Biology 353 Exam 1: Hubert Schwabl Questions and Answers 100% Pass

Biology 353 Exam 1: Hubert Schwabl Questions and Answers 100% Pass In Negative Feedback control systems - The value of the controlled variable fluctuates around a narrow range of set-point value The concept of homeostasis is best defined as - The tendency of organisms to maintain a constant internal milieu Blood glucose concentrations are regulated by the hormones insulin and glucagon. When the blood glucose levels increase after eating a carbohydrate-rich meal, insulin secretion increases and causes blood glucose to decrease towards set point concentrations by stimulating the uptake of glucose into tissues (Such as liver/skeletal muscle). In terminology of control systems which of the following statements is correct? - Glucose concentrations represents the "regulated variable", insulin the "Pathway" to the effector, and the tissues the "effectors'" An example of negative feedback regulation at the cellular level is the rhythmic expression of clock genes in the clock cells. Here transcription and translation of the Per gene into the PER proteins cycles with a rhythm of about 24 hours. Which component of this loop is the controlled variable. - PER protein concentration 2Katelyn Whitman, All Rights Reserved © 2025 Which of the following best represents the distribution of ions in the ECF and ICF of animals? - Na+ High in the ECF, K+High in the ICF, A- (anions) High in the ICF According to Fick's equation the diffusion rate of solutes through a cell membrane increases with - Increased concentration gradient of the solute. Greater Permeability of the membrane for the solute. High lipid solubility of the solute. A mammalian cell membrane composed of 75% phospholipids and 25% proteins is likely to: - Be found in cells that associate themselves with the axons of neurons to "electrically" insulate them from the ECF Based on the Nernst equation the equilibrium potentials across the neuron membranes results in values of +60mv for Na+ AND -90mv for K+. The difference in sign of voltage (positive versus negative) result from: - The opposite concentration gradient for Na+ and K+ (check this one) The principle cause of depolarization of a nerve cell is - An increase in membrane permeability for Na+ Action potential generally originate at a location called axon hillock because - The hillock contains the highest number of voltage-gated K+ Channels. The hillock has the highest number of voltage-gated Na+ channels. The absolute refractory period of a neuron - Is caused by Na+ channels being closed, and no action potential can occur because these channels are inactivated 3Katelyn Whitman, All Rights Reserved © 2025 The phase in an action potential during which a stronger than normally required stimulus can elicit an additional action potential in a neuron is the - Relative refractory period Unidirectional propagation of action potentials along the axon of the neuron towards the synaptic terminal results from - The absolute refractory period Saltatory conduction of action potentials along an axon occurs in - Myelinated axons Autoimmune disease destroys the myelin sheaths of neuron axons in multiple sclerosis. At a cellular level, the most likely effect of the loss of myelin is - Prevention of action potentials jumping between Nodes of Ranvier, thereby slowing the speed of transmission of action potential along the axon