Which statement is FALSE? a. according to the fluid mosaic model of membrane str
ID: 204299 • Letter: W
Question
Which statement is FALSE?
a. according to the fluid mosaic model of membrane structure, the plasma membrane consists primarily of a bilayer of mobile phospholipid molecule studded with an ever-changing mosaic pattern of proteins.
b. if 2 similar molecules can both combine wwith the same carrierm the presence of one of these molecules may decrease the rate of entry of the other
c. endocytosis can be accomplished by phagocytosis and pinocytosis
d. the sodium-potassium pump indirectly offers the energy source for glucose transport across interstinal cell
e. Carrier molecules alwasy require energy to accomplish transport of substance across the membrane.
2. Assume a hypothetical postsynaptic neuron has three presynaptic inputs: X, Y and Z. Also assume that presynaptic neuron Z is excitatory.
2a) If presynaptic neuron X is stimulated, the postsynaptic cell membrane becomes slightly hyperpolarized. What kind of a synapse is involved between presynaptic neuron X and the postsynaptic neuron?
a) Excitatory synapse.
b) Inhibitory synapse.
c) It could be either an excitatory or an inhibitory synapse.
d) Collateral axoaxonic.
e) Insufficient information is given to know what kind of synapse is involved.
2b: If presynaptic neuron Y is stimulated, the postsynaptic cell membrane becomes slightly depolarized. What kind of synapse is involved between presynaptic neuron Y and postsynaptic neuron?
a) Excitatory synapse.
b) Inhibitory synapse.
c) It could be either an excitatory or an inhibitory synapse.
d) Collateral axoaxonic.
e) Insufficient information is given to know what kind of synapse is involved.
3. choose the statement that is incorrect.
a. hormones are long-range chemical mediators secreted by endocrine glands into the blood, which carries them to distant target organs.
b. Once a steroid hormone binds with its intracellular receptor, the hormone receptor complex binds with a specific hormone response element on DNA, thereby activating a particular gene.
c. the same chemical messenger may be either a hormone or a neurotansmitter, depending on its sourse and mode of delivery to the target issue.
d. steroid hormones are derived from cholesterol
e. with dorn regulation, one hormone induces the loss of another hormone's receptors.
Explanation / Answer
Ans 1. (e) Carrier molecules always require energy to accomplish transport of substances accross the membrane.
Explaination:- every carrier molecule doesnot require energy as there are various types of carrier molecules and which doesnot need enery for eg. some of the carreir molecules undergo the confprmation change and hence help in drawing a molecules across the membranes.
Ans 2. (b) Inhibitory synapse
Explaination:- Hyperpolization inhibits the action potentials.
Ans 3. (e) with down regulation, one hormone induces the loss of another hormones receptors.
Explaination:- because of the down regulation only that particular hormone receptor number is decreased but it does not effect the receptors of other hormones.
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