Skin Concise ICSE Class-9 Biology Selina Solutions
Chapter-13 Skin "The Jack Of All Trades " Solved Exercise Questions
Skin Concise ICSE Class-9 Biology Selina Solutions Chapter-13. We Provide Step by Step Answer of Progress Check , MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured / Applications / Skill Type Questions of Exercise-13 Skin The Jack Of All Trade. Visit official Website CISCE for detail information about ICSE Board Class-9
Skin Concise ICSE Class-9 Biology Selina Solutions Chapter-13 The Jack Of All Trade
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Note :- Before Viewing Concise Solutions of Chapter-13 Skin The Jack Of All Trade . Read the whole chapter carefully with figure. Focus on Structure and function . Various part and their function. Special derivatives of the Skin with reference to sweet gland sebaceous gland, hair ,nail and mammary glands. Heat regulation – vasodilation and vasoconstriction.
1_Progress Check (page-128), Chapter-13 Skin The Jack Of All Trade Concise Selina Biology Solutions
(i) Entry of germs: Skin prevents the entry of harmful substances or infectious agents inside the body.
(ii) Excessive loss of heat in severe cold: Skin prevents energy loss from the body. It conserves body heat in cold weather and facilitates loss of heat in hot weather.
(iii) Entry of harmful ultra-violet rays: Skin protects the body against harmful ultraviolet light.
(iv) It Protect from Mechanical shock.
Respiration ,Digestion and Secretion of hormones are not the function of Human Skin.
2_Progress Check (page-129), Selina Solutions of Chapter-13 Skin The Jack Of All Trades
Outer Carnified Layer
Middle granular layer
Write True (T) or False (F) for……..
3_Progress Check (page-131), Solutions of Chapter-13 Skin The Jack Of All Trades
Match………….with Column II
(ii)…….Rudimentary in male
(v)……Races of hot countries
Hair provided the sensation of touch as the nerve fibers extend up to their bases
The outer surface of the skin made waterproof due to presence of sebaceous glands which secrete oil know as sebum to keep the epidemis supple and to prevent water loss by evaporation.
4_Progress Check (page-133), Skin Solutions of Chapter-13 for Selina Concise Biology
The statement …………..form
solution – All mammals are endothermal
Solution- Hibernation is also knows as winter sleep
Solution – vigorus activity overheats on a hot day
Solution – the principal heat regulating center is located in hypothalamous
Solution- Increasd body heat causes vasodilation
A.Multiple Choice Questions Skin Chapter-13 Biology Concise Selina Solutions
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
(d) the skin will turn dry and rough
Which one pair of two conditions includes both as abnormal conditions of skin pigmentation?
(a) Leucoderma, Ringworm
(b) Albinism, Leucoderma
(c) Baldness, Albinism
(d) Rickets, Baldness
(b) Albinism, Leucoderma
Which one out of the organs listed below, most actively functions in regulating our body temperature?
Sweat glands are situated in:
(d) None of the above
The epidermis is highly thickened in:
B. VERY SHORT ANSWER TYPE Solutions of Selina Biology Skin Chapter-13
Name the principal body heat regulating centre in our brain.
Hypothalamus, a portion of the forebrain is the principal body heat regulating centre in our brain.
Name any one modified sweat gland and any one modified sebaceous gland.
Modified sweat gland: Mammary gland
Modified sebaceous gland: Ceruminous gland
Name the skin glands which when inflamed cause acne.
C. SHORT ANSWER TYPE Chapter-13 Skin Selina Concise Solutions for ICSE Biology
State any two functions of the mammalian skin other than those concerned with heat regulation.
Functions of the mammalian skin other than those concerned with heat regulation:
(i) Storage of food: Skin acts as a storehouse of energy by storing reserve food in the form of fat in the hypodermis.
(ii) Synthesis of Vitamin D: Skin has the ability to synthesize small quantity of Vitamin D in the presence of sunlight.
What is “goose-flesh”? How is it brought about?
A peculiar roughness of the skin produced by cold or fear, in which the hair follicles become erect and form bumps on the skin is called goose flesh.
