Which hormone is released in response to low blood glucose levels?

Correct Answer: B

Rationale: Glucagon is the hormone released in response to low blood glucose levels. When blood glucose levels drop, the pancreas secretes glucagon to stimulate the liver to break down glycogen into glucose, increasing blood sugar levels. This helps to restore the body's glucose balance. Insulin, on the other hand, is released in response to high blood glucose levels to lower blood sugar by promoting glucose uptake by cells. Cortisol is a stress hormone, and adrenaline is released in response to stress or danger, not specifically to regulate blood glucose levels.

Correct Answer: A

Rationale: Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. Its secretion is influenced by light exposure, with levels typically rising in the evening to promote sleep and falling in the morning to encourage wakefulness. Insulin is involved in regulating blood sugar levels, not the sleep-wake cycle. Cortisol plays a role in the body's stress response and circadian rhythm but is not the primary hormone regulating sleep-wake cycles. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle.

Correct Answer: B

Rationale: Adrenaline, also known as epinephrine, is the correct hormone produced by the adrenal medulla. It plays a crucial role in the body's fight-or-flight response, increasing heart rate, dilating airways, and mobilizing energy stores to prepare the body for perceived threats. Insulin (Choice A) is produced by the pancreas and regulates blood sugar levels, not by the adrenal medulla. Cortisol (Choice C) is produced by the adrenal cortex and is involved in regulating metabolism, immune response, and stress. Melatonin (Choice D) is produced by the pineal gland and regulates the sleep-wake cycle.

Correct Answer: B

Rationale: Vitamin K is essential for the synthesis of proteins required for blood clotting. It specifically assists in the activation of clotting factors to prevent excessive bleeding from injuries. Vitamin K plays a crucial role in maintaining a balance between clotting and bleeding in the body. Choices A, C, and D are incorrect. Vitamin A is important for vision, immune function, and skin health. Vitamin C is essential for collagen synthesis and acts as an antioxidant. Vitamin D is crucial for calcium absorption and bone health.

Correct Answer: B

Rationale: A pivot joint, such as the one found in the neck, allows for rotational movement, enabling the head to turn from side to side. This type of joint provides a specific axis of rotation, allowing for a turning motion around that axis. Choice A, the hinge joint, primarily allows movement in one plane, like the elbow joint's flexion and extension. Choice C, the ball and socket joint, allows for a wide range of motion in multiple directions, but it is not primarily known for rotational movement. Choice D, the saddle joint, allows for movements like bending, straightening, and limited rotation, but it is not primarily designed for rotational movement like the pivot joint.