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Chapter 4

Allergy

Class 7 - Living Science Biology Ratna Sagar


Tick the most appropriate answer

Question 1

Which of the following is not a symptom of allergy?

  1. itching
  2. sleeping
  3. rashes
  4. swelling

Answer

sleeping

Reason — Sleeping is not an allergic symptom but a normal state of rest of our body.

Question 2

Which of the following is not an allergen?

  1. water
  2. milk
  3. perfume
  4. dust

Answer

water

Reason — Water does not cause any type of allergy.

Question 3

Diagnosis of an allergy cannot be done by

  1. surgery
  2. scratch test
  3. blood test
  4. skin test

Answer

surgery

Reason — Diagnosis of allergy is done by scratch test, blood test and skin test.

Question 4

Which of the following is caused due to pollen grains?

  1. hay fever
  2. insect bite
  3. nettlerash
  4. eczema

Answer

hay fever

Reason — Hay fever is caused due to pollen grains.

Question 5

Which of the following is a long-term lung disease?

  1. hay fever
  2. insect bite
  3. asthma
  4. eczema

Answer

asthama

Reason — Asthma is a long-term lung disease in which the air passage in the lungs swells and narrows down.

Fill in the blanks

Question 1

Allergies caused due to sunlight exposure are ............... .

Answer

Allergies caused due to sunlight exposure are seasonal allergies.

Question 2

When the pollen grains come in contact with the ..............., a substance called ............... is released.

Answer

When the pollen grains come in contact with the antibodies, a substance called histamine is released.

Question 3

Higher the IgE antibody value, ............... the chances of allergic symptoms.

Answer

Higher the IgE antibody value, greater the chances of allergic symptoms.

Question 4

Hay fever is also known as allergic ............... .

Answer

Hay fever is also known as allergic rhinitis.

Question 5

Wear a ............... to cover your nose and mouth while travelling.

Answer

Wear a mask to cover your nose and mouth while travelling.

Match the following

Question 1

Sl.
No.
Column AColumn B
1.strong sunlightrashes
2.pollen grainsvomiting
3.dustsmall blisters
4.animal fursneezing
5.insect stingasthma
6.eggshives

Answer

Sl.
No.
Column AColumn B
1.strong sunlightsmall blisters
2.pollen grainssneezing
3.dustasthma
4.animal furrashes
5.insect stinghives
6.eggsvomiting

Define the following terms

Question 1

allergy

Answer

Allergy — Allergy is defined as a reaction or response of our immune system to specific substances that are normally harmless.

Question 2

allergen

Answer

Allergen — A substance that causes allergic reactions is called allergen.

Question 3

allergist

Answer

Allergist — The doctor who diagnoses and treats allergy is called allergist.

Question 4

anaphylaxis

Answer

Anaphylaxis — Anaphylaxis is a potentially life-threatening reaction that can impair breathing and send the body into shock.

Differentiate between

Question 1

allergy and allergen

Answer

Sl.
No.
AllergyAllergen
1.The response of our immune system to a specific substance is called allergy.The substance that causes allergy is called allergen.
2.Hives, sneezing and itching are allergic reaction.Pollen grains, dust and insect sting are allergens.

Question 2

seasonal and perennial allergy

Answer

Sl.
No.
Seasonal AllergyPerennial Allergy
1.When the allergy occurs at a particular time of the year, it is called seasonal allergy.It is not linked to any season.
2.Particular allergens prominently found in a season cause such allergy.It occurs at anytime of the year.
3.For example: Hay FeverFor example: Dust Allergy

Question 3

hay fever and eczema

Answer

Sl.
No.
Hay feverEczema
1.It is caused due to pollen grains, animal hair, dust, mites and mould.It is caused due to a particular food, cosmetics, soap, dye etc.
2.It causes runny nose, itchy eyes, sore throat, asthma.It causes itching and redness of skin.

Mention any two symptoms of each of the following allergies.

Question 1

Hay fever

Answer

Symptoms of hay fever are:

  1. Runny nose
  2. Itchy eyes, mouth or skin

Question 2

Dust allergy

Answer

Symptoms of dust allergy are:

  1. Sneezing
  2. Wheezing or coughing and shortness of breath

Question 3

Nettlerash

Answer

Symptoms of Nettlerash are:

  1. Raised itchy bumps on skin, which are either red or skin coloured.
  2. They resemble bug bites and can appear on any area of the body

Question 4

Eczema

Answer

Symptoms of eczema are:

  1. Itching of skin
  2. Redness of skin

Question 5

Asthma

Answer

Symptoms of asthma are:

  1. Persistent coughing that worsen at night or early in the morning.
  2. Shortness of breath or difficulty in breathing.