Goose flesh occurs when the muscles at the base of hair known as erectors or arrectors, contract. The erector muscles are obliquely placed between the hair follicle and the outer part of dermis. They are smooth muscles that are necessary to move the hair. The contraction of erector muscle pulls the hair vertical and depresses the epidermis, resulting in goose flesh.
What is the difference between leucoderma and albinism?
Answer 3 difference between leucoderma and albinism
|Loss of skin pigmentation from smaller or larger patches at different regions of the body||Complete loss of pigmentation of the skin all over the body|
Name any two glands found in the human skin. State their functions.
Two glands found in the human skin are:
Ceruminous gland: It is a modified sebaceous gland found in the auditory canal. It secretes wax-like substance called ear wax.
Mammary gland: It is a modified sweat gland. It is related to reproductive hormones and pregnancy.
An otherwise normal healthy young man started perspiring while it was intensely cold outside. What could have been one reason for it?
Fever and sickness or any kind of vigorous activity can lead to perspiration even in cold outside.
D. LONG ANSWER TYPE ICSE Biology Class 10th Selina Solutions Chapter-13 Skin
Enumerate in a tabular form the different structures found in the epidermis and dermis of the human skin respectively.
It is the outermost layer having layers of flattened dead cells made up of horny protein called keratin.
|It consists of elastic fibres, blood vessels, nerves, etc.|
layer: It is very thin middle layer having two or three sublayers of flattened cells.
layer: It is the innermost region of the epidermis. The cells can actively divide to produce new cells.
Explain the terms “vasodilation” and “vasoconstriction”. How do these processes contribute in temperature regulation of the body?
Dilation of blood vessels in the skin leading to an increase in the blood supply.
Narrowing of blood vessels leading to reduction in the blood supply to the skin.
Temperature regulation in cold weather:
At low temperature, the blood vessels get narrowed or vasoconstriction. This reduces the blood supply to the skin.
There is less loss of heat by convection, conduction and radiation. There is less loss of heat through vaporization as reduced blood supply lowers the secretion of sweat by sweat glands.
Temperature regulation in hot weather:
- At high temperature, the blood supply to the skin is increased by vasodilation or dilation of blood vessels in the skin.
- This results in greater loss of heat by convection, conduction and radiation.There is more loss of heat through vaporization as more sweat is secreted due to rich supply of blood to the skin.
How does our skin provide protection to our body against the following?
(a) Entry of germs ____________
(b) Excessive loss of heat in severe cold ____________
(c) Entry of harmful ultra-violet rays ____________
(a) Entry of germs: Skin prevents the entry of harmful substances or infectious agents inside the body.
(b) Excessive loss of heat in severe cold: Skin prevents energy loss from the body. It conserves body heat in cold weather and facilitates loss of heat in hot weather.
(c) Entry of harmful ultra-violet rays: Skin protects the body against harmful ultraviolet light.
E. STRUCTURED/APPLICATION/SKILL TYPE Solutions of Chapter-13 for Selina Biology
Draw a labelled diagram of the generalized vertical section of the mammalian skin.
Vertical section of the mammalian skin
Given below is a diagrammatic sketch of the vertical section of the human skin.
(a) Label the parts numbered from 1 to 9.
(b) State one main function of each of the following parts :
Name any one of the above parts which has at least three functions.
(C) Part 4 may add to one’s good appearance or the “figure”. State one example of this function which may be common to both men and women.
1: Sweat pore
2: Sebaceous gland
3: Sweat gland
6: Stratum malpighian
7: Stratum corneum
Function of part 2 (Sebaceous gland):
It produces oil called sebum, which plays a role in keeping our skin moist.
Function of part 4 (Fat):
The skin reserves food in the form of a layer of fat.
Function of part 3 (Sweat gland):
It secretes a transparent liquid (sweat) containing water and salts from the body in order to regulate body temperature.
Function of part 9 (Hair):
Hair provide a sensation of touch and are also helpful in forensic investigations.
Part which has at least three functions:
(i) Skin protection
(ii) Secretes an oily substance known as sebum that lubricates hair and skin of mammals
(iii) Presence of sebum enables to experience a wet skin even when we have not taken bath for days
(c) The one function which may be common to both men and women is that the fat serves as a food reserve and heat insulating layer as well as a shock absorber.
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