Test: Skin - Class 9 MCQ

Keratin is the primary protein found in the outer layer of the skin, providing strength and protection against mechanical damage, pathogens, and water loss.

The subcutaneous fat layer serves multiple purposes, including storing energy in the form of fat, insulating the body to maintain temperature, and acting as a cushion to protect underlying structures from shock.

The cornified layer (stratum corneum) is the outermost layer of the epidermis, consisting of flattened, dead cells that form a protective barrier against mechanical damage, pathogens, and water loss.

Acne is characterized by inflamed sebaceous glands, often due to hormonal changes that lead to increased sebum production and bacterial growth, particularly during adolescence.

The primary function of the skin is to protect underlying tissues from mechanical shocks, excessive water loss, harmful substances, and UV light. This protective barrier is essential for maintaining the body's integrity.

The skin synthesizes vitamin D when exposed to ultraviolet (UV) light from the sun. This vitamin is essential for calcium absorption and bone health. However, excessive UV exposure can lead to skin damage.

The hair follicle is responsible for the production of new hair cells. It contains a hair bulb at its base, where active cell division occurs, leading to hair growth.

During cold weather, blood vessels in the skin constrict (vasoconstriction) to reduce blood flow to the surface. This helps to conserve body heat and maintain core body temperature.

Sweat glands play a vital role in regulating body temperature through the process of evaporation. As sweat evaporates from the skin surface, it cools the body, helping to maintain a stable internal temperature.

When the body overheats, vasodilation occurs, widening blood vessels to increase blood flow to the skin for heat loss through radiation and sweating, which helps cool the body down through evaporation.

The dermis is primarily composed of connective tissue, which provides strength, elasticity, and support to the skin. This connective tissue is rich in elastic fibers and collagen.

The dermis is the inner layer of skin that contains blood vessels, nerve fibers, and various sensory receptors. It plays a critical role in sensation and nutrient supply to the skin.

Melanin is the pigment that determines skin color and provides protection against the harmful effects of UV radiation. It absorbs UV rays, reducing the risk of skin damage and cancer.

The Malpighian Layer, also known as the stratum germinativum, is the innermost layer of the epidermis where actively dividing cells produce new cells that eventually move outward to replace the outer layers.

Sebaceous glands secrete sebum, an oily substance that waterproofs and moisturizes the skin and hair. This helps prevent water loss and keeps the skin supple.

Hair color is primarily determined by genetics, specifically the type and amount of melanin produced in the hair follicles. While hair does have growth cycles, it does not grow continuously without rest.

Ceruminous glands, which are modified sebaceous glands located in the ear canal, secrete earwax (cerumen) to protect the eardrum from dust, debris, and microorganisms.

The skin has numerous nerve endings located in the dermis that are responsible for sensing touch, pain, pressure, and temperature. These sensory receptors allow the skin to play a crucial role in our sense of touch.

Sweat is primarily composed of about 99% water, along with small amounts of salts and urea. This composition helps to cool the body through evaporation.

Vitiligo is a skin condition characterized by patches of skin losing their pigment due to the destruction of melanocytes, the cells responsible for producing melanin. This results in lighter areas on the skin.