How many neurons typically comprise a sensory pathway?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: C
Rationale: A sensory pathway generally consists of three neurons: a first-order neuron, a second-order neuron, and a third-order neuron. The first-order neuron carries sensory information from the periphery to the spinal cord or brainstem. The second-order neuron then transmits this information to the thalamus or cerebellum. Finally, the third-order neuron projects the sensory input to the cerebral cortex for processing and perception. Therefore, the correct answer is 3 (C). Choices A, B, and D are incorrect as they do not align with the typical structure of a sensory pathway involving three neurons.
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Which level of protein structure is defined by the folds and coils of the protein's polypeptide backbone?
- A. Primary
- B. Secondary
- C. Tertiary
- D. Quaternary
Correct Answer: B
Rationale: The correct answer is B: Secondary. The secondary structure of a protein is defined by the folds and coils of the protein's polypeptide backbone. This level of structure is characterized by the formation of alpha helices and beta sheets, which are stabilized by hydrogen bonds between amino acids along the polypeptide chain. Choice A, Primary, refers to the linear sequence of amino acids in the protein. Choice C, Tertiary, involves the 3D folding of the entire polypeptide chain. Choice D, Quaternary, pertains to the arrangement of multiple polypeptide subunits in a protein complex.
What is the process of cell division in somatic (most body) cells called?
- A. Mitosis
- B. Meiosis
- C. Respiration
- D. Cytogenesis
Correct Answer: A
Rationale: Mitosis is the correct answer. It is the process of cell division in somatic cells, leading to the formation of two identical daughter cells with the same number of chromosomes as the parent cell. Meiosis, on the other hand, is the type of cell division that occurs in sex cells, leading to the formation of gametes with half the number of chromosomes. Respiration is a completely different biological process related to energy production, and cytogenesis is not a recognized term for cell division.
Which of the following correctly lists the four properties that all types of muscle tissue share?
- A. Contractile, excitable, elastic, extensible
- B. Contractile, voluntary, elastic, extensible
- C. Contractile, excitable, voluntary, extensible
- D. Contractile, excitable, elastic, voluntary
Correct Answer: A
Rationale: The correct answer is A: 'Contractile, excitable, elastic, extensible.' All types of muscle tissue share these four properties. Muscle tissue can contract, respond to stimuli, stretch and return to its original shape (elastic), and extend or stretch (extensible). Choice B is incorrect because not all muscle tissues are voluntary (some are involuntary). Choice C is incorrect because not all muscle tissues are voluntary. Choice D is incorrect because not all muscle tissues are voluntary and lack the elastic property.
Which of the following statements about the autonomic nervous system (ANS) is true?
- A. It controls involuntary functions
- B. It contains motor (efferent) neurons
- C. It contains sensory (afferent) neurons
- D. It contains both parasympathetic and sympathetic nerves
Correct Answer: D
Rationale: The correct answer is D because the autonomic nervous system (ANS) is responsible for controlling involuntary functions and contains both parasympathetic and sympathetic nerves. Choices A and B are incorrect as they do not fully capture the role of the ANS. While the ANS does control involuntary functions, this is a broader concept than just the reflex arc. While the ANS does contain motor (efferent) neurons, it also includes sensory (afferent) neurons, which are not specifically mentioned in the question. Therefore, choice C is not fully accurate. Choice D provides the most accurate and comprehensive description of the autonomic nervous system by highlighting its components, the parasympathetic and sympathetic nerves, which work together to regulate various bodily functions.
Which of the following is a representation of a natural pattern or occurrence that is difficult or impossible to experience directly?
- A. A theory
- B. A model
- C. A law
- D. An observation
Correct Answer: B
Rationale: A model is a representation of a natural pattern or occurrence that is difficult or impossible to experience directly. Models are used to simplify complex systems or phenomena to aid in understanding or making predictions about them. The other options (A, C, and D) do not specifically refer to representations of natural patterns or occurrences as models do. A theory is an explanation based on observations, experiments, and reasoning. A law is a statement that describes a consistent natural phenomenon observed to occur without exception. An observation is a direct result of perceiving something using the senses, without being a representation or abstraction of a natural pattern.