which of the following cell transport mechanism requires a transport protein, but not energy? A-...

which of the following cell transport mechanism requires a transport protein, but not energy?

A- facilitated diffusion.

B- osmosis

C- active transport.

D- diffusion.

E- secondary active transport.

Solutions

Expert Solution

Answer : (A) facilitated diffusion

Here, diffusion, osmosis and facilitated diffusion are passive. / Facilitated diffusion requires a transport protein.

Active transport and secondary active transport requires energy.

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TRANSPORT MECHANISMS

The transport mechanisms across cell membranes can be divided into passive transprt and active transport.

Passive transport - without expenditure of energy

(i) Diffusion - Transport occurs passively along a concentration gradient. Osmosis is the diffusion of water across a semipermeable membrane according to the concentration gradient of water.

(ii) Facilitated diffusion - Carrier molecules are involved in transport, but there is no energy expenditure.

(iii) Ion channels - Membranes have ion channels for specific molecules, which span the membrane. Here transport occurs along the concentration gradient

Active transport - requires energy

Here transport can occur against the concentration gradient and driven by energy. Specific proteins called transporters are present.

In primary active transport energy is obtained from ATP. Whereas in secondary active transport, electrochemical gradients set up by primary active transport is used for transport of another molecule. So, the transport of a molecule is coupled with another transport which requires energy.

Sydney Mullin answered 9 months ago

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