Sore muscles (cramping and fatigue) following anaerobic exercise is usually due to a buildup of _____.

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#Question id: 14738

#Unit 4. Cell Communication and Cell Signaling

Choose correct statements about Muscarinic receptors;

a. An acetylcholine analog, In activated condition, these receptors slow the rate of heart muscle contraction.

b .This type of receptor is coupled to a Gαi protein, and ligand binding leads to the opening of an associated K+ channel.

c .The subsequent influx of K+ ions from the cytosol causes an increase in the magnitude of the usual inside-negative potential across the plasma membrane that lasts for several seconds. 

TLS Online TPP Program

#Question id: 14739

#Unit 4. Cell Communication and Cell Signaling

In heart muscle, activation series of the muscarinic acetylcholine receptor its effector K+ channel via the Gβγ subunit of a Gi protein.

a. Binding of acetylcholine triggers activation of the Gαi subunit and its dissociation from the Gβγ subunit in the usual way. 

b. The released Gβγ subunit (rather than Gαi∙GTP) binds to and opens the associated effector protein, a K+ channel. 

b. The increase in K+ permeability hyperpolarizes the membrane, which reduces the frequency of heart muscle contraction. 

d. Activation is terminated when the GTP bound to Gαi is hydrolyzed (by a GAP enzyme that is an intrinsic part of the Gαi subunit) to GDP and Gαi∙GDP recombines with Gβγ.

TLS Online TPP Program

#Question id: 14740

#Unit 4. Cell Communication and Cell Signaling

Rod cells sense light with the aid of a light-sensitive GPCR known as rhodopsin; choose incorrect statements

a. Rhodopsin consists of the protein opsin, which has the usual seven–transmembrane segment GPCR structure, covalently linked to a light-absorbing pigment called retinal. 

b. Rhodopsin, found only in rod cells, is localized to the thousand or so flattened membrane disks that make up the inner segment of each of these rod-shaped cells.

c. A human rod cell contains about 4 × 10⁷ molecules of rhodopsin. 

d. The heterotrimeric G protein coupled to rhodopsin, called transducin (Gt), contains a Gα unit referred to as Gαt; like rhodopsin, Gαt is found only in rod cells.

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#Question id: 14753

#Unit 6. System Physiology – Plant

German scientist Adolf Fick discovered that the rate of diffusion is directly proportional to the concentration gradient (∆cs /∆x)—that is, to the difference in concentration of substance s (∆cs ) between two points separated by the distance ∆x. According to Fick’s first law,

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#Question id: 14754

#Unit 6. System Physiology – Plant

Plant cells have several internal compartments, each of which can differ in its ionic composition. The cytosol and the vacuole are the most important intracellular compartments that determine the ionic relations of plant cells, Ion concentrations in the cytosol and the vacuole are controlled by passive (dashed arrows) and active (solid arrows) transport processes

  

Which of the following statement INCORRECT from the above figure;

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#Question id: 14755

#Unit 6. System Physiology – Plant

Any active transport mechanism that results in the movement of a net electric charge will tend to move the membrane potential away from the value predicted by the Goldman equation. Such a transport mechanism is called