(A) Keratin

Hair is primarily composed of a protein called keratin. Keratin is a fibrous structural protein that forms the main component of hair, as well as nails and the outer layer of the skin. It provides strength and resilience to these structures. The other options—Casein, Globulin, and Mucin—are proteins found in other parts of the body and have different functions.

(C) Bulimia

Bulimia nervosa is an eating disorder characterized by binge eating, which involves consuming large amounts of food in a short period of time, often with a lack of control. Individuals with bulimia then engage in compensatory behaviors, such as vomiting, excessive exercise, or fasting, to prevent weight gain. The person described in the question, who does not know when to stop eating, may be exhibiting characteristics of binge eating, which is a key feature of bulimia. Diabetes, anorexia, and hyperacidity are different health conditions and not typically associated with an inability to stop eating in the described manner.

(D) Cells which are similar in origin, form and function.

Tissues are groups of cells that are similar in origin, form, and function, working together to perform specific tasks in the body. Tissues can be classified into four main types: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Each type of tissue is composed of cells that share common characteristics and collaborate to carry out specialized functions within the body.

(B) Urethra

The urethra is the structure that forms a common passage for both urine and sperm in human males. It connects the urinary bladder to the external opening and serves as the channel through which urine and semen pass out of the body. The other options—Oviduct, Ureter, and Vas deferens—are not involved in the passage of urine in males. Oviduct is part of the female reproductive system, while the ureter carries urine from the kidneys to the bladder, and the vas deferens is a duct that transports sperm from the testes to the urethra.

(A) Small Intestine

The absorption of nutrients from food primarily occurs in the small intestine. The small intestine is a long, coiled tube that follows the stomach in the digestive tract. It is the primary site for the absorption of nutrients such as sugars, amino acids, fatty acids, vitamins, and minerals into the bloodstream. The small intestine has specialized structures called villi and microvilli that increase its surface area, facilitating efficient absorption of nutrients. The large intestine primarily absorbs water and electrolytes but is not the main site for nutrient absorption. The stomach plays a role in digestion but is not a major site of nutrient absorption. The liver is involved in processing and storing nutrients but does not directly absorb them from the digestive tract.

(D) Kwashiorkor

Kwashiorkor is a disease caused by the deficiency of protein in the diet. It is a form of malnutrition that particularly affects children in regions where there is a lack of access to an adequate protein source. Symptoms of kwashiorkor include edema (swelling), stunted growth, and changes in skin and hair. The other options listed—Hypokalemia, Dermatosis, and Goitre—are not specifically caused by a deficiency of protein. Hypokalemia is a low potassium level, dermatosis refers to various skin disorders, and goitre is often associated with iodine deficiency leading to thyroid gland enlargement.

(B) Allethrins

Allethrins are active chemicals commonly used in mosquito repellents and insecticides to deter or eliminate mosquitoes. They belong to a class of synthetic pyrethroid insecticides, which are designed to mimic the insecticidal properties of pyrethrins, natural insecticides derived from chrysanthemum flowers. These chemicals are effective in repelling and killing mosquitoes and other insects. The other options (Benzene Hexachlorophene, Atropine, and 2-Isopropoxiphimyal) are not typically used for mosquito control.

(B) Spleen

The organ primarily affected by malaria is the spleen. Malaria is a parasitic infection caused by Plasmodium parasites that are transmitted through the bites of infected mosquitoes. The parasites multiply in the liver and then infect red blood cells, leading to symptoms such as fever, chills, and an enlarged spleen. The spleen plays a crucial role in the immune response against malaria, but the infection can cause it to enlarge as it filters out infected red blood cells from the circulation. If left untreated, severe cases of malaria can lead to complications, including damage to the spleen and other organs.