What is the primary function of the cardiovascular system?

Correct Answer: A

Rationale: The correct answer is A: 'To transport oxygen and nutrients.' The primary function of the cardiovascular system is to transport oxygen, nutrients, and hormones to cells throughout the body and remove waste products. Choice B is incorrect because regulating body temperature is primarily the function of the body's thermoregulatory system, including sweat glands and blood vessels near the skin surface. Choice C is incorrect because while the cardiovascular system does help remove waste products through circulation, it is not its primary function. Choice D is incorrect as hormone production is mainly carried out by endocrine glands, not the cardiovascular system.

Correct Answer: B

Rationale: Adrenaline, also known as epinephrine, is released during the body's fight-or-flight response. This hormone prepares the body for rapid action by increasing heart rate, dilating airways, and redirecting blood flow to essential organs in response to stress or danger. Insulin is not released during the fight-or-flight response; its primary role is to regulate blood sugar levels. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, and cortisol is released in response to stress to regulate various bodily functions, but adrenaline is the hormone specifically associated with the fight-or-flight response.

Correct Answer: C

Rationale: The correct answer is option C: Retina. The retina contains photoreceptor cells, including cones that are responsible for color vision. Cones are sensitive to different wavelengths of light, allowing us to perceive and differentiate various colors. Choice A, Cornea, is the transparent outer layer of the eye that helps focus light. It does not play a direct role in color vision. Choice B, Iris, is the colored part of the eye that controls the size of the pupil and regulates the amount of light entering the eye. While it is essential for adjusting light levels, it is not directly involved in color vision. Choice D, Lens, is responsible for focusing light onto the retina. It helps to form clear images on the retina but does not play a role in color vision.

Correct Answer: A

Rationale: The correct answer is the pancreas. The pancreas is responsible for producing insulin, a hormone crucial for regulating blood glucose levels. Insulin plays a key role in allowing cells to take in glucose, thereby helping to keep blood sugar levels in check. The liver (choice B), gallbladder (choice C), and kidneys (choice D) do not produce insulin. The liver is involved in glycogen storage and glucose regulation, the gallbladder stores bile, and the kidneys filter blood and regulate fluid balance.

Correct Answer: C

Rationale: The correct answer is C: Cortisol. Cortisol, produced by the adrenal glands, is involved in the body's stress response. It helps regulate metabolism, immune function, and the body's response to stressors by increasing blood sugar levels, suppressing the immune system, and aiding in the metabolism of fats, carbohydrates, and proteins. Choice A, Insulin, is a hormone that regulates blood sugar levels and is not primarily involved in the stress response. Choice B, Adrenaline, is also known as epinephrine and is involved in the fight-or-flight response, which is related to stress but is not the main hormone in the body's stress response. Choice D, Melatonin, is a hormone that regulates sleep-wake cycles and is not directly involved in the stress response.

Correct Answer: A

Rationale: The cochlea, situated in the inner ear, is responsible for detecting sound waves and converting them into neural signals that are transmitted to the brain for processing. The cochlea contains specialized sensory cells that respond to different frequencies of sound, allowing us to hear a wide range of sounds. The other structures listed, such as the eustachian tube, ossicles, and semicircular canals, play roles in functions like equalizing pressure, transmitting vibrations, and maintaining balance, respectively, but they are not directly involved in the detection of sound.

Correct Answer: A

Rationale: The cerebellum is the correct answer. It is responsible for controlling balance, coordination, and fine motor movements. The cerebrum is mainly associated with higher brain functions such as thinking and decision-making, not specifically balance and coordination. The brainstem is responsible for basic life functions like breathing and heartbeat, while the medulla oblongata is involved in regulating autonomic functions like breathing, heart rate, and blood pressure. Therefore, the cerebellum stands out as the key brain region for maintaining physical control and movement.

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).

Correct Answer: C

Rationale: The correct answer is the front portion of the parietal lobe. The motor cortex, located in this area, is responsible for planning, controlling, and executing voluntary movements. It plays a crucial role in coordinating the body's movement. Choice A, the top, middle portion of the parietal lobe, is incorrect as this region is more involved in processing sensory information rather than controlling movement. Choice B, the back of the head, is incorrect as it typically refers to the occipital lobe responsible for processing visual information. Choice D, around the auditory cortex, is incorrect as the auditory cortex is primarily involved in processing auditory information, not controlling body movement.