Nokea
Which of these body parts does not contain melanin?
- A. Hair
- B. Nails
- C. Skin
- D. Iris
Correct Answer: D
Rationale: The iris is the colored part of the eye that determines the eye's color. Melanin is not present in the iris, unlike hair, nails, and skin. Melanin gives color to hair, nails, and skin, but not to the iris. Therefore, the correct answer is the iris (Choice D). Choices A, B, and C contain melanin and are incorrect.
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How does water affect the temperature of a living thing?
- A. Water increases temperature.
- B. Water keeps temperature stable.
- C. Water decreases temperature.
- D. Water does not affect temperature.
Correct Answer: B
Rationale: Water has a high specific heat capacity, which means it can absorb and release a large amount of heat energy without causing a significant change in temperature. This property allows water to help regulate the temperature of living things by buffering against sudden temperature changes in the environment. Overall, water helps to maintain a stable temperature within living organisms, which is crucial for their survival and physiological processes. Choices A, C, and D are incorrect because water's high specific heat capacity enables it to stabilize temperatures rather than increasing, decreasing, or having no effect on them.
Which of the following structures is the natural pacemaker of the heart?
- A. Sinoatrial node
- B. Submental node
- C. Atrioventricular node
- D. Scalene node
Correct Answer: A
Rationale: The sinoatrial (SA) node is often referred to as the natural pacemaker of the heart because it is a group of cells located in the right atrium responsible for initiating the electrical signals that coordinate the heart's contractions. The SA node sets the rate and rhythm of the heartbeats, making it a crucial component in the heart's function. The other options, Submental node, Atrioventricular node, and Scalene node, are not related to the regulation of the heart's electrical activity. The Submental node is a lymph node located under the chin, the Atrioventricular node is responsible for passing electrical signals from the atria to the ventricles, and the Scalene node does not exist in the context of the heart's electrical system.
To which of the following bone types do the spine and hips belong?
- A. Curved bones
- B. Irregular bones
- C. Flat bones
- D. Long bones
Correct Answer: B
Rationale: The correct answer is B: Irregular bones. The spine and hips belong to the category of irregular bones. Irregular bones have complex shapes that do not fit into other bone type categories. These bones serve functions such as support and protection, and their shapes vary depending on their specific roles in the body. Choice A, curved bones, is incorrect because bones like ribs are typically described as curved, not the spine and hips. Choice C, flat bones, is incorrect as flat bones include the skull and ribs, but not the spine and hips. Choice D, long bones, is also incorrect because long bones include bones like the femur and humerus, which are elongated with a shaft and distinct ends, unlike the spine and hips.
Which of the following terms describes the enlargement of an organ or tissue?
- A. Dystrophy
- B. Atrophy
- C. Hypertrophy
- D. Eutrophy
Correct Answer: C
Rationale: Hypertrophy refers to the enlargement of an organ or tissue, typically due to an increase in the size of individual cells. This can occur in response to increased workload, hormonal stimulation, or other factors. On the other hand, dystrophy refers to the degeneration and deterioration of tissue, atrophy describes the decrease in the size of an organ or tissue, and eutrophy denotes a state of normal nutrition or growth. Therefore, the correct answer is 'Hypertrophy' as it specifically relates to the increase in size or volume of an organ or tissue.
What is the action of the triceps reflex?
- A. Forces contraction of the triceps and extension of the arm.
- B. Forces contraction of the biceps, relaxation of the biceps, and arm extension.
- C. Causes the triceps to contract, causing the forearm to supinate and flex.
- D. Causes the triceps to relax and the upper arm to pronate and extend.
Correct Answer: A
Rationale: The triceps reflex causes the triceps muscle to contract, leading to the extension of the arm. This reflex is a protective response to sudden stretching of the triceps muscle, as seen when a physician taps the triceps tendon during a physical examination. Choice A is the correct answer as it accurately reflects the action of the triceps reflex. Choices B, C, and D are incorrect because they describe actions that are not associated with the triceps reflex. Biceps contraction, forearm supination, flexion, triceps relaxation, and pronation are not part of the triceps reflex arc.