Integumentary System Questions in English

(B) The correct answer is $B$. The skin of a frog is thin,moist,and highly vascular due to the secretion of mucus. This allows the frog to perform cutaneous respiration,where gas exchange occurs directly through the skin,especially when the animal is underwater or hibernating.

(C) The epidermis is $Avascular$ because it does not contain any blood vessels. It receives nutrients and oxygen via diffusion from the underlying dermis,which is vascular.

(A) Melanin is a group of pigments found in animals.
These are derived from the amino acid $Tyrosine$.

(C) The correct answer is $(c)$.
Sweat glands are located deep within the dermis of the skin in mammals.
They produce a watery secretion known as sweat.
As sweat evaporates from the surface of the skin,it absorbs heat from the body,thereby helping in thermoregulation (maintaining body temperature).

(A) The skin on the human body varies in thickness depending on the location. The skin of the eyelids is the thinnest skin in the human body,measuring approximately $0.5 \ mm$ in thickness. In contrast,the skin on the palms of the hands and the soles of the feet is the thickest,as it is designed to withstand mechanical stress and friction.

(C) Scleroproteins,also known as fibrous proteins,are structural proteins that are insoluble in water and provide mechanical support to cells and tissues.
Examples of scleroproteins include $Keratin$,which is found in hair,nails,and skin,and $Collagen$,which is the main structural protein in connective tissues.
Therefore,both $Keratin$ and $Collagen$ are classified as scleroproteins.

(D) Carotenoids are yellow,orange,red,or brown pigments. They are classified into two types: carotenes and xanthophylls.
Carotene is found in the cells of the epidermis and in the adipose cells located in the hypodermis.
Therefore,the correct answer is $D$.

(A) The different colours of frog skin are primarily regulated by hormones.
Specifically,the hormone $MSH$ (Melanocyte Stimulating Hormone) secreted by the pituitary gland controls the dispersion of pigment granules in the melanophores.
Metachrosis is the phenomenon of changing skin colour,which serves as a protective mechanism for the frog against its enemies.

(B) Predation is a biological interaction where one organism,the predator,kills and eats another organism,its prey. Animals have evolved various defensive mechanisms to avoid being eaten.
$A$. Puffer fish swallow air to increase their body size,making them difficult for predators to swallow.
$B$. Melanism in moths (like the peppered moth) is an example of industrial melanism,which is an adaptation for camouflage against soot-covered backgrounds,not a direct mechanism to escape predation through active defense or warning.
$C$. Poison fangs in snakes are defensive mechanisms used to deter or kill predators.
$D$. Colour change in chameleons is primarily used for camouflage to blend into the environment and avoid detection by predators.
Therefore,melanism is an evolutionary adaptation for camouflage,but it is not a direct behavioral or morphological mechanism to escape predation in the same sense as the others listed.

(B) The epidermis is derived from the embryonic ectoderm. It consists of a stratified squamous epithelium composed of several layers of epithelial cells that provide a protective barrier for the body.

(D) Epidermal derivatives are structures that develop from the epidermis of the skin. These include hair,nails,and various skin glands such as sweat glands and sebaceous glands. Therefore,hair,sweat glands,and sebaceous glands are all considered epidermal derivatives.

(C) Sebaceous glands secrete an oily substance called sebum. This secretion lubricates the hair shafts and forms a protective layer on the skin,which makes the skin waterproof and prevents it from drying out.

(B) The secretion of sebaceous glands is an oily substance known as sebum.
Sebum helps to lubricate and waterproof the skin and hair of mammals.

(B) The term $Sudorific$ is derived from the Latin word $sudor$,which means sweat.
Therefore,$Sudorific$ glands are commonly referred to as sweat glands.
These glands are responsible for the secretion of sweat,which helps in thermoregulation and excretion of metabolic wastes.

(C) Meibomian glands are specialized glands located in the eyelids that secrete an oily substance called meibum.
This oily secretion helps to prevent the evaporation of the eye's tear film.
These glands are structurally and functionally modified sebaceous glands,which are responsible for producing sebum.

(C) The correct answer is $C$.
Perineal glands,also known as inguinal glands or scent glands,are located in the dermis of the perineum,surrounding the genital organs and the anus in animals like rabbits.
These scent glands produce secretions that aid in the recognition of members of the same species.
Additionally,these secretions release pheromones that play a crucial role in attracting the opposite sex for mating purposes.

(A) The hair of a mammal is an epidermal derivative.
Epidermal derivatives are structures formed by the epidermis of the skin.
These include epidermal glands and hard,horny structures such as scales,scutes,beaks,horns,claws,hoofs,and hairs.

(B) Sebaceous glands are exocrine glands in the skin that secrete an oily or waxy matter,called sebum,to lubricate and waterproof the skin and hair of mammals.
These glands are located in the dermis layer of the skin,typically associated with hair follicles.

(C) The lachrymal gland is a compound tubuloacinar gland located in the orbit of the eye.
It secretes tears,which are a watery solution containing salts,some mucus,and a bactericidal enzyme called lysozyme.
Therefore,the correct option is $C$.

