1. The pigment that gives color to human skin is (a) Melanin. Melanin is a pigment produced by specialized cells called melanocytes, which are found in the basal layer of the epidermis. The amount and type of melanin synthesized by melanocytes determine an individual's skin color, ranging from pale toRead more

    The pigment that gives color to human skin is (a) Melanin. Melanin is a pigment produced by specialized cells called melanocytes, which are found in the basal layer of the epidermis. The amount and type of melanin synthesized by melanocytes determine an individual’s skin color, ranging from pale to dark.
    Melanin plays a crucial role in protecting the skin from the harmful effects of ultraviolet (UV) radiation from the sun. It absorbs UV radiation and dissipates it as heat, thereby reducing the risk of DNA damage and skin cancer.
    The distribution and activity of melanocytes can be influenced by factors such as genetics, sun exposure, hormonal changes, and aging, leading to variations in skin color among different populations and individuals.
    While rhodopsin (b), idopsin (c), and anthocyanin (d) are all important in various biological processes, they are not directly involved in determining the color of human skin.

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  2. The largest organ of the human body is (c) Skin. Covering an average adult's body surface area of about 1.5 to 2 square meters, the skin serves as a protective barrier against external threats such as pathogens, chemicals, and physical injury. It consists of multiple layers, including the epidermis,Read more

    The largest organ of the human body is (c) Skin. Covering an average adult’s body surface area of about 1.5 to 2 square meters, the skin serves as a protective barrier against external threats such as pathogens, chemicals, and physical injury. It consists of multiple layers, including the epidermis, dermis, and hypodermis, each with distinct functions.

    Apart from protection, the skin regulates body temperature through sweating and blood flow, senses touch, pressure, temperature, and pain, and plays a crucial role in synthesizing vitamin D when exposed to sunlight. Additionally, the skin houses a variety of specialized cells that contribute to immune surveillance and defense against infections.

    While the brain (a), heart (b), and liver (d) are vital organs with essential functions, none match the skin’s extensive surface area and diverse roles in maintaining overall health and homeostasis in the human body.

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  3. The skin is thickest at (a) On the sole. The skin on the soles of the feet, specifically the plantar surface, is notably thicker compared to other areas of the body. This increased thickness is due to the presence of a thick layer of keratinized skin, known as the stratum corneum, which serves to prRead more

    The skin is thickest at (a) On the sole. The skin on the soles of the feet, specifically the plantar surface, is notably thicker compared to other areas of the body. This increased thickness is due to the presence of a thick layer of keratinized skin, known as the stratum corneum, which serves to protect the foot from friction, pressure, and abrasion associated with standing, walking, and other weight-bearing activities.
    Similarly, the skin on the palms of the hands (b) is also relatively thick due to the constant use and exposure to friction and pressure. However, the skin on the soles tends to be slightly thicker than that on the palms.
    In contrast, while the skin on the buttocks (c) and the head (d) may vary in thickness, they generally tend to be thinner compared to the skin on the soles and palms.

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  4. The heart is deprived of (c) Voluntary muscle. Unlike skeletal muscles, which are under conscious control and allow us to move our limbs voluntarily, the heart consists of cardiac muscle, which is involuntary. Cardiac muscle is a specialized type of muscle tissue found only in the heart and is respoRead more

    The heart is deprived of (c) Voluntary muscle. Unlike skeletal muscles, which are under conscious control and allow us to move our limbs voluntarily, the heart consists of cardiac muscle, which is involuntary. Cardiac muscle is a specialized type of muscle tissue found only in the heart and is responsible for the heart’s rhythmic contractions that pump blood throughout the body.
    Unlike voluntary muscles, such as those in our arms and legs, we cannot consciously control or regulate the contractions of cardiac muscle. Instead, the heart’s contractions are controlled by a specialized electrical conduction system within the heart itself, as well as by regulatory signals from the autonomic nervous system.
    This involuntary nature of cardiac muscle is essential for maintaining the heart’s continuous rhythmic contractions, which are vital for pumping blood to deliver oxygen and nutrients to tissues and organs throughout the body, ensuring their proper function and survival.

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  5. The function of the Iris is (c) Controlling the size of the pupil. The Iris, the colored, ring-shaped structure behind the cornea, regulates the amount of light entering the eye by adjusting the size of the pupil, the central opening in the middle of the Iris. In bright light conditions, the Iris coRead more

    The function of the Iris is (c) Controlling the size of the pupil. The Iris, the colored, ring-shaped structure behind the cornea, regulates the amount of light entering the eye by adjusting the size of the pupil, the central opening in the middle of the Iris.
    In bright light conditions, the Iris contracts, reducing the size of the pupil to limit the amount of light entering the eye and preventing overexposure. Conversely, in dim lighting, the Iris dilates, enlarging the pupil to allow more light to enter and improve visibility.
    By adjusting the size of the pupil, the Iris helps to optimize visual acuity and clarity in varying light environments. This mechanism ensures that the appropriate amount of light reaches the retina for optimal vision while protecting the delicate structures of the eye from potential damage due to excessive light exposure. The Iris’s ability to dynamically regulate pupil size contributes to the eye’s adaptability to different lighting conditions.

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