Tutor profile: Amir H.
Thymol blue is added to a reaction designed to determine the pK. of acetylsalicylic acid. Which of the following statements best describes the purpose of thymol blue? A. Serve as a buffer for acetylsalicylic acid. B. Serve as a proton source for acetylsalicylic acid. C. Absorb a proton from acetylsalicylic acid. D. Donate a proton to solution upon reaching a certain pH
Thymol blue is an example of an indicator that functions in an acidic range. An indicator undergoes a color change upon reaching a certain pH, typically by donating or accepting a proton. When a compound is added to a titration reaction, which is usually used to determine the pK. of an acid, it is usually an indicator for the pH of the solution. It does not necessarily serve as a buffer, eliminating choice A. It would al o not necessarily serve as a proton donor or acceptor specifically for the acetylsalicylic acid compound, but rather for many molecules in solution, eliminating choices 8 and C. As an indicator, it could donate a proton or accept a proton from solution to undergo a color change, making choice D more Likely to be the best answer.
Enteric nervous system stimulation is one of the major inputs to GI organs. Which of the following does NOT describe a consequence of stimulating these nerve fibers? A. Enhanced peristaltic action of smooth muscle B. Vasoconstriction of gastrointestinal blood vessels C. Changes in hormone release D. Increased GI tract fluid exchange
After ganglion cells are excited in the retina, their axons gather to form the optic nerve, which leaves the eye to convey visual information to the brain. The optic nerve synapses at the lateral geniculate nucleus (LGN) of the thalamus which preserves the visual map created by the ganglion cells. The LGN does not integrate or process information but serves as an intermediate relay point to the primary visual cortex. The primary visual cortex is located in the occipital lobe and receives input from the LG . It is specialized for the detection of specific aspects of the visual stimulus, including lines and edges of different orientations. This is called feature detection. Damage to the primary visual cortex would prevent the detection of some of these orientation features, making choice B the best answer. The medial geniculate nucleus of the thalamus receives auditory stimuli, not visual stimuli, eliminating choice C. The semicircular canal is part of the vestibular system that is responsible for detecting changes in position and relaying these signals to the body to maintain balance. Jt does not play a role in transmitting visual stimuli, eliminating choice D.
Which of the following most limits the applicability of Bernoulli's equation to modeling aortic blood flow? A. High velocity of blood exiting the heart B. Elasticity of the aorta C. Low viscosity of blood D. Downstream branching of arteries
Choice A points out that blood exiting the heart does so at a high velocity. Fluids moving at high velocities are prone to turbulent flow. Turbulent flow dissipates energy of the system, making it a non-conservative system. This choice fits our prediction and is therefore a strong choice. Choice B proposes that the ability of the aorta to expand and contract cannot be accounted for. Cross-sectional area will be variable throughout a heart beat, but this can be accounted for because Bernoulli's equation incorporates the flow continuity equation A1v1 = A2v2, for which cross-sectional area is a variable. Choice C suggests that low viscosity will disrupt the model, but low viscosity allows for laminar flow, a requirement of Bernoulli's principle. Although downstream branching in Choice D diverts blood to different routes, there is no suggestion that energy or blood are lost in the process.
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