(A) $Mammary$ glands are a characteristic feature of mammals. In most mammals (Eutheria),they are considered to be modified sweat glands (apocrine glands). In some primitive mammals like Prototheria (monotremes),they are associated with sebaceous glands.

(C) The integument of a frog contains multicellular mucous glands that secrete mucus to keep the skin moist for cutaneous respiration.
In mammals,the skin contains sebaceous glands (oil glands) and sweat glands,but it lacks the specific type of mucous glands found in amphibians.
Therefore,mucous glands are a characteristic feature of the frog's integument that is absent in mammals.

(B) The skin of mammals consists of two main layers: the outer $Epidermis$ and the inner $Dermis$.
Leather is produced through the tanning process,which primarily acts on the $Dermis$ layer.
The $Dermis$ is composed of dense connective tissue rich in collagen fibers,which provides the strength and durability required for leather products.
The $Epidermis$ is removed during the processing of hides because it does not possess the structural properties necessary for leather.

(B) The process of converting animal skin or hide into leather is known as Tanning. During this process,the dermis layer of the skin of large-sized mammals is treated with tannins to make it durable,flexible,and resistant to decay. Taxidermy,on the other hand,is the art of preserving an animal's body via mounting or stuffing for display.

(A) In humans,sweat glands are absent in the skin of the lips,glans penis,and nail beds. Among the given options,the lips are the specific area where sweat glands are not found.

(A) The glands of $Zeis$ are modified sebaceous glands that are associated with the follicles of the eyelashes. Their oily secretion helps to keep the eyelashes lubricated and healthy.

(C) The hair shaft is the visible part of the hair that extends above the skin surface.
It is composed of dead,keratinized cells that have been pushed upward from the hair follicle.
While the root and bulb are living tissues located within the dermis,the shaft is fully keratinized and consists of non-living cells.

(C) Human sweat glands,specifically the eccrine glands,perform two primary functions:
$1$. Thermoregulation: By secreting sweat,which evaporates from the skin surface,the body cools down,thereby regulating body temperature and water balance.
$2$. Excretion: Sweat contains water,electrolytes (primarily sodium and chloride ions),and small amounts of urea,which helps in the removal of excess salts and metabolic waste from the body.

(B) Finger nails are derivatives of the skin. They are formed by the keratinization of the epidermal cells. Specifically,the nail plate is derived from the stratum germinativum of the epidermis. Therefore,the correct origin of finger nails is the epidermis.

(B) $Keratin$ is a specialized, insoluble, fibrous structural protein found in the epidermis of terrestrial vertebrates. It is the primary component of horny tissues such as hairs, feathers, nails, claws, and hoofs, providing them with strength and protection.

(C) The correct answer is $C$.
Lachrymal glands are associated with the eyes and are considered modified sweat glands.
They secrete tears,which help in keeping the eyes and eyelids clean,lubricated,and moist.

(C) The integument of a rabbit (a mammal) is characterized by the presence of specialized skin glands,including sebaceous glands and sweat glands,which are absent in the frog (an amphibian).
Sebaceous glands produce sebum,an oily secretion that keeps the skin and hair greasy,soft,and waterproof.
In contrast,the skin of a frog is moist and contains numerous mucous glands to keep the surface slippery and facilitate cutaneous respiration.
Therefore,the presence of sebaceous glands is a distinct feature of the mammalian integument compared to that of amphibians.

(A) The nails, claws, horns, and hoofs in mammals are derivatives of the epidermis. Specifically, they are formed by the keratinization of the $Stratum \text{ } corneum$ layer of the skin. This layer consists of dead, flattened cells filled with the protein keratin, which provides hardness and protection to these structures.

(B) The correct answer is $B$. In mammals,true horns are bony outgrowths of the skull,which are covered by a sheath of keratinized epidermis (stratum corneum). However,the primary structural foundation and origin of the horn core in most horned mammals are the frontal bones of the skull. Therefore,they are considered to be produced by the skull.

(D) Hair acts as an insulating layer by trapping air near the skin surface. This trapped layer of air prevents the excessive loss of body heat,thereby helping in thermoregulation.

(C) In rabbits and hares,sweat glands are not distributed over the entire body surface as they are in humans. Instead,they are restricted to specific regions. Specifically,the sweat glands in these animals are confined to the soles of the paws (footpads).

(D) In $Rabbit$ $(Oryctolagus \, cuniculus)$, the skin is rich in various types of epidermal glands.
$1$. $Sebaceous$ glands are associated with hair follicles and secrete sebum to lubricate the skin and hair.
$2$. $Sweat$ glands ($sudoriferous$ glands) are present to assist in thermoregulation.
$3$. $Ceruminous$ glands are modified sweat glands found in the external auditory canal.
$4$. $Mammary$ glands are specialized epidermal glands present in females for milk production.
$5$. $Meibomian$ glands and $glands \, of \, Moll$ are specialized sebaceous and sweat glands, respectively, found in the eyelids.
Therefore, all the listed glands are present in the $Rabbit$.

