question 1 which statement is false a according to the fluid

question 1. 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.

question 2. 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.

Solution

1. Option e is false. The carrier molecules has a process for the transport of molecules across the mebrane: Facilitated diffusion. Faciliated difffuison is the process of transport of molecules into and out of the cell without the need of energy.

2. Option e is incorrect. Downregulation of receptors happens when receptors have been chronically exposed to an excessive amount of neurotransmitters, whether endogenous or drugs. This results in ligand-induced desensitization or internalization of that receptor. This causes loss of same receptor.