Nokea
Which of the following is an example of an aromatic compound?
- A. Ethanol
- B. Toluene
- C. Acetone
- D. Butanal
Correct Answer: B
Rationale: Toluene is an aromatic compound due to its benzene ring structure, which satisfies the criteria of aromaticity. Aromatic compounds contain conjugated pi electrons in a ring structure, providing extra stability. Ethanol, acetone, and butanal are not aromatic compounds as they do not possess a benzene ring or meet the aromaticity criteria. Ethanol is an alcohol, acetone is a ketone, and butanal is an aldehyde, none of which have the characteristic benzene ring structure of aromatic compounds.
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What is a condition characterized by an overactive thyroid gland and excessive production of thyroid hormones called?
- A. Diabetes mellitus
- B. Hyperthyroidism
- C. Hypothyroidism
- D. Cushing's syndrome
Correct Answer: B
Rationale: Hyperthyroidism is a condition where the thyroid gland is overactive and produces an excessive amount of thyroid hormones. This can lead to symptoms such as weight loss, rapid heartbeat, sweating, and nervousness. Diabetes mellitus is a condition characterized by high blood sugar levels due to either insufficient insulin production or the body's inability to respond to insulin. Hypothyroidism is the opposite of hyperthyroidism, where the thyroid gland is underactive and produces insufficient thyroid hormones. Cushing's syndrome is a disorder that occurs when the body has a high level of the hormone cortisol for a long time.
The tonsils and adenoids, located in the throat, are part of the:
- A. Lymphatic system
- B. Endocrine system
- C. Respiratory system
- D. Digestive system
Correct Answer: A
Rationale: The tonsils and adenoids are part of the lymphatic system, not the respiratory, endocrine, or digestive systems. The lymphatic system plays a crucial role in the body's defense against infections and diseases by producing white blood cells and lymphatic fluid, which help in filtering harmful substances. The respiratory system is primarily responsible for breathing and gas exchange in the body, the endocrine system regulates hormones, and the digestive system is involved in the breakdown and absorption of nutrients from food. Therefore, the correct answer is the lymphatic system.
Osteoporosis is a condition that leads to weakened bones and an increased risk of fractures. Which hormone plays a key role in bone health and is often affected in osteoporosis?
- A. Estrogen
- B. Testosterone
- C. Thyroid hormone
- D. Insulin
Correct Answer: A
Rationale: Estrogen plays a crucial role in maintaining bone health by inhibiting bone resorption and promoting bone formation. In postmenopausal women, estrogen levels decrease, leading to an increased risk of osteoporosis due to accelerated bone loss. This hormonal imbalance contributes to weakened bones and an increased risk of fractures in individuals with osteoporosis. Testosterone and thyroid hormone do play roles in bone health, but estrogen has a more significant impact. Testosterone is more commonly associated with muscle mass and strength, while thyroid hormone regulates metabolism. Insulin is not directly involved in bone health and is not typically affected in osteoporosis.
What is the main difference between white and brown adipose tissue?
- A. Location only
- B. Function and energy metabolism
- C. Color only
- D. Both white and brown have the same function
Correct Answer: B
Rationale: The main difference between white and brown adipose tissue lies in their function and energy metabolism. White adipose tissue is primarily involved in energy storage, while brown adipose tissue is specialized for energy expenditure and thermogenesis. This functional disparity is the key dissimilarity between white and brown adipose tissue, rather than just their location or color. Choice A is incorrect because the difference is not only in location but also in function. Choice C is incorrect as color is not the defining factor in their distinction. Choice D is incorrect as white and brown adipose tissues serve different functions in the body.
What property of matter explains why ice floats on water?
- A. Viscosity
- B. Density
- C. Buoyancy
- D. Surface tension
Correct Answer: C
Rationale: The correct answer is C, buoyancy. Ice floats on water due to buoyancy, a property of matter. When water freezes into ice, it becomes less dense than liquid water, causing it to float. This phenomenon occurs because the molecules in ice are more spread out compared to liquid water, resulting in ice being less dense and able to float on the surface.
Choice A, viscosity, is incorrect because viscosity refers to a fluid's resistance to flow, not its ability to float.
Choice B, density, is incorrect because while ice being less dense than water is the reason it floats, this choice does not explain the specific property that causes this phenomenon.
Choice D, surface tension, is incorrect as it pertains to the cohesive forces between molecules at the surface of a liquid, not the reason why ice floats on water.