Write one allergic response

Question 1

Write one allergic response of these allergens.

  1. pollen grains
  2. dust
  3. milk
  4. animal fur
  5. insect bites
  6. medicines

Answer

One allergic response of each of these allergens is listed in the table below:

Sl.
No.
AllergenAllergic response
1.pollen grainsRunny nose
2.dustRed, Itchy eyes
3.milkVomiting
4.animal furRashes on skin
5.insect bitesHives
6.medicinesDiarrhea

Answer these questions in short

Question 1

Define allergy. Give any two examples.

Answer

Allergy is defined as a reaction or response of our immune system to specific substances that are normally harmless.

For example:

  1. Skin Rashes due to strong sunlight
  2. Sneezing and Runny nose due to dust

Question 2

What is an allergen? Name any two allergens.

Answer

A substance that causes allergic reactions is called allergen.

For example:

  1. Dust
  2. Pollen

Question 3

What is hay fever?

Answer

Hay fever is the most common type of allergy that is caused due to pollen grains, dust, mites, moulds and animal hairs.

Question 4

What is seasonal allergy? Give any two examples of seasonal allergies?

Answer

When the allergy occurs at a particular time of the year, it is called seasonal allergy.

For example, regular sneezing and coughing during winter indicates seasonal allergy; and allergy to pollen grains is very common during spring season.

Question 5

What is perennial allergy? Give any two examples of perennial allergies.

Answer

Perennial allergy are allergy that are not linked to any particular season and can occur at any time of the year. Allergy to dust and insect bites are the examples of perennial allergy.

Answer these questions in detail

Question 1

Explain how an allergic reaction occurs.

Answer

When a person who is allergic to a particular allergen comes in contact with it, an allergic reaction occurs. This reaction begins when the allergen (for example, pollen grains) enters the body and causes special cells in the body tissues to make a chemical called an antibody. When the allergen comes in contact with the antibodies, a substance called histamine is released. Histamine causes allergic reaction and results in swelling and inflammation.

Question 2

Write at least four precautions to be taken to prevent allergy.

Answer

Following are the precautions to be taken to prevent allergy:

  1. If one has food allergies, the only way to avoid allergic reactions is to avoid allergic foods. After allergen is identified the food(s) should be removed from the diet.
  2. Eating good amount of fresh fruits and vegetables improves the immunity and develops resistance against allergens.
  3. Wear full-sleeved clothes and closed shoes. Apply insect-repellent cream when travelling outdoors.
  4. Wear a mask to cover your nose and mouth while travelling.

Question 3

Write a short note on the medications used to treat allergy.

Answer

Medication in the treatment of common allergies includes:

  1. Antihistamines — Antihistamines are available as pills, nasal sprays or eye drops. They prevent symptoms such as hives by blocking histamines receptors so our body does not react to the allergens.
  2. Decongestants — Decongestants are used to clear a stuffy nose, especially in case of seasonal allergy.
  3. Bronchodilators and steroids — Bronchodilators give instant relief from chest tightness and wheezing. Steroids reduce the inflammation of bronchioles. Asthma patients need to take regular doses of these medicines.
  4. Creams and lotions — Creams and lotions reduce swelling, redness and itching.

Question 4

What are the causes of asthma? How can it be prevented?

Answer

The causes of asthma are:

  1. Can be passed on from parents to their children
  2. Certain respiratory infections
  3. Contact with air-borne allergens such as tobacco smoke, pollen grains, chemicals, dust, mites or some food substances.
  4. Cold and cough

Following are the ways to prevent it:

  1. A person suffering from asthma should know about the allergens causing asthma.
  2. Medicines should be taken after consultation with a doctor.
  3. Hygienic and healthy lifestyle should be maintained.
  4. Regular checkups for asthma should be done.

Think and answer

Question 1

Lily starts coughing continuously whenever she helps her mother in dusting her room. It became so severe that she had to visit a doctor. What do you think is the cause of Lily's ailment? Why have all medications failed to treat her ailment?

Answer

It seems that Lily is allergic to dust. Dust allergy causes narrowing of the wind pipe and coughing. All other medications have failed because allergic cough cannot be treated with normal medicines. But medicines like Bronchodilators and steroids provide instant relief.

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