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Bio 9 icse, Chapter 13 - Skin, A Differentiate between the following 1. Leucoderma and Albinism, 2. Cornified layer and Malpighian layer of epidermis, 3. Epidermis and Dermis, 4. Pimple and Acne, 5. Sebum and Sweat, 6. Mammary gland in male and female, 7. Endothermic and Ectothermic animals, 8. Hibernation and Aestivation, 9. Vasoconstriction and Vasodilation, B Answer the following questions 1. Explain the different functions of skin., 2. How is the skin protective in nature?, 3. How is the skin sensory in nature?, 4. Why do we not consider skin as an excretory organ?, 5. What is the advantage of having ridges and grooves present in the skin of fingers?, 6. Name the three regions of epidermis., 7. Write a short note on epidermis., 8. Write a short note on the cornified layer of epithelium., 9. Why is the cornified layer necessary?, 10. What is the role of the Malpighian layer?, 11. Write a short note on dermis., 12. What is the role of fat below the dermis?, 13. Structure responsible for growth and elongation of hair?, 14. Why does the hair appear grey?, 15. What is goose flesh?, 16. How do hair provide a sensation of touch?, 17. How are hairs useful?, 18. Write a short note on nails., 19. How is sebum useful?, 20. What are the variations observed in skin during hot, humid weather and cool, dry, weather?, 21. What is the function of the secretary part of sweat glands?, 22. What is the major function of sweat glands?, 23. What is the composition of sweat?, 24. In which cases is sweat pathological?, 25. What is the function of the meibomian gland?, 26. What is the function of the ceruminous gland?, 27. How is ear wax important?

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28. What do you mean by endothermic organisms?, 29. Why is it important to maintain optimum temperature in our body?, 30. What are the different sources of heat production in our body?, 31. How is heat lost from our body?, 32. How does hypothalamus act like a thermostat?, 33. What precautions should be taken in summer?, 34. When does heat stroke occur?, C Correct the following sentences 1. Skin is permeable barrier, 2. Skin cannot hold the body fluids inside, 3. Skin cannot protect against ultraviolet light, 4. Skin stores reserve food in the form of glycogen, 5. Blood vessel is present in epidermis, 6. Cells of cornified layer are actively dividing, 7. Leather is the epidermis part of skin, 8. Adipose layer is present beneath epidermis, 9. Sebum is a watery secretion, 10. In hot humid weather skin is rough, 11. In Cold dry weather skin is oily, 12. Commonest problem in adolescent is black head, 13. Human in hotter countries have less sweat pores than the ones in colder countries, 14. Sweat contains 99% salts, 15. Milk is secreted by sebaceous gland, 16. Milk is highly dangerous for the new born baby, 17. Meibomian gland is modified sweat gland, 18. Cerumen is secreted in eye, 19. Poikilothermic means warm blooded, 20. Muscle activity absorbs heat, 21. Majority of heat loss in our body takes place through urine and faeces, 22. Hypothalamus is located in hindbrain, 23. Shivering occurs in hot weather, D Name the following 1. Largest organ of our body, 2. Outermost covering of our body, 3. Skin is a part of which system, 4. Harmful rays of sun from which skin protects us, 5. Skin stores reserve food in the form of a layer of, 6. The vitamin that skin can synthesize when exposed to sunshine, 7. Substances which skin excrete (2), 8. Outer thinner part of skin, 9. The epithelium that comprises epidermis, 10. Epidermis becomes thick in which area of body

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11. Cornified layer of epidermis is called, 12. Fibrous structural protein present in cornified layer is called, 13. Structures in which keratin is present (2), 14. Cells of cornified layer are replaced by those arising from the deeper, 15. Middle layer of epidermis is called, 16. Last layer of epidermis is called, 17. Skin is coloured due to a pigment, 18. Disorder in which melanin is lost in patches, 19. Disorder in which there is complete loss of pigmentation, 20. Type of fibres present in dermis, 21. Place where skin is very thin, 22. Outer region of dermis containing blood capillaries and nerve endings is called, 23. Nerve endings are concerned with sensations of (2), 24. Layer present beneath dermis, 25. Part of hair which projects from the skin, 26. Part of hair embedded within the dermis, 27. Lowest part of hair root is expanded to form the, 28. Blood supply to hair comes from, 29. Structure enclosing the hair root, 30. Colour of the hair is due to varying quantities of, 31. Piloerection is caused due to muscle, 32. Dead keratinized cells present in nail, 33. Whitish half moon present at base of nail is, 34. Oily secretion of sebaceous gland is, 35. Name the problems related to sebaceous gland (2), 36. Name a branched gland, 37. Name a gland with simple coiled tube, 38. Outer openings of sweat glands are called, 39. Name a modified sweat gland, 40. Hormone that controls the activity of mammary gland, 41. Modified sebaceous gland present in eye is, 42. Modified sebaceous gland present in ear is, 43. Wax like substance in ear is, 44. Two warm blooded organisms, 45. Human body temperature is, 46. Principal heat regulating centre is located in