Skin The Jack of All Trades Short Answer Biology Class-9 ICSE Selina Publishers

Skin The Jack of All Trades Short Answer Biology Class-9 ICSE Selina Publishers Solutions Chapter-13. Step By Step ICSE Selina Concise Solutions of Chapter-13 Skin The Jack of All Trades with Exercise-13 including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured/Application Questions Solved Visit official Website CISCE for detail information about ICSE Board Class-9.

Skin The Jack of All Trades Exe-13 Short Answer Biology Class-9 ICSE Concise Selina Publishers

Board ICSE
Publications Selina Publication
Subject Biology
Class 9th
Chapter-13 Skin The Jack of All Trades
Book Name Concise
Topics Solution of C. Short Answer Type
Academic Session 2023-2024

C. Short Answer Type 

Skin The Jack of All Trades Class-9 Biology Concise Solutions  

Page 141

Question 1.

Define:

(a) Skin

(b) Piloerection

(c) Heatstroke

(d) Perspiration

(e) Stratum malpighi

Answer:

(a) Skin — Skin is the outermost covering of the body stretching all over in the form of a layer. It is the largest organ of our body.

(b) Piloerection — In Piloerection, the hair is lifted due to contraction of the erector muscle and the surface of the skin presents a somewhat contracted and wrinkled appearance.

(c) Heatstroke — Heatstroke or sunstroke is a condition in which sweat production is unable to keep pace with its evaporation in very hot winds.

(d) Perspiration — The process of sweating out as a result of thermoregulation is called perspiration.

(e) Stratum malpighi — The innermost germinative layer of epidermis is called stratum malpighi.

Question 2.

Distinguish between:

(a) Leukoderma/Vitiligo and Albinism.

(b) Cold blooded and Warm blooded animals.

(c) Vasodilation and Vasoconstriction.

(d) Hibernation and Aestivation.

(e) Pimples and Black heads.

Answer:

(a) Difference between Leukoderma/Vitiligo and Albinism :

Leukoderma/Vitiligo Albinism
Skin pigmentation is lost from smaller or longer patches at different region of the body. Complete loss of pigmentation all over the body including hair, eyebrows, eyelashes and even the iris.
Exact cause of Leukoderma is not yet known. Albinism is a recessive trait caused due to inheritance.

(b) Difference between Cold blooded and Warm blooded animals :

Cold blooded animals Warm blooded animals
Body temperature of cold-blooded animals changes with the temperature of their surroundings. Body temperature of warm-blooded animals remains constant and is not affected by the temperature of their surroundings.
Cold blooded animals undergo aestivation or hibernation. Warm blooded animals do not undergo aestivation or hibernation.
Example: Reptiles Example: Mammals
(c) Difference between Vasodilation and Vasoconstriction :
Vasodilation Vasoconstriction
Dilation of blood capillaries near the skin. Constriction of blood capillaries near the skin.
Caused due to increase in temperature. Caused due to decrease in temperature.
Leads to loss of body heat. Conserves body heat.

(d) Difference between Hibernation and Aestivation :

Hibernation Aestivation
Hibernation is a state of reduced metabolic activity and lowered body temperature that animals enter during winter (winter sleep) or periods of food scarcity. Aestivation is a state of dormancy that animals enter during hot and dry seasons (summer sleep), typically in response to extreme heat or drought.
The main purpose of hibernation is to conserve energy and survive unfavorable conditions. The main purpose of aestivation is to avoid excessive water loss and survive in arid environments.
Animals that hibernate experience a significant drop in metabolic rate, heart rate, and body temperature. Animals undergoing aestivation also reduce their metabolic rate and activity, but the reduction is not as extreme as in hibernation.
(e) Difference between Pimples and Black heads :
Pimples Black heads
Pimples are caused by growth of bacteria due to sebum accumulation. Black heads are caused due to open pores getting clogged with dead skin cells and sebum.
Pimples appear as red, inflamed bumps on the skin. Black heads appear black and dark due to oxidation by the air.

C. Short Answer Type 

Skin The Jack of All Trades Class-9 Biology Concise Solutions  

Page 142

Question 3.

Write the exact location of the following:

(a) Melanin

(b) Keratin

(c) Hypothalamus

(d) Granular layer

(e) Matrix

Answer:

(a) Melanin: Malpighian layer (stratum malpighi) which is the innermost layer of the epidermis.

(b) Keratin: Nail.

(c) Hypothalamus: Fore brain.

(d) Granular layer: Middle layer of epidermis present below the outer cornified layer (stratum corneum).

(e) Matrix: Below the surface of the skin at the base of the nail.

Question 4.

Write the important role(s) of:

(a) Cerumen

(b) Sebum

(c) Keratin

(d) Melanin

(e) Secretion of meibomian glands

Answer:

(a) Cerumen: Wax like substance which protects and lubricates the delicate eardrum from dust particles and germs.

(b) Sebum: It makes the hair and outer surface of skin oily and waterproof.

(c) Keratin: In nails, Keratin forms the nail plate which provides a hard, protective covering over the nail bed.

(d) Melanin: It is responsible for colouration of the skin. It also protects the inner parts of the body from harmful ultraviolet rays of the Sun.

(e) Secretion of meibomian glands: It lubricates the margins of the eyelids and prevents the overflow of tears.

(Skin The Jack of All Trades Short Answer Class-9 ICSE)

Question 5.

Give reasons/Explain:

(a) Skin can be considered as an accessory excretory organ.

(b) A normal healthy young person can start perspiring even when the outside atmosphere is intensely cold.

(c) Hairs can be used in forensic investigation.

Answer:

(a) Skin assists in the process of excretion of water, salts and to a very limited extent, urea through sweating. Since sweating occurs mainly for temperature regulation hence skin can be considered as an accessory excretory organ.

(b) A normal healthy young person can start perspiring even in cold atmosphere due to psychic influences such as fright or nervousness. This is referred to as “cold sweat”.

(c) Hairs from different part of body show subtle differences. Hair follicles, found at the root of the hair, have the highest concentration of DNA, making them particularly valuable for DNA analysis. Therefore, hairs can be used in forensic investigation.

Question 6.

State any two functions of the mammalian skin other than those concerned with heat regulation.

Answer:

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.

Question 7.

What is “goose-flesh”? How is it brought about?

Answer:

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.

—  : End of Skin The Jack of All Trades C. Short Answer Class-9 ICSE Biology Solutions :–

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