(D) In mammals,scent glands are specialized structures used for chemical communication. These glands are typically modified forms of either sebaceous glands (oil glands) or sudorific glands (sweat glands). For example,in many species,specialized sweat glands or oil glands produce pheromones or other scent-marking substances. Therefore,both types of glands can serve as the origin for scent glands.

(C) The $Paniculus$ $\text{ } carnosus$ is a thin layer of striated muscle found in the subcutaneous tissue of many mammals. It is responsible for the movement and twitching of the skin, which allows animals to shake off insects or debris. In humans, this muscle is largely vestigial, represented primarily by the $platysma$ muscle in the neck.

(B) The human skin consists of two main layers: the epidermis and the dermis.
The epidermis is the outermost layer,which is avascular.
The dermis is the deeper layer composed of dense connective tissue.
Sweat glands (sudoriferous glands),hair follicles,sebaceous glands,and blood vessels are located within the dermis layer of the skin.

(D) Sebum is an oily secretion produced by the sebaceous glands in the skin.
$1$. It acts as a lubricant for the skin and hair,preventing them from becoming dry or brittle.
$2$. It forms a protective barrier on the skin surface,helping to retain moisture and protect against environmental damage.
$3$. It contains fatty acids that provide an antibacterial and antifungal effect,helping to inhibit the growth of harmful microorganisms on the skin surface.
Therefore,sebum performs all these functions.

(C) The glands of $Moll$ (also known as ciliary glands) are specialized sweat glands located at the margin of the eyelid. They are modified apocrine sweat glands that open into the follicles of the eyelashes. Therefore,they are classified as modified sweat glands.

(B) The epidermis gives rise to several kinds of cutaneous glands.
These include sebaceous glands,sweat glands,lacrimal glands,mammary glands,and other highly specialized glands.
Cutaneous glands are associated with the skin (integumentary system),whereas gastric glands are part of the digestive system,and thyroid and thymus glands are endocrine glands.

(D) The $Erector$ $\text{pilli}$ (also known as $Arrector$ $\text{pili}$) are small smooth muscles attached to the hair follicles.
When the body experiences cold, these muscles contract, causing the hair to stand upright (piloerection).
This action helps trap a layer of air near the skin surface, which acts as an insulator to reduce heat loss from the body.

(C) The correct answer is $C$. Sebaceous glands are simple branched alveolar glands that are closely associated with hair follicles. They secrete sebum,an oily substance,which lubricates the hair and the skin surface.

(C) The correct match is $C$.
$1$. Saliva helps in the digestion of starch and lubrication of food,not primarily in the taste of food.
$2$. The $Humerus$ is a bone of the forelimb (arm),not the hind limb.
$3$. Sweat is produced by sweat glands and is essential for thermoregulation (temperature regulation) in the body.
$4$. Sebum is an oily secretion that lubricates the skin and hair,not primarily for sexual attraction.

(B) Placoid scales are found in cartilaginous fishes (Chondrichthyes) like sharks.
These scales are homologous to mammalian teeth because they consist of an outer layer of enamel-like material (vitrodentine) and an inner core of dentine surrounding a pulp cavity.
Like teeth,they develop from the dermis and epidermis,making their structure and origin similar to the teeth of mammals.

(B) An exoskeleton is a rigid external covering for the body in some invertebrate animals,providing both support and protection.
In vertebrates,the term refers to structures like scales,feathers,hair,nails,or claws.
$A$. Shark: Possesses placoid scales (dermal denticles),which are considered an exoskeleton.
$B$. Frog: Amphibians like frogs have moist,glandular skin without scales or other hard external structures,thus lacking an exoskeleton.
$C$. Bat: Being a mammal,it possesses hair,which is an epidermal derivative and part of the exoskeleton.
$D$. Mammals: Generally possess hair,nails,or claws,which are considered part of the exoskeleton.
Therefore,the correct answer is $B$ (Frog).

(D) The correct answer is $D$.
The $Stratum$ $corneum$ is the outermost layer of the epidermis.
It consists of dead,flattened,keratinized cells that have lost their nuclei.
These cells are tightly packed and provide a tough,protective barrier that is waterproof and germproof,preventing the entry of water and harmful substances into the body.

(C) In human skin, melanocytes (often referred to as melanophores in a broader biological context) are specialized cells responsible for the production of melanin pigment.
These cells are primarily located in the $Stratum \text{ } germinativum$ (also known as the $Stratum \text{ } basale$), which is the deepest layer of the epidermis.
From this layer, the melanin granules are transferred to the surrounding keratinocytes to provide protection against ultraviolet radiation.

(A) Evaporation is an endothermic process that requires latent heat of vaporization. When sweat evaporates from the surface of the skin,it absorbs the necessary heat energy directly from the body of the animal. This process helps in thermoregulation by cooling the body. Therefore,the heat required for the evaporation of sweat is derived from the body of the animal.