DOWNLOAD MOBILE APPLICATION TO LEARN MORE: SKIN CLASS 9 ICSE QUESTIONS
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: SKIN CLASS 9 ICSE QUESTIONS
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SKIN CLASS 9 ICSE QUESTIONS
Q1. List the four ways in which the skin serves as a protective layer for our body.
Ans. (i) Protects the underlying tissues from mechanical shocks.
(ii) Prevents excessive loss of water.
(iii) Prevents the entry of harmful substances or disease causing germs.
(iv) Protects the body against excess ultra-violet light.
Q2. Match the items in Column I with those in Column II:
Column I Column II
(i) Air spaces (a)Hair
(ii) Mammary glands (b) Sebaceous glands
(iii) “Goose-flesh” (c) Rudimentary in males
(iv) Traces of urea (d) Races of hot countries
(v) More numerous sweats pores (e) Gray hair
(vi) Oily secretion (f) Sweat
Ans. (i) e (ii) c (iii) a (iv) f (v) d (vi) b
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Q3. How do hairs provide the sensation of touch?
Ans. Hair provides a sensation of touch because nerve-fibres extend up to their bases.
Q4. How the outer surface of skin made waterproof?
Ans. Sebaceous glands sometimes open directly to the outside. They give out an oily secretion which makes the outer surface of the skin oily and waterproof.
Q5. If for some reason the sebaceous glands fail to function.
(a) the body will not be able to regulate the body temperature
(b) the skin will turn darker with more melanin
(c) the hairs will fail to grow
(d) the skin will turn dry and rough
Ans. (d) the skin will turn dry and rough
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Q6. Which one pair of two conditions includes both as abnormal conditions of skin pigmentation?
(a) Leucoderma, Ringworm
(b) Albinism, Leucoderma
(c) Baldness, Abinism
(d) Rickets, Baldness
Ans. (b) Albinism, Leucoderma
Q7. Which one out of the organs listed below, most actively functions in regulating our body temperature.
(a) Heart (b) Lungs
(c) Skin (d) Stomach
Ans. (c) Skin
Q8. Name the principal body heat regulating centre in our brain.
Ans. Principal Body heat regulating centre in our brain is located in the hypothalamus a portion of the fore brain. It acts as a thermostat. When the body tends to cool below the normal temperature. It switches on or speeds up the heat producing process, and when the body tends the become overheated, it increases the cooling process and heat producing process is switched off.
Q9. Name any one modified sweat gland and any one modified sebaceous gland.
Ans. Modified sweat gland is mammary gland modified sebaceous gland is ceruminous gland.
Q10. Name the skin glands which when inflamed cause acne.
Ans. Sebaceous glands.
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Q11. What is “goose-fleshâ? How is it brought about?
Ans. During winter or some emotion our hair gets lifted and the surface of the skin presents a somewhat contracted and wrinkled appearance, this experience is known as “goose flesh.”
“Goose-flesh” is caused by the erector muscle of hair which runs obliquely between the hair follicle and the outer part of the dermis. Due to contraction of this muscle at one end pulls the hair to vertical position, and at the other end, depresses the epidermis.
Q12. Why do you shiver and why do your teeth chatter when it is very cold in winter?
Ans. In cold weather the blood vessels get narrowed (vasoconstriction). This reduces the blood supply and as a result, there is less loss of heat and person shivers and his teeth chatter.
Q13. Name any two glands found in the human skin. State their functions.
Ans. Sweat Glands-Secretory part of sweat gland absorbs fluid from the surrounding cells and blood capillaries of dermis and passes it into the excretory sweat duct which pours it out on the surface.
Sweat consists of 99% water, 0.2-0.5% salts, 0.08% urea.
Mammary glands-These are related to the reproductive hormones and pregnancy-the milk secreted by the mammary glands is highly nutritious for newly born baby.
Q14. Explain the terms “vasodilation” and “vasoconstriction”. How do these processes contribute in temperature regulation of the body?
Ans. Vasodilation-Dilation of blood vessels in the skin leading to increase in blood supply. Vasoconstriction– Narrowing of blood vessels leading to reduction in the blood supply of skin.
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Temperature-regulation
Cold weather-When temperature is low, the blood vessels get narrowed. This reduces the blood supply to the skin. As a result, there is less loss of heat by convection, conduction and radiation and also less loss of it through vaporisation of sweat because with reduced blood supply. The sweat glands secrete less sweat.
Hot Weather-When outside temperature is high, there is vasodilation which results in greater loss of heat by radiation etc, and also by vaporisation of sweat which is now produced in larger quantities due to the rich system of blood to the skin. Air movements over the body help to speed up evaporation of sweat leading to cooling effect on our body.
Q15. Why should be keep our skin clean?
Ans. Skin must be kept clean otherwise pores get blocked with dust, grease and germs attack and breed over there causing various diseases.
A clean intact skin is a barrier to bacteria and fungi. So regular bathing with a mild soap and using clean dry towel will keep the hair follicles open.
Q16. What basic care must be taken to maintain our skin healthy?
Ans. Skin: Skin must be kept clean otherwise pores get blocked with dust, grease and germs attack and breed over there producing foul smell. A clean intact skin is a barrier to bacteria and fungi. So regular bathing will keep the hair follicles open. Soap dries out the skin and strips it off its protective sebum. Strong soaps can even cause allergic reactions like itching and soreness. Hence a mild soap is recommended.
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Q17. Why is it advisable to use a mild soap?
Ans. Mild soap is recommended for skin as strong soaps can cause allergic reactions like Itching and soreness. Soap dries out skin and strips it off its protective sebum.
Q18. In which region of the skin (epidermis or dermis) are the following located? Also state the function of each:
(i) Malpighian layer: (ii) Sweat gland:
(iii)Sebaceous gland: (iv) Cornified layer:
(v) Granular layer:
Ans. (i) Epidermis-It prevents the loss of Tissue fluid. It gives colour to skin and protects body against harmful effect of ultra-violet rays.
(ii) Dermis- Regulate the body temperature and eliminates about 1% of metabolic waste through sweat. (iii) Dermis- Keep skin soft and supple and prevents it from drying up.
(iv) Epidermis– Protects underling tissues from mechanical damage, bacterial invasion and dehydration. (v) Epidermis- Its function is to form KERATIN- a protein found in hair and nails.
Q19. Why is it advisable to wear gloves when working in the garden or when washing clothes and dishes?
Ans. There is always threat, hand have to face [While working in the garden or when washing clothes and dishes] of in fection from the soil or is subjected to chemical irritants like detergents. Hands can be protected by wearing gloves they also protect finger nails from picking germs.
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ALSO VISIT:
9TH ICSE
| Also Learn: | Attempt the Quiz on Chemistry | Attempt the Quiz on Mathematics | Attempt the Quiz on Physics | |
| ATOMS AND MOLECULES GRAVITATION MENSURATION Archimedes Principle | QUIZ ON ATOMS AND MOLECULES– Quiz on Periodic classification of elements | CIRCLES– MATHEMATICS QUIZ 2 ON CIRCLES QUIZ 3 ON CIRCLES | QUIZ ON GRAVITATION- PHYSICS |
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: SKIN CLASS 9 ICSE QUESTIONS
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: SKIN CLASS 9 ICSE QUESTIONS