Which gland is responsible for regulating metabolism and calcium levels?

Correct Answer: C

Rationale: The correct answer is the thyroid gland (Choice C). The thyroid gland plays a crucial role in regulating metabolism by producing hormones like thyroxine, which control the body's metabolic rate. It also helps in controlling calcium levels in the blood through the release of calcitonin. The pituitary gland (Choice A) is known as the 'master gland' as it controls other glands but is not primarily responsible for regulating metabolism and calcium levels. The adrenal gland (Choice B) produces hormones like cortisol and adrenaline, which are involved in the stress response and metabolism, but they do not specifically regulate calcium levels. The pineal gland (Choice D) mainly produces melatonin, a hormone that helps in regulating sleep-wake cycles and has no direct role in metabolism or calcium level regulation.

Correct Answer: B

Rationale: The correct answer is a hinge joint. The knee is a hinge joint that allows for flexion and extension movements, enabling the leg to bend and straighten. This type of joint is designed for movement along one plane, similar to a door hinge. Choice A, ball and socket joint, is incorrect as this type of joint allows for a wider range of motion in multiple directions, unlike the knee joint. Choice C, pivot joint, and Choice D, saddle joint, are also incorrect as they do not accurately describe the type of joint found in the knee.

Correct Answer: A

Rationale: The genetic material, which is composed of DNA, is primarily located in the nucleus of a cell. The nucleus serves as the control center of the cell, housing the genetic information that directs the cell's functions and characteristics. Choice B (Mitochondria), C (Ribosome), and D (Golgi apparatus) are incorrect because while these cellular components play essential roles in the cell, they do not house the genetic material. Mitochondria are known as the powerhouse of the cell, responsible for energy production; ribosomes are involved in protein synthesis, and the Golgi apparatus is responsible for processing and packaging proteins for transport.

Correct Answer: B

Rationale: Vitamin B12 is the correct answer. It is crucial for the formation and maturation of red blood cells, playing a vital role in preventing megaloblastic anemia. Additionally, Vitamin B12 is essential for maintaining nerve function. Vitamin A is important for vision and immune function, Vitamin C is necessary for collagen synthesis and immune health, and Vitamin D is crucial for bone health and immune function. Therefore, options A, C, and D are incorrect as they do not play a direct role in the formation of red blood cells.

Correct Answer: B

Rationale: The correct answer is the Glomerulus. The glomerulus is a network of tiny blood vessels located within the Bowman's capsule. It acts as the initial filtering component in the nephron, filtering blood and allowing waste products and excess substances to pass through to form urine. Choice A, Nephron, is incorrect as the nephron is the structural and functional unit of the kidney composed of several parts, including the glomerulus. Choice C, Bowman's capsule, is where the glomerulus is located, but it is not the structure responsible for filtering blood. Choice D, Loop of Henle, plays a role in reabsorption of water and electrolytes but is not the primary structure for blood filtration in the kidney.

Correct Answer: B

Rationale: White blood cells, also known as leukocytes, play a crucial role in the immune system by primarily combating infections. These cells can identify and destroy pathogens, such as bacteria and viruses, helping the body defend against illnesses and maintain overall health. Red blood cells are responsible for oxygen transport, platelets aid in blood clotting, and plasma carries various components throughout the circulatory system, but none of these functions involve fighting infections like white blood cells do.

Correct Answer: C

Rationale: The occipital lobe, located at the back of the brain, is primarily responsible for processing visual information received from the eyes. It plays a crucial role in interpreting and making sense of the visual stimuli perceived by the eyes, such as shapes, colors, and movement. This region is essential for visual perception and is specialized for processing and analyzing visual input, making it the correct answer. The frontal lobe is primarily involved in higher cognitive functions like decision-making and problem-solving, not visual processing. The parietal lobe is more related to sensory processes and spatial awareness, while the temporal lobe is primarily involved in processing auditory information and memory, not visual processing.

Correct Answer: B

Rationale: Thyroxine, produced by the thyroid gland, is the hormone responsible for regulating metabolism. It plays a fundamental role in controlling the body's metabolic rate, affecting processes such as energy production and utilization. Thyroxine also influences growth and development in the body. Choice A, Insulin, is involved in regulating blood sugar levels and promoting the storage of glucose. While insulin has an impact on metabolism, it is not primarily responsible for regulating overall metabolic rate. Choice C, Glucagon, acts in opposition to insulin, stimulating the release of glucose from the liver to increase blood sugar levels. Glucagon primarily targets glucose regulation rather than overall metabolism. Choice D, Cortisol, is known as the stress hormone and plays a role in the body's response to stress, regulation of blood pressure, immune function, and anti-inflammatory actions. While cortisol can have some effects on metabolism during stress responses, it is not the primary hormone responsible for regulating overall metabolic rate.

Correct Answer: B

Rationale: The correct answer is B: 'To produce bile and detoxify substances.' The liver's primary functions include producing bile, which aids in the digestion and absorption of fats, and detoxifying harmful substances in the blood. While the liver does play a role in blood filtration, its key functions are related to bile production and detoxification. Choices C and D are incorrect because the liver does not produce insulin (produced by the pancreas) or red blood cells (produced in the bone marrow).