Human Physiology and Anatomy

A person with blood group AB is known as the universal recipient because they have both A and B antigens on their red blood cells and no anti-A or anti-B antibodies in their plasma, allowing them to receive blood from any group safely.

The tibia is one of the two long bones in the lower leg, commonly known as the shinbone. It is not found in the skull, arm, or face, making 'Leg' the correct answer.

The cerebrum is the largest part of the human brain, responsible for higher brain functions such as thought and action. The medulla oblongata and cerebellum are smaller parts involved in autonomic functions and coordination, respectively.

The medulla oblongata is a part of the human brainstem that controls vital autonomic functions such as breathing and heart rate. Therefore, it is correctly identified as part of the brain.

Leukemia is a type of cancer that affects the blood and bone marrow, characterized by the overproduction of abnormal white blood cells. Therefore, the correct answer is 'Blood'.

The average resting heart rate for a normal adult male is typically around 70 beats per minute, which is within the normal range of 60 to 100 bpm.

The average adult resting pulse rate typically ranges from 60 to 100 beats per minute, with a common average around 72-80 bpm, making option C the most accurate choice.

Hemoglobin is a protein in red blood cells responsible for transporting oxygen from the lungs to body tissues. This is its primary function, making option A correct.

Red blood corpuscles, or red blood cells, are primarily formed in the bone marrow, which is the soft tissue inside bones responsible for hematopoiesis.

Hemoglobin is a protein in red blood cells that contains iron, which binds oxygen for transport in the blood. Iron is the main constituent responsible for oxygen binding, making option B correct.

The total blood volume in a normal adult human is approximately 5-6 liters, which is the widely accepted standard range in physiology.

Most nutrient molecules are absorbed in the small intestine because it has a large surface area with villi and microvilli that facilitate nutrient absorption. The stomach mainly digests food, the liver processes nutrients but does not absorb them, and the large intestine absorbs water and some minerals, not most nutrients.

A newly born infant has approximately 270 to 300 bones, which later fuse to form the 206 bones found in an adult human skeleton. Therefore, option D (300) is the closest and correct answer.

The external ear's shape is maintained by elastic cartilage, which provides both structure and flexibility. Fibrocartilage and articular cartilage are found in other parts of the body and do not contribute to the ear's shape.

Anti Diuretic Hormone (ADH) is secreted by the posterior pituitary gland, which regulates water balance in the body by controlling the amount of water reabsorbed by the kidneys.

A baby with blood type O+ cannot have an AB- mother because the mother with AB blood type has A and B alleles, so the baby cannot inherit O blood type from her. Also, the Rh factor incompatibility is possible, but the ABO incompatibility makes AB mother impossible for an O baby.

The aorta is the largest artery in the human body, responsible for carrying oxygenated blood from the heart to the rest of the body. The other arteries listed are smaller and serve more localized regions.

Serum is the component of blood plasma that remains after the blood has clotted and the clotting proteins have been removed. Therefore, serum is plasma minus its clotting proteins.

The heart pumps deoxygenated blood from the right ventricle to the lungs for oxygenation. This blood is low in oxygen and high in carbon dioxide before reaching the lungs.

The largest organ of the human body is the skin, which covers the entire body surface. Although the interstitium was proposed as a new organ in 2018, it is not considered the largest organ, but rather a fluid-filled space within connective tissues.

Reptiles have a 'mixed heart' structure, typically a three-chambered heart with two atria and one ventricle that is partially divided, allowing some mixing of oxygenated and deoxygenated blood. Birds have a four-chambered heart with complete separation, and fish have a two-chambered heart.

Authoritative sources including clinical and physiology references confirm that approximately 99% of the body's calcium is stored in bones and teeth, while about 1% of total calcium is present in the blood and extracellular fluid. The blood calcium exists in three forms: about 40% bound to proteins, 10% complexed with anions, and 50% as free ionized calcium. Therefore, the correct answer to the question about the percentage of total calcium present in the blood is about 1%, corresponding to option C.

The average normal body temperature for a healthy adult is 98.6°F. This value is widely accepted in medical science as the standard normal temperature.

Normal human body temperature is commonly accepted as 98.6°F, which is equivalent to 37°C. This is a standard conversion in both medical and scientific contexts.

Vitamin D is synthesized in the skin when it is exposed to sunlight, specifically ultraviolet B (UVB) rays. The other vitamins listed are not produced in the skin in response to sunlight.