Nokea
Which hormone is responsible for regulating sleep-wake cycles and is influenced by light exposure?
- A. Melatonin
- B. Cortisol
- C. Estrogen
- D. Glucagon
Correct Answer: A
Rationale: The correct answer is A: Melatonin. Melatonin is the hormone responsible for regulating sleep-wake cycles, also known as the circadian rhythm. Its production is influenced by light exposure, with levels increasing in the evening in response to darkness, signaling the body that it is time to sleep. Choice B, cortisol, is a stress hormone and does not directly regulate sleep-wake cycles. Choice C, estrogen, is a sex hormone and is not primarily involved in regulating sleep. Choice D, glucagon, is a hormone that increases blood glucose levels and is not related to sleep-wake cycles.
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Which of the following is NOT a common symptom of lactose intolerance?
- A. Gas
- B. Bloating
- C. Diarrhea
- D. Nausea
Correct Answer: D
Rationale: A) Gas: Gas is a common symptom of lactose intolerance. When lactose is not properly digested, it can ferment in the colon, leading to the production of gas.
B) Bloating: Bloating is another common symptom of lactose intolerance. The buildup of gas in the digestive system can cause bloating and discomfort.
C) Diarrhea: Diarrhea is a common symptom of lactose intolerance. When lactose is not broken down in the small intestine, it can draw excess water into the colon, resulting in diarrhea.
D) Nausea: Nausea is not a common symptom of lactose intolerance. While some individuals may experience mild stomach discomfort or cramps, nausea is not typically associated with lactose intolerance.
Which organ produces insulin?
- A. Pancreas
- B. Liver
- C. Stomach
- D. Kidneys
Correct Answer: A
Rationale: Insulin is a hormone that regulates blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. The pancreas, located behind the stomach, is the organ responsible for producing insulin. Within the pancreas, specialized cells known as beta cells synthesize and secrete insulin in response to changes in blood glucose levels. The liver, although vital for metabolism, does not produce insulin. Similarly, the stomach and kidneys do not play a role in insulin production. Hence, the correct answer is the pancreas.
During photosynthesis, plants capture sunlight and convert water and carbon dioxide into glucose and oxygen. This is an example of a:
- A. Decomposition reaction
- B. Combustion reaction
- C. Synthesis reaction
- D. Double displacement reaction
Correct Answer: C
Rationale: This is an example of a synthesis reaction because simpler substances (water and carbon dioxide) are combined to form a more complex substance (glucose) in the presence of sunlight. Choice A (Decomposition reaction) involves breaking down a compound into simpler substances, which is the opposite of what happens in photosynthesis. Choice B (Combustion reaction) typically involves a substance reacting with oxygen to produce heat and light, not the formation of glucose and oxygen from simpler substances. Choice D (Double displacement reaction) involves an exchange of ions between two compounds, which is not what occurs in photosynthesis.
A car skids on a wet road. What is the main force preventing the car from stopping?
- A. Friction
- B. Gravitational force
- C. Normal force from the road
- D. Air resistance
Correct Answer: A
Rationale: The correct answer is A: Friction. Friction is the force that opposes the motion of the car on the wet road surface, making it harder for the car to stop. When the car skids, the friction between the tires and the wet road surface is reduced, leading to a loss of traction and making it challenging for the car to come to a halt. Gravitational force (choice B) is the force that pulls objects toward each other due to gravity and does not directly impact the car's ability to stop on a wet road. The normal force from the road (choice C) is the force exerted by the road surface perpendicular to the car's tires and does not play a significant role in stopping the car. Air resistance (choice D) is the force that opposes the motion of an object through the air, but it is not the main force preventing the car from stopping on a wet road.
What is the purpose of the periosteum, the tough outer layer of bone?
- A. Produces red blood cells
- B. Provides protection and nourishment to bone
- C. Forms the joint surface
- D. Stores minerals
Correct Answer: B
Rationale: The periosteum, the tough outer layer of bone, serves the purpose of providing protection to the bone and nourishing it through the blood vessels it contains. It acts as a protective layer for the bone structures. Choices A, C, and D are incorrect because the periosteum does not produce red blood cells (which is the function of bone marrow), form joint surfaces (which is typically the role of articular cartilage), or store minerals (which is primarily done by bone tissue itself and not the periosteum).