BIO 311 Walton Name: Practice exam: Exam 1 Multiple choice section: Gircle the l
ID: 147468 • Letter: B
Question
BIO 311 Walton Name: Practice exam: Exam 1 Multiple choice section: Gircle the letter of the best arswer for each question. (2 pts each) 1. Which type of protein forms an open pore through the membrane only in response to a specific signal? a Intracellular receptor b. Carrier protein c Open channe d. Gated channel 2. All of the following are true of diffusion in the animal body except a Diffusion occurs more slowly at higher temperatures than at lower temperatures b. Smaller molecules diffuse more quickly than larger ones c. Net movement of molecules occurs until the osmolarity is equal d. Diffusion is rapid over short distances and slower over longer distances 3. In a reflex pathway, an integrating center a is the disturbance or change that sets the pathway in motion. b. is an electrical and/or chemical signal that travels to the effector. e evaluates incoming signals and compares it with the setpoint. d. is the minimum stimulus that must be achieved to set the reflex response in motion. 4. Why do some normal cells fail to respond to a chemical signal? a. Chemical signals are only delivered to specific cells b. Some cells lack the necessary receptors e. Some cells are completely without receptors d. Some cells are completely without ligands 5. Why is the resting membrane potential approximately -70 mV for most cells? a Most membranes are 40 times more permeable to K than to No b. Most membranes are 10 times mere permeable to Na" than to K c. The large concentration of proteins in the interstitial space draws Na" out of the cell making it negatively charged. Most cells contain a large concentration of Cl making them negatively charged d. 6. Which type of transport generally requires that the molecule being transported is lipophilic? a. Phagocytosis b. Exocytosis c. Simple diffusion d. Facilitated diffusion e. Primary active transport Assume a resting membrane potential of -70 mV. Which term would be used to describe a change in membrane potential from resting potential to-90 mV? 7. a Depolarization Hyperpolarization c. Repolarization d. Equilibrium potentialExplanation / Answer
Answer 1 Correct option is D i.e. Gated Channels
Reason: Intracellular receptors are not present in membranes, Carrier proteins do not form pores and Open channels are always open.
Answer 2 Correct option is A i.e. Diffusion occurs more slowly at higher temperatures than at lower temperature.
Reason: This is false because diffusion occurs faster at high temperature. All others are true.
Answer 3 Correct option is C i.e. Evaluates incoming signals and compares with set point
Reason: It is the function of of integration centre. It is not a signal but a synapse of neurons
Answer 4 Correct option is B i.e. Some cells lack necessary receptors
Reason: Not all signals are meant for every cell.
Answer 5 Correct option is A i.e. Membranes are 40 times more permeable to K+ than Na+
Reason: Impermeability to Na+ makes membranes more -ve
Answer 6 Correct option is C i.e. Simple Diffusion
Reason: Lipophillic molecules can easily diffuse through lipid bilayer
Answer 7 Correct option is B i.e. Hyperpolarization
Reason: Hyperpolarization is a condition when membrane potential becomes more negative.
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