Nokea
What is the primary function of nephrons?
- A. Store urine
- B. Filter blood and remove waste products
- C. Produce hormones
- D. Control blood pressure
Correct Answer: B
Rationale: Nephrons are the functional units of the kidneys responsible for filtering blood to remove waste products, excess ions, and water. This process leads to the formation of urine, aiding in maintaining the body's fluid and electrolyte balance. The primary function of nephrons is not to store urine but to filter blood and eliminate waste products. Choice C, 'Produce hormones,' is incorrect as nephrons primarily focus on filtration rather than hormone production. Choice D, 'Control blood pressure,' is also incorrect as while the kidneys do play a role in regulating blood pressure, it is not the primary function of nephrons within the kidneys.
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Homologous structures are those that:
- A. Have the same function but different origins
- B. Have different functions but the same origin
- C. Are similar in appearance and function due to shared ancestry
- D. Are identical in both appearance and function
Correct Answer: C
Rationale: Homologous structures are defined as anatomical features that are similar in appearance and function due to shared ancestry. This means that these structures are inherited from a common ancestor and may have evolved to fulfill different functions in different species. Option A, which mentions structures with the same function but different origins, describes analogous structures, not homologous ones. Option B, which refers to structures with different functions but the same origin, actually characterizes vestigial structures. Option D, stating that structures are identical in appearance and function, does not necessarily imply homology; such structures could result from convergent evolution rather than shared ancestry. Understanding homologous structures provides insights into the evolutionary relationships between different species and supports the concept of common descent.
Which part of the brainstem controls heart rate and breathing?
- A. Medulla oblongata
- B. Pons
- C. Midbrain
- D. Thalamus
Correct Answer: A
Rationale: The medulla oblongata is a critical part of the brainstem responsible for regulating essential functions such as heart rate, breathing, and blood pressure. It houses centers that oversee these involuntary processes, making it the correct answer. The pons, midbrain, and thalamus do not primarily control heart rate and breathing, thus making them incorrect choices for this question.
Which property of a substance refers to its ability to be hammered or pressed into thin sheets without breaking?
- A. Malleability
- B. Ductility
- C. Viscosity
- D. Conductivity
Correct Answer: A
Rationale: Malleability is the correct answer as it is the property of a substance that allows it to be hammered or pressed into thin sheets without breaking. This property is crucial for materials like metals that need to be shaped without breaking. Ductility, on the other hand, refers to the ability of a substance to be drawn into thin wires, not hammered into sheets. Viscosity is a measure of a fluid's resistance to flow, indicating its thickness or thinness, and is unrelated to the ability to be hammered. Conductivity, on the other hand, refers to a substance's ability to conduct electricity or heat, which is not related to its ability to be hammered or pressed into thin sheets.
Which of the following reagents can be used to convert a primary alcohol to an alkyl halide?
- A. HI
- B. H2O
- C. NaOH
- D. SOCl2
Correct Answer: D
Rationale: SOCl2 (thionyl chloride) is commonly used to convert primary alcohols to alkyl halides through an SN2 mechanism. Thionyl chloride reacts with the alcohol to form an alkyl chloride. HI (hydroiodic acid) is typically used to convert alcohols to alkyl iodides specifically, not alkyl halides in general. H2O (water) and NaOH (sodium hydroxide) are not reagents used for converting alcohols to alkyl halides. Therefore, the correct answer is SOCl2 as it facilitates the conversion of primary alcohols to alkyl halides, unlike the other options provided.
Which type of muscle is characterized by voluntary control and is responsible for body movement?
- A. Cardiac muscle
- B. Smooth muscle
- C. Skeletal muscle
- D. Connective tissue
Correct Answer: C
Rationale: The correct answer is skeletal muscle. Skeletal muscle is characterized by voluntary control, meaning it is under conscious control. It is responsible for body movement, such as walking, running, and lifting objects. Cardiac muscle is involuntary and found in the heart, while smooth muscle is also involuntary and found in organs like the intestines. Connective tissue is not a type of muscle but rather a type of tissue that provides support and structure in the body.