cosmetics, plant sap, insect bites, injections.
A blood test measures the concentration of specific IgE antibodies in the blood. A higher value of IgE antibodies indicates a greater likelihood of symptoms and helps predict the type of allergy and the risk of a severe allergic reaction.
Three key precautions are:
Identify the causative allergen and strictly avoid exposure to it.
Take allergy shots to keep seasonal allergies under control.
Consult with specialized allergy doctors for proper medical management.
Anaphylactic shock is a medical emergency because the large-scale release of histamines dilates arteries, causing a dangerous drop in blood pressure and swelling of tissues in the throat/mouth, which can block the airway and cause sudden death.
Symptoms: Face and lips swelling, shortness of breath, skin rashes all over.
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SECTION G: DIAGRAM-BASED QUESTION

Pointer 1: Nose (Breathing) ​Pointer 2: Mouth (Eating) ​Pointer 3: Skin (Contact)
Wheat (or milk, peanuts, eggs, fish).
Route 3 (Skin / Contact).
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SECTION H: CASE-BASED / LONG ANSWER QUESTION

Ritika is suffering from a seasonal allergy (specifically Spring allergy or Hay fever). The likely allergen is pollen grains.
In normal individuals like Rohan, the immune system functions properly. His T-cells recognize environmental allergens (like pollen) as harmless substances and prevent the B-cells from responding to them. In Ritika, her immune system is hyperactive.
The skin condition is called urticaria (or hives).
Food allergies like nut allergy are classified as perennial allergies because they are not dependent on seasonal changes; they can be triggered at any time of the year whenever the specific food item is consumed.
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