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 the amygdala. It is a small, almond-shaped structure located within the temporal lobe of the brain. The amygdala plays a crucial role in processing emotions such as fear, anger, pleasure, and other emotional responses. It is involved in the formation of emotional memories and helps regulate emotional responses to various stimuli. The frontal lobe is mainly responsible for higher cognitive functions such as decision-making and problem-solving, not processing emotions. The parietal lobe is involved in processing sensory information and spatial awareness, while the occipital lobe is primarily responsible for processing visual information.

Correct Answer: C

Rationale: The pituitary gland, often referred to as the 'master gland,' controls the release of hormones from other endocrine glands in the body. It secretes various hormones that regulate many bodily functions, making it a central and vital component of the endocrine system. The thyroid gland (Choice A) regulates metabolism, the adrenal gland (Choice B) produces hormones like adrenaline, and the pineal gland (Choice D) secretes melatonin, but none of these glands are considered the 'master gland' that controls the functions of other endocrine glands.

Correct Answer: B

Rationale: The correct answer is a hinge joint. The elbow joint is a hinge joint that allows for flexion and extension movements, much like the movement of a door hinge. This type of joint permits movement in one plane, similar to the action of opening and closing a door. The other choices are incorrect: A) Ball and socket joints allow for a wide range of motion in multiple directions, such as the hip and shoulder joints. C) Pivot joints allow rotation around a single axis, like the joint at the top of the neck that allows the head to turn from side to side. D) Saddle joints are found in the thumb and have a biaxial range of motion allowing flexion, extension, adduction, abduction, and circumduction.

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.