Nokea
Which hormone is produced by the thyroid gland to regulate metabolism?
- A. Adrenaline
- B. Thyroxine
- C. Cortisol
- D. Insulin
Correct Answer: B
Rationale: Thyroxine, also known as T4, is the hormone produced by the thyroid gland to regulate metabolism. It is essential for controlling the body's metabolic rate, heart and digestive function, muscle control, brain development, and bone maintenance. Adrenaline is produced by the adrenal glands, not the thyroid gland. Cortisol is produced by the adrenal cortex, not the thyroid gland. Insulin is produced by the pancreas, not the thyroid gland. Therefore, the correct answer is Thyroxine (B).
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Which hormone is responsible for regulating blood sugar levels?
- A. Thyroxine
- B. Insulin
- C. Adrenaline
- D. Cortisol
Correct Answer: B
Rationale: The correct answer is B: Insulin. Insulin, produced by the pancreas, plays a crucial role in regulating blood sugar levels by facilitating glucose uptake into cells. Thyroxine, adrenaline, and cortisol do not directly regulate blood sugar levels. Thyroxine is produced by the thyroid gland and regulates metabolism. Adrenaline and cortisol are hormones involved in stress responses and do not have a primary function in blood sugar regulation. Understanding the functions of these hormones is crucial in differentiating their roles in the body and identifying the specific hormone responsible for blood sugar regulation.
What is the difference between polygenic inheritance and pleiotropy?
- A. Polygenic inheritance involves multiple genes influencing one trait, while pleiotropy involves one gene affecting multiple traits.
- B. Polygenic inheritance is found in simple Mendelian traits, while pleiotropy is found in complex traits.
- C. Polygenic inheritance is always quantitative, while pleiotropy can be qualitative or quantitative.
- D. Both involve multiple genes and multiple traits, but the specific mechanisms differ
Correct Answer: A
Rationale: - Polygenic inheritance refers to the situation where a trait is influenced by multiple genes, each contributing a small effect to the phenotype. These traits often show continuous variation and are not easily categorized into discrete categories.
- Pleiotropy, on the other hand, occurs when a single gene influences multiple, seemingly unrelated traits. This means that a mutation in one gene can lead to multiple phenotypic effects across different traits or characteristics.
- Therefore, the key difference between polygenic inheritance and pleiotropy lies in the number of genes involved in influencing a trait (multiple genes in polygenic inheritance vs. one gene in pleiotropy) and the direction of influence (one trait affected by multiple genes in polygenic inheritance vs. multiple traits affected by one gene in pleiotropy).
Which condition can lead to blood clots and stroke?
- A. Aneurysm
- B. Arrhythmia
- C. Asthma
- D. Hypertension
Correct Answer: D
Rationale: Hypertension is the correct answer. Hypertension can cause damage to blood vessels, increasing the risk of blood clots forming, which can potentially lead to a stroke. Aneurysm is a localized, abnormal dilation of a blood vessel that can lead to complications but does not directly cause blood clots and strokes. Arrhythmia refers to irregular heart rhythms and is not directly linked to the formation of blood clots. Asthma is a chronic respiratory condition and does not typically lead to blood clots and strokes.
Which of the following accurately describes saltatory conduction?
- A. It is faster than normal nerve conduction
- B. It occurs from one node of Ranvier to the next
- C. It only occurs in myelinated neurons
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, 'All of the above.' Saltatory conduction is faster than normal nerve conduction, occurs from one node of Ranvier to the next, and is exclusive to myelinated neurons. This form of conduction allows for the rapid transmission of nerve impulses by the action potential jumping between the nodes of Ranvier in myelinated neurons, enhancing the efficiency of signal propagation along the axon. Choice A is correct as saltatory conduction is indeed faster than normal conduction. Choice B is accurate as it describes the mechanism of conduction 'jumping' from one node of Ranvier to the next. Choice C is correct because saltatory conduction occurs specifically in myelinated neurons where the myelin sheath insulates the axon except at the nodes of Ranvier, facilitating faster transmission of nerve impulses.
What is the term for a solution that has exactly the same concentration of solute as another solution?
- A. Saturated solution
- B. Unsaturated solution
- C. Isotonic solution
- D. Concentrated solution
Correct Answer: C
Rationale: An isotonic solution is a solution that has the same concentration of solute as another solution. When cells are placed in an isotonic solution, there is no net movement of water across the cell membrane, maintaining equilibrium. Choice A, a saturated solution, refers to a solution that contains the maximum amount of solute that can be dissolved at a given temperature. Choice B, an unsaturated solution, is a solution that contains less solute than a saturated solution under the same conditions. Choice D, a concentrated solution, is a solution with a high amount of solute compared to the solvent.