Tutor profile: Lauren G.
Your lab is asking that you identify an unlabeled substance that has been in storage for a while. You withdraw 10 mL, and note that the substance has been stored at 298 K and the pressure in the room was 1 atm. You also weigh the substance after withdrawing it, and record its weight as 0.05 g. Knowing this information, how can you discern the unknown substance?
To begin, you would use the ideal gas law (PV = nRT), and solve for n, or the number of moles. Make sure to convert the 10 mL into L (0.01 L) before substituting it into the equation so that all units cancel out. After substituting, you get: P = 1 atm V = 0.01 L n = ? R = Ideal gas constant, 0.08205 L atm/mol K T = 298 K (1 atm)(0.01 L) = n(0.08205 L atm/mol K)(298 K) n = 0.00040898 mol Your next step would be to record the mass of the unknown substance. To do so, weigh an empty beaker and record its mass in grams. Then, add the unknown substance into the same beaker and weigh it again, also in grams. Take the difference between these two numbers to get the mass of the substance itself. Now, you know the number of moles in the substance and the weight of it in grams. To determine the identity of the substance, you need to calculate its molar mass and compare that to the periodic table to see which element it most closely resembles. To find molar mass, you need to know how many grams are in 1 mole. You can use the known amount of moles and grams to set up a ratio to find the unknown value, like so: 0.05 grams/0.00040898 mol = ? grams/1 mol ? = 122.25 grams This means the unknown substance is most likely antimony, since its molar mass is 121.7 grams/mol.
What is the central dogma of biology, and in general, how can it be regulated?
The central dogma of biology describes the process of turning our genetic code into proteins. It involves transcribing DNA into RNA, and translating RNA into protein. Regulation can occur prior to both transcription and translation. Transcription is mainly regulated by transcription factors, which are proteins that aid in starting or stopping the initial transcription process. Translation is mainly regulated by RNA splicing, which determines which area of the RNA is attached to ribosomes to become protein.
A patient in your clinic presents with an inability to verbalize their concerns out loud to you. Upon further examination, you notice that they are able to understand and respond to yes or no questions, and can write out fully fledged responses to your questions, but still cannot verbalize their answers. Assuming this is a neurological deficiency, what area of the brain would you hypothesize is affected and why?
There are two primary areas in the brain responsible for language interpretation and speech production - Broca's and Wernicke's area. I would hypothesize that the patient has injured Broca's area. This area is responsible for speech production, and the patient is unable to verbalize their concerns. This means that Wernicke's area, which is responsible for language interpretation, is most likely uninjured, as the patient has demonstrated that they can understand the questions posed to them. Additionally, we know there are not any motor deficiencies, as the patient is able to write down their concerns.
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